The Strength Running Podcast · Jason Fitzgerald

Impact, Force, and Load: Exploring the Real Drivers of Injuries with Professor Brent Edwards

·59 min·4 clips

Brent says impact forces themselves “really don’t have a deleterious effect” on the musculoskeletal system.

1. The Strength Running Podcast episode 448 centers on Professor Brent Edwards and his work on impact, force, and load in running injuries. 2. Jason Fitzgerald interviews Brent Edwards, a University of Calgary biomechanics professor who studies how mechanical loading influences musculoskeletal health and injury risk. 3. The episode asks whether runners should fear impact forces, or whether the larger loading patterns of running matter more. 4. Brent defines impact forces as the brief foot-ground event that occurs within about 50 milliseconds after foot strike. 5. He separates that early spike from the longer stance phase, where larger forces challenge the ankle, knee, and hip. 6. He says his research repeatedly finds no consistent deleterious effect from impact forces alone. 7. He contrasts that with higher-magnitude loading after foot strike, which he sees as more relevant to injury risk. 8. Brent describes lab work on bone and tendon where tissues are loaded at different magnitudes and cycle counts outside the body. 9. He says force magnitude matters more than the number of cycles, because a 10% reduction in force can increase tolerated loading cycles by 100-fold. 10. He argues that increasing running speed by 10% may be more consequential than increasing distance by 10%. 11. He says rest matters because the body repairs damage and adapts its tissues over time. 12. He explains that osteocytes inside bone sense mechanical strain and need rest to recover their shape and sensing ability. 13. Brent says the bone-building benefits of a run are strongest early in the run and then show diminishing returns. 14. He points out that high-magnitude dynamic loading is what matters most for building bone. 15. He says wearable sensors can only provide proxies for what bone and tendon feel, not direct tissue readings. 16. He notes that the Avelo system is using lab-based loading data to build an “impact score” that weights higher loads more heavily. 17. The conversation also covers fatigue, and Brent says sensor data can identify movement changes, but fatigue-related changes do not clearly map to injury. 18. Jason Fitzgerald and Brent Edwards keep the tone technical but practical, with frequent references to training decisions runners actually make. 19. Listeners interested in injury prevention, biomechanics, and training load management will get the most from it. 20. Listeners seeking a simple shoe-ranking answer or a strict injury prediction rule may skip it.

Listen to the show on

Apple Podcasts Spotify

Play clips from this episode More from The Strength Running Podcast