Dr. Duncan French — Vice President of Performance at the UFC Performance Institute with over 20 years working with elite, professional, and Olympic athletes. An exercise physiologist whose PhD research explored how resistance training drives testosterone, cortisol, and catecholamine responses.
The gist
Andrew Huberman interviews Dr. Duncan French about the science of training for strength, muscle growth, and hormone optimization. French explains that testosterone release is driven by both intensity and volume, favoring protocols like six sets of ten reps at 80% with short two-minute rests to maximize metabolic stress. The conversation covers how acute stress and epinephrine actually boost testosterone and performance, why cold exposure should be periodized to avoid blunting hypertrophy, and how heat acclimation trains the body to sweat more efficiently. French also details metabolic efficiency and needs-based eating, where carbohydrates are timed around training while the rest of the diet stays more ketogenic, all under the UFC's philosophy of adaptation-led programming.
Big reveals
- Testosterone is driven by both intensity AND volume, while growth hormone is largely driven by intensity alone.
- Going from six sets of ten to ten sets of ten can actually be counterproductive for testosterone because intensity drops off, revealing a narrow margin.
- Shorter two-minute rests beat three-minute rests for hypertrophy because the metabolic stress, not just the load, drives muscle growth.
- Acute stress and a big epinephrine spike (like a parachute jump) can actually increase testosterone, contradicting the 'stress is always bad' narrative.
- Cold exposure can blunt the mTOR/hypertrophic pathway, so ice baths can short-circuit muscle and strength gains if used during growth phases.
- French does NOT recommend a fully ketogenic diet for high-intensity intermittent athletes like MMA fighters.
- The UFC's tongue-in-cheek mantra: 'it's 90% mental apart from the 60% that's physical.'
- The UFC Performance Institute is venturing into research areas including CBD and psychedelics, plus thermal and Bluetooth monitoring technologies.
Things worth remembering
- In women, the adrenal glands are the only source of testosterone release, and resistance training raises it through the same downstream cascade.
- Testosterone has androgen receptors on neural tissue and influences tendons, ligaments, and even bone, not just muscle.
- Mechanical load comes from the weight on the bar while volume provides the metabolic stimulus that signals further anabolic testosterone release via lactate.
- Skill acquisition is quality over quantity; as soon as fatigue degrades movement accuracy, training should stop.
- Great athletes should leave skill sessions mentally fatigued, not just physically, because they are fully cognitively engaged.
- Metabolic efficiency, a concept from Bob Seebohar of USA Triathlon, trains the body to use fat at low intensities and carbs at high intensities.
- The UFC uses ketones primarily after events to sustain brain energy supply in athletes who may have taken brain trauma.
- Heat acclimation starts at about 15 minutes, builds to 30-45 minutes, and takes roughly 14 sauna exposures over 8-10 weeks to drive adaptation.
- For 99% of physiological adaptations, a 12-week intervention is more than enough to see whether something works for you.
- Fifteen athletes given the identical workout will produce fifteen different responses because the human organism is so complex.