Yarasheski, K. E., Campbell, J. A., Smith, K., Rennie, M. J., Holloszy, J. O., & Bier, D. M. (1992). Effect of growth hormone and resistance exercise on muscle growth in young men. American Journal of Physiology - Endocrinology and Metabolism, 262, E261-E267.

This study determined whether growth hormone administration enhanced muscle anabolism associated with heavy-resistance exercise. Men were assigned randomly to a resistance training plus growth hormone group (N = 7) or to a resistance training plus placebo group (N = 9). For 12 weeks, both groups trained all major muscle groups in an identical fashion while receiving 40 mg/kg/day of recombinant human growth hormone or placebo.

Fat-free mass and total body water increased in both groups but more in the growth hormone Ss. Whole body protein synthesis rate increased more, and whole body protein balance was greater in the growth-hormone group, but quadriceps muscle protein synthesis rate, torso and limb circumferences, and muscle strength did not increase more than in the placebo group. The larger increase in fat-free mass with growth hormone treatment was probably due to an increase in lean tissue other than skeletal muscle. Resistance training supplemented with growth hormone did not further enhance muscle anabolism and function.

Implication. Growth hormone supplementation does not enhance strength. Its effect on free-fat mass body structure is on most tissues with only a minor portion of those changes being muscle. Resistance training without growth hormone is just as effective as with it.

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