Testosterone, growth hormone and IGF-I responses to acute and chronic resistive exercise in men aged 55-70 years

B. J. Nicklas, A. J. Ryan, M. M. Treuth, S. M. Harman, Marc R. Blackman, B. F. Hurley, M. A. Rogers

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Abstract

We investigated the responses of serum testosterone (T) and human growth hormone (hGH) concentrations to a bout of heavy resistive exercise and the responses of T, hGH, and insulin-like growth factor I (ICF-I) to a 16 wk progressive resistive training program in 13 men (60 ± 4 yrs). Body composition via hydrostatic weighing and muscle strength using a 3 repetition maximum (3RM) test on 6 variable resistance exercise machines were assessed before and after the training program. Pasting blood samples were drawn on 2 consecutive days prior to training and again on 2 consecutive days after the last day of exercise. Blood was also drawn immediately before and ~ 10 min after a single exercise session during the first wk of training, and after an exercise session of the same relative resistance during the last wk of training. The training program resulted in a 37% increase in upper body strength and a 39% increase in lower body strength (both p <0.01). Lean body mass increased significantly (61.8 ± 2.1 vs 63.7 ± 7.8 kg; p <0.001) while % fat decreased (26.5 ± 1.5 vs 24.9 ± 6.0%; p <0.01) as a result of training. Serum T concentration was unchanged, but GH increased ~ 18-fold in response to a single bout of resistive exercise before (0.24 ± 0.08 vs 4.60 ± 1.35 mg/l) and after (0.26 ± 0.06 vs 4.66 ± 1.46 mg/l; p <0.01) training. Baseline serum concentrations of T, hGH, and IGF-I were unaffected by the training program. We conclude that an acute bout of resistive exercise causes a substantial hGH response in older men, but 16 wks of progressive resistive training does not affect baseline concentrations of the anabolic hormones.

Original languageEnglish (US)
Pages (from-to)445-450
Number of pages6
JournalInternational Journal of Sports Medicine
Volume16
Issue number7
DOIs
Publication statusPublished - 1995
Externally publishedYes

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Keywords

  • Human growth hormone
  • Insulin-like growth factor I
  • Strength training
  • Testosterone

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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