Maximum anaerobic performance of childhood-onset GH-deficient adults

To date, physical capacity of adults with GH deficiency (GHD) has been stud ied in terms-of muscle strength, contractile properties and aerobic perform ance. As a result, scanty data are available regarding the maximum anaerobi c performance of these patients with reference to healthy controls. Therefo re, the objective of this study was to evaluate maximum anaerobic power of adults with GHD and of age-matched controls by two methods, one testing lac tacid power ((w) over cap(c)) through 15-s-maximal bout on a bicycle ergome ter, the other testing alactic power((w) over cap(i)) through a vertical ju mp on a force platform. Absolute (w) over cap(c) and (w) over cap(j) values were both found to be 35% lower(P<0.04) in GHD patients than in controls. Similarly, peak pedalling velocity (V-peak) was 21% lower (P<0.04) in patie nts. When (w) over cap(c) and (w) over cap(j) were respectively normalized for thigh and lower limb muscle plus bone volumes and V-peak for muscle len gth, differences between patients and controls were no longer significant. Furthermore, the rate of power loss during the cycling bout was similar to 35% in both groups. This observation was in line with similar delta (peak m inus baseline) lactate capillary blood concentrations, being 6.3 mM/I in pa tients and 7.5 mM/I in controls (NS). Lactacid capacity, which represents t he energy extracted from lactate metabolism, normalized for body mass was s imilar in the two groups. In conclusion, the maximum anaerobic power that c an be developed by short-statured childhood-onset GHD adults is significant ly lower in terms of absolute values, but not different from that of contro ls once appropriately normalized. Therefore, the changes in maximum anaerob ic power of GH deficient patients seem to be a consequence of their smaller muscle mass. (C) 1999 Harcourt Publishers Ltd.