Podcast Episode #46: A “Green” Triathlon, Vitamin D, and How To Convert Fast-Twitch Muscle to Slow-Twitch Muscle.

29 Jan 2026 · 35 min
Episode

29 Jan 2026 · 35 min

0:00

Ben Greenfield podcast episode covering three main themes: (1) practical self-treatment and supplements—Ben reports using transdermal magnesium (magnesium flakes and magnesium oil), including a homemade bath mix and topical use; (2) listener Q&A—Nick asks about converting fast-twitch to slow-twitch muscle for endurance and Ben explains muscle fiber types, training strategies (long slow distance, avoid heavy power work, pre-cooling) and basic nutritional adjustments; Chris asks about vitamin D and Ben summarizes literature linking seasonal vitamin D levels to athletic performance and gives supplementation guidance; (3) featured interview with Jeff Henderson about making the Portland Triathlon environmentally friendly (online registration, compostable cups, no bike-course aid station for Olympic distance, bamboo shirts, recycled-material finish arch). The episode also promotes local classes, a 63-day fat-loss challenge, and a 10-CD audio collection.

Questions this episode answers

About 1/2 to 1 cup magnesium flakes mixed one-to-one with aluminum-free baking soda (so ~1/2–1 cup baking soda), dissolved in a warm bath (about 103–106°F) and soak ~15 minutes.

He sprays 100% absorbable magnesium oil on forearms before workouts.

Slow-twitch (type I/red) ~10–30 twitches/sec; fast-twitch (type II/white) ~30–70 twitches/sec.

Endurance-trained group: ~70% slow-twitch (front-thigh sample) vs ~37% in untrained; trained group fast-twitch ~25–30% vs ~50–60% in untrained controls.

Frequent long slow-distance aerobic sessions (stay below hard ventilation that signals high carbohydrate use), limit heavy weight/power work, consider pre-cooling (ice baths/cryotherapy) before long efforts to delay fatigue.

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