Fatigue in Training

Fatigue is something we all deal with in marathon training. And when it hits, it can feel like we’re losing fitness. But fatigue isn’t just something to push through… it’s something to understand. When we know where it’s coming from, we can train smarter, recover better, and stay locked into our goals.

01. Cumulative Fatigue:

This builds over time, not from one specific workout, but from weeks of training stacking up. Long runs, tempo work, strength, and mileage all layer together. Legs start to feel heavy, stride loses some bounce. That’s not failure… that’s adaptation. You’re training your body to perform under stress, which is exactly what races demand. But if fatigue piles up too much, it can lead to burnout or injury. Balance is key.

02. Metabolic Fatigue:

This comes from a specific effort… like a hard workout or race. It’s that “last rep burn” when glycogen is low and lactate is building. It hurts, but it builds aerobic and anaerobic strength. The trick is to be strategic and not to chase this kind of fatigue every day.

03. Heat Induced Fatigue:

Our fall marathon specialty. Heat forces your body to redirect blood for cooling, not to your muscles. HR climbs, effort soars, pace slows. You lose more fluids, burn more energy, and fatigue builds faster, even on easy days. But training in the heat builds grit and long term efficiency. Hydrate, adjust expectations, and trust the process.

Feeling worn down? That’s not a sign of failure… it’s a sign of growth. You’re not broken, you’re building.