Hormones in resistance training
Exercise is a hormonal event. Lifting, cardio, sprinting — each triggers a different hormonal cascade. Understanding these helps you program intentionally and answer client questions accurately.
Testosterone
Increases acutely after compound resistance training. Bigger increases from larger muscle groups (squats > bicep curls), heavier loads (>75% 1RM), and shorter rest (30-60s for hypertrophy work).
Long-term: trained men and women have higher resting testosterone than sedentary peers. The differences are real but modest — far smaller than what users of exogenous steroids see.
Growth hormone (GH)
Spikes after high-volume, short-rest training. Also elevated by sleep — GH peaks during deep sleep stages. This is one reason sleep is non-negotiable for muscle gain.
GH supports tissue repair and fat metabolism. The acute spike from training is real but modest in its anabolic effects compared to the chronic baseline you maintain with consistent training and sleep.
Cortisol
The "stress hormone." Rises during exercise (necessary for energy mobilization). Problem comes when it stays elevated.
Chronically high cortisol from overtraining, poor sleep, or life stress:
- Suppresses immune function
- Catabolizes muscle tissue
- Impairs recovery
- Disrupts sleep
Insulin
Lowers during fasted exercise. Spikes when you eat carbs/protein post-workout — this is anabolic, driving nutrients into muscle cells.
Insulin sensitivity (how well the body uses insulin) improves dramatically with training. This is the mechanism by which exercise reverses prediabetes and reduces type 2 diabetes risk.
Adrenaline / noradrenaline
Mobilize energy during intense exercise. Drive heart rate, breathing, and the "amped up" feeling. Spike highest during heavy lifts, sprints, and competition.
Endorphins
Endogenous opioids. The "runner's high." Acute mood elevation post-exercise. One of the most reliable mental-health benefits of consistent training.
What clients should know
Most clients ask "how do I increase my testosterone?" or "is this hurting my hormones?" The honest answer:
- Resistance training, adequate sleep, and a balanced diet support healthy hormonal function
- Overtraining, chronic under-eating, and chronic sleep loss suppress it
- The chronic baseline matters more than acute spikes
- Trying to "biohack" hormonal responses with rest interval tweaks doesn't move the needle much
TL;DR
Exercise triggers acute hormone changes: testosterone, GH, cortisol, insulin, adrenaline, endorphins. Chronic training adapts baseline hormonal function. Sleep, recovery, and nutrition matter more for hormonal health than tiny training tweaks.