Impaired repletion of intramyocellular lipids in patients with growth hormone deficiency after a bout of aerobic exercise.

BACKGROUND: Ectopic lipids such as intramyocellular lipids (IMCL) are depleted by exercise and repleted by diet, whereas intrahepatocellular lipids (IHCL) are increased immediately after exercise. So far, it is unclear how ectopic lipids behave 24 h after exercise and whether the lack of growth hormone (GH) significantly affects ectopic lipids 24 h after exercise.

METHODS: Seven male patients with growth hormone deficiency (GHD) and seven sedentary male control subjects (CS) were included. VO2max was assessed by spiroergometry; visceral and subcutaneous fat by whole body MRI. 1 H-MR-spectroscopy was performed in M. vastus intermedius and in the liver before and after 2 h of exercise at 50% VO2max and 24 h thereafter, while diet and physical activity were standardized.

RESULTS: Sedentary male subjects (7 GHD, 7 CS) were recruited. Age, BMI, waist circumference, visceral and subcutaneous fat mass was not significantly different between GHD and CS. VO2max was significantly lower in GHD vs. CS. IMCL were diminished through aerobic exercise in both groups: (-11.5 ± 21.9% in CS; -8.9% ±19.1% in GHD) and restored after 24 h in CS (-5.5 ± 26.6% compared to baseline) but not in GHD (-17.9 ± 15.3%). IHCL increased immediately after exercise and decreased to baseline within 24 h.

CONCLUSION: These findings suggest that GHD may affect repletion of IMCL 24 h after aerobic exercise.