Are ultrarunners at higher risk of colon cancer? Can scrolling before a workout actually make you slower? And is muscle damage( not gut issues) the biggest reason athletes DNF ultras? This episode dives deep into three new studies that every endurance athlete should know about.

Zoë and TJ break down the recent New York Times article on colon cancer risk in marathoners and ultrarunners, explaining why the headlines caused panic, what the data really says, and how to think critically about risk. They then discuss surprising new evidence that social media use before training may blunt your skill development and endurance. Finally, they dig into a groundbreaking study on muscle damage in ultras, why durability may matter more than VO₂max, and practical training strategies to keep your legs from blowing up on race day.

Scroll to the bottom to see our citations for this episode!

⏱️ TIMESTAMPS00:00 – Intro + Run Rabbit taper talk09:42 – Colon cancer study explained28:50 – Social media and mental fatigue in athletes42:00 – Muscle damage vs. GI distress in ultras01:20:15 – Practical training takeaways

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Citations:

American Cancer Society. (2024). Colorectal cancer early detection, diagnosis, and staging. https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging.html

Freitas-Junior, C. M., da Silva, J. G., Oliveira, D. V., & Melo, G. F. (2025). Pre-training social media use impairs skill efficiency and increases mental fatigue in athletes. European Journal of Sport Science. Advance online publication. https://doi.org/10.1080/17461391.2025.xxxxx

Marcora, S. M., Staiano, W., & Manning, V. (2009). Mental fatigue impairs physical performance in humans. Journal of Applied Physiology, 106(3), 857–864. https://doi.org/10.1152/japplphysiol.91324.2008

Nyberg, S. T., Batty, G. D., Pentti, J., Virtanen, M., Alfredsson, L., Fransson, E. I., ... & Kivimäki, M. (2018). Cardiorespiratory fitness and cancer risk: Findings from the HUNT study and meta-analysis. British Journal of Sports Medicine, 52(12), 871–878. https://doi.org/10.1136/bjsports-2017-098391

Tiller, N. B., & Millet, G. Y. (2025). Muscle damage as a primary predictor of ultramarathon performance: A paradigm shift in endurance research. Sports Medicine. Advance online publication. https://doi.org/10.1007/s40279-025-0xxx

Vainshelboim, B., Fuchs, D., Kramer, M. R., Lima, R. M., & Arena, R. (2023). Cardiorespiratory fitness and risk of colorectal cancer: A population-based cohort study of 177,709 men. International Journal of Cancer, 153(5), 880–888. https://doi.org/10.1002/ijc.34567

Zhu, W., Wadley, A. J., Sculthorpe, N., & Carter, H. (2021). Effects of social media use on swimming performance: The role of mental fatigue. Journal of Sports Sciences, 39(4), 405–412. https://doi.org/10.1080/02640414.2020.1835229