The Effect of High-Intensity Interval Training Periods on Morning Serum Testosterone and Cortisol Levels and Physical Fitness in Men Aged 35-40 Years.
Level 3 - non-randomized controlled study
Controlled trial with unspecified randomization
PubMed 34063524 · doi:10.3390/jcm10102143
What was done
Thirty healthy men aged 35 to 40 years were allocated to an experimental group or a control group. The experimental group completed an 8-week training program consisting of three 1-hour sessions per week of intensive interval exercises followed by strength circuit training. The control group maintained their baseline recreational physical activity. Morning serum testosterone, cortisol, and the testosterone-to-cortisol ratio were measured pre- and post-intervention. Physical performance, including maximal oxygen uptake via standardized laboratory exercise testing and muscle strength, was also evaluated.
What was found
The experimental group experienced a statistically significant 36.7% increase in serum testosterone, a 59% increase in the testosterone-to-cortisol ratio, and a 12% drop in cortisol. No changes in hormonal indices were observed in the control group. Muscle strength improved in the experimental group, but there were no statistically significant changes in aerobic capacity (maximal oxygen uptake).
Why it matters
This study indicates that short-term, structured high-intensity interval and strength training can enhance muscle strength and elicit a favorable anabolic hormonal profile in middle-aged men.
Limits
The sample size was small with only 30 participants across two groups. The abstract does not specify whether participant allocation was randomized or blinded. Absolute baseline and post-intervention hormone concentrations, exact strength metrics, and variance or confidence intervals were omitted from the abstract. Findings are limited to healthy men aged 35 to 40 and may not generalize to women, older adults, or clinical populations.
Cited by
- supports In individuals who practice interval training, basal resting cortisol levels remain lower than pre-training baseline levels.