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How is Your Gym Cleaning?

You hear it at the gym. Be a good Do-bee and wipe down that equipment after use. Not so fast, there might be a slew of unintended consequences and some of them potentially harmful.

How does Covid19 spread? The virus is predominantly an airborne virus. Hence the initial advice on masks and staying six feet away from other individuals. Like other viruses, it can spread via contact if you get the virus on your hands and then touch your eyes. The CDC even notes it is very rare or unlikely someone could get Covid from touching a surface at a gym.

It is difficult to say why athletic facilities went on the disinfectant rampage and asked everyone to wipe down equipment before and after use. I suspect much of the impetus came first from the companies that made commercial disinfectants and wipes. Obviously, if everyone is wiping things off all the time, more product is used. It may be the clubs decided this was a good practice from a variety of perspectives. Maybe making users feel more comfortable so they don’t quit their membership? There were messages of telling people that clubs were taking safety seriously.

What about safety versus results? First, these compounds are generally approved for commercial disinfectant purposes and cleaning, such as hospitals. Make no mistake, when used as directed, they do kill bacteria and viruses. They have rigid guidelines about how they are to be used, how it is supposed to be removed after use, and what kind of protective gear the person is supposed to use for personal protection. If the professional cleaner at your facility is wearing rubber gloves and a facemask, maybe that should be a clue as to toxicity and contact issues of these compounds.

In some instances, the commercial compounds in some cases are being diluted. Down the list compared to contracting Covid is the fact many of these compounds are toxic to fish, wildlife, and the environment. Eventually, they are washed off and they do head down stream.

This is a complex issue, and not everything can be addressed in this short blog. You should perform further research on what your facility is using in this regard and make your own decision. You can use what they provide or go the other direction and use your own protective clothing and not come in direct contact with any of the compounds.

In a review of some of the more popular compounds in this area, it is clear they have hazards. And, just because they have not been proven to be cancer-causing is probably more about the fact they were not ever tested in this application. However, they all have some potential level of irritation posed by touching and handling outside of guidelines. Included in reported warnings are skin, eye and respiratory irritation. And the rush to cleaning was so overwhelming, most people did not ask about safety of what the compounds can do to the human system.

One of the interesting considerations is how long the compound should remain on the surface until removal. Many of them stipulate the compound should dry for 3-5 minutes. How to remove the compound? Many of these suppliers do recommend rinsing with water, then letting dry completely. Right there we have what is quite different than how this is being applied in clubs. I went to three clubs, using some of the compounds referred to in the spec sheets. I watched people wipe or spray it on, and immediately use the machine. Some sprayed it on a paper towel, some right on to the machine. For sake of comparison, I made notes about how many people in the three instances had on any kind of gloves in the resistance training area. It was less than 10%, and the majority were spraying the equipment, and then immediately using without drying or removal, or wearing gloves.

The EPA does have a quick view of both safety and effectiveness with commercial disinfectants. Classification for toxicity is normally a 1-4 rating, with 1 being the highest level and 4 being very low toxicity. Should you be concerned about products in level 4? The answer is likely yes because it may not be administered within the guidelines that resulted in this general rating. Asking everyone to spray down handles or a machine does not mean everyone does that the same way. And, it does not mean each facility is using the minimum potency to get results.

Here are links to three of the common products used and their spec-sheets with some safety and use information.

Virex

Hillyard Re-juv-al

Athletix Wipes

Ethanol is in some cleaning compounds, and it does have serious interaction with humans as well. You should read carefully for the full list of potential irritations with any compound used at your facility (s). And, maybe more important, how the product is supposed to be applied.

It maybe you are best off not coming into direct contact with these compounds, especially given the rapid reduction in Covid statistics. If you are concerned about skin irritation or another other potential side effect, but want to still protect yourself, try the following:

If you are going to clean the equipment

-Ask if your facility will use something less caustic like a simple alcohol or a hydrogen peroxide solution.

-Don’t spray commercial disinfectants in the air and onto the machine, spray a small amount on a towel, then wipe the machine.

-Let anything you spray on dry before use.

-Don’t touch your eyes or face during or just after your visit.

-Avoid contact with your skin during the cleaning process.

If you don’t want to come in contact with these compounds

-Wear complete gloves that cover the hands, like gardening gloves that have a water barrier on the hands.

-Long athletic pants to reduce directly touching seats.

-A long tee shirt for resistance training when you come into contact with the pads and support.

-Hand washing on your way out, and even during your visit is a positive step.

-When you get home, take off the clothes, and wash.

Select References

Allen, L. V., Jr. (2017). Quality Control: (Material) Safety Data Sheets. Int J Pharm Compd, 21(2), 118-124.

Fuls, J. L., Rodgers, N. D., Fischler, G. E., Howard, J. M., Patel, M., Weidner, P. L., & Duran, M. H. (2008). Alternative hand contamination technique to compare the activities of antimicrobial and nonantimicrobial soaps under different test conditions. Appl Environ Microbiol, 74(12), 3739-3744.

Goldhammer, K. A., Dooley, D. P., Ayala, E., Zera, W., & Hill, B. L. (2006). Prospective study of bacterial and viral contamination of exercise equipment. Clin J Sport Med, 16(1), 34-38.

Honda, H., & Iwata, K. (2016). Personal protective equipment and improving compliance among healthcare workers in high-risk settings. Curr Opin Infect Dis, 29(4), 400-406.

Larson, E. L., Quiros, D., & Lin, S. X. (2007). Dissemination of the CDC’s Hand Hygiene Guideline and impact on infection rates. American journal of infection control, 35(10), 666-675.

Nielsen J. The occurrence and course of skin symptoms on the hands among female cleaners. Contact Dermatitis. 1996 Apr;34(4):284-91

Markley, J. D., Edmond, M. B., Major, Y., Bearman, G., & Stevens, M. P. (2012). Are gym surfaces reservoirs for Staphylococcus aureus? A point prevalence survey. American journal of infection control, 40(10), 1008-1009.

Mukherjee, N., Dowd, S. E., Wise, A., Kedia, S., Vohra, V., & Banerjee, P. (2014). Diversity of Bacterial Communities of Fitness Center Surfaces in a U.S. Metropolitan Area. International Journal of Environmental Research and Public Health, 11(12), 12544-12561.

Rutala, W. A., & Weber, D. J. (2016). Monitoring and improving the effectiveness of surface cleaning and disinfection. Am J Infect Control, 44(5 Suppl), e69-76.

Song, X., Vossebein, L., & Zille, A. (2019). Efficacy of disinfectant-impregnated wipes used for surface disinfection in hospitals: a review. Antimicrobial resistance and infection control, 8, 139-139.

West, A. M., Nkemngong, C. A., Voorn, M. G., Wu, T., Li, X., Teska, P. J., & Oliver, H. F. (2018). Surface area wiped, product type, and target strain impact bactericidal efficacy of ready-to-use disinfectant Towelettes. Antimicrob Resist Infect Control, 7, 122.

Wiemken, T. L., Powell, W., Carrico, R. M., Mattingly, W. A., Kelley, R. R., Furmanek, S. P., Johnson, D., & Ramirez, J. A. (2016). Disinfectant sprays versus wipes: Applications in behavioral health. American journal of infection control, 44(12), 1698-1699.

Environmental Protection Agency, “List N: Disinfectants for Coronavirus (COVID-19),” [Online]. Available: https://www.epa.gov/pesticide-registration/list-n-disinfectants-coronavirus-covid-19.

Mirabelli MC, Vizcaya D, Martí Margarit A, Antó JM, Arjona L, Barreiro E, Orriols R, Gimenez-Arnau A, Zock JP. (2012) Occupational risk factors for hand dermatitis among professional cleaners in Spain. Contact Dermatitis. 66(4):188-96.

Tse TJ, Purdy SK, Shen J, Nelson FB, Mustafa R, Wiens DJ, Reaney MJT. (2021) Toxicology of alcohol-based hand rubs formulated with technical-grade ethanol. Toxicol Rep. 2;8:785-792.

National Research Council (US) Safe Drinking Water Committee. Drinking Water and Health: Volume 2. Washington (DC): National Academies Press (US); (1980). III, The Chemistry of Disinfectants in Water: Reactions and Products.

Cosmetic Ingredient Review Expert Panel. Final report of the safety assessment of Alcohol Denat., including SD Alcohol 3-A, SD Alcohol 30, SD Alcohol 39, SD Alcohol 39-B, SD Alcohol 39-C, SD Alcohol 40, SD Alcohol 40-B, and SD Alcohol 40-C, and the denaturants, Quassin, Brucine Sulfate/Brucine, and Denatonium Benzoate. Int J Toxicol. 2008;27 Suppl 1:1-43

A. Chang, A. H. Schnall, R. Law, A. C. Bronstein, J. M. Marraffa, H. A. Spiller, H. L. Hays, A. R. Fun, M. Mercurio-Zappala, D. P. Calello, A. Aleguas, D. J. Borys, T. Boehmer and E. Svendsen. (2020) Cleaning and Disinfectant Chemical Exposures and Temporal Associations with COVID-19 — National Poison Data System, United States, January 1, 2020–March 31, 2020. Morbidity and Mortality Weekly Report (MMWR), vol. 69, no. 16, pp. 496-498,.

Wolkoff P, Schneider T, Kildesø J, Degerth R, Jaroszewski M, Schunk H. (1998) Risk in cleaning: chemical and physical exposure. Sci Total Environ. Apr 23;215(1):135–56.

Sherriff A, Farrow A, Golding J, Henderson J. (2005) Frequent use of chemical household products is associated with persistent wheezing in pre-school age children. Thorax. 1;60(1):45.

Weinmann T, Gerlich J, Heinrich S, Nowak D, Mutius E von, Vogelberg C, et al (2017). Association of household cleaning agents and disinfectants with asthma in young German adults. Occup Environ Med. 1;74(9):684.

Parks, J., McCandless, L., Dharma, C., Brook, J., Turvey, SE., Mandhane, P., Becker, AB., Kozyrskyj, AL., Azad, MB., Moraes, TJ., Lefevbre, DL., Sears, MR., Subbarao, P., Scott, J., Takaro, TK. (2020). Association of use of cleaning products with respiratory health in a Canadian birth cohort. Canadian Medical Association Journal. 192(7); E154-161

Zock J-P, Plana E, Jarvis D, Antó JM, Kromhout H, Kennedy SM, et al. (2007) The use of household cleaning sprays and adult asthma: an international longitudinal study. Am J Respir Crit Care Med. 176(8):735–41.

Flyvholm MA. (1993) Contact allergens in registered cleaning agents for industrial and household use. Occupational and Environmental Medicine 50:1043-1050.

Archangelidi O, Sathiyajit S, Consonni D, et al. (2021) Cleaning products and respiratory health outcomes in occupational cleaners: a systematic review and meta-analysis. Occupational and Environmental Medicine. 78:604-617.

Hamstring Strength: A key to leg FUNCTION

Neil E. Wolkodoff, PhD, Medical Program Director

After the age of 30, strength declines in the legs more than any other area in the human body. With that decline in power comes a loss of muscle mass, which negatively affects metabolism and a host of other health and performance factors.

Less muscle at rest, less idle in metabolic terms or calories when not exercising. Less muscle in exercise means that there will be fewer calories burned in exercise (smaller engine), and that means less health and fitness benefits. With less strength in the legs, the ligaments that help hold joints together lose some support, and injury rates rise.

So, whether it is golf, skiing, or flag football, the potential of knee sprains and ruptures of the cruciate ligaments in the back of the knee go up with age. Besides ranking high on the not-fun-scale, ACL tears and subsequent reconstruction will take months to heal, ruining summer and winter recreational activities. Additionally, if your hamstrings are chronically weak, it is likely a rigorous stretching program is in your pain relief future. And with limited effectiveness.

Entering the 30s, it is harder to maintain muscle mass, let alone develop more. Most people are deficient in hamstring strength, which involves the three muscle groups of the semimembranosus, semitendinosus, and biceps femoris in the back of the upper leg. As one passes that age milestone, these leg muscles have even more of a deficit to overcome, which is a more difficult task. This post is a primer on important hamstring strength concepts, not the complete reference.

The hamstrings provide knee stability with their tendons and the cruciate ligaments. They are primarily responsible for flexing the knee, and interconnecting with the hip and back muscles in coordinated, whole-body movements that use knee and hip extension, like a squat. They also help rotate the hips in activities like the golf swing and function in holding an athletic posture and maintaining balance.

So just how strong should the hamstrings be to help with function and contribute to fewer knee injuries? While a subject of quite a bit of research, the starting point of a ratio of hamstring to quadriceps (front of the thigh) strength of 55% is a good target minimum. This was first discovered by the San Diego Chargers FB team in its’ relationship to hamstring pulls in running. In simple terms, their data showed if you could perform 100 pounds in a leg extension, the corresponding leg curl should be 66 pounds of weight/resistance. That is with young, professional athletes, so a bit less is reasonable as noted at 55%.

While this does not sound important, some research and experience evidence show overbuilding the quadriceps at the expense of the hamstrings can simply point to the back of the knee as the weak structural link. Some of this conjecture came from observations of strength ratios and injuries with skiers on the World Cup. After a point, too much quad strength without the hamstrings keeping up increases injury risk in this area when combined with the limitation of ski bindings in releasing in certain, backward and twisting movements. Other factors in ACL injuries include knee stability, bone angles, jumping/landing patterns and even foot structure. However, here the key concept is how to improve that hamstring:quad ratio as step one.

Remember, if the injury is violent enough or the knee is in a weak position, no amount of conditioning will totally protect you from an injury. A skiing fall at even 17 m.p.h/27 k.p.h., if done backwards and twisting, can put enough stress on the rear of the knee to rupture the ligaments. And sometimes it is just a twisting movement getting out of a car or on ice and snow.

First, if you can get tested, isokinetic testing will give you a baseline of your muscular endurance to power ratios compared to optimal. Here the machine is set to move at a maximum speed, and it can measure how much force you can produce at that speed. Like other things in the physiological realm, good isokinetic equipment is key. More important is someone who has performed numerous leg-strength tests and can understand the data relevant to your situation.

If that is not available, you can do some estimates by performing seated leg extensions compared to seated leg curls. Pick a weight/resistance you must stop at for 10-12 repetitions. Compare the weight used. When you perform that ratio of 55:100, you are probably ahead of most people. 60:100 is better, and 70:100 puts an “S” on your chest. This ratio holds if you can perform reasonable weight with your quadriceps. After age 49, 50% of your body weight is a good target point for your quads in a leg extension if you have no orthopedic issues. Easy to calculate by taking what you can lift for 10 repetitions, then multiplying by 1.33 to get your 1 RM, or repetition maximum.

Building strength in the hamstrings involves simple concepts but various training equipment/methods. In short, your training should have some movements that isolate the muscle group paired with exercises that integrate the hamstrings into full-body flexion and extension movements. In addition, the hamstrings do best with multiple sets of 12-15 repetitions as they are more oriented towards endurance than the quadriceps.

Simple to apply, perform isolation exercises like seated or prone leg curls on one day. Two days later, switch the focus to multi-joint movements. Dumbbell dead lifts, hip extension + flexion movements on a fit ball, glute-hamstring raises (if your center has one of these devices), Nautilus Glute Drive, a VALD, and multi-hip extensions with a kickback. These are examples of multi-joint exercises that improve functional integration and whole-body movements. Be prepared. Most athletic centers aren’t oriented in this way, so you will have to piece together these integrative exercises based upon availability. Part of the rationale for multi-joint, various exercises is to increase body awareness. Very important in skiing so if you are in the “backseat” position, you can stop and recover before the ACL is in a position where rupture is more likely.

One final consideration, doesn’t activity like walking or cycling build leg strength? The answer is a definite no from the research. If you did absolutely nothing, you might gain a tiny bit of strength from walking. However, if you are moderately active, simply adding more moderate activity, which is aerobic in nature, has virtually no effect on strength.

There has to be significant overload to build strength and structural support in the legs, especially the hamstrings. And that simply means the weight room.

Select References

Ettlinger CF, Johnson RJ, Shealy JE. A method to help reduce the risk of serious knee sprains incurred in alpine skiing. Am J Sports Med. 1995;23(5):531-537.

Borde R, Hortobágyi T, Granacher U. Dose-Response Relationships of Resistance Training in Healthy Old Adults: A Systematic Review and Meta-Analysis. Sports Med. 2015;45(12):1693-1720.

Johnson SC. Anterior cruciate ligament injury in elite Alpine competitors. Med Sci Sports Exerc. 1995;27(3):323-327.

Pieters D, Witvrouw E, Wezenbeek E, Schuermans J. Value of isokinetic strength testing for hamstring injury risk assessment: Should the ‘strongest’ mates stay ashore? [published online ahead of print, 2020 Dec 6]. Eur J Sport Sci. 2020;1-12.

Chen N, He X, Feng Y, Ainsworth BE, Liu Y. Effects of resistance training in healthy older people with sarcopenia: a systematic review and meta-analysis of randomized controlled trials. Eur Rev Aging Phys Act. 2021;18(1):23.

Fyfe JJ, Hamilton DL, Daly RM. Minimal-Dose Resistance Training for Improving Muscle Mass, Strength, and Function: A Narrative Review of Current Evidence and Practical Considerations [published online ahead of print, 2021 Nov 25]. Sports Med. 2021;10.1007/s40279-021-01605-8.

Lee JWY, Mok KM, Chan HCK, Yung PSH, Chan KM. Eccentric hamstring strength deficit and poor hamstring-to-quadriceps ratio are risk factors for hamstring strain injury in football: A prospective study of 146 professional players. J Sci Med Sport. 2018;21(8):789-793.

Koller A, Fuchs B, Leichtfried V, Schobersberger W. Decrease in eccentric quadriceps and hamstring strength in recreational alpine skiers after prolonged skiing. BMJ Open Sport Exerc Med. 2015;1(1):bmjsem-2015-000028.

Kim S, Endres NK, Johnson RJ, Ettlinger CF, Shealy JE. Snowboarding injuries: trends over time and comparisons with alpine skiing injuries. Am J Sports Med. 2012;40(4):770-776.

Bechler JR, Jobe FW, Pink M, Perry J, Ruwe PA. Electromyographic analysis of the hip and knee during the golf swing. Clin J Sport Med. 1995;5(3):162-166.

Šarabon N, Kozinc Ž, Perman M. Establishing Reference Values for Isometric Knee Extension and Flexion Strength. Front Physiol. 2021;12:767941.

Färber S, Heinrich D, Werner I, Federolf P. Is it possible to voluntarily increase hamstring muscle activation during landing from a snow jump in alpine skiing? – a pilot study. J Sports Sci. 2019;37(2):180-187.

Ireland A, Mittag U, Degens H, et al. Age-Related Declines in Lower Limb Muscle Function are Similar in Power and Endurance Athletes of Both Sexes: A Longitudinal Study of Master Athletes [published online ahead of print, 2021 Sep 9]. Calcif Tissue Int. 2021;10.1007/s00223-021-00907-3.

Abdalla PP, Dos Santos Carvalho A, Dos Santos AP, et al. Cut-off points of knee extension strength allometrically adjusted to identify sarcopenia risk in older adults: A cross-sectional study. Arch Gerontol Geriatr. 2020;89:104100.

Wiegmann S, Felsenberg D, Armbrecht G, Dietzel R. Longitudinal changes in muscle power compared to muscle strength and mass. J Musculoskelet Neuronal Interact. 2021;21(1):13-25.

VO2 Gets You to The Max!

By Neil E. Wolkodoff, PhD

The explosion of smartwatches has resulted in an awareness of VO2 levels (volume of oxygen used) are important. Most people probably think that measuring endurance abilities is something for pro athletes. The opposite is true – it is more vital for recreational exercisers in terms of fitness and health.

A typical Hans-Rudolph face mask used in gas exchange testing for VO2 with Cosmed System

Pro athletes already have excellent fitness levels and use VO2 testing to tweak parts of their program. According to the research, the better your VO2 or endurance, the likelihood that you will live longer and live better increases. Important because recent data indicate that in terms of these levels, only 23% of Americans who exercise get to a level where their endurance profile helps reduce their risk of disease. The chances are 3:1 that any person is not performing endurance exercise to an adequate level. A higher endurance score is a longer, better life, including elevating good cholesterol and oxygenating the brain.

Enter the VO2 test, the best scientific method to measure endurance. It measures the VO2 or volume of oxygen used per minute, customarily expressed as milliliters of oxygen per minute per kilogram (2.2 pounds) of body weight (example: 34 ml/kg/min-1). It is always expressed as a function of weight, so people with varying weights can be compared because there is no advantage to being larger or smaller.

Portable VO2 systems like the Oxycon Mobile can be used on any exercise machine

In this test, administered by a trained physiologist or physician, the exerciser is fitted with a special mask and sensor that measures oxygen (O2) consumption, breathing rate, heart rate, and how much carbon dioxide (CO2) is expelled as the primary data points. Either a bike or treadmill is the most common form of VO2 testing.

Submaximal testing (which rarely uses actual or complete measurement equipment), stops well short of maximum effort. It attempts to extrapolate or project from information gained to that point to a VO2 max number. Two problems here – the research is detailed over 30 years that the projections are highly inaccurate for various reasons. Mainly because stopping at the burn point, commonly termed Anaerobic Threshold (AT), can be anywhere from 40-93% of your peak speed. Knowing that number and relationship first establishes exercise that is distance in nature from sprint exercise. That in turn can result in personal training zones by heart rate or other metrics.

The portable metabolic systems allows measurement without movement restriction

Another issue is that the test asks people to rate perception of effort or exercise feelings to determine testing points where they have little experience. For a marathon runner, the test can be a fraction closer. Submaximal tests can be as simple as ride the bike, type in age, enter finished at the requested point, and the little equation kicks out a projected VO2 number. Sorry, but it is not better than nothing because it is irrelevant and inaccurate. In less common cases, the exerciser can be tethered to a metabolic system. The technician can see when they approach this anaerobic point, stop the test and project a number. This gets closer to knowing the burn point yet remember its’ relationship to max varies by up to 53%.

Cart-based systems like the Vyntus, offer the ability to test on either a bike or treadmill

Another common VO2 projection is made via smartwatches. First, they take some limited studies on VO2 and different activities and compare that specific activity. Human energy use is only about 25% efficient. Take a known activity and efficiency ratio, and the watch tries to predict a VO2 score. Once again, no absolute max, and the input equations have proven less than scientific. Sometimes they use heart rate versus activity and assume a lower heart rate means a higher potential VO2 max. It is not uncommon for people at max to be 15% above or 15% below their age-predicted maximum heart rate.

Furthermore, the tracker assumes that everyone’s max HR is 220-age for calculation purposes. In short, fitness trackers do a reasonable job of tracking heart rate during exercise. However, when it comes to actual calories and VO2, they are not accurate.

A real VO2 max test, to maximal effort, with the correct measurement gear, and professional administration, is the only way to know all the applicable information for fitness and health needs.

Cart-based systems allow the physiologist to adjust testing loads immediately as well as perform an in-test explanation

First, max is defined by how much CO2 is expelled compared to O2 consumed. For max, the ratio where CO2 export is at least 10% higher than O2 into the system is defined as a maximal test. This can only be done with gas exchange testing. Asking a person if they are at max is not sufficient in the least. This takes a testing system of a certain level of sophistication and measurement, generally costing at least $33K or more.

Additionally, the tester should be a trained physiologist or physician who has more than book knowledge of how to do a test. In terms of experience, performing at least 500 tests is probably sufficient to see all the variables and situations encountered in the test. The test should only last 9-17 minutes if done correctly. And, the tester should have full insurance, safety procedures, and be trained on a nearby de-fibulator.

The newer masks allow any form of mouth and nasal breathing specific to subject preferences

The application points from an actual maximal profile and from a trained physiologist are what sets this apart from any sub-maximal assessment, even if they were accurate, and they are not. First, one needs to have a number to determine if cardio efforts are paying off in terms of warding off disease and improving fitness. Another key derivative is that a trained tester with the right gear can generate training zones specific to personal physiology. Cardio training is most effective if performed right below AT. Aging changes circulatory and respiratory responses to exercise, another reason that a high level of tester training is needed to administer and interpret the test data for optimal application.

The Wasserman Nine is a common display option on the medical-grade systems enabling the physiologist to cross-match data for precise interpretation

Many people perform resistance training twice per week and ride the bike another three days per week. The VO2 profile will also determine the exact mix of interval training (HIIT is a common term for intervals) versus cardio or endurance training that is best for one’s situation from the profile numbers. Another set of information not available from a sub-max assessment using a projected max or limited data equipment. The data points from the sophisticated measurement metrics in a complete gas exchange test are crucial. The best ratio between cardio and HIIT will result in performance in the weight room increasing.

Is max testing worth the time? If you want to live longer, better, or just increase your performance, this might be the best fitness testing measurement you can perform!

Select References

Albouaini K, Egred M, Alahmar A, Wright DJ. Cardiopulmonary exercise testing and its application. Heart. 2007;93(10):1285-1292.

Bennett H, Davison K, Parfitt G, Eston R. Validity of a perceptually-regulated step test protocol for assessing cardiorespiratory fitness in healthy adults. Eur J Appl Physiol. 2016;116(11-12):2337-2344.

Coquart JB, Garcin M, Parfitt G, Tourny-Chollet C, Eston RG. Prediction of maximal or peak oxygen uptake from ratings of perceived exertion. Sports Med. 2014;44(5):563-578.

Egger F, Blumenauer D, Fischer P, et al. Effects of face masks on performance and cardiorespiratory response in well-trained athletes. Clin Res Cardiol. 2021;1-8.

Ganse B, Degens H. Current Insights in the Age-related Decline in Sports Performance of the Older Athlete. Int J Sports Med. 2021;42(10):879-888.

Hollar DW. Biomarkers of chondriome topology and function: implications for the extension of healthy aging. Biogerontology. 2017;18(2):201-215.

Lenti M, De Vito G, Scotto di Palumbo A, Sbriccoli P, Quattrini FM, Sacchetti M. Effects of aging and training status on ventilatory response during incremental cycling exercise. J Strength Cond Res. 2011;25(5):1326-1332.

MacIntosh BR, MacDougall KB, Falconer TM, Holash RJ. In support of the continued use of the term anaerobic threshold. J Physiol. 2021;599(5):1709-1710.

Mann T, Lamberts RP, Lambert MI. Methods of prescribing relative exercise intensity: physiological and practical considerations. Sports Med. 2013;43(7):613-625.

Matabuena M, Vidal JC, Hayes PR, Huelin Trillo F. A 6-minute sub-maximal run test to predict VO2 max. J Sports Sci. 2018;36(22):2531-2536.

Mezzani A. Cardiopulmonary Exercise Testing: Basics of Methodology and Measurements. Ann Am Thorac Soc. 2017;14(Supplement_1):S3-S11.

Murray AJ. Taking a HIT for the heart: why training intensity matters. J Appl Physiol (1985). 2011;111(5):1229-1230.

Neuberg GW, Friedman SH, Weiss MB, Herman MV. Cardiopulmonary exercise testing. The clinical value of gas exchange data. Arch Intern Med. 1988;148(10):2221-2226.

Poole DC, Rossiter HB, Brooks GA, Gladden LB. The anaerobic threshold: 50+ years of controversy. J Physiol. 2021;599(3):737-767.

Roldán A, Monteagudo P, Cordellat A, Sanchis-Soler G, Blasco-Lafarga C. Inspiratory Muscle Strength and Cardiorespiratory Fitness Association With Health-Related Quality of Life in Healthy Older Adults. Front Sports Act Living. 2021;3:624947.

Shcherbina A, Mattsson CM, Waggott D, Salisbury H, Christle JW, Hastie T, Wheeler MT, Ashley EA. Accuracy in Wrist-Worn, Sensor-Based Measurements of Heart Rate and Energy Expenditure in a Diverse Cohort. Journal of Personalized Medicine. 2017; 7(2):3.

Strasser B, Burtscher M. Survival of the fittest: VO2max, a key predictor of longevity?. Front Biosci (Landmark Ed). 2018;23:1505-1516.

Interval Training/HIIT

Interval training has received lots of attention in the media, but does it really provide superior fitness benefits? The answer is yes but mostly no. This is also termed High Intensity Interval Training. In terms of pure physiology, not so much of a new concept as a marketing phrase designed to increase appeal to sell programming/classes or equipment.

Interval training is simply alternating some increased intensity activity with some type of recovery, or l0wer level activity. For example, in walking you could walk up a steep hill for one minute, then casually stroll down the hill for one minute, then repeat. By broad definition, anything where there is a higher intensity/difficulty/speed period that is balanced by a lower level of the same 0r complete rest fits the definition. That is half the issue in comparing interval training results, there are quite a few variations all with different physiological nuances and uses.

Historically, interval training had a boost when fitness activities increased in the 70’s and 80’s. It was easy for athletic facilities to take a row of machines, and put some type of recovery or moderate activity between each weight station. That was generally a trampoline, running in place or a stationary bicycle. The weight training was theoretically the high intensity activity (or some type of body-weight movement), while the aerobic activity was supposed to either keep your heart rate up or provide recovery. That was really the start of promising better fitness results in less time.

This also became known as circuit training, and almost all athletic clubs/facilities have some kind of circuit in their training area. Strength circuits of this nature have come and gone and are back again in popularity and usage. Group cycling provided the largest organized push with interval training. At first, not by design, but by promising a difficult workout with motivational music. One must remember when you are in the fishbowl of group cycling, you can’t leave the class very easily without the whole group noticing your departure. In the last 10 years, group cycling has really jumped on the interval tandem.

At the same time, CrossFit gained popularity due to the same promises of an overall, muscle and energy system workout. Covid also resulted in people getting apps and videos at home to take light weights and body weight exercises and alternate them in some format. A myriad of converging messages that you should do interval training.

Like most things in human physiology, there has been a significant amount of research about fitness benefits of these various forms of interval training. One of the most studied aspects of these programs is the promise of increased strength in less time that traditional resistance training. Down to the muscular gritty, a muscle needs significant work, then adequate recovery. A research-based generalization would be to gain strength, one needs to lift a weight or resistance they can only perform 10-12 times, then rest for 60-75 seconds and perform additional sets.

In circuit programs, the weight is greatly reduced based upon a time to work the muscle, like 45 seconds, with a short period between exercises of sometimes only 20 seconds. The research is really clear on this one, you gain a little bit of strength, but much, much lower compared to traditional resistance training. The reason is not enough resistance and not enough recovery. Additionally, the aerobic recovery compromises the muscle’s ultimate strength gain.

An off-shoot conclusion from these studies was that a circuit approach was useful in someone starting a fitness program. However, the results from combining both resistance and aerobic work capped at about three weeks. After that, people were better off with separate training sessions of strength or aerobic training if they wanted to get beyond a basic fitness increase.

Does your metabolism increase from Interval Training? A lot of the hype has been that Exercise Post Oxygen Consumption or EPOC, the rise in metabolism to replenish lost energy stays elevated for hours. The initial research started in the 90’s and the measurement equipment was not as good as current technology, and interval training and results were not near as defined. The results were limited in application. However, as a general observation, the EPOC idea lost a large amount of caloric justification because the measurements did not prove current lore and promises.

In most studies, resting metabolism was only slightly elevated after exercise, and that was for a short period of 15-30 minutes. Also important to consider is that the athletes will be at the shorter end of that time scale, while those with less than moderate levels of fitness will be closer to the 30 minute mark. However, it’s definitely not hours, and not 100’s of calories. And more importantly, it does not add significantly to the actual energy burned in the exercise itself. That is the most important consideration in this regard.

In testing thousands of athletes, I can tell you from personal experience and the data, that after a VO2 max test, most of the athletes were fully recovered in five minutes. Joe and Jill Exerciser were normally recovered in in 10 minutes. And, the caveat to to this finding is that with moderate or greater fitness levels, recovery from maximal exercise is much quicker in this sense. Out of shape, and it’s 30 minutes in the recliner no matter what you do in exercise.

Does HIIT burn significantly more kcal than cardio training? In our short research study, we confirmed that interval training and cardio training came out almost equal in how many kcal you burn per hour. We used an Oxycon Mobile measurement system to measure actual kcal burned to determine if interval training burned more energy that aerobic/”cardio” training. It’s a matter that the intervals balance with the recoveries in terms of energy expenditure.

The real benefit of interval training is not the kcal you actually burn, but that you increase your ability to burn more kcal in steady state training. In technical terms, you elevate your Anaerobic Threshold. So, when you hop on that elliptical you can burn 10 kcal a minute versus 7 kcal a minute. Over 50 minutes, that really adds up in terms of weight loss, fitness benefit and even overall health.

So, use interval training once or twice per week, and spend the balance of time in steady-state/”cardio” training and that will likely provide an optimal fitness benefit.

Select References

LaForgia J, Withers RT, Gore CJ. Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. J Sports Sci. 2006;24(12):1247-1264.

Quinn TJ, Vroman NB, Kertzer R. Postexercise oxygen consumption in trained females: effect of exercise duration. Med Sci Sports Exerc. 1994;26(7):908-913.

Børsheim E, Bahr R. Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Med. 2003;33(14):1037-1060.

Tsirigkakis S, Mastorakos G, Koutedakis Y, et al. Effects of Two Workload-Matched High-Intensity Interval Training Protocols on Regional Body Composition and Fat Oxidation in Obese Men. Nutrients. 2021;13(4):1096.

Schmidt D, Anderson K, Graff M, Strutz V. The effect of high-intensity circuit training on physical fitness. J Sports Med Phys Fitness. 2016;56(5):534-540.

Weston M, Taylor KL, Batterham AM, Hopkins WG. Effects of low-volume high-intensity interval training (HIT) on fitness in adults: a meta-analysis of controlled and non-controlled trials. Sports Med. 2014;44(7):1005-1017.

Short KR, Sedlock DA. Excess postexercise oxygen consumption and recovery rate in trained and untrained subjects. J Appl Physiol (1985). 1997;83(1):153-159.

Schaun GZ, Pinto SS, Praia ABC, Alberton CL. Energy expenditure and EPOC between water-based high-intensity interval training and moderate-intensity continuous training sessions in healthy women. J Sports Sci. 2018;36(18):2053-2060.

Martínez-Rodríguez A, Rubio-Arias JÁ. Effects of Resistance Circuit-Based Training on Body Composition, Strength and Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis. Biology (Basel). 2021;10(5):377. Published 2021 Apr 28.

Hortobágyi T, Katch FI, Lachance PF. Effects of simultaneous training for strength and endurance on upper and lower body strength and running performance. J Sports Med Phys Fitness. 1991;31(1):20-30.

Häkkinen K, Alen M, Kraemer WJ, et al. Neuromuscular adaptations during concurrent strength and endurance training versus strength training. Eur J Appl Physiol. 2003;89(1):42-52.

Performance Hype or Real Results?

Very rarely in discussing how to improve performance in a sport, do people talk about the applicability of those things younger athletes do in applicability to those over 50.

Take golfer Bryson DeChambeau.

He went on a different conditioning program, gained a fair amount of muscle and is now averaging drives of 322 yards on tour. He now weighs 235 pounds. Let’s look at power as a calculation of body weight/muscular mass versus distance in golf. That is a good way to determine if these things are revolutionary.

Justin Thomas weighs 160 pounds, and his drives are 302 yards. If we look at the ratio of yards per pound of weight, Thomas has a power ratio of 1.88 yards per pound of body weight. Another example is Rory McIlroy. He also checks in at 160 pounds, and his average drives are 318 yards. His power ratio is 1.98 yards per pound of body weight.

Yes, a few more yards might able a golfer to hit over certain obstacles and get closer to the hole. This could enhance the chances of the second or third shot being more productive in terms of scoring.

DeChambeau drives the ball an average 322 yards and weighs 235 pounds. His ratio is 1.37 yards per pound of body weight. Quite a bit less than the other two golfers described. What’s the conclusion?

First, golf performance and power have a mechanical swing connection. It is not all about gaining muscle mass. Up to a point muscle mass helps, however power is defined as how much force the muscles and sets of joints can move quickly through a resistance. Power = Speed through a resistance/distance. And, in physiology numerous studies have shown that more muscle mass is not always more powerful in application.

Another consideration is the more the sport movement is outside the parameters of sound technique, the more the athlete needs to train just to keep up with those athletes with what is considered optimal technique. Since DeChambeau is a very different in playing with single length irons versus progressive lengths, maybe the conditioning is needed just to bring mechanics and performance to a reasonable level to overcome the issues with single length clubs.

Athletes tend to get stuck in physical training ruts. That is an important consideration in golf performance because training adds a dimension of coordination or neurological activation. This is often seen when an athlete changes their training style and regime, and performance increases for a while. Then it decreases not because the training program is not effective, but for the simple reason that coordination and body awareness benefits decrease.

Periodization, or the science of how to change training variables and cycles for optimal improvement originally started with Olympic Weightlifting. The concepts then spread to strength/power sports such as football. In the last 10 years, sport scientists have begun the quantification process of how best to apply these concepts to other sports where there is a strong coordination component. In the realm of golf, most trainers and physical therapists don’t possess the understanding and application of how training interacts with the coordination dimension. In short, the professional golfer hits so many golf balls they almost get “numb” to how the body moves, and how they can feel parts of the swing. The new training program might not be different in terms of the muscles yet might positively impact coordination and body awareness.

This dimension is critical, but almost never applied, and can be seen in how a player has great performances for a short period of time, say two or three months. Then performance wanes, not because of lack of effort or desire. Simply described, they don’t have the same body awareness they did when they started the new training program.

Is there a simple answer without hiring a $600 per hour “training guru”? First, being consistent with physical training as a base every week is important for golfers over 50. With a broad conceptual brush, two resistance sessions per week, three energy system session. Needed core training and flexibility addressed as separate sessions based upon individual needs.

In resistance training, it is important to give the system some training variation. For some people, just reversing the exercise order will heighten body awareness and effects. Some days, just perform the exercise with a lighter load and more repetitions. The reverse is true as well, some days up the load and perform more repetitions. Especially important to keep access to the fast twitch or power muscle fibers. Altering speed and stance helps with coordination as well. In the end, it is a function of what you have in terms of equipment access, knowledge of how to safely perform the exercise (s) and the overall training progression. In the world of performance enhancement, important to have a guru and not a gnu in this sense!

No, you should not do what tour players do! First, when you are 25 everything works, and you make a very quick training adaptation. Over 50, that training adaptation crawls to a halt and takes almost 40% longer. In the case of building muscle, somewhat easy to do under 30 and incredibly difficult to do over the age of 50. What DeChambeau did is not helpful over 50, and highly unlikely you can achieve this no matter the effort level.

Possibly the key consideration over 50 is recovery. It simply takes almost 40% more time to recover from any kind of moderate exercise or greater. That means walking a hilly course the first time when you haven’t in a while will be debilitating for a couple of days. You are best having at least one day off from exercise per week and then one light day of just core training and flexibility.

Consistency first, variability second and recovery third will make your physical training for golf have maximum benefits if you are over 50.

Select References

van der Kruk E, van der Helm FCT, Veeger HEJ, Schwab AL. Power in sports: A literature review on the application, assumptions, and terminology of mechanical power in sport research. J Biomech. 2018;79:1-14.

Taborri J, Keogh J, Kos A, et al. Sport Biomechanics Applications Using Inertial, Force, and EMG Sensors: A Literature Overview. Appl Bionics Biomech. 2020;2020:2041549.

Khuyagbaatar B, Purevsuren T, Kim YH. Kinematic determinants of performance parameters during golf swing. Proc Inst Mech Eng H. 2019;233(5):554-561.

Mun F, Suh SW, Park HJ, Choi A. Kinematic relationship between rotation of lumbar spine and hip joints during golf swing in professional golfers. Biomed Eng Online. 2015;14:41.

Kawamori N, Haff GG. The optimal training load for the development of muscular power. J Strength Cond Res. 2004;18(3):675-684

Cronin JB, McNair PJ, Marshall RN. Is velocity-specific strength training important in improving functional performance?. J Sports Med Phys Fitness. 2002;42(3):267-273.

Kraemer WJ, Duncan ND, Volek JS. Resistance training and elite athletes: adaptations and program considerations. J Orthop Sports Phys Ther. 1998;28(2):110-119.

Otte FW, Millar SK, Klatt S. Skill Training Periodization in “Specialist” Sports Coaching-An Introduction of the “PoST” Framework for Skill Development. Front Sports Act Living. 2019;1:61.

Williams TD, Tolusso DV, Fedewa MV, Esco MR. Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis. Sports Med. 2017;47(10):2083-2100.

Evans JW. Periodized Resistance Training for Enhancing Skeletal Muscle Hypertrophy and Strength: A Mini-Review. Front Physiol. 2019;10:13.

Mujika I, Halson S, Burke LM, Balagué G, Farrow D. An Integrated, Multifactorial Approach to Periodization for Optimal Performance in Individual and Team Sports. Int J Sports Physiol Perform. 2018;13(5):538-561.

Hartmann H, Wirth K, Keiner M, Mickel C, Sander A, Szilvas E. Short-term Periodization Models: Effects on Strength and Speed-strength Performance. Sports Med. 2015;45(10):1373-1386.

Relationships During Covid and Beyond

By Neil Wolkodoff, PhD

Despite the daily tally of infections and deaths, the actual toll for everyone over 50 may be depression, loneliness, and a toll on mental well being. It was really pretty instant, switching from a regular schedule of in-person contact plus some phone and email to almost no personal connection and every contact being in some electronic form. Add to the issues the direct and indirect warnings to older adults at risk from Covid. The result of all this is in-person social relationships essentially ground to a halt.

Interestingly enough, researchers have already studied this during the pandemic. Some of the results may surprise, some may seem logical. The whirlwind of the last year simply means people are just getting to take a step back and assess the social and mental toll of the changed situation. An important point is that for any age, and especially after 50, social isolation and reduced personal contact, and lessened meaning have a drastic effect on health. There will be healthy people, and post-Covid will exhibit all sorts of maladies from stress symptoms to heart disease and stroke. How you interact socially has a direct relationship to health.

Here are some simple takeaways that might give a bit of substantiation to the direction taken or give some new ideas. Not all experts will have the same list. Thus it is essential to utilize ideas specific to a personal situation. Remember, the statistics point to the fact you are not the same in outlook and needs, and neither are those you previously had contact with before Covid.

Social Engagement is of Limited Value. Twitter, texting, and FB don’t have the typical depth needed in the current situation. Those platforms are designed to be almost guerilla communication – quick, some kind of point, and see you later. And the significance of the research has been no matter how much of that is included in a week, it is still not enough to make up for the depth take-a-ways from pre-Covid.

Substance over Volume. The first observation is that without the volume of weekly relationships, substance wins. In other words, the relationship needs some regularity, at least enough that the mutual sharing back and forth has more depth than usual. Conversations in any form are less in number, so the psychological reverb of the messages and situations needs to ring for a while. “What’s up?” is probably not the depth meter point that people should gauge interaction.

Keep a Schedule. In the spirit of control, what you can control, getting on a regular schedule has a significant effect on personal mental health. Human beings, for the most part, like regularity. It is best to have a daily time for exercise and, more importantly, self-care, whether that be reading a book, meditation, relaxation, stretching, etc. It is also an opportune time to get involved with a community cause that deals with basic needs, like a clothing or food bank in your community.

Your Compass May Have Changed. Everyone is some type of blend of giving and receiving in relationships. Whatever the mix, that functioned based upon many connections each week under normal circumstances. Covid brought that down to almost nothing, and as described, text messages are not the same as having a 47-minute meeting over coffee. The chances are your needs have changed, and the needs of your friends. Conversations that start off with the assumptions of give-get needs on both ends after a significant time away, like over 30 days are likely to not go very well. If the other person doesn’t explore what is going on, then best in the perspective of honesty to tell them how your compass points have changed. At that juncture, they will either respond in a way that makes going forward work, or it might be time to stop the relationship, at least for a while. The reality is that everyone has limited energy, and knowing limits and how to proceed is best for both sides.

Reach out for Support. Everyone has limits, and it may come to the point that friends and acquaintances are sparse in contact with their own issues and their ability to give you a lift. That translates into they are likely to be of lessened value with empathetic listening and support. With the hit-and-run nature of social media without face-to-face contact, those texts and media channels will likely not be enough. Mental health professionals can help navigate through your specifics and, if nothing else, are good listeners, which has significant value.

Become a Wise Guy/Gal. Some research indicates that wisdom, or looking at the big picture, influences compassion and how people see other people and the world. A little tricky with travel restrictions to head to Tibet for a two-week refresher. However, reading and even podcasts on anything related to the human condition and the self will likely spur some exciting ideas and perspectives.

Towel Time. A harsh reality of the current situation is the decreased volume of social interaction highlights the depth of everyday interaction to be minimal. For example, chatting with acquaintance A before Covid was just another arrow in the contact quiver once a month. Now A has pulled back and no contact with A for over three months. Critical decision time as that may not be enough to meet the need for more depth. It may be best to decide on the current point on the give-receive scale. Even people who were regular givers most of the time are now running out of giving energy and need to re-charge. This means possibly taking a break from some past acquaintances, and in some instances stopping the relationship altogether.

References

Wu, B. Social isolation and loneliness among older adults in the context of COVID-19: a global challenge. glob health res policy 5,27 (2020). https://doi.org/10.1186/s41256-020-00154-3

Webster, Jeffrey & Westerhof, Gerben & Bohlmeijer, Ernst. (2012). Wisdom and Mental Health Across the Lifespan. The journals of gerontology. Series B, Psychological sciences and social sciences. 69. 10.1093/geronb/gbs121.

Wang J, Mann F, Lloyd-Evans B, Ma R, Johnson S. Associations between loneliness and perceived social support and outcomes of mental health problems: a systematic review. BMC Psychiatry. 2018;18(1):156.

Nicholson NR. A review of social isolation: an important but underassessed condition in older adults. J Prim Prev. 2012;33(2–3):137–52.

Hawkley LC, Cacioppo JT. Loneliness matters: a theoretical and empirical review of consequences and mechanisms. Ann Behav Med. 2010;40(2):218–27.

Valtorta NK, Kanaan M, Gilbody S, Ronzi S, Hanratty B. Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies. Heart. 2016;102(13):1009–16.

Hawkley LC, Thisted RA, Masi CM, Cacioppo JT. Loneliness predicts increased blood pressure: 5-year cross-lagged analyses in middle-aged and older adults. Psychol Aging. 2010;25(1):132–41.

Hartup, W. W. (1997). Friendships and adaptation in the life course. Psychological Bulletin, 121, 355–370.

Perissinotto CM, Stijacic Cenzer I, Covinsky KE. Loneliness in Older Persons: A Predictor of Functional Decline and Death. Arch Intern Med. 2012;172(14):1078–1084.

Ryan Van Patten, Ellen E. Lee, Rebecca Daly, Elizabeth Twamley, Xin M. Tu, Dilip V. Jeste, Assessment of 3-dimensional wisdom in schizophrenia: Associations with neuropsychological functions and physical and mental health, Schizophrenia Research, Volume 208,
2019, Pages 360-369.

Buchman AS, Boyle PA, Wilson RS,  et al.  Loneliness and the rate of motor decline in old age: the Rush Memory and Aging Project, a community-based cohort study.  BMC Geriatr. 2010;10(1):7720969786

Yang YC, Boen C, Harris KM. Social relationships and hypertension in late life: evidence from a nationally representative longitudinal study of older adults. J Aging Health. 2015;27(3):403–31.

Coyle CE, Dugan E. Social isolation, loneliness and health among older adults. J Aging Health. 2012;24(8):1346–63.

Rosemary Blieszner, PhD, Aaron M Ogletree, PhD, Rebecca G Adams, PhD, Friendship in Later Life: A Research Agenda, Innovation in Aging, Volume 3, Issue 1, January 2019, igz005.

Jeste, D. V. & Lee, E. E. (2019). The Emerging Empirical Science of Wisdom. Harvard Review of Psychiatry.

Bouwman, TE, Aartsen, MJ, van Tilburg TG, Stevens NL. Does stimulating various coping strategies alleviate loneliness? Results from an online friendship enrichment program. Journal of Social and Personal Relationships, 2017:34, 793–811.

Adjusting to Daylight Savings Time

by Neil E. Wolkodoff, PhD

It is no secret, that after age 50, people have a more difficult time sleeping. Add the time change to DST, and the next couple of weeks might be short on winks.

Not getting adequate and schedule rest over the next two weeks intertwines negatively with the circadian rhythm. This is a natural and internal process that regulates the sleep–wake cycle and repeats on each rotation of the Earth, approximately every 24 hours of time. All sorts of things influence the CR such natural light, blue light from digital screens, abnormal food intake close to retiring, traveling across multiple time zones, excessive alcohol, and even late exercise periods.

More importantly, disrupting the sleep cycle at this time of year can have serious health consequences even if the disruption is only a week. Heart attacks, strokes, fatal car accidents, more pronounced psychological disturbances, increased immune disorders and even decreased liver function can be the result. From a performance perspective, adequate sleep contributes to optimal skill performance, such as a tennis match. Premature aging is fueled by inadequate rest as well. These simple tips will help maintain health and ward off the negative effects of the time change.

Change Bedtime. For the next three nights, go to bed 30 minutes earlier than normal. That is enough to start the body clock in the right direction without too much disruption. Sometime after the third day, increase this to one hour.

Rigid Schedule. It is important to stick to a schedule over the next week. While these cues aren’t as powerful a modifier of the internal clock as some others, they do have an effect. And staying on a regular schedule helps to make the brain-body link, it is even more important in providing a psychological cue that life is normal. This is equally true for meals, social interaction, sleep and exercise. Upon arising, immediately open the curtails to take advantage of the light, another factor in re-setting your internal clock.

Late Blue. The link between blue light, emitted from electronic devices, and disruption of sleep patterns has been well documented. While not 100% applicable to disrupting in sleep for all individuals, the research demonstrated that using things like cell phones, tablets and computers right before retiring will result in taking longer to fall into a deep state of sleep. In addition, older adults generally suffer from less macular protection against blue light reaching the back of the eye, another reason to limit exposure to daytime and not have blue light exposure right before bed.

Six and Stimulants. For the six hours before retiring, cease either caffeine or alcohol intake. And, while a nip right before bed is popularly theorized to help with sleep, it actually increases the time it takes to get to the deep sleep stage.

No Nappin’. While one might be tempted to take a nap, that will also interfere with resetting natural rhythms. For the next week, it is simply best to avoid naps altogether.

Select References

Mander BA, Winer JR, Walker MP. Sleep and Human Aging. Neuron. 2017;94(1):19-36.

Dijk DJ, Duffy JF, Riel E, Shanahan TL, Czeisler CA. Ageing and the circadian and homeostatic regulation of human sleep during forced desynchrony of rest, melatonin and temperature rhythms. J Physiol. 1999;516:611–627.

Tucker M, McKinley S, Stickgold R. Sleep optimizes motor skill in older adults. J Am Geriatr Soc. 2011;59:603–609.

Sandhu A, Seth M, Gurm HS. Daylight savings time and myocardial infarction. Open Heart. 2014;1(1):e000019. Published 2014 Mar 28.

Zhang H, Dahlén T, Khan A, Edgren G, Rzhetsky A. Measurable health effects associated with the daylight saving time shift. PLoS Comput Biol. 2020;16(6):e1007927. Published 2020 Jun 8.

Menet JS, Rosbash M. When brain clocks lose track of time: Cause or consequence of neuropsychiatric disorders. Current Opinion in Neurobiology. 2011.

St Hilaire MA, Rüger M, Fratelli F, Hull JT, Phillips AJ, Lockley SW. Modeling Neurocognitive Decline and Recovery During Repeated Cycles of Extended Sleep and Chronic Sleep Deficiency. Sleep. 2017;40(1):zsw009.

Mukherji A, Bailey SM, Staels B, Baumert TF. The circadian clock and liver function in health and disease. J Hepatol. Elsevier BV; 2019;71: 200–211.

Cajochen C, Munch M, Kobialka S, Krauchi K, Steiner R, Oelhafen P, Orgul S, Wirz-Justice A. High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light. J Clin Endocrinol Metab. 2005;90(3):1311–1316.

Chang AM, Scheer FA, Czeisler CA, Aeschbach D. Direct effects of light on alertness, vigilance, and the waking electroencephalogram in humans depend on prior light history. Sleep. 2013;36(8):1239–46.

Manfredini R, Fabbian F, Cappadona R, Modesti PA. Daylight saving time, circadian rhythms, and cardiovascular health. Intern Emerg Med. 2018;13(5):641-646.

Facemasks and Breathing During Exercise

Neil Wolkodoff, PhD, Medical Program Director

When exercising with a mask in cardiovascular activities, do you feel that you cannot breathe quite well and get over-heated? Fact or feeling?

Can you really exercise effectively in a face mask?

Most people in the cardiovascular area of facilities are wearing a bit more clothes when it is winter, there is perceived protection from infection (long-sleeved shirt and pants), and they are also wearing a mask.

Most athletic clubs were down 30+ percent in members during Covid19. If you talk to most people, exercise in a mask in less than tolerable. So, while the air was a bit more humid than normal as described in this blog, time to set out some facts about how mask use works or doesn’t in terms of exercise.

Examining what goes on with masks in straightforward terms is both perceptions, and part of it is physiology. Furthermore, remember, all masks are not created equal in terms of protection, individual fit and physiological interaction. Masks may provide some level of protection to particles assuming all the air goes through the mask and not around it in any form. Fitting is critical.

You can breath at the same rate in a mask as without a mask at rest. At least for a short while and if respiratory frequency is limited to low-level or moderate activity. In cardio-vascular (CV) of a moderate level, airflow is low enough to go through the mask in both directions. Once a Forced Voluntary Contraction or a big exhale, at maximum speed, occurs, the mask cannot work correctly, and there is air leakage around the mask. Low-level CV activities should not be an issue with the airflow, yet activities like maximal sprints or efforts, the mask may not keep up with airflow requirements. However, there are other issues/factors which interact with the perceptions of breathing ease with a mask.

The huge issue is that face masks have dead space or trapped air that quickly does not move in and out of the mask. In this regard, masks for Covid-19 are very similar to the masks used in VO2 testing and those worn by firefighters and other first responders in dead space. VO2 testing usually is 13-19 minutes. Firefighters practice with the mask and respiratory requirements, so a bit of short time frame or being accustomed to the breathing system’s feelings and performance and having to wear their gear. 

A typical Hans-Rudolph mask used in metabolic/VO2 testing

The dead space around a mask, where air does not flow in or out immediately, means the Carbon Dioxide, or CO2 level will be higher around the mask. There have been reports of some people essentially experiencing a panic disorder partially triggered by the additional CO2. In general, panic attacks trigger shorter and less complete breathing, which further worsens the situation.

Now add to this fact the mouth and face connect somewhere between 30-39% of sensory and motor nerves. In other words, small things seem pretty big when applied to the face and mouth. Moisture around the mask enhances sensory perception. Furthermore, with those having or on the borderline of Chronic Obstructive Pulmonary Disorder (COPD), the mask may push up the feeling of CO2 level another notch due to the condition. Perception and feeling do change respiratory or breathing mechanics. Some have postulated in this sense, masks contribute to hyper ventilation.

Another co-contributor to this feeling of reduced breathing is simply the mask, and in almost any porous material, retains more moisture in the breathing process as time goes on. Humidity and heat have a relationship that as moisture rises, the perception of heat index goes up. The “I Can’t Breath Feeling” has some basis in reality, and the higher moisture levels around the mask elevate perception.  And moisture does affect permiability. Take walking through an airport with baggage with a coat on. Even a short to moderate walk could do it based upon temperature. Likely that humidity is up, and it won’t take long before the humidity gain in the mask reduces the permeability to the point all the airflow is through the sides and around the mask.

What are simple steps to ease both the perception and physiology of the mask toleration point in exercise? 

Make your own assessment if the mask really does any good, as the data is conflicting as to benefit.

First, wear a fresh mask when exercising, so there is no residual moisture from anything earlier in the day. 

Ask the gym to turn down temperature two or three degrees in the CV area to take down the heat index by the mask.

Emphasize nasal rather than mouth breathing.

Use a dynamic warm-up or increase in intensity or speed to enable respiratory rate to increase slowly over the first five minutes.

If the perception is still present after 20 minutes, consider a break to somewhere to remove the mask for up to a minute or two to allow both CO2 and humidity to dissipate.

Carry a personal towel and wipe off the face and forehead every 10 minutes during exercise.

Bring a second mask to the exercise session and change out at 20 minutes to a new dry one.

References

Amirav I, Newhouse MT. Dead space variability of face masks for valved holding chambers. Isr Med Assoc J. 2008;10(3):224-226.

Davies A, Thompson KA, Giri K, Kafatos G, Walker J, Bennett A. Testing the efficacy of homemade masks: would they protect in an influenza pandemic?. Disaster Med Public Health Prep. 2013;7(4):413-418. doi:10.1017/dmp.2013.43

Faruque Ahmad M. A Novel Perspective Approach to Explore Pros and Cons of Face Mask in Prevention the Spread of SARS-CoV-2 and other pathogens [published online ahead of print, 2020 Dec 31]. Saudi Pharm J. 2020;10.1016/j.jsps.2020.12.014.

Freemas JA, Wilhite DP, Greenshields JT, Adamic EM, Mickleborough TD. Comparison between a facemask and mouthpiece on breathing mechanics and gas exchange variables during high-intensity exercise. Eur J Sport Sci. 2020;20(2):211-218.

Furutani Y, Shiigi T, Nakamura H, Nakamura Y, Ishizaki H, Uchiyama K, Harada M, Shimizu A, Matsuzaki M. [Influence of the dead space induced by the face mask on the measure of heart rate variability]. J Cardiol. 1997 Mar;29(3):171-6. Japanese. PMID: 9095448.

Kyung SY, Kim Y, Hwang H, Park JW, Jeong SH. Risks of N95 Face Mask Use in Subjects With COPD. Respir Care. 2020;65(5):658-664.
Li DF, Cadnum JL, Redmond SN, Jones LD, Donskey CJ. It’s not the heat, it’s the humidity: Effectiveness of a rice cooker-steamer for decontamination of cloth and surgical face masks and N95 respirators. Am J Infect Control. 2020;48(7):854-855.

Parlin AF, Stratton SM, Culley TM, Guerra PA. A laboratory-based study examining the properties of silk fabric to evaluate its potential as a protective barrier for personal protective equipment and as a functional material for face coverings during the COVID-19 pandemic. PLoS One. 2020;15(9):e0239531. Published 2020 Sep 18.

Roberge RJ, Kim JH, Coca A. Protective facemask impact on human thermoregulation: an overview. Ann Occup Hyg. 2012;56(1):102-112.

Scarano A, Inchingolo F, Lorusso F. Facial Skin Temperature and Discomfort When Wearing Protective Face Masks: Thermal Infrared Imaging Evaluation and Hands Moving the Mask. Int J Environ Res Public Health. 2020;17(13):4624. Published 2020 Jun 27.

Computer Brain Training?

Getting some memory and function back in your brain after 50 is now a top-three health goal. Many senior association groups like AARP have been promoting online tests and training in memory and thinking skills, but do they work?

Consider that brain function and thinking, obviously crucial as you get older, is multifaceted. Some of these associations offer simple online assessments to get at your level in detecting the aging brain’s mental skills and measures. Compared with the clinical tests, these are better than nothing, yet you should know clinicians use assessments that function from several angles and depth. Those simple assessments try to measure such things as verbal & visual memory and symbol recognition and matching.

One test often not included in the simple applications is the Stroop Test, a combined measure of reaction time, inhibition or not reacting to specified information, and even attention. If you are going to get a complete brain function idea compared to age, then these more complete tests are essential. Many in the know about brain function after 50 believe the simple, online tests just don’t include enough areas and depth to really determine your brain function compared to age, and what is your best course of action to improve weak areas.

The computerized training games are likely good to a point for some simple and basic abilities. A significant consideration is many of these games focus on just one or two skills. And that may not translate into better thinking. For example, you can improve your visual memory, yet that will not directly translate into getting closer to Einstein. The reason is simple – complex reasoning involves assessing, remembering, and then formulating conclusions based upon the information. Maybe your issue is attention. Perhaps it is keeping the information in short term memory. Many simple computer games just don’t get to this level of detection and inclusion and thus applicability.

You might get better at the computer game or training, yet it does not translate to life and more complex thinking. Wasn’t that the whole point?

Over the last three years, more and more exercise equipment has some type of tie-in to a computer, phone, or pad. An informal term often used to describe their relationship to the user is “engagement.” Off in the cosmos of inadequate definitions, it can be referred to as “mindfulness.” That includes everything from watching yourself run or cycle a course, keeping pace with an aerobic or resistance training machine, or even performing a new exercise movement. Most of the research in this area is in dysfunction, like the loss of control of a limb due to neurological consideration or an injury, so a little difficult to extrapolate to a normal life situation. In a simple equation, the more you have to think about the exercise and the movement, the better the mindfulness experience and results.

I would contend that exercise equipment companies have not really thought of their equipment as having a specific impact in this area, so expect results to be just a bit additional to the actual physical benefits, which are primary. However, each time you perform resistance training, take one exercise to accomplish it a little differently. That could be a cable versus dumbbell, staggered stance, change of tempo, etc.

If the online computerized games are a bit like Swiss Cheese, how do you fill the holes? Remember, those online applications are working on a few basic abilities, like verbal memory. What is really missing is putting it all together in something like problem solving and application. You have heard it before, learn a new skill or subject. Workbooks in things like math fit the requirement. Playing a musical instrument can stimulate those executive functions in the brain. And some of the new keyboards make it relatively easy to learn the piano without Mrs. Grinch keeping time on your shoulder with a ruler.

Another factor to consider is that Covid and the increased stay at home mean you have likely already over doubled your daily time in front of a screen, phone, or otherwise. Consider that too much computer time actually takes multi-media users and results in the ability to switch tasks being diminished. The total opposite of what you might think, which probably means you should get away from the computer and screen every so often. And because most people would add brain games to the mix, rather than subtract time in front of the screen, then add the brain game, maybe another factor to consider in modifying the approach.

How much of these complex activities should you do? That is where the research really has no firm direction. When you were working every day in your 30s, you were doing this pretty much each day. Based on what the person needs to work on from the assessment, two days per week of 30 minutes of these complicated tasks seems to be a good starting point. It is doable and not so overwhelming you will give up if you haven’t learned anything lately. It is not about what you learn or how fast. It is about putting the process into gear.

And, the result is a younger brain.

References

Kable JW, Caulfield MK, Falcone M, et al. No Effect of Commercial Cognitive Training on Brain Activity, Choice Behavior, or Cognitive Performance. J Neurosci. 2017;37(31):7390-7402.

Owen AM, Hampshire A, Grahn JA, Stenton R, Dajani S, Burns AS, Howard RJ, Ballard CG. Putting brain training to the test. Nature. 2010 Jun 10;465(7299):775-8.

Stojanoski B, Lyons KM, Pearce AAA, Owen AM. Targeted training: Converging evidence against the transferable benefits of online brain training on cognitive function. Neuropsychologia. 2018 Aug;117:541-550.

Nouchi R, Taki Y, Takeuchi H, et al. Brain training game boosts executive functions, working memory and processing speed in the young adults: a randomized controlled trial. PLoS One. 2013;8(2):e55518. doi:10.1371/journal.pone.0055518

Castells-Sánchez A, Roig-Coll F, Lamonja-Vicente N, et al. Effects and Mechanisms of Cognitive, Aerobic Exercise, and Combined Training on Cognition, Health, and Brain Outcomes in Physically Inactive Older Adults: The Projecte Moviment Protocol. Front Aging Neurosci. 2019;11:216. Published 2019 Aug 14. doi:10.3389/fnagi.2019.00216

Hampshire A, Sandrone S, Hellyer PJ. A Large-Scale, Cross-Sectional Investigation Into the Efficacy of Brain Training. Front Hum Neurosci. 2019;13:221. Published 2019 Jul 9. doi:10.3389/fnhum.2019.00221

Baniqued PL, Lee H, Voss MW, et al. Selling points: What cognitive abilities are tapped by casual video games?. Acta Psychol (Amst). 2013;142(1):74-86. doi:10.1016/j.actpsy.2012.11.009

Wilke J, Stricker V, Usedly S. Free-Weight Resistance Exercise Is More Effective in Enhancing Inhibitory Control than Machine-Based Training: A Randomized, Controlled Trial. Brain Sci. 2020;10(10):702.

Legault J, Fang SY, Lan YJ, Li P. Structural brain changes as a function of second language vocabulary training: Effects of learning context. Brain Cogn. 2019;134:90-102.

Han K, Davis RA, Chapman SB, Krawczyk DC. Strategy-based reasoning training modulates cortical thickness and resting-state functional connectivity in adults with chronic traumatic brain injury. Brain Behav. 2017;7(5):e00687.

de Aquino MPB, Verdejo-Román J, Pérez-García M, Pérez-García P. Different role of the supplementary motor area and the insula between musicians and non-musicians in a controlled musical creativity task. Sci Rep. 2019 Sep 10;9(1):13006.

Kwok JYY, Kwan JCY, Auyeung M, et al. Effects of Mindfulness Yoga vs Stretching and Resistance Training Exercises on Anxiety and Depression for People With Parkinson Disease: A Randomized Clinical Trial. JAMA Neurol. 2019;76(7):755-763.

Ophir E, Nass C, Wagner AD. Cognitive control in media multitaskers. PNAS. 2009:106 (37) 15583-15587.

Can You Eat Your Way to Immunity?

With the COVID situation, more and more people are taking a multi-dimensional approach to stay healthy. Is just eating better, or are supplements a line of defense in optimal health?

YMCAFoodDonation

You are probably under more stress with a greatly diminished work schedule. Social outlets and regular exercise outlets are minimized due to contact restrictions. The likely result is you are feeling more mental stress combined with less resilience in the body because you are off your regular routine.

There is a bit of inference or scientific projection in this area of nutritional defense. Things like pandemic outbreaks don’t make for a good subject pool, so many of these studies look at other areas with similar physiological pathways. Coronary heart disease and cancer are the main study areas. However, there is evidence that nutritional strategies aimed at antioxidant and inflammation reduction may also be necessary. These components have a role in disease prevention, and maybe more so in they can retard the onset or severity of conditions that are more susceptible to, in this case, COVID.

It is true upping your servings of fruits and vegetables has a positive effect on reducing heart disease and cancer. In one of the most recent studies at the Imperial College in London, this initial threshold was re-affirmed as five servings per day. In fact, when the subjects got to the level of 10 servings per day, the results were greatly enhanced. The flip side application is simply only 12.9% of Americans at best get those five servings a day. And no surprise, the number of people at 10 servings per day less than one percent.

VegetablesonParade

There are a number of popular strategies to increase the intake of these power foods. One simple one that is easy to follow is to decrease the number of carbohydrates like french fries or bread by 1/2. And then double the amount of vegetables. That way, the plate stays the same size, yet the nutrient density per kcal goes way up. And ketchup on the fries does not count as a vegetable.

Practically, more is better. However, most people we know do not share rabbit food preferences in the volume dimension. So after a point, there is just so much you can eat. Given the reality of American intakes of fruits and vegetables, are there good supplement options, and are they supported by research? There is solid evidence that certain essential supplements do help with immune responses and fight off stress.

RabbitMunching

Vitamin C is one of the top nutrients you can consume at this time. If you are deficient in C, your immune system will be impaired, and your possibility of infections increases. Interestingly enough, supplementation with C is a good prevention measure. In the case of already acquired respiratory and other infections, it can be part of an effective treatment plan.

How much C should you consume? Guidelines put this intake at 100-200 milligrams (MG) per day from foods. Oranges are the go-to visual fruit for C, but do they deliver? A medium orange is 70 MG of C. A great start to prevent scurvy. Yet for those who aren’t pirates at sea, you will really need to up your intake. Two other C-rich foods are strawberries and kiwis. In the case of vitamin C, minor supplementation might be wise, depending upon your intake.

Vitamin D is not talked about much in this regard. Yet, this fat-soluble vitamin is an essential line of defense. It is known mostly for its function in bone health by helping to modulate the constant rebuilding of bone. There have been several studies demonstrating low levels of D with increased infection. At the turn of the last century, Cod liver oil, which has significant levels of D, was used to treat tuberculosis.

bondi beach

The problem is very few foods contain vitamin D. Previously, before the ozone issues that removed some of our atmospheric protection from harmful UV-B light, you could get most vitamin D by being outside. Now, most people should use sunscreen for outside activities, and thus the vitamin D effect is lessened due to less time. So, you are still getting some benefit while wearing sunscreen, yet unlikely all the D you need. However, in some studies, food intake plus moderate sunlight exposure did raise elevate D levels. Most people don’t or can’t spend excessive time in the sun, so a supplement is probably a good idea. Your intake should be roughly 400 International Units (IU) per day. In some relatively recent estimates of consumption, Americans averaged between 150-200 IU per day.

In children, not getting enough Zinc can lead to the slowing of growth. In adults, it is a contributory mineral in the immune system functioning at lessened levels. One of Zinc’s most essential functions is with enhancing T-cells, which help regulate immune responses.

MrLobster

Foods with high zinc content include oysters, shell fish, meat, and whole grains, especially fortified breakfast cereals. Intake should typically be 8 mg for women and 11 mg for men. It appears that most people are getting either enough Zinc or are just a bit shy. 55% of the U.S. population is getting enough from a combination of food and supplements.

Polyphenols are plant compounds that chemically can be thought of as long chains of natural alcohol + acid compounds. They occur in a wide variety of fruits and vegetables. Most notably, resveratrol in red wine has received attention over the last few years for health benefits.

In general, polyphenols such as those from the Bergamot fruit have positive research in the areas of prevention of Coronary Heart Disease and other similar conditions through reduction of inflammation, decreased blood lipids, and increased circulation. Polyphenols also have a function in reducing oxidative stress and appear to have a positive role in cancer prevention. These compounds likely have a base effect of improving essential functions such as circulation and removing free radicals, which in turn support immune response.

BergamotFruit

When viewing polyphenol research, one of the keys is the amount of polyphenol versus the results. This is one where it appears to a point, more is better. And, given then are 8,000 types of polyphenols, separating foods into the most practical classes is not easy. However, eating a variety of fruits and vegetables is a good start. Some supplements on the market provide high levels of polyphenols combined with other essential compounds like Zinc and vitamin C. The capsules that contain compressed and dehydrated fruit and vegetable juice do appear to work. Yet, labeling most of the time does not disclose actual nutrient levels.

It is important if you are taking medications to consult with your physician and health care provider on specific supplement usage. Some supplements can interfere with medications, so a consult about specific supplements is wise before radically changing your routine and intake.

References

Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies. Int J Epidemiol. 2017;46(3):1029–1056.

Aranow C. Vitamin D and the immune system. J Investig Med. 2011;59(6):881–886.

Bailey RL, Dodd KW, Goldman JA, Gahche JJ, Dwyer JT, Moshfegh AJ, et al. Estimation of total usual calcium and vitamin D intakes in the United States. J Nutr. 2010;140:817-822.

Bales CW, DiSilvestro RA, Currie KL, Plaisted CS, Joung H, Galanos AN., Lin PH. Marginal zinc deficiency in older adults: responsiveness of zinc status indicators. Journal of the American College of Nutrition. 1994;13(5), 455-462.

Carr AC, Frei B. Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am. J. Clin. Nutr. 1999;69:1086–1087.

Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017;9(11):1211.

Dobnig H, Pilz S, Scharnagl H, et al. Independent Association of Low Serum 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Levels With All-Cause and Cardiovascular Mortality. Arch Intern Med. 2008;168(12):1340–1349.

Ferlazzo N, Cirmi S, Calapai G, Ventura-Spagnolo E, Gangemi S, Navarra M. Anti-inflammatory activity of Citrus Bergamia derivatives: where do we stand? Molecules. 2016;21(10).

Grosso G. Effects of Polyphenol-Rich Foods on Human Health. Nutrients. 2018;10(8):1089.

Lamprecht M, Oettl K, Schwaberger G, Hofmann P, Greilberger JF, Several Indicators of Oxidative Stress, Immunity, and Illness Improved in Trained Men Consuming an Encapsulated Juice Powder Concentrate for 28 Weeks, The Journal of Nutrition. 2007;137(12):2737–2741.

Levine M., Dhariwal K.R., Welch R.W., Wang Y., Park J.B. Determination of optimal vitamin C requirements in humans. Am. J. Clin. Nutr. 1995;62:1347S–1356S.

Maggini S, Wintergerst ES, Beveridge S, Hornig DH. Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses. Br. J. Nutr. 2007;98:S29–S35.

Magrone, T., & Jirillo, . Polyphenols from red wine are potent modulators of innate and adaptive immune responsiveness. Proceedings of the Nutrition Society. 2010;69(3), 279-285.

Manach C, Scalbert A, Morand C, Rémésy C, Jiménez L. Polyphenols: food sources and bioavailability The American Journal of Clinical Nutrition, 2004;Volume 79(5):727–747.

Nicholson LB. The immune system. Essays Biochem. 2016;60(3):275–301.

Norman AW, Henry HH. Vitamin D. In: Bowman BA, Russell RM, eds. Present Knowledge in Nutrition, 9th ed. Washington DC: ILSI Press, 2006.

Passeron T, Bouillon R, Callender V, et al. Sunscreen photoprotection and vitamin D status. Br J Dermatol. 2019;181(5):916–931.

Petersen B, Wulf HC, Triguero‐Mas M et al Sun and ski holidays improve vitamin D status, but are associated with high levels of DNA damage. J Invest Dermatol 2014; 134:2806–13.

Prasad AS. Zinc in human health: effect of zinc on immune cells. Mol Med. 2008;14(5-6):353–357.

Prasad AS, et al. Zinc supplementation decreases incidence of infections in the elderly: Effect of zinc on generation of cytokines and oxidative stress. Am J Clin Nutr. 2007;85:837–44.

Risitano R, Currò M, Cirmi S, et al. Flavonoid fraction of Bergamot juice reduces LPS-induced inflammatory response through SIRT1-mediated NF-κB inhibition in THP-1 monocytes. PLoS One. 2014;9(9):e107431.

Ronette RB, Bialostosky K, Kennedy-Stephenson J, McDowell MA, Ervin RB, Wright JD, Zinc Intake of the U.S. Population: Findings from the Third National Health and Nutrition Examination Survey, 1988–1994, The Journal of Nutrition, 2000;130(5):1367S–1373S.

Urashima M, et al. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr. 2010;91(5):1255–60.

Williams C. On the use and administration of cod-liver oil in pulmonary consumption. London Journal of Medicine. 1849;1:1–18.

Young A, Narbutt J, Harrison G, Lawrence K, Bell M, O’Connor C, Olsen P, Grys K, Baczynska K, Rogowski‐Tylman M, Wulf H, Lesiak A, Philipsen P. Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. Br J Dermatol, 2019;181:1052-1062.

Zhou Y, Zheng J, Li Y, et al. Natural Polyphenols for Prevention and Treatment of Cancer. Nutrients. 2016;8(8):515.