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 lane9project.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.

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