Is there an association between total physical activity level and VO(2max) among fitness club members? A cross-sectional study

BACKGROUND: Since cardiorespiratory fitness is an important predictor for all-cause mortality, it is of interest to know if meeting the physical activity (PA) recommendations is associated with higher levels of maximal oxygen uptake (VO(2max)). We aimed to investigate the association between total PA level given as counts per minute (cpm) and minutes in moderate-to-vigorous PA (MVPA), and VO(2max) in new fitness club members. METHODS: A total of 62 men and 63 women (≥ 18 years), defined as healthy (no disease considered to hinder PA) participated in this study. VO(2max) (mL kg(−1) min(−1)) was measured with a cardiopulmonary exercise (modified Balke protocol), and total PA level was measured with ActiGraph GT1M for seven consecutive days. All participants accumulating ≥ 10 h of activity recordings ≥ 4 days were included in the data analysis. To examine associations between PA level and VO(2max), a Pearson correlation and a multiple linear regression analysis adjusted for covariates were used. RESULTS: VO(2max) (mL kg(−1) min(−1)) was 40.5 ± 7.2 in men and 35.1 ± 6.0 in women. Total PA level (cpm) and MVPA (min) were 352.4 ± 123.4 and 260.0 ± 132.6 in men and 361.4 ± 103.8 and 273.2 ± 137.0 in women. Total PA level (men: r = 0.346, p < 0.01, women: r = 0.267 p < 0.01) and MVPA (men: r = 0.359, p = < 0.01, women: r = 0.236, p = 0.03) was associated with VO(2max). When adjusting for age and body fat percentage, total PA level and MVPA were no longer associated with VO(2max) (men: p = 0.11 and p = 0.79, women: p = 0.40 and p = 0.61). In men, age (β = − 0.469 p < 0.01) and body fat percentage (β = − 0.483, p < 0.01) were the strongest predictor for VO(2max). For women, body fat percentage was the strongest predictor for VO(2max) (β = − 0.483, p < 0.01). CONCLUSIONS: Total PA level and MVPA were associated with VO(2max), but the association was low and diminished when adjusted for age and body fat percentage. Body fat percentage (men and women) and age (men) were more strongly associated with VO(2max) than total PA level and MVPA.