Plasma steroids and cardiorespiratory fitness response to regular exercise

The aim of this report is to evaluate the relationships between baseline levels of adrenal, gonadal and conjugated steroids and baseline cardiorespiratory fitness, as assessed by maximal oxygen uptake (VO₂max), as well as its response to a standardized exercise program. To address this aim we used a subset of the HERITAGE Family Study (N = 448). In men, significant positive associations were found between baseline VO₂max/kg weight and plasma levels of androsterone glucuronide (ADTG), dihydrotesterone (DHT), 17 hydroxy progesterone (OHPROG), sex hormone binding globulin (SHBG), and testosterone (TESTO), and negative association with aldosterone (ALDO). In women, only the free androgen index (FAI) was negatively associated with baseline VO₂max/kg weight. Neither baseline plasma steroid levels nor SHBG concentrations were associated with the gains in VO₂max resulting from exposure to the 20-week aerobic exercise program after adjustment for baseline values, age and ethnicity (white or black). We conclude that baseline plasma steroid levels are only weakly associated with individual differences in cardiorespiratory fitness in the sedentary state in men but not in women, whereas no association could be detected with trainability, as defined by the change in VO₂max with the exercise program.