Search PubMed⌕ Search

Biomedical subjects

R J Shephard

Publications and source records attributed to R J Shephard.

At least 73 records · Page 4Linked to original sources
PubMed1998

Associations between physical activity and susceptibility to cancer: possible mechanisms.

Physical activity is associated with a reduced risk of all-cause and colonic cancers, and it seems to exert a weaker effect on the risk of breast, lung and reproductive tract tumours. This review examines possible mechanisms behind the observed associations. Restriction of physical activity by pre-existing disease may contribute to the association with lung cancers, but seems a less likely explanation for other types of tumour. Indirect associations through activity-related differences in body build or susceptibility to trauma seem of minor importance. Potential dietary influences include overall energy balance and energy expenditure, the intake and/or bioavailability of minerals, antioxidant vitamins and fibre, and the relative proportions of protein and fat ingested. Links between regular exercise and other facets of lifestyle that influence cancer risks are not very strong, although endurance athletes are not usually smokers, and regular leisure activity is associated with a high socioeconomic status which tends to reduce exposure to airborne carcinogens, both at work and at home. Overall susceptibility to cancer shows a 'U'-shaped relationship to body mass index (mass/height2) reflecting, in part, the adverse influences of cigarette smoking and a tall body build for those with low body mass indices and, in part, the adverse effect of obesity at the opposite end of the body mass index distribution. Obesity seems a major component in the exercise-cancer relationship, with a particular influence on reproductive tract tumours; it alters the pathways of estradiol metabolism, decreases estradiol binding and facilitates the synthesis of estrogens. Among the hormonal influences on cancer risk, insulin-like growth factors promote tumour development and exercise-mediated increases in cortisol and prostaglandin levels may depress cellular components of immune function. However, the most important change is probably the suppression of the gonadotropic axis. Apparent gender differences in the benefits associated with regular exercise reflect gender differences in the hormonal milieu and also a failure to adapt activity questionnaires to traditional patterns of physical activity in females. The immune system is active at various stages of tumour initiation, growth and metastasis. However, acute and chronic changes in immune response induced by moderate exercise are rather small, and their practical importance remains debatable. At present, the oncologist is confronted by a plethora of interesting hypotheses, and further research is needed to decide which are of practical importance.

Diet↗
PubMed1998

Immunological hazards from nutritional imbalance in athletes.

This review examines the influences of nutritional imbalance on immune function of competitive athletes, who may adopt an unusual diet in an attempt to enhance performance. A major increase in body fat can have adverse effects on immune response. In contrast, a negative energy balance and reduction of body mass are likely to impair immune function in an already thin athlete. A moderate increase in polyunsaturated fat enhances immune function, but excessive consumption can be detrimental. Since endurance exercise leads to protein catabolism, an athlete may need 2.0 g/kg protein rather than the 0.7-1.0 g/kg recommended for a sedentary individual. Both sustained exercise and overtraining reduce plasma glutamine levels, which may contribute to suppressed immune function postexercise. A large intake of carbohydrate counters glutamine depletion but may also modify immune responses by altering the secretion of glucose-regulating hormones. Vitamins are important to immune function because of their antioxidant role. However, the clinical benefits of vitamin C supplementation are not enhanced by the use of more complex vitamin mixtures, and excessive vitamin E can have negative effects. Iron, selenium, zinc, calcium, and magnesium ion all influence immune function. Supplements may be required after heavy sweating, but an excessive intake of iron facilitates bacterial growth. In making dietary recommendations to athletes, it is important to recognize that immune response can be jeopardized not only by deficiencies but also by excessive intake of certain nutrients. The goal should be a well-balanced diet.

Amino Acids↗
PubMed1998

Exercise, immune function and HIV infection.

The implications of HIV infection for exercise and sport are reviewed. HIV infection leads to impairment in a number of key elements of immune function, most obviously a progressive decline in the numbers of CD4+ T helper/inducer lymphocytes. Nevertheless, patients with early through moderately advanced HIV-1 infection can engage in moderate sport and exercise without risk to themselves or other participants; the resulting gains of aerobic power and muscle strength are similar to those observed in healthy individuals of comparable initial fitness. In fully developed AIDS, the ability to exercise may be compromised by deteriorations in cardiorespiratory and neuromuscular function. Given the impairment of resting immune function, the potential immunosuppression from very intensive bouts of competitive exercise must be avoided. Review of all published papers to date provides a relatively limited data base. During a bout of moderate physical activity, HIV seropositive individuals apparently have an impaired ability to mobilize neutrophils, NK and LAK cells into the circulation. Nevertheless, programmes of moderate training can be sustained without any large change in CD4+ count or CD4+/CD8+ ratio. In some studies, training has also attenuated psychological stress, possibly for this reason checking the anticipated fall in CD4+ count. However, further large-scale randomized and long-term studies of HIV are needed, comparing the therapeutic value of exercise alone with that of psychotherapy or a combined programme of exercise and psychotherapy.

CD4-Positive T-Lymphocytes↗
PubMed1998

Exercise without dietary restriction as a means to long-term fat loss in the obese cardiac patient.

BACKGROUND: To examine the effects of a 12-month daily walking program without dietary restriction on the metabolic rate, body composition and blood lipid profile of overweight and moderately obese patients following myocardial infarction. METHODS DESIGN: longitudinal training (preliminary study). SETTING: out-patient cardiac rehabilitation program. PARTICIPANTS: twelve consecutive volunteers (8M, 4F) with a body mass index of 25-40 kg/m2. Relative to average cardiac patients, the men but not the women were significantly heavier (100.8 vs 77.4 kg [M], 70.7 vs 74.2 kg [F]) and fatter (hydrostatic estimate of body fat 34.0% vs 23.1% [M]; 38.3% vs 36.3% [F]) than the general cardiac patient. MEASURES: body mass, hydrostatic weighing, triglycerides, total, HDL- and LDL-cholesterol, resting and peak oxygen intake, one week food intake diaries. RESULTS: Daily walking increased progressively from 20 min to 43 min over 3 months, and was then held constant for 9 months. Peak aerobic power increased 24%, from 19.9 to 24.6 ml/[kg.min] (p < 0.001). Resting oxygen intake rose from 3.1 to 3.4 ml/[kg.min], (p < 0.05). Energy intake increased from 6.10 to 6.57 MJ/day, but body mass decreased by an average of 4.5 kg (p < 0.05, 4.1 kg [M], 5.1 kg [F]), and body fat content diminished from 35.4 to 33.2% (p < 0.02, 1.8% [M], 3.2% [F]), with no change in lean body mass (57.7 vs 57.8 kg). Triglycerides diminished from 2.63 to 2.28 mmol/L (p < 0.005). Total and LDL-cholesterol also tended to change favorably (from 6.15 to 5.80 and 4.44 to 3.80 mmol/L respectively, but HDL-cholesterol was unchanged). CONCLUSIONS: A daily walking program without dietary restriction induces a favorable change in body composition and lipid profile in moderately obese cardiac patients. An exercise-induced increase of resting metabolism apparently makes an important contribution to this outcome.

Body Composition↗
PubMed1997

Spectral analysis of heart rate variability during heat exposure and repeated exercise.

This study examined indices of parasympathetic (PNS) and sympathetic (SNS) nerve activity during exposure to heat and/or two successive bouts of exercise. Seven healthy males [age = 27.1 (3.6) years; mean (SD), maximum oxygen consumption (VO2max) = 48.1 (7.6) ml x kg(-1) x min(-1)] were assigned to each of four experimental conditions according to a randomized-block design. While in a thermoneutral (23 degrees C) or heated (40 degrees C, 30% relative humidity) climatic chamber subjects performed exercise on a cycle ergometer (two 30-min bouts at approximately 50% VO2max, separated by a 45-min recovery period, (CEx and HEx, respectively) or remained seated (CS and HS, respectively) for 2 h. The R-R intervals of the subjects' ECGs were analyzed for selected near-steady-state time periods [termed Phase I (25-40 min) and Phase II (100-115 min)] according to the method of Yamamoto and Hughson (J Appl Physiol 71:1143-1150, 1991). Total (P(T)), low-frequency (P(LF) = 0-0.15 Hz) and high-frequency (P(HF) = 0.15-0.5 Hz) power spectra were calculated using coarse-graining spectral analysis. Heat exposure alone did not alter autonomic balance or levels of circulating catecholamines significantly. Exercise in both environmental conditions induced a significant decrease in an index of PNS tone (PHF:PT) [PNS indicator for CS = 0.084 (0.04) vs CEx = 0.023 (0.015) and HS = 0.065 (0.027) vs HEx = 0.015 (0.009)], with an increase in catecholamine concentrations. Although the index of SNS activity (P(LF):P(HF)) tended to rise with exercise in both environmental conditions, increments reached levels of significance only during exercise in the heat [SNS indicator for CS = 8.22 (5.58) vs CEx = 34.06 (21.73) and HS = 8.94 (5.49) vs HEx = 54.29 (49.80)]. The relative magnitudes of SNS and PNS indicators did not differ significantly between the first and second bouts of exercise. These results indicate the substantial contribution of vagal withdrawal and catecholamine secretion to the increase in heart rate that occurs during repeated moderate exercise at room temperature and the additional contribution from SNS activity during such exercise in the heat.

Adult↗
PubMed1997

The impact of heat exposure and repeated exercise on circulating stress hormones.

To determine if heat exposure alters the hormonal responses to moderate, repeated exercise, 11 healthy male subjects [age = 27.1 (3.0) years; maximal oxygen consumption, VO2max = 47.6 (6.2) ml x kg x min(-1); mean (SD)] were assigned to four different experimental conditions according to a randomized-block design. While in a thermoneutral (23 degrees C) or heated (40 degrees C, 30% relative humidity) climatic chamber, subjects performed either cycle ergometer exercise (two 30-min bouts at approximately 50% VO2max, separated by a 45-min recovery interval, CEx and HEx conditions), or remained seated for 3 h (CS and HS conditions). Blood samples were analyzed for various exercise stress hormones [epinephrine (E), norepinephrine (NE), dopamine, cortisol and human growth hormone (hGH)]. Passive heating did not alter the concentrations of any of these hormones significantly. During both environmental conditions, exercise induced significant (P < 0.001) elevations in plasma E, NE and hGH levels. At 23 degrees C during bout 1: E = 393 (199) pmol x l(-1) (CEx) vs 174 (85) pmol x l(-1) (CS), NE = 4593 (2640) pmol x l(-1) (CEx) vs 1548 (505) pmol x l(-1) (CS), and hGH = 274 (340) pmol x l(-1) (CEx)vs 64 (112) pmol x l(-1) (CS). At 40 degrees C, bout 1: E = 596 (346) pmol x l(-1) (HEx) vs 323 (181) pmol x l(-1) (HS), NE = 7789 (5129) pmol x l(-1) (HEx) vs 1527 (605) pmol x l(-1) (HS), and hGH = 453 (494) pmol x l(-1) (HEx) vs 172 (355) pmol x l(-1) (HS). However, concentrations of plasma cortisol were increased only in response to exercise in the heat [HEx = 364 (168) nmol x l(-1) vs HS = 295 (114) nmol x l(-1)]. Compared to exercise at room temperature, plasma levels of E, NE and cortisol were all higher during exercise in the heat (P < 0.001 in all cases). The repetition of exercise did not significantly alter the pattern of change in cortisol or hGH levels in either environmental condition. However, repetition of exercise in the heat increased circulatory and psychological stress, with significantly (P < 0.001) higher plasma concentrations of E and NE. These results indicate a differential response of the various stress hormones to heat exposure and repeated moderate exercise.

Adult↗
PubMed1997

What is the optimal type of physical activity to enhance health?

This review examines the potential of active daily living as a means of gaining the cardiovascular and health rewards previously sought through vigorous aerobic fitness programmes. Cross-sectional studies of occupational and leisure activity show encouraging associations between such activity and good health; in workers, the gross intensity of effort needed for health benefits has seemed to be 20 kJ/min. There has been less unanimity on the threshold intensity needed in leisure activities, but various recent "position statements" have decreased the recommendation to 50% of an individual's maximal oxygen intake, sustained for one hour three to five times per week. Life-style activities such as walking seem likely to reach this intensity in older individuals, but are unlikely to do so in young adults. A growing number of controlled longitudinal studies of walking programmes have demonstrated gains in aerobic fitness, modest reductions in blood pressure, improvements in lipid profile, increased bone density, and enhanced mood state, with less consistent reductions of body fat. However, gains have been greatest in the elderly, sedentary, and obese populations. The main component of active living, fast walking, seems likely to enhance health in such populations, but it is unlikely to be effective in young adults who are in good initial health.

Adult↗
PubMed1997

Interactions between sleep, other body rhythms, immune responses, and exercise.

Biological rhythms can influence both exercise tolerance and immune function. Most studies have focussed upon circadian rhythms, but some circaseptan, circatrigintan, and circannual cycles have also been described. Rhythms may have an endogenous or an exogenous basis. Endogenous rhythms originate in the cells of the suprachiasmatic nucleus. Impulses from this region pass to the pineal gland, where they regulate the production of melatonin, a compound that modulates the sleep/wakefulness cycle. Endocrine, physiological, and psychological parameters all show evidence of periodicity. Most components of the immune system, both cellular and humoral, also show large rhythmic changes. It is not yet clear how far such periodicity is secondary to changes in other body systems. Nevertheless, the magnitude of variation is such that it is vital to obtain experimental and control data at identical time points in both acute and chronic studies of exercise and immune function. Disturbance of the sleep/wakefulness cycle can constitute a form of stress, with adverse consequence for immune function.

Circadian Rhythm↗
PubMed1997

Circulating levels of peripheral blood leucocytes and cytokines following competitive cycling.

The objective of the study was to determine if prolonged and strenuous cycling leads to a polarized cytokine response, and/or unique mobilization of circulating leucocyte populations. Resting venous blood samples were collected from 6 amateur cyclists, 24 hr before, and at 10-25 min and 150 min after completion of a 250-km road race (race time: 404 +/- 3.5 min). Total leucocyte counts were significantly elevated following competition. Cell counts of CD3+CD8bright+ lymphocytes were depressed by 50% 150 min after competition. A significant increase in CD4+ cells expressing the IL-2R alpha chain was evident 150 min after competition. IL-6 concentrations were greatly increased, both at 10-25 min and 150 min after competition. Resting TNF-a concentrations were approximately doubled at both time points after competition. Plasma levels of IFN-gamma, IL-10 and IL-12 were below detection thresholds at all time points. These results suggest that performance of a 6.5 h competitive cycle-race does not induce a Type-1 or Type-2-dominated cytokine response, but one that is typical of a proinflammatory cytokine response.

Adult↗
PubMed1997

Physical activity and cancer: how may protection be maximized?

A series of meta-analyses have examined relationships between regular physical activity and susceptibility to various forms of cancer. Regular physical activity protects animals against cancer from a variety of sources: subcutaneous, intraperitoneal or intragastric carcinogens, intravenous infusion of tumor cells, or tumor implantation. In humans, regular exercise reduces susceptibility to all-cause cancer, colonic adenomas, colon but not rectal cancers, breast cancers, uterine tumors, prostate and testicular tumors, and possibly lung cancers. At most tumor sites, the average response of women is similar to that of men, but because of a limited number of studies, the effect in women is commonly nonsignificant. The relative effects of occupational and leisure activity are generally similar, an observation that suggests that the optimum response of cancer defense mechanisms is obtained from moderate levels of energy expenditure. In general, the data show a dose-response relationship, the risk of a sedentary lifestyle approximately doubling on passing from a moderate to a low level of habitual physical activity. To date, the findings have not demonstrated the postulated j-shaped relationship, but the cross-sectional comparison of low vs. high levels of leisure activity suggests that the adoption of an active lifestyle could reduce all-cause cancer rates by as much as 46%.

Animals↗
PubMed1997

Exercise for patients with congestive heart failure.

Congestive heart failure is a widely prevalent sequel to myocardial infarction and other chronic conditions (including ischaemia without infarction, hypertension, various infections, toxic metabolic and endocrine disorders). Exercise tolerance is severely limited; the cardiac ejection fraction is often less than 20% and the peak oxygen intake may be less than 10 ml/kg x min, with a resulting deterioration in the quality of life. Possible factors contributing to the poor tolerance of exercise include: (i) disturbances of myocardial function (damage to the ventricular wall; decreased inotropic response, mitral valve regurgitation and increased diastolic pressures); (ii) peripheral vascular factors (decreased metaboreceptor discharge, reduced vasodilator response, increased activity of sympathetic afferents and less efficient distribution of cardiac output); (iii) hormonal disturbances (increases of catecholamines, renin/angiotensin/aldosterone, antidiuretic and natriuretic factors, endothelin and decreased endothelium-relaxing factor); (iv) impaired muscle function (loss of lean tissue, increase of type II fibres, increased impedance to perfusion, enzyme changes); (v) ventilatory disturbances (increased oxygen cost of activity, pulmonary congestion, increased ventilatory drive, mismatching of ventilation and perfusion, increased anaerobic effort); and (vi) psychological factors (anxiety, depression and iatrogenic limitation of effort). The prognosis with conventional treatment is poor, but patients with stable congestive heart failure respond favourably to a progressive exercise programme. Reported gains depend on the cause of congestive failure, initial status, study duration and compliance, and the type of training programme. Most studies to date have been short term (4 to 16 weeks), and relatively few have adopted a randomised controlled design. Suggested bases for the enhancement of aerobic performance of up to 20% include an increased intensity of peak effort, an enhanced matching of ventilation to perfusion, improved cardiac function, a strengthening of skeletal muscle and an increase of aerobic enzyme activity in the muscles. A few studies have continued for a year or longer and it appears that the gains realised over the first 16 weeks of training can be sustained for this period; the quality of life is enhanced, but data are as yet insufficient to judge effects upon mortality rates. Useful clinical information can be obtained from a 6-minute walk, but the choice for more precise evaluation lies between a measurement of ventilatory threshold or peak oxygen intake. Given initial muscle wasting, prescribed exercise should include both aerobic activity and resisted muscle exercises.

Cardiovascular System↗
PubMed1997

Interactions of physical training and heat acclimation. The thermophysiology of exercising in a hot climate.

Physical training and heat acclimation are both commonly adopted tactics to improve performance and/or tolerance times when individuals must compete or work in the heat. Potential benefits include: (i) improved aerobic fitness and thus a greater cardiovascular reserve (probably seen mainly after training); (ii) a lower resting body temperature that allows greater heat storage (probably seen mainly after acclimation); (iii) a decreased energy cost of a given intensity of exercise (seen after acclimation and also as the learning component of training); (iv) an enhanced sweating response at a given percentage of maximal effort (probably developed by both treatments); (v) a slower increase in body temperature owing to (iii) and/or (iv) [seen after both treatments]; (vi) a reduced cardiovascular stress because of changes in the autonomic nervous system (probably realised mainly by training), expansion of blood volume (seen after both treatments) and/or a decreased peripheral pooling of blood (probably found after both treatments); and (vii) improved subjective tolerance reflecting a decrease in the relative intensity of a given activity (probably seen mainly after training), a reduction in the physiological strain (found after both treatments) and/or habituation to heat-exercise stress (probably developed by both treatments). Factors affecting improvements in physiological and psychological responses to a given set of conditions include: (i) the individual's initial fitness and acclimatisation to heat; (ii) age, gender, hydration, sleep deprivation, circadian rhythms and in women the menstrual cycle: (iii) use of ergogenic aids such as fluid ingestion, carbohydrate and/or electrolyte replacement and blood doping; (iv) event or test conditions such as the mode of exercise, the severity of environmental heat stress and the type of clothing worn; and (v) treatment conditions such as the intensity, duration and frequency of exercise and/or heat exposure, the length of any rest intervals and cumulative depletion of body water and minerals.

Acclimatization↗
PubMed1997

Exercise and relaxation in health promotion.

The growing size of world cities and ever more competitive working conditions are thought to cause subjective stress, anxiety and depression, with a resulting decrease in the quality of life, sleep disturbances, drug and alcohol abuse and poor productivity. Acute stress may suppress immune function, leading to an increased incidence of infections, and chronic stress may predispose to a number of ailments, including digestive disturbances, hypertension, ischaemic heart disease and neoplasia; jointly, these factors cause a substantial shortening of life expectancy. The control of stress thus makes an important contribution to health. Stress levels can be reduced by anxiolytic drugs, or by a variety of psychological techniques; however, an appropriate programme of physical activity may be the preferred option, since exercise has many positive effects on health that are unrelated to stress. If exercise is to be effective in inducing relaxation, it must be noncompetitive, moderate in intensity, and pursued in pleasant surroundings.

Brain↗
PubMed1997

Biology and medicine of sailing. An update.

The sport scientist's understanding of the biomechanics and physiology of sailing, together with its application to nutrition, training and injury prevention in the elite competitor, has continued to develop over the past decade. Very large mechanical forces are imposed in the vertical axis of the body, which give rise to frequent complaints to low back and knee pain and, occasionally, even to muscle rupture. Training programmes should emphasise the development of isometric endurance in the relevant muscle groups, such preparation continuing throughout the winter months. The oxygen cost of sailing is relatively light, and development of aerobic fitness should be advocated for reasons of general health rather than competitive success. Because of the intense muscle contractions that are developed during competition, heart rates and blood pressures are high in relation to oxygen consumption. However, during normal sailing, tacking and fluctuations of wind speed limit the development of muscle fatigue. In contrast to the operation of small craft, the crew of large ocean-going vessels may have a very high daily energy expenditure, probably related to difficulty in relaxing at any point of day or night. Windsurfers face similar physiological demands to the dinghy sailor and they also have frequent complaints of back pain. Knowledge of the relevant health issues remains limited, even among elite competitors, and there remains substantial scope for increased education of team members.

Biomechanical Phenomena↗
PubMed1997

Autoimmune disorders, physical activity, and training, with particular reference to rheumatoid arthritis.

Rheumatoid arthritis arises from a reaction of the immune system to normal body components, sometimes triggered by bacterial or viral infection. The synovia of affected joints are infiltrated by CD4+, CD19-, and plasma cells. The synovial fluid shows a sterile inflammation, with high neutrophil counts and increased concentrations of proinflammatory cytokines (particularly IL-1, IL-8, TNF-alpha and JFN-gamma). The plasma shows increased CD4+ counts and a pro-inflammatory shift in T cell populations with high titers of rheumatoid factors. Traditional treatment has included rest of the affected part, which can cause a reduction of physical condition. However, exercise induces changes in circulating immune function (including a decrease of CD4+ count) that would appear helpful in regulating inflammation. Further, there is evidence that patients can tolerate a program of regular moderate aerobic exercise. Moreover, empirical data suggest that such a prescription substantially enhances physical performance, without exacerbating either clinical or immunological markers of the disease process.

Adult↗
PubMed1997

Aging, exercise, training, and the immune system.

Human immune function undergoes adverse changes with aging, including development of a relative immune deficiency and an immune dysregulated state. The T cells show the largest age-related differences in distribution and function. The antibody production capacity of B cells also shows an age-related decline. Acute bouts of exercise modulate many immune parameters as seen in peripheral blood. With regard to NK cell activity, a single bout of moderate exercise seems to be well tolerated by the elderly, and the resting NK cell activity of elderly subjects seems to increase with training. Cross-sectional comparisons of immune status imply that habitual physical activity may enhance NK cell activity and check certain aspects of the age-related decline in T cell function. Future studies are required to clarify whether such long-term exercise and resulting improvements of immune function give rise to any beneficial effects on infections, malignancies, and autoimmune disorders.

Adult↗
PubMed1996

Impact of heat exposure and moderate, intermittent exercise on cytolytic cells.

This study examined the impact of heat exposure and moderate, intermittent exercise on the CD16+ and CD56+ cell counts and cytolytic activity. Eleven healthy male subjects [mean (SD): age = 27.1 (3.0) years, peak oxygen intake, VO2peak = 47.6 (6.2) ml. kg-1. min-1] were assigned to each of four different experimental conditions according to a randomized-block design. While in a climatic chamber maintained at a comfortable temperature (23 degrees C) or heated (40 degrees C, 30% relative humidity, r.h.), subjects performed either two 30-min bouts of cycle-ergometer exercise at approximately 50% VO2peak (separated by a 45-min recovery interval), or remained seated for 3 h. Blood samples were analyzed for CD16+ and CD56+ cell counts, cytolytic activity and the concentrations of various exercise stress hormones (norepinephrine, epinephrine and cortisol). Heat exposure alone had no significant effect on cytolytic cells. The (CD16+ and CD56+) cell count increased significantly (P < 0.0001) during each exercise bout under both environmental conditions, but returned to baseline levels 15-45 min following each exercise bout. Total cytolytic activity (determined by a standard 51Cr release assay using K562 cells) followed a similar pattern, but cytolytic activity per CD16+ or CD56+ cell was not significantly modified by exercise. Our findings show a strong association between hemodynamic factors and recruitment of cytolytic cells into the peripheral circulation. Alterations in cytolytic activity of the whole blood during and following moderate exercise seem to be the result of changes in CD16+ and CD56+ cell counts.

Adult↗