Does Higher Testosterone Always Mean More Muscle? Hormones and Hypertrophy — What the Research Shows

What research says

• A key RCT by Westers et al.
• (2010, 2012) had subjects perform arm curls under two conditions: one arm trained immediately after leg training (with acute testosterone elevation) and the other arm trained alone (without elevation).
• After 12–15 weeks, bicep hypertrophy was identical between conditions — strongly suggesting that acute hormone spikes are not a direct driver of hypertrophy.

What research says

• Within the normal physiological range, resting testosterone is a poor predictor of hypertrophy.
• A cohort study by Roberts et al.
• (2020) found that pre-training testosterone levels did not predict hypertrophic response magnitude.
• In contrast, pharmacological doses (far exceeding natural levels, as in steroid use) do produce clear anabolic effects.
• Within normal physiological variation, testosterone alone does not explain individual differences in hypertrophy.

What research says

• Correcting deficiencies — poor sleep, zinc deficiency, vitamin D deficiency — can restore testosterone to normal ranges and improve overall conditioning including hypertrophy.
• However, whether further elevation in already-normal individuals enhances hypertrophy is a different question.
• Over-the-counter testosterone booster supplements (e.g., tribulus terrestris) have no convincing evidence for meaningfully increasing muscle hypertrophy.