Oxidation produces free radicals, which cause peroxidation, enzyme inhibition and genetic damage in muscle cells. Genetic damage to cells and tissues caused by free radicals facilitates aging. Therefore, the functional capacity of the antioxidant system against free radicals is important to protect cells and tissues. The health benefits of regular exercise are well documented in a large number of reports. Moderate exercise can result in greater health benefits than vigorous exercise, because intense activity may generate free radicals. This is evidenced by an increase in effects such as lipid peroxidation, glutathione oxidation, and oxidative protein damage. These are regarded as an indirect sign of muscle cell damage. During exercise, increased aerobic metabolism is a potential source of free radicals (oxidative stress) in mitochondria. In muscle cells, mitochondria are one important source of reactive intermediates that include superoxides, hydrogen peroxide, and possibly hydroxyl radicals. Unfortunately, because research focusing on oxidative stress and antioxidants following exercise has up to now been narrow in scope, the mechanism linking oxidative stress and antioxidants in muscle tissue during exercise, is not fully understood. Knowledge of the mechanism of free radical formation during exercise will be useful and may lead to the prevention of oxidative stress and damage associated with physical activity. Although the capability of an antioxidant system can be estimated by measuring the content or activity of cellular superoxide dismutase isozymes, catalase and glutathione peroxidase, scavenger capacity against free radicals in muscle cells has not been investigated. Recent progress in electronics has made it possible, using electron spin resonance and a spin-trapping technique, to determine and quantify the reactive oxygen species involved in chemical reactions. Biological applications of electron spin resonance include detecting the production of free radicals and radical scavenging activity in living specimens. This review paper provides a brief account of how exercise leads to oxidative stress and the link with antioxidants, and suggests future paths of research.

This study examined the effects of weight-bearing training on frail elderly whose level of care service is "care level 1" or "support required". Thirty-seven frail elderly (67-94 years old, mean age 82.8±6.8 years, men : N=8, 67-94 years, mean age 81.5±9.8 years, women : N=29, 69-92 years, mean age 83.1±5.8 years) participated in weight-bearing training including the use of a rubber band to improve physical function and lower limb muscle strength for eight weeks. Subjects were measured by a physical fitness test before and after the training. Ninety-two percent of the subjects completed the study. There was a significant improvement in knee extension maximum strength (1 RM)(p<0.01, n=32), functional reach (p<0.01, n=30), and sit-and-reach (p<0.01). There was a significant correlation between initial fitness level and improvement value (sit and reach : r=-0.362, p<0.05, n=33, functional reach : r=-0.563, p<0.01, n=31, stand up and sit down test : r=-0.729, p<0.01, n=31, stepping : r=-0.433, p<0.05, n=33, normal walking speed : r=-0.393, p<0.01, n=34). In conclusion, these results suggest that weight-bearing training may be a feasible and effective means of preventing muscle weakness and physical frailty for frail elderly. However, it is suggested that individual training programs need to be designed considering initial level of physical fitness.

The effect of daily physical activity on oxidative stress is still an unknown issue, especially in middle-aged and elderly individuals. In this study, we examined the relationships of oxidative stress and antioxidant capacity with daily physical activity, taking into consideration the dietary antioxidant vitamin intake (vitamin B₂, C and E) of middle-aged and elderly people (66.0±7.0 years, n= 21; 10 males and 11 females, including 5 male trained runners) . Daily physical activity was measured using both a calorie counter and a questionnaire over a period of two weeks. The plasma concentration of thiobarbituric acid reactive substance ( [TBARS] ) and both oxidized and reduced glutathione concentrations ( [GSSG] and [GSH] ) in whole blood were determined in blood samples obtained at rest and immediately after two periods of acute exercise: maximal cycle ergometric exercise and steady state cycle exercise at 80% of ventilatory threshold (VT) for 30 minutes. At a given statistically controlled dietary antioxidant vitamin intake level (vitamin B₂, C and E), the amount of daily physical activity was associated with neither [TBARS], [GSH] and the ratio of [GSSG] / [GSH] at rest, nor changes in levels of these substances after both exercise tests. These data suggest that the amount of daily physical activity may have little influence on oxidative stress or antioxidant capacity at rest and after acute cycle ergometric exercise. Further investigation would be necessary to clarify how much volume or intensity of physical activity induces increased oxidative stress, from the aspect of habitual physical training and nutrition.

This study collected the questionnaire from the new participants who are middle-aged and elderly people in project of incentives led by local governments. This study focuses on the exercise group and non-exercise groups proportion of pefered incentives and the correlation of perfered incentives in these two groups. This study analyzed 9,590 middle-aged and elderly people who participated in a health promotion project with incentives and answered a questionnaire during the period of participation. The incentives were included 4 types: (1.) regional gift cards; (2.) national gift cards; (3.) rewards points that could be used at department stores and convenience stores nationwide, and (4.) donations. The result shows that both non-exercise and exercise groups preferred financial incentives over non-financial incentives. By type of monetary incentive, non-exercise group were more likely to prefer national gift certificates 1.39 times (OR: 1.39, 95%CI: 1.03-1.89); significantly more likely to prefer rewards point 1.44 times (OR: 1.44, 95%CI: 1.07-1.95) over non-monetary incentives compared to exercise group. Among the middle-aged and elderly people who participated in a health promotion program with incentives, the majority of two groups showed the preference that financial incentives over nonfinancial incentives. Comparing monetary incentives, both groups preferred local gift certificates than national gift certificates and rewards point.