Short-Term Exercise Training Inconsistently Influences Basal Testosterone in Older Men: A Systematic Review and Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis combining randomized controlled trials and uncontrolled trials
PubMed 30692929 · doi:10.3389/fphys.2018.01878
What was done
A PRISMA-guided systematic review and random-effects meta-analysis evaluated the effects of exercise training on basal total, bioavailable, free, and salivary testosterone in men aged 60 and older. Searches through February 20, 2018, identified 22 eligible studies (9 randomized controlled trials and 13 uncontrolled trials). Meta-analyses using standardized difference in means (SDM) were performed across endurance, resistance, and interval training modalities.
What was found
Endurance training significantly increased basal testosterone (SDM = 0.398, 95% CI 0.034 to 0.761, P = 0.010), as did interval training (SDM = 0.283, 95% CI 0.030 to 0.535, P = 0.028). Resistance training showed no overall effect on basal testosterone (SDM = -0.003, 95% CI -0.330 to 0.324, P = 0.986). In resistance training subgroup analyses by hormone fraction, free testosterone showed an SDM of 0.253 (95% CI -0.043 to 0.549, P = 0.094), total testosterone showed an SDM of 0.028 (95% CI -0.204 to 0.260, P = 0.813), and bioavailable testosterone showed an SDM of -0.373 (95% CI -0.789 to 0.042, P = 0.078).
Why it matters
The findings demonstrate that exercise mode determines endocrine adaptation in older men, with endurance and interval training modestly elevating basal testosterone while resistance training yields inconsistent basal changes.
Limits
More than half of the included evidence came from uncontrolled trials (13 of 22), introducing potential confounding. The abstract does not report total participant count, and the small number of studies prevented subgroup analyses for endurance and interval protocols.
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