Does strength training affect testosterone — by how much?

Acute resistance training produces a transient testosterone surge of 15–25% during and immediately after the session, returning to baseline within 30–60 minutes, this acute spike does not reliably translate to sustained higher resting testosterone in men with normal testosterone, but consistent resistance training over months does improve testosterone sensitivity (androgen receptor upregulation) in muscle and may modestly increase resting testosterone in men with below-normal or low-normal baseline (Kraemer & Ratamess, Endocrinology, 2005).

The claim that "resistance training increases testosterone" requires qualification. In healthy men with normal testosterone, the acute spike does not produce chronically elevated resting testosterone, the feedback regulation of the HPG axis corrects the acute signal. In men with low-normal testosterone (270–350 ng/dL) who combine resistance training with visceral fat reduction and sleep improvement, the combination can produce clinically meaningful testosterone increases (20–40 ng/dL) without hormone therapy. Resistance training is not TRT.

Honesty Scale: Solid (1) for acute testosterone surge during resistance training. Promising (2) for chronic modest testosterone increase in low-normal men through consistent training.

What to do: Do not start resistance training primarily for testosterone normalization. Start it for muscle mass, bone density, insulin sensitivity, and the mortality benefits. Any testosterone improvement is a secondary benefit of the complete lifestyle picture that includes training.

For the full picture, read The Strength/Grip Deep Dive