Episode
Ultramarathons: Can vitamin D protect your bones?
- Published
- Oct 6, 2025
- Duration seconds
- 3475
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Summary
Ultramarathoners push their bodies to the limit, but can a giant pre-race dose of vitamin D really keep their bones from breaking down? In this episode, we dig into a trial that tested this claim – and found a statistical endurance event of its own: six highly interchangeable papers sliced from one small study. Expect missing runners, recycled figures, and a peer-review that reads like stand-up comedy, plus a quick lesson in using degrees of freedom as your statistical breadcrumbs. Statistical topics Data cleaning and validation Degrees of freedom Exploratory vs confirmatory analysis False positives and Type I error Intention-to-treat principle Multiple testing Open data and transparency P-hacking Salami slicing Parametric vs non-parametric tests Peer review quality Randomized controlled trials Research reproducibility Statistical sleuthing Methodological morals “Degrees of freedom are the breadcrumbs in statistical sleuthing. They reveal the sample size even when the authors do not.” “Publishing the same study again and again with only the outcomes swapped is Mad Libs Science, better known as salami slicing.” References Boswell, Rachel. Pre-race vitamin D could do wonders for ultrarunners’ bone health, according to science. Runner’s World. September 25, 2025. Mieszkowski J, Stankiewicz B, Kochanowicz A, et al. Ultra-Marathon-Induced Increase in Serum Levels of Vitamin D Metabolites: A Double-Blind Randomized Controlled Trial. Nutrients . 2020;12(12):3629. Published 2020 Nov 25. doi:10.3390/nu12123629 Mieszkowski J, Borkowska A, Stankiewicz B, et al. Single High-Dose Vitamin D Supplementation as an Approach for Reducing Ultramarathon-Induced Inflammation: A Double-Blind Randomized Controlled Trial. Nutrients . 2021;13(4):1280. Published 2021 Apr 13. doi:10.3390/nu13041…