Even when young men get stronger and their muscles grow bigger from lifting weights with one arm, their body’s hormone levels don’t go up or down — they stay the same.

A randomized controlled trial in healthy young men where each participant undergoes both acute (single session) and chronic (8–12 weeks) unilateral resistance training on one limb, with the contralateral limb as within-subject control. Blood samples are drawn pre-intervention, 24h post-acute session, and at baseline, midpoint, and endpoint of chronic training. Hormone levels (testosterone, GH, IGF-1, cortisol, LH, SHBG) are measured via standardized immunoassays, and muscle hypertrophy is quantified via MRI or DEXA. Statistical analysis compares changes within subjects across time points.

A prospective study following healthy young men (n=40) undergoing unilateral resistance training for 10–12 weeks. Blood samples are collected at baseline, 1 week, 4 weeks, and 12 weeks. A matched control group performs no training. Hormone levels are measured at identical time points. Muscle hypertrophy is tracked via ultrasound or MRI. Analysis compares within-group changes over time and between training and control groups for each hormone.

A single-group pre-post study where healthy young men (n=25) perform unilateral resistance training for 8 weeks. Blood samples are taken immediately before the first session and within 24 hours after the final session. Hormone concentrations and muscle size are measured. Paired t-tests compare pre- and post-intervention values for each hormone and hypertrophy metric.

A case series of 10–15 healthy young men undergoing unilateral resistance training, with intensive biomarker sampling: blood drawn at baseline, 1h, 24h, 48h, and 7d post-acute session, and weekly during chronic training. Hormones are measured using mass spectrometry for precision. Muscle growth tracked via serial MRI. Data are presented as individual trajectories to assess consistency of null hormone response.

Analysis of archived data from prior resistance training studies where healthy young men performed unilateral training, and serum hormone levels and muscle hypertrophy were measured. Only datasets with complete pre/post measures of all six hormones and imaging-based hypertrophy are included. Statistical analysis tests for within-subject changes across time.