Longitudinal changes in VO2max as a function of fitness training and body composition changes in women

Numerous cross-sectional studies have reported an inverse relationship between VO2,,,ax and age. However, few longitudinal investigations have compared the rate of decline in VO2,,.x between women who did or did not report exercise habits consistent with the 1990 ACSM position stand for quantity and quality of exercise. The purpose of this study was to determine if changes in exercise habits and body composition affected age-related changes in VO2.x. Subjects were 91 women (age 40.9 ± 8.8 years at baseline) tested twice between 1973 and 1996 (range of 3.1 - 21.9 years, mean interval of 9.3 ± 4.2 years). The subjects were divided into four physical activity groups based on their reported exercise habits at baseline and follow-up as: non-exercise - exercise (NE-EX; n = 21), NE-NE (n=36), EX-EX (n=19), and EX-NE (n=15). Baseline VOz,,,ax (ml-kg-1-min-1) was significantly higher for the EX vs. NE ( 38.4 ± 8.4 vs.28.8 ± 5.7; f42.2; P<.0001). ANOVA revealed significant differences between the physical activity change groups and mean percent changes in VO2. (% A ml•kg'.min'-yr') (F =10.887; P<.0001) which are listed in the following:NE-NENE-EXEX-EXEX-NE-1.081.58*-1.25-2.21* NE-EX vs. EX-NE; NE-EX vs. EX-EX; and NE-EX vs. NE-NE (P<0.05)There were differences between the following groups: NE-EX vs. EX-NE; NE-EX vs. EX-EX; and NE-EX vs. NE-NE for percent change in VO2max (nl•kg'-min 1•yr 1) with the EX-NE group having the largest decline in VO2max during the follow-up period.Using a multiple regression model after adjusting for the exercise habit groups, the exercise group scheme accounted for 27.3 percent of the variance in percent change in VO2max at step 1 of the analysis (f = 1.09; P < 0.001). Change in percent body fat and change in maximal ventilation accounted for an additional 7.2 percent and 6.5 percent of the variance at steps 2 and 3, respectively. The change in maximal heart rate accounted for an additional 2.5 percent of the variance at step 4, although the statistical significance of the contribution was low (P = 0.057). Increases in body fat and decreases in pulmonary ventilation were found associated with declines in aerobic power while a decline in maximal heart rate between the tests was associated with a decline in percent change in aerobic power.In conclusion, these data demonstrate that: 1) adoption or maintenance of a regular exercise program is associated with less decline in VO2,,. during long-term follow-up compared to women who did not exercisers, and 2) changes in exercise habits, body composition, maximal ventilation, and maximal heart rate accounted for nearly half (43 %) percent of the percent decline per year.School of Physical EducationThesis (M.S.