Cardiorespiratory fitness and its association with body composition and physical activity in Hong Kong Chinese women aged from 55 to 94 years

Abstract

Background Low levels of cardiorespiratory fitness have proven to be associated with a higher risk of premature death from all causes, specifically from cardiovascular disease. However, there has been no study conducted to describe the cardiorespiratory fitness normative values in Chinese midlife and elderly. Objectives To provide normative values of cardiorespiratory fitness expressed as maximal oxygen uptake (VO 2max) and its association with body composition and physical activity in Chinese midlife and elderly women in Hong Kong. Methods 659 Chinese women aged from 55 to 94 years were recruited from two existing cohorts: the carotid atherosclerosis in women Hong Kong cohort study and the Osteoporotic Fractures in Women (MsOS) Hong Kong cohort study. Symptom-limited maximal exercise testing on an electrically braked bicycle ergometer was performed to assess VO 2max, where the subject was connected to a calibrated metabolic cart for gas analysis. Their body composition and physical activity data were also assessed. Results The body mass index was 23.4 kg/m 2 and the mean fat mass and lean body mass were 16.6 kg and 37.3 kg, respectively. The mean VO 2max was 20.3 ± 4.1 ml/kg/min (range, 7.9–35.7 ml/kg/min). VO 2max decreased with age, with the rate of decline 0.25 ml/kg/min/yr (7.1% per decade). In a subgroup of 475 women from the MsOS study, the decline in VO 2max was found to depend on ageing ( β = 0.31, P < 0.001), body mass index ( β = −0.30, P < 0.001) and levels of physical activity ( β = 0.02, P < 0.001). Fat mass was also independently associated with VO 2max ( β = −0.20, P < 0.001). Conclusions This study describes the normative values of VO 2max in a sample of Chinese midlife and elderly women which provides a valuable reference to assess health and fitness in Chinese elderly. Results from this study also suggested that body composition and levels of physical activity were important determinants of the age-related decline in VO 2max.