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WEIGHT-LIFTING
- BODY-BUILDING |
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It is well known that moderate exercise,
as opposed to strenuous exercise, can significantly improve
one’s health and make life longer. Different studies
have attempted to show how exactly exercise affects one’s
health. The credit to physical activity is given for various
effects, for example for it’s ability to relieve
stress, lower blood pressure, and increase the level of
endorphins (brain hormones that increase the feeling of
happiness and well-being and also reduce the amount of
fat); physical activity increases the fat burning enzymes
in the muscles and helps you stay fit and maintain weight
loss; it strengthens heart muscles and improves circulation
of blood thereby reducing the risk of heart disease; it
reduces the level of glucose and cholesterol in blood and
calcium in bones (the cause of osteoporosis); it improves
your respiratory system, strengthens your lungs and helps
to control asthma; finally, it creates the feeling of self-confidence
and control over one’s body and life. Mainly due
to all these benefits of moderate exercise, physical activity
is considered to be essential for those who want to prolong
their life span. Several extracts from the studies that
show the correlation between moderate physical activity,
on the one hand, and the risk of some major diseases and
all-cause mortality, on the other, can be found below. |
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Cooper Institute for Aerobics Research, Dallas, Texas 75230, USA.
We studied physical fitness and
physical activity in relation to all-cause and cancer
mortality in a cohort of 7080 women and 25,341 men
examined at the Cooper Clinic in Dallas, Texas, during
1970 to 1989. Physical fitness was assessed at baseline
by a maximal treadmill exercise test, while physical
activity was self-reported on the attendant health
habits questionnaire. Both men and women averaged about
43 years of age at baseline (range, 20 to 88 years),
and they were followed for approximately 8 years on
average. Through the end of 1989, the women contributed
52,982 person-years of observation and incurred 89
deaths, including 44 deaths due to cancer. The men
contributed 211,996 person-years and incurred 601 deaths,
with 179 due to cancer. After adjustment for baseline
differences in age, examination year, cigarette habit,
chronic illnesses, and electrocardiogram abnormalities,
we found a strong inverse association between risk
of all-cause mortality and level of physical fitness
in both men and women (P for trend < 0.001). Physically
active men also were at lower risk of all-cause mortality
than were sedentary ones (P for trend = 0.01). Among
women, however, self-reported physical activity was
not significantly related to risk of death from all
causes. The risk of mortality from cancer declined
sharply across increasing levels of fitness among men
(P for trend < 0.001), whereas among women the gradient
was suggestive but not significant (P for trend = 0.07).
Physically active men also were at lower risk of death
from cancer than were sedentary men (P for trend =
0.002), but among women physical activity was unrelated
to cancer mortality.
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Tokyo Gas Health Promotion Center.
This study was conducted to examine the relationship between physical fitness and all-cause mortality in Japanese men. We evaluated the physical fitness and risk for all-cause mortality of 9,986 Japanese men who were given a submaximal exercise test and a medical examination between 1982 and 1984. Physical fitness was measured using a bicycle ergometer test, and maximal oxygen uptake was estimated. The average follow-up time was 14 years, for total of 139,836 person-years of observation. There were 247 deaths during the observation period. The relative risk and 95% confidence intervals (95% CI) for all-cause mortality were obtained using the Cox proportional hazards model. Following age adjustment, and using the lowest physical fitness (quintile I) group as a reference, the hazard ratios for quintiles II through V were, 0.54 (0.39-0.77), 0.66 (0.47-0.94), 0.58 (0.39-0.86), and 0.46 (0.27-0.78), respectively. After being adjusted for age, body mass index, hypertension, and urinary protein, the hazard ratios were, 0.52 (0.37-0.73), 0.60 (0.42-0.87), 0.50 (0.33-0.75), and 0.39 (0.22-0.67), respectively. The results presented here support the hypothesis that a low level of physical fitness in an important risk factor for all-cause mortality in Japanese men.
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Department of Kinesiology, University of Illinois at Urbana/Champaign, 906 South Goodwin Avenue, Urbana, Illinois 61801, USA.
Many strategies have been used to improve immune function in the aged. Unfortunately, many of these interventions have been disappointing, impractical, costly to develop and administer, or accompanied by adverse side effects. Aside from dietary manipulation (caloric restriction without malnutrition or antioxidant supplementation), research involving behavioral preventative or restorative therapies has been lacking. Moderate exercise training has been shown to elicit beneficial outcomes in both the prevention and rehabilitation of many diseases of the elderly. It has been hypothesized that moderate levels of exercise improves, whereas strenuous exercise or overtraining suppresses, various immune function measures. Three general approaches have been implemented to study the impact of exercise on immune functioning in the elderly: (1) cross-sectional studies, (2) longitudinal studies, and (3) animal studies. In general, cross-sectional studies examining highly active elderly have demonstrated improved in vitro T cell responses to polyclonal stimulation when compared to sedentary elderly. This is corroborated by several animal studies that have shown improved splenic T cell responses in vitro. Unfortunately, human prospective studies have failed to demonstrate consistent improvements in various measures of immune function in older adults. However, it should be cautioned that these studies have included small samples followed over a short duration, measuring a limited number of in vitro immune parameters, with some failing to account for potential confounding influences. Although such findings have the potential to be of substantial public health importance, very few systematic studies have been conducted.
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Division of Epidemiology, Cooper Institute for Aerobics Research, Dallas, TX 75230.
Physical inactivity is associated with higher mortality rates in most studies in men, but studies in women are more equivocal. The purpose of this study was to evaluate the relationship of sedentary living habits to all-cause mortality in women. A group of 3,120 adult women completed a preventive medical examination, and were followed for approximately 8 years for mortality. There were 43 deaths and a total of 25,433 person-years observed during follow-up. Physical fitness was assessed at baseline by a maximal exercise test on a treadmill, and physical activity was estimated by a self-administered questionnaire. Age-adjusted all-cause mortality rates were significantly inversely associated with physical fitness. Death rates were 40, 16, and 7 per 10,000 person-years of follow-up across low, moderate, and high categories of physical fitness, respectively. However, death rates did not differ across low, moderate, and high categories of physical activity. These findings are different than for men in the same study, where both physical activity and physical fitness were inversely associated with mortality risk. We attribute the lack of association between physical activity and mortality in women to be due to inadequate assessment of activity, and that this also is the likely explanation for the difference in results between women and men.
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Arbejdsmedicinsk klinik, Rigshospitalet, Kobenhavn.
Physical activity in leisure time and physical fitness are strongly correlated, and both are inversely correlated to risk of ischaemic heart disease (IHD). Does it mean, however, that a very fit man has a lower risk of IHD, even if he is inactive? And does it also mean that an unfit, but active man, does not have a lower risk of IHD than an unfit sedentary man? In The Copenhagen Male Study we studied the joint effect of physical activity in leisure time and physical fitness. In 1970/71 4,999 men free from IHD aged 40-59 years were classified according to level of physical activity, and to level of physical fitness, ie indirectly measured maximal oxygen uptake, and their mortality was recorded over the next 17 years. In sedentary men, fitness was no predictor of risk of death from IHD. Age-adjusted baseline values were similar in later IHD cases and survivors: 32.3 versus 32.1 ml O2 x kg-1 x min-1, p = 0.91. In medium and highly active men, however, fitness was a strong predictor. The corresponding fitness values were: 33.1 versus 34.8 ml O2 x kg-1 x min-1, p < 0.001. The least fit physically active men had a lower IHD mortality rate (6%) than the least fit sedentary men (10%). Adjusted for age, social class, and smoking in a multiple logistic regression equation, this was estimated to a RR(95% C.I.) of RR = 1.7 (1.1-2.6), p = 0.03.(ABSTRACT TRUNCATED AT 250 WORDS)
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Department of Kinesiology, Interdisciplinary Nutritional Science, and Institute on Aging, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Maintaining mobility is a critical element for the quality of life. Skeletal muscle, the primary organ for locomotion, undergoes age-associated deterioration in size, structure, and function. Recent research suggests that oxidative stress is an important etiology for sarcopenia. The level of oxidative stress imposed on aging muscle is influenced by two fundamental biological processes: the increased generation of reactive oxygen species (ROS) and age-associated changes in antioxidant defense. It appears that despite increased ROS production, aging muscle has a decreased gene expression of antioxidant enzymes possibly due to a diminished ability for cell signaling. A major benefit of nonexhaustive exercise is to induce a mild oxidative stress that stimulates the expression of certain antioxidant enzymes. This is mediated by the activation of redox-sensitive signaling pathways. For example, gene expression of muscle mitochondrial (Mn) superoxide dismutase is enhanced after an acute bout of exercise preceded by an elevated level of NF-kappaB and AP-1 binding. An increase in de novo protein synthesis of an antioxidant enzyme usually requires repeated bouts of exercise. Aging does not abolish but seems to attenuate training adaptations of antioxidant enzymes. Thus, for senescent muscle, training should be assisted with supplementation of exogenous antioxidants to research the optimal level of defense.
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Department of Primary Health Care, Goteborg University, Sweden.
In 1968-1969, a population-based sample of Swedish women aged 38-60 years was recruited for a health survey, and 20-year survival was later ascertained from national registries. Occupational and leisure-time physical activity data from the baseline and 6-year follow-up examinations were evaluated in relation to all-cause mortality among 1,405 women who were initially free of major diseases. In comparison with being inactive, the mortality relative risk associated with being somewhat active was 0.28 (95% confidence interval 0.17-0.46) for occupational activity and 0.56 (95% confidence interval 0.39-0.82) for leisure-time activity. Being in the most active occupational or leisure activity category further decreased mortality risk to a minor extent. A within-subject decrease in leisure activity over 6 years was also a significant risk factor for all-cause mortality (relative risk = 2.07, relative to no change), although there was no evidence of a benefit from increasing physical activity levels. Since exclusion of early endpoints did not affect the associations in any significant way, underlying illness is unlikely to have played a major role in these analyses. It is concluded that decreases in physical activity as well as low initial levels are strong risk factors for mortality in women, and that their predictive value persists for many years.
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Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, 181 Longwood Ave, Boston, MA 02115, USA
OBJECTIVES: This study examined the association between recreational physical activity and mortality in middle-aged and older women and the possibility that physical activity serves as an important marker of health. METHODS: Analyses were conducted among participants in the Nurses' Health Study. Levels of physical activity were assessed by questionnaire in 1980 and updated every 2 to 4 years. RESULTS: Levels of physical activity were inversely associated with mortality risk; however, each activity level above the reference level had approximately the same level of risk reduction (20%-30%). The inverse association was stronger for cardiovascular deaths than for cancer deaths and was strongest for respiratory deaths. Women who died of noncardiovascular, noncancer causes were more likely to have reported that poor health limited their physical activity than were women who died of other causes or who remained alive. CONCLUSIONS: Part of the link between physical activity and mortality risk is probably spurious and difficult to remove analytically; however, on the basis of epidemiologic evidence, much of the health benefit of activity is real.
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Division of Epidemiology, Cooper Institute for Aerobics Research, Dallas, TX 75230, USA.
OBJECTIVE--To evaluate the relationship between changes in physical fitness and risk of mortality in men. DESIGN--Prospective study, with two clinical examinations (mean interval between examinations, 4.9 years) to assess change or lack of change in physical fitness as associated with risk of mortality during follow-up after the subsequent examination (mean follow-up from subsequent examination, 5.1 years). SETTING--Preventive medicine clinic. STUDY PARTICIPANTS--Participants were 9777 men given two preventive medical examinations, each of which included assessment of physical fitness by maximal exercise tests and evaluation of health status. MAIN OUTCOME MEASURES--All cause (n = 223) and cardiovascular disease (n = 87) mortality. RESULTS--The highest age-adjusted all-cause death rate was observed in men who were unfit at both examinations (122.0/10,000 man-years); the lowest death rate was in men who were physically fit at both examinations (39.6/10,000 man-years). Men who improved from unfit to fit between the first and subsequent examinations had an age-adjusted death rate of 67.7/10,000 man-years. This is a reduction in mortality risk of 44% (95% confidence interval, 25% to 59%) relative to men who remained unfit at both examinations. Improvement in fitness was associated with lower death rates after adjusting for age, health status, and other risk factors of premature mortality. For each minute increase in maximal treadmill time between examinations, there was a corresponding 7.9% (P = .001) decrease in risk of mortality. Similar results were seen when the group was stratified by health status, and for cardiovascular disease mortality. CONCLUSIONS--Men who maintained or improved adequate physical fitness were less likely to die from all causes and from cardiovascular disease during follow-up than persistently unfit men. Physicians should encourage unfit men to improve their fitness by starting a physical activity program.
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Prevention Center, School of Public Health, University of South Carolina, Columbia 29208, USA.
PURPOSE: A cohort of middle-aged and older men and women were followed for an average of 5.5 yr to examine the association between physical fitness, physical activity, and the prevalence of functional limitation. METHODS: The participants received medical assessments between 1980 and 1988 and responded to a mail-back survey regarding functional status in 1990. RESULTS: Among 3495 men and 1175 women over 40 yr of age at baseline, 350 (7.5%) reported at least one functional limitation in daily or household activities at follow-up. The prevalence of functional limitation was higher among women than men. Physically fit and physically active participants reported less functional limitation than unfit or sedentary participants. After controlling for age and other risk factors, the prevalence of functional limitation was lower for both moderately fit (odds ratio = 0.4, 95% CI = 0.2-0.6) and high fit men (odds ratio = 0.3, 95% CI = 0.2-0.4), compared with low fit men. Corresponding figures for women were 0.5 (0.3-0.7) and 0.3 (0.2-0.5) for moderately fit and high fit women. The association between physical activity and functional limitation was similar to the data for physical fitness. CONCLUSIONS: These data support a protective effect of physical fitness and physical activity on functional limitation among older adults and extend this protective effect to middle-aged men and women.
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Division of Kinesiology, University of Michigan, Ann Arbor.
Early studies agree that fasting is detrimental to overall physical performance and to endurance performance in humans; however, a study in rats reported an ergogenic effect where time to exhaustion was increased by a glycogen-sparing effect of elevated free fatty acids in blood resulting from a 24-hour fast. Later studies on humans have also found a detrimental effect of fasting on exercise endurance, with the exception of 1 study which found no difference. The discrepancy between humans and rats could not be explained by level of glycogen sparing, mode of exercise, duration of the fast, physiological differences or level of training. The intensity of exercise, and a potential placebo effect of fasting, are possible reasons for the conflicting results. Despite reduced endurance performance, fasted humans are able to exercise and maintain blood glucose homeostasis; the specific cause of an earlier onset of fatigue during a single bout of exercise in the fasted state remains uncl ear.
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Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
Food restriction increases maximal life span in rodents. Male rats that exercise in voluntary running wheels do not have an increase in maximal longevity despite a relative caloric deficit. In contrast, sedentary rats that are food restricted so as to cause the same caloric deficit have an extension of maximal longevity. It seemed possible that exercise-induced oxidative stress might prevent a maximum life span-extending effect of a caloric deficit to manifest itself. This study was done to determine if antioxidants would allow a maximal longevity-extending effect of exercise to manifest itself in male rats. The antioxidant diet had no effect on longevity of the runners (Antiox., 951 +/- 158 days versus control 937 + 171 days), or of the sedentary controls (875 +/- 127 versus 858 +/- 152 days). As in previous studies, wheel running modestly increased average longevity (approximately 9%), but had no effect on maximal life span. The finding that antioxidants had no effect on longevity of the wheel runners supports the interpretation that the caloric deficit induced by exercise in male rats does not have a life-extending effect that is countered by oxidative tissue damage.
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Department of Veterinary Clinical Sciences, Veterinary Teaching Hospital, The Ohio State University, Columbus 43210, USA.
OBJECTIVES: To determine effects of dietary antioxidant supplementation on plasma concentrations of antioxidants, exercise-induced oxidative damage, and resistance to oxidative damage during exercise in Alaskan sled dogs. ANIMALS: 62 Alaskan sled dogs. PROCEDURE: Dogs were matched for age, sex, and ability and assigned to 1 of 3 groups: sedentary and nonsupplemented (control [C]; n = 21), exercised and supplemented (S; 22), and exercised and nonsupplemented (N; 19). Dogs in group S were given 400 units of alpha-tocopherol acetate, 3 mg of beta-carotene, and 20 mg of lutein orally per day for 1 month, then dogs in groups S and N completed 3 days of exercise. Blood samples were collected before and after 1 and 3 days of exercise and after 3 days of rest. Plasma antioxidant concentrations were determined, and oxidative damage to DNA (plasma 7,8 dihydro-8-oxo-2'deoxyguanosine [8-oxodG] concentration) and membrane lipids (plasma hydroperoxide concentration) and resistance of plasma lipoproteins to oxidation were assessed. RESULTS: Supplementation increased plasma concentrations of alpha-tocopherol, beta-carotene, and lutein. Plasma concentration of alpha-tocopherol increased and concentration of lutein decreased in group S with exercise. Concentration of 8-oxodG decreased in group S but increased in group N during and after exercise. Lag time of in vitro oxidation of lipoprotein particles increased with exercise in group S only. Dietary supplementation with antioxidants resulted in increased plasma concentrations of antioxidants. Moreover, supplementation decreased DNA oxidation and increased resistance of lipoprotein particles to in vitro oxidation. Antioxidant supplementation of sled dogs may attenuate exercise-induced oxidative damage.
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