Fueling for a Sub-3 Marathon: Laura Filla on Ferritin, Nutrition, and a Breakthrough Marathon

What does it take to reach sub-3 with your period intact and your body well-fueled? That's the question Coach Laura Filla can now answer from experience. After four years, ten marathons, low ferritin, grief, a coaching business, and two kids, Laura crossed the finish line at Bayshore 2026 in 2:58:43. Host Heather Caplan, RDN, sits down with Laura to talk through the whole arc: what changed, what didn't, and why the breakthrough finally came when she stopped white-knuckling her training and started thriving through it. Laura Filla is a marathoner, mom, RRCA Level 2 Certified Running Coach, and ACE Certified Personal Trainer. She founded Filla Endurance in 2021 with a focus on helping runners get the best out of themselves in a way that supports their long-term health. She's also a Lane 9 Directory coach. Chapters 03:58- Laura's first marathon and what made her want to go faster 08:20- When sub-3 first felt possible: the 3:06 breakthrough at Indianapolis 12:31- What people don't see behind a fast marathon time 13:52- Fueling in the early seasons and working with a dietitian for the first time 17:58- Navigating grief, setbacks, and a ferritin of 14 19:32- How low ferritin showed up in training and how she finally fixed it 26:31- Tracking cycles and fueling through high-mileage weeks 29:41- Process-based goals and celebrating wins before the finish line 35:26- Race day at Bayshore: the pace group, recalibrating, and the ducks 40:33- The pain cave during the last couple of miles, the mantra, and crossing sub-3 43:46- Race fueling strategy: 84 grams per hour Resources mentioned: - Filla Endurance - Laura's coaching business; follow her on Instagram at @coachlaura.run - Laces and Legends Podcast - Laura's podcast highlighting women runners in the St. Louis running community - Garmin app (cycle tracking) - Connect with Laura through the Lane 9 Directory at lane9project.org/directory Connect + get support: - Are you an athlete? Find a sports dietitian, DPT, therapist, or coach who understands athletes at https://lane9project.org/directorylane9project.org/directory. - Are you a clinician or coach? If this conversation resonated with you professionally, Lane 9 Membership was built for you. Join a community of dietitians, DPTs, psychologists, sports medicine providers, and coaches who are doing this work, and get listed in the Lane 9 Directory so athletes can find you. Future clinicians and coaches are welcome too. - Follow us on Instagram and get in touch anytime!