Effect of physical exercise in daily life on the aging process in healthy women in terms of aerobic capacity, serum lipid concentration, body composition and bone mineral density

Abstract

A cross-sectional study was carried out to investigate the effect of physical exercise in daily lives of healthy women on the aging process in terms of maximal aerobic capacity (V̇O2max), body fat tissue mass (FTM). lean tissue mass (LTM), bone mineral density (BMD), serum triglyceride (TG), total cholesterol (TC), HDL-C and LDL-C concentrations, and systolic (SBP) and diastolic blood pressure (DBP). These parameters are considered as risk factors of cerebrovascular disease and/or osteoporosis, which are the main causes of becoming bedridden and demented in middle-aged and older women. One hundred sixty-five healthy female volunteers aged 20 to 76 years participated in the study, 82 of whom were postmenopausal with a mean age at menopause of 49.7±3.1 years. Eighty-two of the subjects had been exercising regularly by jogging, swimming, aerobic dancing, or playing tennis more than twice a week for 2 years (Ex group), whereas 83 individuals had not been engaging in regular exercise (Cont group). Serum lipid concentrations, SBP and DBP measurements at rest and treadmill V̇O2max and HRmax measurements were determined in the morning after an overnight fast. Whole-body BMD (TBMD), head, lumbar, arm and leg BMD, FTM and LTM were measured by dual-energy X-ray absorptiometry one to two hours after a light lunch. The mean and SD of each measurement were calculated for five-year age groups between 40 and 60 years and one group each under 40 and over 60 years. The results were as follows : 1. V̇O2max (r = -0.590) and HRmax (r = - 0.632) decreased significantly with age. The V̇O2max of the Ex group was significantly higher than that of the Cont group in all each age groups. However, no differences in the aging process in terms of HRmax were found between the two groups. 2. Resting SBP (r= -0.391) and DBP (r = 0.315) increased significantly with age. However, no hypertensive individuals (160/95 mmHg∼) were found among the 165 subjects. 3. Only serum TC (r = 0.346) and LDL-C (r = 0.339) among the blood constituents measured changed with age. No changes in serum HDL-C were detected with age. Lower TC (189.2 ± 23.3 mg/dl) and higher HDL-C (72.2 ± 10.9 mg/dl) were observed in eleven runners (49.7 ± 7.7years) among the subjects who participated frequently in official races than in subjects of the same ages in the Cont group. The highest serum HDL-C (75.8 ± 15.8 mg/dl) and HDL-C/TC ratios (0.362) were noticed among the subjects (n = 26) who both regularly exercised and consumed alcoholic beverages. 4. A tendency for FTM to increase and LTM to decrease with age were observed in both groups, and a lower %FTM (percentage of FTM to body weight) and higher %LTM were evident in the Ex group. Differences in %FTM and %LTM between the Ex and Cont groups at 40-45 years were significant. 5. Partial and whole BMDs decreased significantly with age (TBMD-Age ; r = -0.527). Significantly higher leg BMDs in both the 20 - 39-year and 40 - 45-year groups, and spine and TBMD in the 20 - 39 years in the Ex group, who were premenopausal women, were shown. No significant differences in BMDs between the two groups were observed in postmenopausal women, but the Ex group tended to have higher partial and whole BMDs. The postmenopausal official race runners (n = 5, 52.6 ± 1.5 years) also had higher TBMD and leg BMD values than subjects of the same ages in the Cont group. 6. Investigation of correlations between V̇O2max. LTM, FTM, BMDs and serum lipid concentrations, yielded a significantly higher correlation (r = 0.669) between LTM (kg) and absolute V̇O2max (l/min). Although V̇O2max per LTM (V̇O2max/LTM) decreased with age (r = -0.595), V̇O2max/LTM in the Ex group was significantly higher than in the Cont group in each age group. The V̇O2max per body weight (ml/kg/min) was negatively correlated with %FTM (r = -0.442) and positively correlated with %LTM (r = 0.422). There were no correla-tions between V̇O2max and serum TC levels or HDL-C concentrations. BMD was strongly correlated with body weight, especially LTM, in addition to the aging process. V̇O2max per body weight was not always highly correlated with TBMD (r = 0.354, p < 0.001). Stepwise multiple regression analysis yielded the following regression equations : TBMD(g·cm-2) = 0.9525 - 0.0045 × Age + 0.0059 × FTM (kg) + 0.0072 × LTM (kg) V̇O2max(ml·kg-1·min-1) = 47.97 - 0.391 × Age + 0.175 × LegBMD - 0.531 × %FTM (%) All of the partial regression coefficients in the above two equations were significant at the 0.001 level. These results indicate that the present exercise program contributes to improving V̇O2max. the maximal oxidative ability of muscle (V̇O2max/LTM) and muscle mass (LTM), but that it is extremely difficult for postmenopausal women to prevent the decrease in BMDs or to improve the increases of the serum lipid concentrations during the aging process by the present exercise program. Severer exercise and dietary regimens may be required to improve BMDs and serum lipid concentrations in postmenopausal women. However, based on the positive correlations between V̇O2max per body weight and both BMDs and %LTM, maintenance of higher V̇O2max levels by a physically active life style may prevent the decreases in bone and muscle mass with aging. Physical exercise in daily life may therefore contribute to improving and/or excluding the risk factors of the causes of becoming bedridden and demented in older women.