Optimizing Strength, Hormones, and Recovery: Exercise Protocols, Metabolic Efficiency, and Cold Exposure with Dr. Duncan French

This episode of Huberman Lab Essentials features Dr. Duncan French, an expert in exercise physiology, discussing the intricate relationship between resistance training, hormone optimization, and recovery strategies. Dr. French explains that testosterone release is primarily stimulated by both mechanical and metabolic stress, with growth hormone being more intensity-driven. He delves into the physiological cascade involving the HPA axis, catecholamines like epinephrine and noradrenaline, and cortisol, which ultimately signals androgen release from the adrenals (in women) and gonads (in men). A key nuance highlighted is that acute stress can transiently increase testosterone, a concept often overlooked in discussions about stress's negative impacts.

The conversation provides actionable protocols for maximizing anabolic responses. Dr. French recommends a 6 sets of 10 repetitions protocol at 80% of one-repetition maximum (1RM) with 2-minute rest periods for multi-joint exercises like back squats, emphasizing the importance of maintaining intensity and volume. He distinguishes this from higher volume approaches like 10x10, which can be unsustainable at high intensities and lead to diminished mechanical stimulus. For general fitness, he suggests two such challenging workouts per week, complemented by other sessions focusing on either higher volume/lower intensity or lower volume/higher intensity to provide varied stimuli.

A significant portion of the discussion is dedicated to the strategic use of recovery modalities, particularly cold exposure. Dr. French clarifies that while cold can be used for mindset training or managing discomfort, its physiological effects on muscle tissue are complex. Robust data suggests that cold exposure, such as ice baths, can dampen the mTOR pathway and hypertrophic signaling, thereby hindering muscle growth and strength adaptations. Therefore, he advocates for the periodization of cold exposure: avoiding it during muscle-building phases (general preparatory work) when inflammation is a necessary stimulus for adaptation, but utilizing it during competition phases to reduce inflammation and maintain performance quality.

The episode also touches on metabolic efficiency and nutrition. Dr. French explains that high-performance athletes in intermittent, high-intensity sports like MMA often benefit from a diet that trains the body to use fats at lower intensities and carbohydrates at higher intensities. He describes a tactical approach where athletes maintain a largely ketogenic-like diet but strategically time carbohydrate intake immediately before, during, and after high-intensity training sessions. This method aims to optimize fuel utilization, ensuring adequate energy for peak performance without relying solely on carbohydrates, thereby promoting metabolic flexibility and sustained output.

It's mechanical stress and it's metabolic stress. And these are, you know, the downstream regulation of of testosterone release at the gonads um comes from many different areas.

Testosterone is really stimulated by an intensity factor uh and also a volume factor. Now growth hormone is a little bit different. That's largely driven by an intensity factor alone.

So that sort of hints at the possibility that the thresholds for going from a workout that increases testosterone to a workout that diminishes testosterone is actually a pretty narrow margin.

If there's an athlete A and he does six six sets of 10 with two minutes rest and there's athlete B that does six sets of 10 with three minutes rest, athlete A will likely see the highest muscle gains because of the metabolic stimulus that they're driving with the shorter rest periods.

From my data, certainly the the greater arousal, the higher the performance was from a from a physical exertion perspective, there's definitely a bio an individual bioinetics to some of these um hormonal kind of releases.

If I if I want to maximize muscle growth or power or you know improvements and adaptations then the inflammation response the delayed onset muscle soreness all the stuff that's uncomfortable and that we hear is so terrible is actually the stimulus for adaptation and so using cold in that situation might shortcircuit my progress.

As soon as fatigue is is influencing that repetition, it's time it's time to stop. And the best coaches understand that it's shorter sessions that are very high quality.

We rarely advocate a high performance athlete in a in a highintensity intermittent sport like MMA being totally ketogenic because at the end of the day, some of those highintensity efforts um usually require, you know, carbohydrate fueling um for for the high and the energy um the energy produced at those high intensities.

We use tactics here where we essentially have athletes on what you would say kind of is a a largely a ketogenic diet, but then we will fuel carbohydrates around training sessions.

You teach the body to use ketones and then you use them at the appropriate time as opposed to just deciding that one of these fuel sources is good and all the others are bad or dispensable.