The influence of acute treadmill exercise on natural killer (NK) cell tumor cytotoxicity in vitro was studied in elderly women after participation in a program of physical exercise training (PET) (n = 7) or after participation in a paralleling nonexercise control (NEC) condition (n = 7). The two study groups were equated (p > 0.05) according to age, percent total body fat, functional status as measured by multi-inventory ranking, and exercise capacity. After the experimental period, the PET subjects had a greater basal level of NK activity than the NEC subjects (PET 38.2 percent specific lysis, %SL, vs. NEC 28.8% SL; p < 0.05). Both groups experienced an increase in NK activity after acute treadmill exercise (PET 38.2–57.4% SL, p < 0.01; NEC 28.8–37.8% SL, p < 0.05), but the increase in the PET subjects was significantly (p < 0.05) grater than that observed in the NEC subjects. We conclude that natural cellular-mediated tumor cytotoxicity is increased in response to acute exercise and long-term PET in elderly women.

The effects of biosynthetic methionyl-human growth hormone (met-hGH) on body composition and endogenous secretion of growth hormone (GH) and insulin-like growth factor I (IGF-I) were studied in eight well-trained exercising adults between 22 and 33 yr of age. By the use of double-blind procedures, met-hGH (2.67 mg/0.5 ml diluent, 3 days/wk) and bacteriostatic water (placebo, 0.5 ml, 3 days/wk) were administered in a repeated-measures design that counterbalanced treatment order. Duration of each treatment was 6 wk. Subjects trained with progressive resistance exercise throughout and were maintained on a high-protein diet monitored by extensive compositional analyses of daily dietary intake records. Hydrodensitometry revealed that met-hGH significantly decreased percent body fat (%fat) and increased fat-free weight (FFW) and FFW/fat weight (FW), whereas the placebo treatment did not change any of these measures. Changes in FFW/FW correlated with the relative dose of met-hGH but did not correlate with either the peak GH response to L-dopa/arginine stimulation or IGF-I levels obtained after treatment with placebo. There were no differences between treatments in the dietary intakes of total kilocalories, protein, carbohydrates, and fat. Mean IGF-I levels were elevated after treatment with met-hGH compared with postplacebo levels. After treatment with met-hGH, five of seven subjects had a suppressed GH response to stimulation from either L-dopa/arginine or submaximal exercise. We conclude that supraphysiological doses of met-hGH will alter body composition in exercising adults in a relative dose-dependent manner and that such treatment may suppress endogenous release of GH in some individuals.

The effects of biosynthetic methionyl human growth hormone (met-hGH) on body composition and endogenous secretion of insulin-like growth factor I (IGF-I) were studied in obese women ranging between 138 and 226% of ideal body weight. Following double-blind procedures, 12 subjects were assigned at random to either treatment with met-hGH (n = 6, 0.08 mg/kg desirable body weight) or placebo (n = 6, bacteriostatic water diluent). Treatments were delivered intramuscularly three times per week for a period of 27–28 days. Subjects were instructed to follow a weight-maintaining diet and their pre- and posttreatment kilocaloric intake was monitored for verification. The baseline peak serum GH response to L-dopa/arginine stimulation for the study population as a whole, was in the hyposecretory range (9.6 ± 1.9 ng/ml), accompanied by a low level of circulating IGF-I (0.56 ± 0.09 U/ml). Hydrodensitometry revealed that the met-hGH-treated subjects had a significant reduction in body fat, while an observed mean increase in fat-free mass (FFM) approached significance. The percent change in body fat was unrelated to pretreatment levels of body fat, total body weight, or initial endogenous GH status. Changes in circulating IGF-I were similar to those for FFM, with increases approaching significance. There were no significant changes in body composition or IGF-I in the placebo-treated subjects. No significant differences were observed in the self-reported dietary intake of kilocalories during the experimental period between the two groups. We conclude that exogenous GH reduces body fat in obese women in the apparent absence of significant kilocaloric restriction. The effect appears to be unrelated to endogenous GH secretion or body composition.

No abstract

The effects of androgenic-anabolic steroids on neuromuscular power and body composition were studied in nine volunteers experienced with progressive-resistance weight training. By use of double-blind procedures, testosterone cypionate, nandrolone decanoate, and sesame oil (placebo) were administered in a repeated-measures design that counterbalanced treatment order. Duration of each treatment condition was 3 wk. Supplemental protein was provided, and dietary records were maintained throughout the study. Subjects were trained with progressive-resistance weight-training exercises. Isokinetic dynamometer testing revealed that peak torque output was not significantly changed between treatments in 7 out of 10 isolated-joint actions. The hydrostatic weighing results revealed insignificant differences in lean body mass and percent body fat. Significant changes in some treatment means of three peak torque output tests were insufficient to identify any consistent treatment alterations. Since protein and caloric intake was sufficient to elicit anabolic effects from the steroid treatments and weight-training program, the lack of significant results could not be attributed to dietary considerations. Subjects reported subjective feelings of increased strength after administration of anabolic agents, which may partially account for their widespread use. In conclusion, anabolic steroids did not substantially change body composition or the objective power measurements used in this study.