EFFORT TOLERANCE IN ELDERLY WOMEN WITH DIFFERENT PHYSICAL-ACTIVITY BACKGROUNDS

To study effort tolerance in elderly women with different physical act ivity backgrounds, 52 physically active (PA) and 42 sedentary control women (CO) aged 66-85 yr were assigned to perform cycle ergometer exer cise to their volitional maximum. Oxygen uptake, respiratory exchange ratio (RER), heart rare, work power, and rate pressure product were me asured to evaluate the severity of exercise. Plasma C-ANP (C-terminus of the atrial natriuretic peptide prohormone) and plasma N-ANP (N-term inus of the atrial natriuretic peptide prohormone) were analyzed as in dicators of cardiac load. Eighty-one percent (N = 42) of the PA and 52 % (N = 22) of CO performed the ergometer exercise. The mean peak oxyge n uptake was 22.6 and 15.1 mL.kg(-).min(-1) among PA and CO, respectiv ely. Twenty-two of the 42 PA and 19 of the 22 CO terminated the ergome ter exercise before attaining the objective maximum. The most common r easons for termination were the subject's own wish, abnormal cardiovas cular response, or lower limb tiredness. Both C-ANP and N-ANP increase d after exercise. The increase in plasma C-ANP correlated significantl y with a few physiological variables, whereas comparable associations with N-ANP were not found. it is concluded that inexperience of physic al exertion and medical as well as physiological factors limit effort tolerance among elderly women. Differences in the response of C-ANP an d N-ANP were found that are suggested to be due to differences in the postsecretory mechanisms between these hormones.