Basal concentrations and acute responses of serum hormones and strength development during heavy resistance training in middle-aged and elderly men and women.
Level 3 - non-randomized controlled study
Prospective non-randomized cohort study with a 1-month pre-intervention control period
PubMed 10737684 · doi:10.1093/gerona/55.2.b95
What was done
Four groups—10 middle-aged men (42 ± 2 years), 11 middle-aged women (39 ± 3 years), 11 elderly men (72 ± 3 years), and 10 elderly women (67 ± 3 years)—completed a 1-month non-training control period followed by 6 months of heavy resistance training combined with explosive exercises. Investigators measured knee extensor 1-repetition maximum (1RM), maximal integrated electromyography (iEMG) of the vastus lateralis and medialis, and both basal and acute exercise-induced serum concentrations of total and free testosterone, growth hormone (GH), DHEA, DHEAS, cortisol, and SHBG.
What was found
During the 1-month control period, 1RM strength and iEMG were unaltered. Over 6 months of training, 1RM knee extension increased by 27 ± 9% in middle-aged men (p < .001), 16 ± 6% in elderly men (p < .001), 28 ± 11% in middle-aged women (p < .001), and 24 ± 10% in elderly women (p < .001), accompanied by significant increases in vastus lateralis and medialis iEMG across all groups (p < .05–.001). Basal concentrations of total and free testosterone, DHEA, DHEAS, GH, cortisol, and SHBG showed no systematic group-level changes. Individual baseline free testosterone in elderly women correlated with strength gains (r = 0.55, p < .05), as did total testosterone across all women (r = 0.43, p < .05). Acute exercise bouts significantly elevated total and free testosterone in both male groups (p < .05–.01) but not in women, while acute GH increased in all groups (p < .05–.01) except elderly women.
Why it matters
The study shows that older adults retain substantial capacity for neural adaptation and maximal strength gains from heavy resistance training despite an absence of resting endocrine changes and attenuated acute hormonal responses in older women.
Limits
Sample size was small (10 to 11 participants per subgroup), limiting statistical power for subgroup endocrine comparisons and correlational findings. The study lacked a concurrent randomized non-exercising control group over the 6-month training phase, relying instead on a 1-month run-in control period. Long-term functional clinical outcomes beyond 1RM and iEMG were not assessed.
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