Doing weight training either heavy or light until you can't do another rep for nine weeks doesn't change your hormone levels in your saliva, and that's okay—your muscles can still get stronger and bigger even if your hormones don't budge.

A randomized, controlled, within-subjects crossover trial with recreationally trained males (n≥30), comparing high-load (75–85% 1RM) and low-load (30–40% 1RM) resistance training to failure over nine weeks, with salivary testosterone and cortisol measured at baseline and immediately after each session, and muscle strength and hypertrophy tracked via DEXA and 1RM testing; no other interventions allowed.

A prospective cohort of recreationally trained males (n≥50) undergoing either high- or low-load resistance training to failure for nine weeks, with salivary hormone levels and strength/hypertrophy outcomes measured at baseline, week 3, week 6, and week 9; no randomization, but strict standardization of training volume, frequency, diet, and sleep.

A single-arm study where recreationally trained males (n≥20) perform nine weeks of combined high- and low-load resistance training to failure (e.g., alternating sessions), with salivary hormone levels and strength/hypertrophy tracked before and after the intervention.

A detailed case series of 10–15 recreationally trained males undergoing nine weeks of resistance training to failure, with intensive salivary hormone sampling (multiple times daily) to capture circadian and acute post-exercise patterns, alongside strength and hypertrophy measures.

A retrospective analysis of archived data from prior resistance training studies involving recreationally trained males, extracting salivary testosterone/cortisol measurements and training load data to assess whether training intensity to failure correlated with hormonal changes.