How to Exercise for Strength Gains & Hormone Optimization _ Dr. Duncan French

Andrew Huberman interviews Dr. Duncan French, a sports scientist with over 20 years of experience across 36 professional and Olympic sports, who now serves as Vice President of Performance at the UFC Performance Institute. French's background spans a PhD in exercise physiology under muscle neuroendocrinologist William Kraemer, work with the British Olympic Association across three Olympic cycles, stints with Premier League soccer (Newcastle United), and a role as Director of Performance Sciences at Notre Dame before joining the UFC.

The conversation opens with a deep dive into how resistance training stimulates testosterone release. French explains that the mechanism involves mechanical and metabolic stress triggering a catecholamine cascade — specifically epinephrine and norepinephrine — that activates the HPA axis, which then signals cortisol release and ultimately stimulates androgen production from both the adrenal glands and the gonads. In women, the adrenal glands are the sole source of exercise-induced testosterone. The science remains divided on whether acute testosterone increases during exercise come primarily from adrenal or gonadal sources in men, suggesting both likely contribute depending on the timeframe.

French then details the specific training protocol his research group used to maximize testosterone output: six sets of ten repetitions at 80% of one-rep maximum, with approximately two minutes of rest between sets, performed on a compound multi-joint movement like the back squat. He explains that this specific combination of intensity and volume creates the optimal hormonal stimulus. When volume was increased to 10 sets of 10, performance dropped and the beneficial hormonal signal diminished because athletes could no longer sustain the required load intensity. Critically, French emphasizes that shorter rest periods (two minutes versus three) produce greater muscle hypertrophy because they maintain the metabolic stress environment — particularly lactate accumulation — that drives anabolic signaling. He recommends this type of protocol no more than twice per week for most people, supplemented with higher-rep, lower-intensity sessions on other training days.

The discussion then shifts to the relationship between psychological stress, epinephrine, and performance. French describes his PhD research, which was inspired by studies on combat parachute jumpers, showing that athletes who anticipated a demanding workout began releasing epinephrine 15 minutes before the session even started. His data demonstrated that individuals with higher pre-exercise sympathetic arousal (greater epinephrine and norepinephrine release) sustained greater force output throughout the workout. This validates the utility of pre-workout psychological preparation, music, and rituals as performance tools with measurable physiological correlates.

On cold exposure, French argues that cold is a physiological stressor identical in mechanism to other stressors — the body cannot distinguish between an ice bath and a threatening situation. While cold can be useful for psychological resilience training, its use for physical recovery must be timed carefully. Using cold immersion during phases focused on muscle building can blunt the mTOR and hypertrophic signaling pathways, reducing training adaptations. Cold is more appropriate during competition phases when the goal is performance maintenance rather than tissue growth.

For nutrition, French advocates a concept called metabolic efficiency, developed by Bob Seebohar of USA Triathlon. The approach trains the body to preferentially use fat as fuel at low intensities and carbohydrates at high intensities, rather than becoming over-reliant on carbohydrates across all effort levels. At the UFC Performance Institute, athletes follow a largely low-carbohydrate diet but receive timed carbohydrate supplementation immediately before, during, and after high-intensity training sessions. For general populations, French suggests cycling between higher-carbohydrate periods during intense training blocks and lower-carbohydrate or ketogenic-adjacent periods during lower-intensity phases. He notes ketones are used at the UFC primarily post-competition to support brain energy in athletes who may have sustained head trauma.

The conversation also covers heat adaptation, where French describes a graduated protocol beginning at 15 minutes of sauna exposure and building toward 30–45 continuous minutes. He notes that approximately 14 sauna sessions are needed before significant adaptations emerge, and that the process should begin 8–10 weeks before a fight to allow the body to develop improved sweat response and thermoregulatory efficiency. This adaptation reduces the time athletes need to spend in the sauna during weight cuts.

On skill acquisition, French defers partly to motor learning researchers but argues that quality always trumps quantity — once fatigue begins to compromise movement accuracy, further repetition reinforces poor patterns rather than correct ones. He advocates for shorter, highly focused sessions over marathon practices, noting that skill learning is cognitively exhausting and requires adequate glucose fueling just as physical training does.

Finally, French describes the UFC Performance Institute's broader mission: not just to optimize the performance of its 600+ global roster athletes, but to advance the science of human performance in ways that can benefit the general population. He highlights individualized adaptation-led programming as the philosophical core of their work, noting that 12 weeks is generally sufficient time for most people to evaluate whether a new training, nutrition, or recovery strategy is producing measurable results.