Dr. Duncan French on Huberman Lab: Why Cold Blunts Gains

French’s research suggests a protocol of 6 sets of 10 reps at ~80% of 1RM on a large multi-joint exercise (e.g., back squat), with ~2 minutes rest between sets, is highly effective for stimulating testosterone and creating a strong anabolic environment. The key is combining heavy mechanical load (intensity) with enough repetitions (volume) to drive both mechanical and metabolic stress. Loads should be adjusted set-to-set so the lifter completes all 10 reps; if they fail early, reduce the weight and still hit 10.

Protocols like 10×10 at 80% 1RM proved unsustainable; lifters were forced to drop loads significantly, which undermines the mechanical tension needed for hormone and strength adaptations. The effective window between ‘enough’ and ‘too much’ volume is narrow. When in doubt, trim sets to preserve intensity rather than grinding out excessive total reps with watered-down loads.

For pure muscle growth (not maximal strength), shorter rests (e.g., 2 minutes vs 3 minutes between heavy sets) increase metabolic stress (lactate, glycogen use) and likely amplify hypertrophy. However, this also makes the session more taxing and harder to repeat frequently. Recreational trainees might do this kind of hard protocol about twice per week and use their other sessions for lighter, higher-rep or heavier, lower-volume work.

Short-term stressors (hard workouts, parachute jumps, intense anticipation) elevate catecholamines (epinephrine, norepinephrine) and can acutely increase testosterone. In French’s PhD work, athletes with higher sympathetic arousal before and during demanding training sustained higher force output for longer. The mindset and pre-arousal going into a known hard session matter: expecting challenge, embracing it, and ‘psyching up’ appropriately can improve performance.

Cold exposure (ice baths, cold tubs) is a real stressor that clamps down blood vessels and can blunt adaptive signaling pathways like mTOR, reducing hypertrophy and impairing strength/power gains when used right after training in high-volume, muscle-building phases. French recommends reserving heavy recovery modalities like ice baths for competition phases, when muscle-building is largely ‘in the bank’ and the focus is on preserving performance quality between events. During general prep or hypertrophy phases, let inflammation and soreness run their course to drive adaptation.