EXERCISE TOLERANCE IN ADULTS WITH GROWTH HORMONE DEFICIENCY 1601

Abstract

Aim of the study was to investigate the exercise tolerance in subjects with adult onset of growth hormone deficiency (GHD) for at least 24 months, who received optimal conventional pituitary hormone replacement therapy. Ten male(M) and 9 female (F) GHD subjects (mean (range)) age 45.9 (24-68)yrs, height 172 (160-185)cm, body weight 72.2 (56.8-98.6)kg, BMI 24.4(19.9-36.7)kg/m2, FFM 51.3 (36.3-64.1)kg, underwent an incremental cycle ergometer test up to exhaustion for assessing (mean±SD) maximal power output (F: 120±23, M: 170±24 Watt),˙VO2max (F: 1656±294, M: 2396±312 ml/min), maximal heart rate (F: 172±19, M: 174±14 bpm) and maximal blood lactate (F: 6.8±2.1, M: 8.3±2.9 mmol/l).˙VO2max was compared with values from predictive equations, used for healthy, sedentary men and women separately. Assuming that˙VO2max declines proportionally with age, and varies exponentially with height (Jones 1988), the predicted˙VO2max (F: 1740±199, M: 2562±436 ml/min) was higher than measured (p=0.06, pooled data, Wilcoxon test). However, the prediction of ˙VO2max from height and age only in overweight(F: n=6, M: n=2), and otherwise from weight and age (Wasserman et al., 1987), showed no significant differences between predicted ˙VO2max(F: 1643±150, M: 2336±370 ml/min) and measured values (p=0.18, pooled data). It is concluded that the exercise tolerance for leg cycling in female GHD adults is 70% of that of male GHD subjects. Furthermore, GHD adults showed a reduced maximal blood lactate level and exercise tolerance is not impaired when predictive equations are used, taking into account the fact that not all GHD subjects are overweight, in spite of their disturbed body composition.