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Exercise Immunology 101: Considerations for the Fitness Professional

by Joseph Giandonato, MBA, MS, CSCS

As the COVID-19 pandemic transforms our society and a myriad of industries, including our own, concerns about safely continuing to pursue fitness goals have emerged as fitness instructors and the clients they support weigh the risks versus rewards during these unprecedented times.

Nationwide, cases have continued to surge in spite of attempts to temper the proliferation of the virus as government organizations at the federal, state, and local levels work to strike a delicate balance between curating the health of citizens and restoring the economy. Measures such as abridging capacity and hours of operation of multiple fitness and recreational facilities, including temporarily shuttering venues and suspending services, while disruptive, are intended to keep us healthy.

Long term held beliefs about exercise adversely impacting immune system is the functioning has been corroborated by a landmark review authored by Gleeson (2007).  The review demonstrated that the inflammatory response of a singular bout of intense and prolonged exercise mirrors that of infection, sepsis, or trauma, triggering the release of inflammatory cytokines, including tumor necrosis factor, and interleukins 6 and 10, C-recreative protein, and interleukin-1-receptor antagonists that, in concert, influence the augmentation of circulating white blood cells, known as leukocytes.

Hormonal secretion following an intense bout of exercise induced activity, specifically epinephrine and cortisol blunt the secretion of leukocytes and impair cell mediated immunity and inflammation, thereby increasing the susceptibility of infection and modulating the morbidity and severity of illness. Previous research established a strong correlation between a exercise dose and upper respiratory tract infection among humans. Health fitness exercise bouts consisting of a stimuli that is too novel, too frequent, too intense, and too voluminous to which the subject is accustomed have been found to increase pathogen infection risk. There has been a considerable amount of studies that have demonstrated the temporary ergolytic effects of acute exercise on immune system functioning, ranging from three to 72 hours post-exercise. Researchers and health and exercise professionals have coined this period of time characterized by temporary suppression of the immune system as “the open window”.

To simultaneously curtail infection risk and facilitate the achievement of improved fitness industry qualities or biomotor skills, one must account for life stress, energy availability, sleep duration and quality, travel, and exposure to environmental or climate extremes beyond the exercise frequency, intensity, volume, and type, according to Professor Neil Walsh, a faculty member at Bangor University in the United Kingdom, who outlined recommendations for athletes to maintain immune health.

Key guidelines among the few dozen presented are summarized below for personal trainers in working with potential clients:

  1. Undulating training stress throughout training cycles and weeks
  2. Incorporating active recovery sessions
  3. Incrementally increasing volume and intensity, but no more than 5-10% per week
  4. Minimize unnecessary life stress
  5. Monitor, manage, and quantify all forms of stress, both psychological and physical
  6. Aim for more than seven hours of sleep each night; nap during the daytime, if able to, or necessary
  7. Monitor sleep duration and quality; ensure darkness at bedtime
  8. Be cognizant of reduced exercise capacity in hotter, more humid environments
  9. Permit acclimatization to changes in, or extreme weather
  10. Uphold optimal or recommended nutrition, hydration, and hygiene practices
  11. Do not engage in extreme dieting; be sure to consume a well balanced diet
  12. Discontinue training if experiencing symptoms “below the neck” as they could be indicative of an upper respiratory tract infection (URTI)
  13. Avoid sick and/or symptomatic people
  14. Practice good hand hygeine

Exercise evokes a hormetic effect, or dose-dependent response, meaning that moderate exposure can be beneficial, but amounts either too minimal or excessive can cause harm. This is precisely why exercise physiology scholars and health and medical professionals alike have embraced the mantra of “exercise is medicine” in recent years. Too little exercise results in greater cardiometabolic disease (aka conditions of “disuse”) risk, whereas too much exercise results in greater injury or illness (aka conditions of “overuse”). As mentioned in an earlier post, “acute singular bouts of exercise at or above lactate threshold (55% of VO2max among untrained individuals; 85% of VO2max among trained individuals) for periods of up to, or more than one hour, contributed to temporary immunosuppression. Regular exercise among individuals has shown to yield immunoprotective benefits. The takeaway here should be, exercise during this time should be regarded as a tool to reinvigorate and recover, not bury and deliberately fatigue. Sparingly perform sets to failure and limit volume at or beyond lactate threshold.”

In summary, immune system performance and overall health can be achieved through regular exercise. During times of greater illness transmission and infection risk, fitness professionals, athletes, and enthusiasts must practice both diligence and vigilance to ward off foreign pathogens. Fitness goals should be targeted and inputs, such as time and effort should be quantified to calculate training load. Rest and recovery should be as equally, if not greater prioritized.

References

  • Gleeson, M. (2007). Immune function in sport and exercise. Journal of Applied Physiology, 103 (2), 693-699.
  • Kakanis, M.W., Peake, J., Brenu, E.W., Simmonds, M., Gray, B., Hooper, S.L., & Marshall-Gradisnik, S.M. (2010). Exercise Immunology Review, 16, 119-137.
  • Murphy, E.A., Davis, J.M., Carmichael, M.D., Gangemi, J.D., Ghaffar, A., & Mayer, E.P. (2008). Exercise stress increases susceptibility to influenza infection. Brain, Behavior, and Immunity, 22, (8), 1152-1155.
  • Nieman, D.C. (1994). Exercise, infection, and immunity. International Journal of Sports Medicine, 15, S131-S141
  • Walsh, N.P. (2018). Recommendations to maintain immune health in athletes. European Journal of Sport Science, 18 (6), 820-831.
  • Wong, C., Lai, H., Ou, C., Ho, S., Chan, K., Thach, T., Yang, L., Chau, Y., Lam, T., Hedley, A.J., & Peiris, J.S.M. (2008). Is exercise protective against influenza-associated mortality? PLoS One, 3 (5): e2108.

 

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