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Roman Deyssig, Herwig Frisch, Werner F Blum, and Thomas Waldhör

The effect of recombinant GH on strength, body composition and endocrine parameters in power athletes was investigated in a controlled study. Twenty-two healthy, non-obese males (age 23.4±0.5 years; ideal body weight 122±3.1%, body fat 10.1±1.0%; mean±sem) were included. Probands were assigned in a double-blind manner to either GH treatment (0.09U (kg BW)−1 day−1 sc) or placebo for a period of six weeks. To exclude concurrent treatment with androgenic-anabolic steroids urine specimens were tested at regular intervals for these substances. Serum was assayed for GH, IGF-I, IGF-binding protein, insulin and thyroxine before the onset of the study and at two-weekly intervals thereafter. Maximal voluntary strength of the biceps and quadriceps muscles was measured on a strength training apparatus. Fat mass and lean body mass were derived from measurements of skinfolds at ten sites with a caliper. For final evaluation only data of those 8 and 10 subjects in the two groups who completed the study were analyzed. GH, IGF-I and IGF-binding protein were in the normal range before therapy and increased significantly in the GH-treated group. Fasting insulin concentrations increased insignificantly and thyroxine levels decreased significantly in the GH-treated probands. There was no effect of GH treatment on maximal strength during concentric contraction of the biceps and quadriceps muscles. Body weight and body fat were not changed significantly during treatment. We conclude that the anabolic, lipolytic effect of GH therapy in adults depends on the degree of fat mass and GH deficiency. In highly trained power athletes with low fat mass there were no effects of GH treatment on strength and body composition.

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Stefan Riedl, Michael Kluge, Katharina Schweitzer, Thomas Waldhör, and Herwig Frisch

Objective

High altitude (HA) provokes a variety of endocrine adaptive processes. We investigated the impact of HA on ghrelin levels and the GH/IGF axis.

Design

Observational study as part of a medical multidisciplinary project in a mountainous environment.

Methods

Thirty-three probands (12 females) were investigated at three timepoints during ascent to HA (A: d −42, 120 m; B: d +4, 3440 m; C: d +14, 5050 m). The following parameters were obtained: ghrelin; GH; GH-binding protein (GHBP); IGF1; IGF2; IGF-binding proteins (IGFBPs) -1, -2, and -3; acid-labile subunit (ALS); and insulin. Weight was monitored and general well being assessed using the Lake Louise acute mountain sickness (AMS) score.

Results

Ghrelin (150 vs 111 pg/ml; P<0.01) and GH (3.4 vs 1.7 μg/l; P<0.01) were significantly higher at timepoint C compared with A whereas GHBP, IGF1, IGF2, IGFBP3, ALS, and insulin levels did not change. IGFBP1 (58 vs 47 μg/l; P<0.05) and, even more pronounced, IGFBP2 (1141 vs 615 μg/l; P<0.001) increased significantly. No correlation, neither sex-specific nor in the total group, between individual weight loss (females: −2.1 kg; males: −5.1 kg) and rise in ghrelin was found. Five of the subjects did not reach investigation point C due to AMS.

Conclusions

After 14 days of exposure to HA, we observed a significant ghrelin and GH increase without changes in GHBP, IGF1, IGF2, IGFBP3, ALS, and insulin. Higher GH seems to be needed for acute metabolic effects rather than IGF/IGFBP3 generation. Increased IGFBP1 and -2 may reflect effects from HA on IGF bioavailability.