Are light runs (Zone 2 runs) better than heavier workouts? Sophie goes on a semi-manic tangent in her most enthusiastic episode yet to answer whether less intense exercise might actually help your fitness level, aerobic threshold and mitochondrial efficiency. Also, Chris tells a funny marathon story and a viewer question tries to fact-check to the fact checkers on whether walking and running burn the same amount of energy. Become a supporter of our show today either on Patreon or through PayPal! Thank you! http://www.patreon.com/thebodyofevidence/ https://www.paypal.com/donate?hosted_button_id=9QZET78JZWCZE Email us your questions at [email protected]. Hosts: Christopher Labos & Sophie Tseng Pellar Editor: Robyn Flynn Researcher: Auriane Journet Theme music: “Fall of the Ocean Queen“ by Joseph Hackl Rod of Asclepius designed by Kamil J. Przybos Chris’ book, Does Coffee Cause Cancer?: https://ecwpress.com/products/does-coffee-cause-cancer Obviously, Chris is not your doctor (probably). This podcast is not medical advice for you; it is what we call information. References: 1. Storoschuk, K. L., Moran-MacDonald, A., Gibala, M. J., & Gurd, B. J. (2025). Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General Population: KL Storoschuk et al. Sports Medicine, 55(7), 1611-1624. 2. Mølmen, K. S., Almquist, N. W., & Skattebo, Ø. (2025). Effects of exercise training on mitochondrial and capillary growth in human skeletal muscle: a systematic review and meta-regression. Sports Medicine, 55(1), 115-144. 3. Inglis, E. C., Iannetta, D., Rasica, L., Mackie, M. Z., Keir, D. A., Macinnis, M. J., & Murias, J. M. (2024). Heavy-, severe-, and extreme-, but not moderate-intensity exercise increase V̇o 2max and thresholds after 6 wk of training. Medicine & Science in Sports & Exercise, 56(7), 1307-1316. 4. McConell, G.K., Wadley, G.D., Le plastrier, K. and Linden, K.C. (2020), Skeletal muscle AMPK is not activated during 2 h of moderate intensity exercise at ∼65% in endurance trained men. J Physiol, 598: 3859-3870. https://doi.org/10.1113/JP277619 5. Meixner, B., Filipas, L., Holmberg, H. C., & Sperlich, B. (2025). Zone 2 Intensity: A Critical Comparison of Individual Variability in Different Submaximal Exercise Intensity Boundaries. Translational sports medicine, 2025, 2008291. https://doi.org/10.1155/tsm2/2008291 6. Harber MP, et al. Impact of Cardiorespiratory Fitness on All-Cause and Disease-Specific Mortality: Advances Since 2009. Progress in Cardiovascular Diseases 2017;60(1):11-20. PubMed 28286137 7. Kodama S, Saito K, Tanaka S, et al. Cardiorespiratory Fitness as a Quantitative Predictor of All-Cause Mortality and Cardiovascular Events in Healthy Men and Women: A Meta-analysis. JAMA 2009;301(19):2024-2035. PubMed 19454641