Objective: There is evidence that a sudden increase in physical activity increases the generation of oxygen free radicals, resulting in oxidative stress or damage. There is also evidence that regular, or chronic exercise increases the production of endogenous antioxidants, or free radical scavengers. In addition, certain antioxidant vitamins have been shown to protect cell membranes from free radical-induced lipid peroxidation. The most important of these antioxidants identified to date is alpha tocopherol, or vitamin E. The object of this study therefore is to determine the best combination of exercise and vitamin E that will reduce oxidative stress in older adults.
Design: Randomized, double-blinded, clinical trial with four arms, or treatment groups.
Population, Sample, Setting, Years. Sixty men and women, age 70-85 years, with no acute medical problems and able to participate in moderate aerobic exercise were recruited from a retirement community in north central Florida. Study began in October, 2000 (2-year study). To date, 46 subjects have completed the study.
Concept or Variables Studied Together or Intervention and Outcome Variables. The intervention consists of moderate intensity cardiovascular exercise and vitamin E or placebos for 16 weeks. Outcome variables include (1) serum concentrations of malondialdehyde (MDA) and lipid hydroperoxide (LHP), biomarkers of free radical-induced lipid peroxidation (that results in oxidative cellular and tissue damage), (2) cardiovascular parameters (blood pressure, resting heart rate, and oxygen consumption during sub-maximal exercise tests (VO2max), and (3) anthropometric parameters (weight and body mass index [BMI]).
Methods. 60 men and women, age 70-85 years were recruited. Following a 4-week vitamin E washout period, baseline (T-1) testing was completed and included: (1) graded treadmill exercise tests, (2) resting blood pressure and heart rate, (3) weight, height, BMI, (4) serum concentrations of alpha tocopherol ( to control for dietary intake of vitamin E and to verify that study drugs were taken as prescribed), and (5) serum concentrations of MDA and LHP. Subjects were then randomized to one of four groups: (1) exercise group taking vitamin E (n=15), (2) exercise group taking placebos (n=15), (3) sedentary control group (no exercise) taking vitamin E (n=15), and (4) sedentary control group (no exercise) taking placebos (n=15). Exercise groups underwent supervised exercise training for one hour/day, 2 days/week on treadmills, stairclimbers, and cycles, progressing in intensity from 50% to 80% of predicated maximum heart rate. Sedentary control groups were asked to not change their daily physical activity patterns. Subjects were given 400 IU vitamin E twice/day (800 IU total daily dose) or placebos. At the end of the 20-week study period, post-testing (T-2)was completed.
Findings: Study is ongoing and remains blinded, but preliminary results indicate significant improvements in VO2max, weight, BMI, resting blood pressures, and resting heart rates (p < 0.05) in the two exercise groups. The serum vitamin E levels indicate that subjects have complied very well with both the vitamin E washout periods, and with taking the study drugs. The final data analyses will be completed by July, 2002.
Conclusions: Final conclusions cannot be made until all data have been analyzed, but preliminary findings indicate significant improvements in cardiovascular fitness and body composition in older men and women resulting from moderate exercise 2 days per week. Based on previous animal studies, and on single-subject human pilot trials, we are confident that we will see significant reductions in the two biomarkers of free radical-induced lipid peroxidation of cell membranes.
Implications: The preliminary findings from this study indicate that men and women in their seventh and eighth decades can achieve improvements in both cardiovascular fitness and body composition through twice weekly moderate intensity aerobic exercise. These improvements suggest that people who exercise can maintain a higher degree of functional fitness in their later years and prolong the onset of many conditions associated with human aging. In addition, if exercise and antioxidant supplementation does in fact reduce lipid peroxidation and cellular injury as anticipated, then our knowledge of the molecular mechanisms of aging and the effects of exercise will be advanced.
Supported by NIH/NINR R-15 AREA grant NR05181
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