Growth Hormone and IGF Research 1998, Vol. 8
Y.J.H. Janssen1, J. Doornbos2, F. Roelfsema
Several studies have shown that in adult patients with growth hormone deficiency (GHD) reduced muscle mass and strength can be reversed by rhGH.
It remains unclear however whether GH influences muscle strength as expressed per muscle cross-sectional area. There are also no data available on the effect of rhGH on muscle energy store as determined by p-nuclear magnetic resonance imaging (P-NMR).
Twenty-eight male patients with GHD aged 22 to 69 years were included in the study. Patients were treated with individually adjusted doses of rhGH for one year, using a dose range of 0.6 to 1.8 IU/day. Maximal isokinetic strength (120o/s) and maximal isometric strength (45o) of the knee extensor muscle were measured with a dynamometer. In a subgroup of patients (n = 20), transverse images of the upper leg (for the determination of the quadriceps volume) and P-NMR spectra were obtained using a whole-body scanner.
Quadriceps volume, isokinetic strength, and isometric strength significantly increased after one year of rhGH treatment (P = 0.001, P = 0.001, and P = 0.055, respectively). Strength per muscle volume unit remained unchanged. No significant changes were found in PCr/ATP, P/PCr or pH during rhGH therapy.

In conclusion, our data suggest that in adults with GHD the increase in muscle strength during rhGH therapy occur as a result of an increase in muscle mass