13: From Pool to Pavement: Low Ferritin, Bone Stress Injuries, and the Swimmer-to-Runner Trap

What happens when a highly conditioned collegiate swimmer transitions into marathon training too quickly? In this episode of Interdisciplinary Case Miles, a 23-year-old former swimmer increases weekly mileage from 15–20 miles to 40 miles, adds hills and speed work, and begins to worry about low ferritin when performance stalls.What initially appears to be an iron concern reveals a broader picture involving low energy availability, fueling gaps, training load errors, and bone stress injury risk, ultimately resulting in a diagnosis of femoral shaft stress fracture.Dr. Sara Raiser (running medicine physician), Kelsey Pontius (sports dietitian), and Dr. Kate Mihevc Edwards (physical therapist) discuss:Why ferritin is often a marker of a larger issueThe relationship between nutrition, iron stores, and bone healthUnique injury risks when transitioning from non-weight-bearing sportsHow cardiovascular fitness can exceed musculoskeletal readinessRehabilitation principles, plyometric loading, and safe return-to-run progressionsThis episode is essential listening for runners, clinicians, coaches, and endurance athletes navigating performance concerns, injury prevention, and the demands of marathon training.00:00 – Welcome to Interdisciplinary Case MilesMeet the hosts and the evidence-informed approach behind real runner cases.02:10 – The Case IntroductionA former collegiate swimmer increases mileage from 20 to 40 miles/week while marathon training.04:45 – “Is It My Ferritin?”Why athletes fixate on iron and ferritin when performance plateaus.07:30 – Ferritin vs Iron ExplainedWhat ferritin actually represents and why it changes slowly.10:15 – Red Flags for Low Energy AvailabilitySleep, libido, GI symptoms, recovery, and early warning signs of REDs.15:40 – Nutrition, Bone Density, and Stress Injury RiskHow low ferritin, low energy intake, and bone health intersect.18:30 – Thigh Pain Isn’t “Just a Quad Strain”Why distance runner thigh pain raises concern for femoral stress fractures.22:15 – Diagnosing a Femoral Shaft Stress FractureWhy this injury matters and how it differs from higher-risk stress fractures.26:40 – The Swimmer-to-Runner ProblemCardio fitness vs bone loading, gravity, and anti-gravity sports.31:50 – The Three Pillars: Nutrition, Training Errors, BiomechanicsA framework for evaluating bone stress injuries.36:20 – Training Errors That Add Up FastMileage spikes, speed work, lack of rest, and life stress post-college.41:10 – Starting PT Before You Run AgainStrength, education, and early rehab during protected weight-bearing.45:30 – Plyometrics, Bone Loading, and Return-to-RunWhy jumping matters and how bones adapt to force.50:40 – Bone Geometry, Density, and Multi-Directional MovementWhy specialization matters—especially in adolescence.55:30 – The “Engine vs Chassis” ProblemWhen cardiovascular fitness outpaces muscles, tendons, and bones.59:20 – Why Return-to-Run Feels So HardManaging athlete frustration while protecting long-term health.1:02:30 – Final Takeaways from Each ExpertBig-picture thinking, history matters, and don’t self-coach in isolation.1:06:00 – Wrap-Up & How to Submit a CaseBecome a supporter of this podcast: https://www.spreaker.com/podcast/interdisciplinary-case-miles--6623567/support.If you enjoyed this episode, don’t forget to follow and subscribe so you never miss a case.Have a question or a case you'd like us to explore on the show? We’d love to hear from you. Reach out anytime at [email protected].