When young men lift weights for 12 weeks, their short-term spikes in testosterone and IGF-1 after workouts don’t seem to predict whether they’ll gain more muscle or get stronger.

A prospective, controlled trial where young men (18–30 years) are assigned to resistance training for 12 weeks, with serial blood draws immediately after each session to measure acute free testosterone and IGF-1 responses, and pre/post assessments of lean body mass (DXA), muscle fiber cross-sectional area (muscle biopsy + microscopy), and leg press 1RM. Statistical analysis tests for correlation between acute hormone spikes and outcome changes, controlling for baseline values and training volume.

A longitudinal observational study tracking young men over 12 weeks of self-selected or supervised resistance training, measuring acute post-workout hormone levels and tracking changes in muscle mass, fiber size, and strength. Statistical models assess whether variation in acute hormone responses predicts outcome variation across individuals.

Analysis of pre-existing datasets from prior resistance training studies where acute hormone responses and muscle/ strength outcomes were measured, to test for statistical association without new data collection.

Comparison of individuals with high vs. low muscle gains to determine whether their acute post-exercise hormone responses differed significantly.

Synthesis of all available studies measuring acute post-exercise testosterone/IGF-1 and muscle/strength outcomes in young men undergoing resistance training to determine overall association strength.