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Exercise is the performance of activities in order to develop or maintain readiness or competence in various forms of endeavors. Prominent among these are physical exercise engaged in for physical fitness and skill, mental exercises for mental fitness and readiness in various fields, and military exercises for readiness in regard to war.


  • But full-blown anorexia has never been the norm among teenage girls; the real epidemic is among the girls with seemingly healthy eating habits, seemingly health bodies, who commit or work their butts off as a result form of anti-fat maintenance. These girls not only look “normal” but consider themselves normal. The new criterion circulating among teenage girls: If you get rid of it through exercise rather than purging or laxatives, you don’t have a problem.
  • Exercise addiction is rarely listed among the criteria for eating problems, but it has become the weight control of choice among an generation emulating Jennifer Lopez’s round tight buns rather than Kate Moss’s skeletal collarbones. Just because a teenager looks healthy and fit does not mean that she is not living her life on a treadmill-metaphorically as well as literally-which she dare not step off lest food and fat overtake her body.
  • This is a culture in which rigorous dieting and exercise are being engaged in by more and younger girls all the time-girls as young as seven or eight, according to some studies. These little girls live in constant fear- a fear reinforced by the attitudes of the boys in their classes-of gaining a pound and thus ceasing to be “attractive.” They jog daily, count their calories obsessively, and risk serious vitamin deficiencies and delayed reproductive maturation. We may be producing a generation of young, privileged women with severely impaired menstrual, nutritional, and intellectual functioning.
  • Better to hunt in fields, for health unbought,
    Than fee the doctor for a nauseous draught.
    The wise, for cure, on exercise depend;
    God never made his work for man to mend.
  • This study was designed to investigate changes in the immune system of elite swimmers compared with well-conditioned age- and sex-matched controls in relation to a competition swim (field study). Furthermore, the aim was to reveal possible differences in immune system changes depending on the type of sport performed by comparing with an earlier study of similar design, from the same laboratory that tested elite runners in relation to a competition run. The swimmers were tested before, immediately after and 2 h and 24 h after a competition swim. Lymphocyte subsets (CD5, CD3, HLA-DR, CD4, CD8, CD19, CD3/CD16+56, CD57, CD18, CD16/CD122) all increased after the run, decreased to normal or subnormal levels after 2 h, and returned to normal after 24 h (absolute numbers). The findings were identical for the swimmers and the age- and sex-matched control group. No change in polymorphonuclear granulocyte migration was found. The lymphocyte proliferative responses decreased 2 h after the exercise. No changes were seen in plasma cytokine levels (interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) in relation to exercise, but significantly lower baseline values for IL-6 were observed in the swimmers. An increase in total natural killer cell activity immediately after exercise, followed after 2 h by a decrease, was seen in both swimmers and controls. Finally, no complement activation was detected. Compared with an earlier study of elite runners, differences were seen in granulocyte chemotactic response, TNF-alpha plasma activity and the lymphocyte proliferative response to mitogen. These differences might be explained by the degree of immune system activation following muscle damage during exercise, inducing an increase in cytokines, which are known to activate and modulate both lymphocytes and granulocyte function. Our findings demonstrate identical exercise-induced, immune system changes in elite swimmers and well conditioned controls, and furthermore, the findings suggest that different types of sport performed at maximum intensity induce different immune system changes.
  • Intense exercise is frequently associated with postexercise alterations in percentage and number of blood lymphocyte phenotypes and suppression of natural killer cell activity and lymphocyte proliferative responses to mitogen. Because suppression is most often observed after intense or prolonged endurance exercise, we hypothesized that high-intensity resistance exercise might elicit similar responses in elderly exercisers. Postresistance exercise suppression of NCMC has been reported previously by two groups of investigators using young males as subjects. Because the elderly are reported to have impaired cellular immune function, we were concerned about the potential of an acute bout of resistance exercise to negatively impact the immune system.
    There have been few studies completed to date that have examined the immune responses to endurance training in elderly subjects, and these findings have been equivocal. Therefore, a second purpose of this investigation was to examine whether 10 wk of resistance training would elicit changes in resting immune function, as measured by phenotypic and functional tests. In summary, acute resistance exercise did not negatively affect immune function either before or after a 10-wk period of resistance training. Additionally, 10 wk of resistance training, while eliciting substantial increases in muscular strength, did not positively influence the immune system in these elderly women compared with inactive controls.
  • In conclusion, immune function in 67- to 84-yr-old women was not suppressed during the recovery period from a single bout of resistance exercise. In addition, a 10-wk resistance training program did not significantly alter resting indexes of immune function in these women, and the exercise-induced immune responses were similar before and after resistance training. The present data lead us to suggest that women aged 69–84 yr can substantially improve strength with chronic resistance training without either detrimental or positive effects on selected indexes of immune system function.
  • I get my exercise running to the funerals of my friends who exercise.
    • Barry Gray, New York magazine (May 19, 1980).
  • Exercise and application produce order in our affairs, health of body, cheerfulness of mind, and these make us precious to our friends.
    • Thomas Jefferson, Letter to his daughter, Martha Jefferson. (March 28, 1787) The Family Letters of Thomas Jefferson, p. 34, eds. E.M. Betts and J.A. Bear, Jr. (1966).
  • My first recollection of the future poetess is that of a plump girl, grown enough to be almost mistaken for a woman, bowling a hoop round the walks, with the hoop-stick in one hand and a book in the other, reading as she ran, and as well as she could manage both exercise and instruction at the same time. The exercise was prescribed and insisted upon: the book was her own irrepressible choice.
    • The Autobiography of William Jerdan, 1852
  • I feel about exercise the same way that I feel about a few other things: that there is nothing wrong with it if it is done in private by consenting adults.
  • Few studies have included subjects of different age groups to examine the age-related differences in immune response after exercise training. Several of the same immune parameters that are transiently affected by acute exercise are also those that are altered during aging. An age-associated decline in T-cell mediated immune parameters is well recognized and is characterized by a reduced lymphocyte proliferative response, decreased frequency and size of delayed type hypersensitivity responses, decreased IL-2 production by T cells, and alterations in T-cell subsets. The effects of exercise training on these already diminished immune parameters is unknown. Recently, there has been increasing emphasis on the benefits of strength-training exercises among elderly individuals in terms of improved muscle strength and function, increased muscle mass, and weight control. Undoubtedly, there are many positive effects of strength training for the elderly. However, given the complex series of changes in many physiological systems that occur as a result of exercise training, the ultimate impact on the immune system is difficult to predict. Therefore, given the age-related declines in immunity, understanding the impact of strength training (which is being increasingly recommended to these individuals) in terms of the immune response is critically important.
    Even less is known about the effect of exercise in patients with autoimmune disorders in whom the immune system is inappropriately activated. Like the elderly, individuals with the chronic inflammatory condition rheumatoid arthritis (RA) demonstrate reduced physical performance capacity, and it has been increasingly recognized that exercise of varying types leads to improvements in physical performance capacity, cardiorespiratory fitness, muscle strength, and activities of daily living without exacerbating clinical disease progression or joint damage. However, subjects with RA also exhibit an altered resting cytokine profile with increased IL-1 and TNF production by PBMC. The effects of an exercise training regimen on the activated immune system of these subjects, compared with healthy individuals, remain to be elucidated.
  • The practice of physical exercise, both in its acute form and in its chronic form, significantly alters the immune system. Studies indicate that the modulation of the immune response related to exercise depends on factors such as regularity, intensity, duration and type of effort applied.
    Moderate-intensity physical exercises stimulate cellular immunity, while prolonged or high-intensity practices without appropriate rest can trigger decreased cellular immunity, increasing the propensity for infectious diseases. According to the International Society for Exercise and Immunology (ISEI), the immunological decrease occurs after the practice of prolonged physical exercise, that is, after 90 min of moderate- to high-intensity physical activity.
  • Walking is the natural recreation for a man who desires not absolutely to suppress his intellect but to turn it out to play for a season.
    • Leslie Stephen, Studies of a Biographer: Second Series (London: Duckworth, 1902) vol. 3, p. 261.
  • If you would get exercise, go in search of the springs of life.
    • Henry David Thoreau, “Walking” (1862), in The Writings of Henry David Thoreau, vol. 5, p. 209, Houghton Mifflin (1906).
  • Health is the vital principle of bliss,
    And exercise, of health.
    • James Thomson, The Castle of Indolence, Canto ii, Stanza 55. (1748).
  • Back in the 2000s, we performed a series of studies in mice and people to understand how individual bouts of exercise and exercise training affect influenza infection and vaccination, respectively. In our animal studies, we found that moderate endurance exercise (30 min/day) could protect mice from death due to influenza. Mice that exercised for longer durations (∼2.5 h/day) exhibited an increase in some illness symptoms, but there was no statistically significant difference in mortality when compared to sedentary mice. We concluded that moderate exercise could be beneficial and that prolonged exercise could be detrimental to influenza-infected mice. For obvious reasons, we have not performed this experiment in people.
    We also did a large study to determine whether 10 months of regular endurance exercise could improve influenza vaccination responses in older adults, a group that is at risk for infectious disease due to immunosenescence. We found that regular, moderate cardiovascular exercise could extend the protective effect of the annual influenza vaccination so that it maintained protective levels of antibodies throughout the entire influenza season (i.e., into March and April in the northern hemisphere). We concluded that regular moderate endurance exercise might be one way to boost the protective effect of annual influenza vaccination. It is very important for all people to receive the annual influenza vaccine.

“The Importance of Physical Activity Exercise among Older People” (2018)


Birgitta Langhammer, Astrid Bergland, and Elisabeth Rydwik; “The Importance of Physical Activity Exercise among Older People”, Biomed Res Int. 2018; 2018: 7856823.

  • PA is a protective factor for noncommunicable diseases such as cardiovascular disease, stroke, diabetes, and some types of cancer and PA is associated with improved mental health, delay in the onset of dementia, and improved quality of life and wellbeing. The health benefits of PA are well documented with higher levels and greater frequency of PA being associated with reduced risk and improved health in a number of key areas.
    The dose of PA or exercise is described by the duration, frequency, intensity, and mode. For optimal effects, the older person must adhere to the prescribed exercise program and follow the overload principle of training, i.e., to exercise near the limit of the maximum capacity to challenge the body systems sufficiently, to induce improvements in physiological parameters such as VO2max and muscular strength.
    Improvements in mental health, emotional, psychological, and social well-being and cognitive function are also associated with regular PA. Despite these health benefits, PA levels amongst older adults remain below the recommended 150 min/week. The crude global prevalence of physical inactivity is 21.4%. This translates to one in every four to five adults being physically inactive, or with activity levels lower than the current recommendations from WHO.
    • p.1
  • Participation in PA and exercise can contribute to maintaining quality of life, health, and physical function and reducing falls among older people in general and older people with morbidities in particular. The increased attention to the relationship between exercise and HRQOL in older adults over the last decade is reflected in a recent review, which showed that a moderate PA level combining multitasking exercise components had a positive effect on activities in daily living, highlighting the importance of physical, mental, and social demands. To reduce falls, balance training is also recommended to be included in physical exercise programs for older adults. Exercise has also been shown to reduce falls with 21%, with a greater efect of exercise programs including challenging balance activities for more than 3 hours/week.
    • p.2
  • Exercise training in older people has been associated with health benefits such as decreased cardiovascular mortality. Explanatory mechanism likely to be involved following exercise was a change in the cardiac autonomic balance producing an increase, or a relative dominance, of the vagal component. Furthermore, endurance exercise training in older people decreases resting and submaximal exercise heart rate and systolic and diastolic blood pressure and increases stroke volume. This is especially notable during peak effort in which stroke volume, cardiac output, contractility, and oxygen uptake are increased, while total peripheral resistance and systolic and diastolic blood pressure decreased. Thus lowering after-load in the heart muscle, which in turn facilitates left ventricular systolic and diastolic function, emphasizes the importance of high intensity training also for the elderly. E. Tamuleviciute-Prasciene et al. focus on the frail elderly individuals and exercise in their contribution “Frailty and Exercise Training: How to Provide Best Care after Cardiac Surgery or Intervention for Elder Patients with Valvular Heart Disease.”
    Exercise may also have benefits for the brain centers that support executive control. It may be that strong executive functioning in itself may facilitate consistency for this challenging activity. Poor executive control has been associated with lower self-reported PA rates over a 2-year period. The executive control's contribution to PA has been found to be 50% greater in magnitude than the contribution of PA to subsequent changes in executive control. In the paper of M. A. McCaskey et al. “Making More of IT: Enabling Intensive Motor Cognitive Rehabilitation Exercises in Geriatrics Using INFORMATION Technology Solutions,” the authors also include new technology to enhance and maintain exercise in cognitive rehabilitation.
    • p.2
  • Promoting exercise among the older population is an important public health and clinical issue. A core issue is how to get older people with comorbidities to exercise.
    • p.2

“Effect of exercise, heat stress, and hydration on immune cell number and function” (December 2002)


Joel B. Mitchell, Jonathan P Dugas, Brian K. McFarlin, and Matthew J. Nelson; “Effect of exercise, heat stress, and hydration on immune cell number and function”, Medicine & Science in Sports & Exercise, (December 2002), 34(12):

  • It is well documented that the immune system is affected by a variety of physiological and psychological stressors. Physical activity has been shown to cause disturbances in circulating white blood cell number and function that appear to be dependent on the intensity and duration of the exercise, and the associated release of stress hormones. Heat exposure is a form of physical stress in which elevations in body core temperature occur with concomitant alterations in hormonal responses and immune system function. Exercise in a thermally stressful environment represents a combination of physical stimuli that appears to have an additive effect on the hormonal and immune system disturbances. The difficulty that researchers have encountered in this area is separating the independent effects of heat exposure and exercise, as many of the immune system changes elicited by these stimuli are similar.
    • p.1941
  • To our knowledge, the interaction between exercise in a hot environment and hydration status on immune function has not been systematically studied. This question is of practical importance because the detrimental effects of severe exercise in a thermally stressful environment may be partially avoided with knowledge of the individual effects of heat and hydration on immune function. The purpose of this investigation was to determine the effects of exercise in a hot environment, in combination with exercise-induced dehydration, on circulating immune cell responses and immune cell function. Specifically, leukocyte and leukocyte subset numbers, lymphocyte proliferation, natural killer cell activity (NKCA), and O2 production by neutrophils were determined before and during recovery from 75 min of exercise in hot (38°C) and neutral (22°C) environments in both dehydrated and euhydrated conditions. It was hypothesized that the greatest disturbance in immune function would occur in the hot environment in combination with dehydration and that the other conditions would produce graded responses with the neutral environment in combination with euhydration eliciting the least disturbance.
    • p.1942
  • The primary findings of this investigation were that the fluid and environmental manipulations produced the expected differences between conditions in the body fluid balance, temperature, and cardiovascular responses; however, environment as an independent factor produced more pronounced differences in these variables than fluid manipulations. Further, there were metabolic and hormonal differences elicited by the experimental manipulations that were in proportion to the relative degree of stress imposed primarily by the differences in environment. The elevations in cell number after exercise were greatest in the hot environment for both levels of hydration; thus, hydration status did not influence the distribution of leukocytes, lymphocytes, or lymphocyte subsets. Elevations in cell function following exercise were also influenced primarily by the exposure to a hot environment with the only dehydration-induced effect being a postexercise elevation in superoxide production by neutrophils in the DH condition. The addition of a resting control condition in the hot environment would have helped in making more definitive conclusions regarding the separate effects of exercise and the hot environment.
    • p.1945
  • The current findings suggest that the combination of physical stressors stimulated the mobilization of all lymphocyte subsets to a greater extent than exercise alone. The additive effects of heat and exercise on circulating lymphocytes was also observed by Rhind et al., and others who found that exertional hyperthermia affects cell distribution via the combination of exercise and thermally induced activation of the sympathetic nervous system and the elevation of hormones associated with a generalized stress response. The significant elevation of cortisol in the EH and DH conditions would support this conclusion. Again, there was no fluid interaction; thus, the hot environment appears to be the primary mediator of the additive response with exercise.
    At 2 h postexercise, there was a significant depression in lymphocyte number that occurred in all conditions. This was driven primarily by the decreases in CD3 cells. Although this has been reported previously (12,22), it is somewhat unexpected in the EN and DN conditions because no exercise-induced elevation was observed and it could be assumed that an exercise and/or stress-induced elevation is a prerequisite to the subsequent depression. This finding suggests that exercise-induced depressions are not always tied to a preceding exercise-induced lymphocytosis.
    • p.1948

David C. Nieman and Laurel M. Went; “The compelling link between physical activity and the body's defense system”, J Sport Health Sci. 2019 May; 8(3): 201–217.

  • This review summarizes research discoveries within 4 areas of exercise immunology that have received the most attention from investigators: (1) acute and chronic effects of exercise on the immune system, (2) clinical benefits of the exercise–immune relationship, (3) nutritional influences on the immune response to exercise, and (4) the effect of exercise on immunosenescence. These scientific discoveries can be organized into distinctive time periods: 1900–1979, which focused on exercise-induced changes in basic immune cell counts and function; 1980–1989, during which seminal papers were published with evidence that heavy exertion was associated with transient immune dysfunction, elevated inflammatory biomarkers, and increased risk of upper respiratory tract infections; 1990–2009, when additional focus areas were added to the field of exercise immunology including the interactive effect of nutrition, effects on the aging immune system, and inflammatory cytokines; and 2010 to the present, when technological advances in mass spectrometry allowed system biology approaches (i.e., metabolomics, proteomics, lipidomics, and microbiome characterization) to be applied to exercise immunology studies. The future of exercise immunology will take advantage of these technologies to provide new insights on the interactions between exercise, nutrition, and immune function, with application down to the personalized level. Additionally, these methodologies will improve mechanistic understanding of how exercise-induced immune perturbations reduce the risk of common chronic diseases.
  • Although exercise immunology is considered a relatively new area of scientific endeavor with 90% of papers published after 1990, some of the earliest studies were published well over a century ago. For example, in 1902, Larrabee provided evidence that changes in white blood cell differential counts in Boston marathon runners paralleled those seen in certain diseased conditions. He also observed that “the exertion had gone far beyond physiological limits and our results certainly show that where this is the case we may get a considerable leukocytosis of the inflammatory type.”
    The immune system is very responsive to exercise, with the extent and duration reflecting the degree of physiological stress imposed by the workload.
  • The earliest exercise immunology studies (1900–1979) focused on exercise-induced changes in basic immune cell counts and function. The human immunodeficiency virus was identified as the cause of the AIDS in 1984. One of the markers for AIDS diagnosis was the CD4 antigen on helper T cells that required a flow cytometer for detection. Many medical universities acquired flow cytometers in the 1980s, and these instruments became available to exercise investigators, initiating the modern era of exercise immunology research. Another impetus was the publication of a brief review in a special issue of the Journal of the American Medical Association for the 1984 Olympic Games in Los Angeles. This review concluded there was “no clear experimental or clinical evidence that exercise will alter the frequency or severity of human infections… Further studies will be needed before it can be concluded that exercise affects the host response to infection in any clinically meaningful way.” This conclusion was consistent with the existing evidence at that time and at the same time provided a framework for future investigations. During the same time period (1980–1989), seminal papers were published with evidence that heavy exertion was associated with transient immune dysfunction, elevated inflammatory biomarkers, and an increased risk of upper respiratory tract infections (URTIs). For example, acute bouts of intense and prolonged exercise were linked by several early exercise immunology pioneer investigators to suppressed salivary immunoglobulin A (IgA) output, decreased natural killer cell (NK) lytic activity, reduced T- and B-cell function, and a 2- to 6-fold increased URTI risk during the 1–2 week postrace time period. In 1989, the International Society of Exercise Immunology was founded, leading to biannual conferences and the highly successful Exercise Immunology Review journal.
  • In general, acute exercise is now viewed as an important immune system adjuvant to stimulate the ongoing exchange of leukocytes between the circulation and tissues. An ancillary benefit is that acute exercise may serve as a simple strategy to enrich the blood compartment of highly cytotoxic T-cell and NK cell subsets that can be harvested for clinical use. Metabolically, moderate exercise induces small, acute elevations in IL-6 that exert direct anti-inflammatory effects, improving glucose and lipid metabolism over time. Another benefit may include an enhanced antibody-specific response when vaccinations are preceded by an acute exercise bout, but more research is needed with better study designs to control for potential confounding influences.
    The measurement of immune responses to prolonged and intensive exercise by athletes continues to receive high attention. Taken together, the best evidence supports that high exercise training workloads, competition events, and the associated physiological, metabolic, and psychological stress are linked to immune dysfunction, inflammation, oxidative stress, and muscle damage. NK cell and neutrophil function, various measures of T- and B-cell function, salivary IgA output, skin delayed-type hypersensitivity response, major histocompatibility complex II expression in macrophages, and other biomarkers of immune function are altered for several hours to days during recovery from prolonged and intensive endurance exercise. The contrast in the magnitude of immune responses between a 30- to 45-min walking bout and 42.2-km marathon race is summarized in These immune changes occur in several compartments of the immune system and body including the skin, upper respiratory tract mucosal tissue, lung, blood, muscle, and peritoneal cavity. Although some investigators have challenged the clinical significance and linkage between heavy exertion and transient immune dysfunction, the majority of investigators in the field of exercise immunology have supported the viewpoint that the immune system reflects the magnitude of physiological stress experienced by the exerciser.
  • Although more research is needed, preliminary data support that immune cell metabolic capacity is decreased during recovery from physiologically demanding bouts of intensive exercise, resulting in transient immune dysfunction. Immunonutrition support, especially increased intake of carbohydrate and polyphenols, has been shown to counter these exercise-induced decrements in immune cell metabolic capacity.
  • The potential linkage between prolonged, intensive exercise and increased risk for illness has been an active area of research since the 1980s. Early epidemiologic studies indicated that athletes engaging in marathon and ultramarathon race events and/or very heavy training were at increased risk of URTI. For example, in a large group of 2311 endurance runners, nearly 13.0% reported illness during the week after the Los Angeles Marathon race compared with 2.2% of control runners (odds ratio (OR) = 5.9; 95% confidence interval (CI): 1.9–18.8). Forty percent of the runners reported at least 1 illness episode during the 2-month winter period before the marathon race, and those running more than 96 km/week vs. less than 32 km/week doubled their odds for illness. A 1-year retrospective study of 852 German athletes showed that URTI risk was highest in endurance athletes who also reported significant stress and sleep deprivation. These seminal studies indicated that illness risk may be increased when an athlete participates in competitive events, goes through repeated cycles of unusually heavy exertion, or experiences other stressors to the immune system including lack of sleep and mental stress. The direct connection between exercise-induced immune changes and infection risk has not yet been established, and will require long-term studies with large cohorts. More research is needed to more clearly demonstrate the linkage between heavy exertion, illness symptoms, and pathogen-based illnesses, and the relative importance of associated factors such as travel, pathogen exposure, exercise-induced immune perturbations, sleep disruption, mental stress, and nutrition support.
  • As illness data from additional studies mounted, several athletic organizations including the International Olympic Committee (IOC) and the International Association of Athletics Federation (IAAF) initiated acute illness surveillance systems to delineate the extent of the problem and underlying risk factors. The stated goal was to improve illness prevention and treatment procedures. The IOC has also focused on the inappropriate management of both internal (e.g., psychological responses) and external loads (e.g., training and competition workloads). Load management is a key strategy, according to the IOC, to decrease illness incidence and associated downturns in exercise performance, interruptions in training, missed competitive events, and risk of serious medical complications. The wealth of acute illness epidemiologic data collected during international competition events has revealed that 2%–18% of elite athletes experience illness episodes, with higher proportions for females and those engaging in endurance events. At least one-half of the acute illness bouts involve the respiratory tract, with other affected systems including the digestive tract, skin tissues, and the genitourinary tract. Significant illness risk factors include female gender, high levels of depression or anxiety, engaging in unusually intensive training periods with large fluctuations, international travel across several time zones, participation in competitive events especially during the winter, lack of sleep, and low diet energy intake. The decrease in exercise performance after an URTI can last 2–4 days, and runners who unwisely start an endurance race with systemic URTI symptoms are 2–3 times less likely to complete the race. Paralympic athletes have unique preexisting medical conditions that predispose them to an increased risk of illness, and the incidence rate of illness is high in the Summer (10.0–13.2 episodes per 1000 athlete-days) and Winter (18.7 episodes per 1000 athlete-days) Paralympic Games.
  • Athletes must train hard for competition and are interested in strategies to keep their immune systems robust and illness rates low despite the physiologic stress experienced. The ultimate objective is to achieve performance goals with little interruption from illness and fatigue from training-induced subclinical immune dysfunction. Several training, hygienic, nutritional, and psychological strategies are recommended, and these require the coordinated involvement of the medical staff, coaches, and athletes. The medical staff should develop and implement an illness prevention program, with a focus on full preventative precautions for high-risk individuals such as female endurance athletes. Adjustments to the guidelines can be applied based on how each individual athlete responds. Here is a summary of the most important guidelines provided from consensus statements:
  • Exercise training has immunomodulating effects that may alter the cross-talk between the immune system and tumorigenesis. For example, exercise may increase intra-tumoral cytotoxic T-cell infiltration and reduce regulatory T-cell infiltration, enhance the recirculation and function of tumor-specific NK cells, and decrease inflammatory influences that support cancer cell growth.
  • The immune system is very responsive to exercise, with the extent and duration reflecting the degree of physiological stress imposed by the workload. Key exercise immunology discoveries since 1980 include the following.
  • Acute exercise (moderate-to-vigorous intensity, less than 60 min) is now viewed as an important immune system adjuvant to stimulate the ongoing exchange of distinct and highly active immune cell subtypes between the circulation and tissues. In particular, each exercise bout improves the antipathogen activity of tissue macrophages in parallel with an enhanced recirculation of immunoglobulins, anti-inflammatory cytokines, neutrophils, NK cells, cytotoxic T cells, and immature B cells. With near daily exercise, these acute changes operate through a summation effect to enhance immune defense activity and metabolic health.
  • In contrast, high exercise training workloads, competition events, and the associated physiological, metabolic, and psychological stress are linked with transient immune perturbations, inflammation, oxidative stress, muscle damage, and increased illness risk. Metabolomics, proteomics, and lipidomics have revealed that metabolism and immunity are inextricably interwoven, providing new insights on how intense and prolonged exercise can cause transient immune dysfunction by decreasing immune cell metabolic capacity.
  • Illness risk may be increased when an athlete competes, goes through repeated cycles of unusually heavy exertion, and experiences other stressors to the immune system. The wealth of acute illness epidemiologic data collected during international competition events has revealed that 2%–18% of elite athletes experience illness episodes, with higher proportions for females and those engaging in endurance events. Other illness risk factors include high levels of depression or anxiety, participation in unusually intensive training periods with large fluctuations, international travel across several time zones, participation in competitive events especially during the winter, lack of sleep, and low diet energy intake.
  • The IOC has also focused on load management of both internal (e.g., psychological responses) and external factors (e.g., training and competition workloads), and lifestyle strategies (e.g., hygiene, nutritional support, vaccination, regular sleep) to reduce illness incidence and associated downturns in exercise performance, interruptions in training, missed competitive events, and risk of serious medical complications.
  • Randomized clinical trials and epidemiologic studies consistently support the inverse relationship between moderate exercise training and incidence of URTI. These data led to the development of the J-curve model that links URTI risk with the exercise workload continuum. Several epidemiologic studies also suggest that regular physical activity is associated with decreased mortality and incidence rates for influenza and pneumonia.
  • Regular exercise training has an overall anti-inflammatory influence mediated through multiple pathways. Epidemiologic studies consistently show decreased levels of inflammatory biomarkers in adults with higher levels of physical activity and fitness, even after adjustment for potential confounders such as BMI.
  • There is increasing evidence that the circulation surge in cells of the innate immune system with each exercise bout and the anti-inflammatory and antioxidant effect of exercise training have a summation effect over time in modulating tumorigenesis, atherosclerosis, and other disease processes.
  • Recent studies indicate that exercise and physical fitness diversifies the gut microbiota, but more human research is needed to determine potential linkages to immune function in physically fit individuals and athletes.
  • The most effective nutritional strategies for athletes, especially when evaluated from a multiomics perspective, include increased intake of carbohydrates and polyphenols. A consistent finding is that carbohydrate intake during prolonged and intense exercise, whether from 6%–8% beverages or sugar-dense fruits such as bananas is associated with reduced stress hormones, diminished blood levels of neutrophils and monocytes, and dampened inflammation. Gut-derived phenolics circulate throughout the body after increased polyphenol intake, exerting a variety of bioactive effects that are important to athletes including anti-inflammatory, antiviral, antioxidative, and immune cell signaling effects.
  • Immunosenescence is defined as immune dysregulation with aging. Emergent data support that habitual exercise is capable of improving regulation of the immune system and delaying the onset of immunosenescence.

“Recovery of the immune system after exercise” (01, May 2017)


Jonathan M. Peake, Oliver Neubauer, Neil P. Walsh, and Richard J. Simpson; “Recovery of the immune system after exercise”, Journal of Applied Physiology, Volume 122, Issue 5, (01, May 2017) pp. 1077-1087

  • The notion that prolonged, intense exercise causes an “open window” of immunodepression during recovery after exercise is well accepted. Repeated exercise bouts or intensified training without sufficient recovery may increase the risk of illness. However, except for salivary IgA, clear and consistent markers of this immunodepression remain elusive.
  • The immune system is integral to the body's defense against infection. It also influences other physiological systems and processes, including [[w:tissue repair, [[w:metabolism, [[w:thermoregulation, [[sleep/fatigue, and mental health. Over the past 40 years, exercise immunology has developed into its own discipline based on the recognition that the immune system mediates many exercise effects and that stress responses mediated through the nervous and endocrine systems play a key role in determining exercise-induced immune changes. A classic paradigm in exercise immunology is that an “open window” of immunodepression can occur during recovery from intense exercise. In particular, this paradigm proposes that after intense exercise, some immune variables (e.g., lymphocyte and natural killer cell numbers and antibody production) transiently decrease below preexercise levels. As a result of this immunodepression, microbial agents, especially viruses, may invade the host or reactivate from a latent state, leading to infection and illness. If exercise is repeated again while the immune system is still depressed, this could lead to a greater degree of immunodepression and potentially a longer window of opportunity for infection.
  • Sleep disturbances influence immunity via activation of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Chronic sleep disturbance and disruption to the normal circadian rhythm are associated with inflammation and desynchronization of rhythmic immune variables. These responses likely contribute to increased risk of infection, cardiovascular disease, and cancer in shift workers. Despite evidence that athletes experience poor sleep patterns compared with nonathletes, surprisingly little is known about how sleep disturbance influences the immune responses to exercise. Compared with normal sleep, a disrupted night's sleep appears to prime the immune system and enhance immunosurveillance by stimulating total lymphocytes, CD8+ T cells, NK cells, and γδ T cells to leave the blood and migrate to potential sites of infection during the early recovery period after exercise. By contrast, other studies indicate that a night without sleep does not influence leukocyte trafficking, neutrophil degranulation, or mucosal immunity at rest or after exercise. Subtle immune changes have been observed after a night without sleep, including a shift toward a T helper 2 cytokine profile.
  • The immunomodulatory effects of carbohydrate may depend on the timing of carbohydrate intake. The ingestion of a glucose solution 15 min, but not 75 min, before 1-h high-intensity cycling prevented immunoendocrine perturbations. The lack of an effect of carbohydrates ingested 75 min preexercise was potentially associated with an insulin-induced decrease in the plasma glucose concentration before exercise, which, in turn, might have enhanced immunoendocrine responses. Carbohydrate ingestion during either the first or the second of two 90-min bouts of cycling on the same day better maintained plasma glucose and attenuated plasma stress hormone responses to the second bout. By contrast, carbohydrate ingestion during the 2-h recovery period between these exercise bouts had no such effects. These findings suggest beneficial effects of a timely carbohydrate supplementation (i.e., shortly before and/or during exercise) on immune responses to exercise. This may be particularly relevant with more prolonged and/or intense exercise protocols and when the recovery duration between two consecutive exercise bouts is short.
  • Recognizing the importance of protein for immunocompetence, there are benefits of postexercise protein ingestion or a diet high in protein on immune responses to exercise. On the basis of previous results indicating that exercise-induced lymphocyte trafficking was impaired during high-intensity training, Witard et al. examined whether a high-protein diet can restore these impaired immune responses. Consuming a high-protein diet (3 g•kg−1•day−1) helped to minimize exercise-induced changes in lymphocyte distribution during a period of intense training. Interestingly, an energy- and carbohydrate-matched normal protein diet (1.5 g•kg−1•day−1) failed to provide the same benefit. The high-protein diet was also associated with fewer self-reported upper respiratory illnesses. Another study demonstrated that protein and leucine supplementation for 1–3 h postexercise during 6 days of high-intensity training enhanced neutrophil respiratory burst activity after the last exercise session. Consuming a carbohydrate-protein solution immediately, but not 1 h, after exercise prevents a decrease in neutrophil degranulation during the postexercise recovery period.
  • Cellular immune function in response to exercise is typically assessed in isolated cells ex vivo or at the cell population level in the blood compartment. This approach can make it difficult to interpret changes in immune cell function after exercise because of the massive alterations in the cellular composition of discrete leukocyte subtypes. On the one hand, it seems intuitive to interpret lower immune cell function measured in blood during the early stages of exercise recovery as indicative of immunodepression. On the other hand, it is equally possible that after exercise, the most functional immune cells (i.e., those with effector phenotypes and high tissue-migrating potential) are redeployed to other areas of the body where they are needed. If true, this suggests that systemic immunosurveillance may be enhanced during exercise recovery, despite an apparent depressed profile in the blood compartment.
  • The validity of the original paradigm of cumulative immunodepression with repeated bouts of exercise is somewhat difficult to assess. Months of intense training increase the incidence of illness in elite athletes. However, on the basis of these studies, we can only assume, but not assert, that increased incidence of illness results from an imbalance between training and recovery. Research that has systematically manipulated the balance between training and recovery has not identified any immune variables that are consistently depressed as a result of insufficient recovery after exercise. However, with one exception, these studies have not tracked the incidence of illness after repeated bouts of exercise.
  • Pedersen et al. suggested that there is a critical threshold for exercise intensity and duration that determines the risk of immunodepression after repeated bouts of exercise. However, no studies have systematically determined the effects of repeated exercise bouts of different intensity and duration. There are also no data on the effects of repeated bouts of anaerobic or resistance/strength exercise, or a combination of different types of exercise on the same day.
  • Among various nutritional interventions that have been studied to counteract immunodepression during exercise recovery, carbohydrate supplementation has proven the most effective. A balanced and well-diversified diet that meets the energy demands in athletes and exercising individuals is certainly a key component to maintain immune function in response to strenuous exercise and intense periods of training. Additional research is warranted to investigate how the timing and pattern in the ingestion of nutrients, particularly carbohydrates and protein/amino acids, influence recovery of the immune system after exercise.
    Sleep disturbances can depress immunity, increase inflammation, and promote adverse health outcomes in the general population. However, the limited data available on how sleep disturbances influence immune responses to exercise are inconsistent.

“Exercise for the older woman: choosing the right prescription.” (1997)


J E Taunton, A D Martin, E C Rhodes, L A Wolski, M Donelly, and J Elliot; “Exercise for the older woman: choosing the right prescription.”, Br J Sports Med. 1997 Mar; 31(1): 5–10.

  • Current research on exercise and the elderly population suggests that strength training may be the exercise mode of choice for maintenance of strength, physical function, bone integrity, and psychosocial health.
    • p.5
  • Because aging muscle adapts more slowly to stress, it is essential that elderly women are encouraged to begin a lifetime change in exercise patterns to maintain or increase strength. Training benefits such as increases in strength are lost with cessation of training. For most of the population, this means a decrease in physical fitness and limitations in physical activity. However, for elderly women, the loss of strength can mean the loss of physical function, independence, and mobility.
    • pp.6-7
  • Whereas strength training has been shown to have a positive influence on function in elderly women, there is still research to be done. It remains unclear whether other forms of exercise that are popular with elderly women, such as walking, stretching, or pool exercises, will elicit the same improvements or maintenance of physical function as strength training. Clark suggested that -walking four to seven days a week may protect against lower body decline; however, other researchers have not been able to show improvements in strength, mobility, or function with walking or general land based or water based exercise programmes.
    • p.7
  • Although it is inevitable that aging produces physiological change, some of the declines in physical and mental dexterity can be retarded through exercise. It is well documented that physical activity in old age can help to sustain muscle mass and bone density. It also helps to maintain other aspects of physical fitness such as maximal aerobic power, motor performance, grip strength, "reaction time," and flexibility. However, the applicability of the improvements in the various components of fitness with functional ability remains unclear. Buchner and Wagner showed that impaired balance and decreased lower limb strength are important risk factors for the loss of physical function. Few researchers have attempted to correlate the benefits of exercise with improvements in the ability to carry out daily functional tasks. The risk factors that are generally assessed, such as smoking, hypertension, body mass index, and heart disease are not strong predictors of functional decline.
    • p.7
  • Exercise prescription for elderly people has typically focused on cardiovascular training and stretching. However, aerobic activities such as walking or running lack lateral and twisting movements and may not induce high enough strain levels to sufficiently maintain bone density.60 Further research is required to determine if an aerobically based exercise programme can be designed to include sufficient bone loading. At the present time, however, strength training seems to be the exercise mode of choice for maintaining bone integrity in elderly women.
    • p.9
  • Many healthy elderly women are at, or near to, functionally important strength related thresholds and so have either lost or are in danger of losing the ability to perform some important everyday tasks. There is much research still to be done on the influence of exercise on strength, function, bone mineral density, and psychological health in elderly women. Current research in the field has shown that there are many advantages to strength training with elderly women. The most important of these are the maintenance of bone mineral density (and the consequent reduction of hip fractures) and functional independence. However, the long term effectiveness of strength training on these variables has yet to be established. Additionally, further research is required to determine if there are other modes of exercise that can elicit the same improvements in functional dependence and bone integrity as seen with strength training.
    • p.9
  • It is a paradox for exercise prescription for elderly subjects that the types of exercise such as strength training that have shown to result in the greatest gains in strength, function, and maintenance of bone integrity are also the type most likely to cause fractures and injury. The development or exacerbation of joint symptoms with exercise is obviously a potential barrier to strength training in elderly women. Both clinicians and patients commonly think that weight bearing exercise produces joint symptoms; however, existing evidence suggests that well regulated exercise does not produce or exacerbate these problems. Although elderly women may have potential limitations for exercise and although there is a potential increased risk of injury with increased activity, the benefits of regular exercise (table) far outweigh the potential drawbacks. The positive influence of physical activity is apparent for all age groups, but the most dramatic differences in functional ability and psychological health are seen within the senior population. Sherman et al, found that women aged 75 years or older who were more active were more independent and lived longer than their inactive cohorts.
    • p.9


The report from Campbell and Turner focuses on highly fit individuals who compete in, and are accustomed to, long endurance, high-intensity events. While I believe there is merit in the evidence they provide to refute the conclusions for that population, studies where sedentary people are forced to exercise at high intensities for prolonged periods might paint a different picture. There are few such studies due to the ethics and safety concerns and there are many other variables that contribute to natural infections that would need to be accounted and controlled for in such studies. The best studies would be ones that control exercise and infectious disease exposure in people. These are difficult to ethically perform in people and it would be very difficult or impossible to get approved by institutional review boards.
  • Zhu: It seems that most studies and reviews say that the intensity of the exercises should be kept moderate. However, Campbell and Turner have recently challenged this belief and claimed that there is no harmful effect on immune function even when a vigorous bout of exercise intervention is employed. What is your view on the appropriate intensity of exercise for improving immune function?
Woods: The report from Campbell and Turner focuses on highly fit individuals who compete in, and are accustomed to, long endurance, high-intensity events. While I believe there is merit in the evidence they provide to refute the conclusions for that population, studies where sedentary people are forced to exercise at high intensities for prolonged periods might paint a different picture. There are few such studies due to the ethics and safety concerns and there are many other variables that contribute to natural infections that would need to be accounted and controlled for in such studies. The best studies would be ones that control exercise and infectious disease exposure in people. These are difficult to ethically perform in people and it would be very difficult or impossible to get approved by institutional review boards. Animal models, including ours as mentioned, may provide valuable insights into this argument and there are many studies demonstrating that prolonged, unaccustomed exercise can increase infectious disease morbidity and mortality. These studies were not reconciled in the Campbell and Turner article. However, as with all animal models, there are limitations, such as species differences, stress associated with forced exercise, the type of pathogen, and timing of exercise in relation to infection that would need to be taken into account before a firm conclusion could be drawn.

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