“It loosens up after the first mile.” “It’s just a dull ache.” “I can still run on it if I go slow.”

These are the phrases that turn minor running injuries into major ones. Not because the runner is wrong about the symptoms — the pain often does decrease after warming up, it often is manageable at slower paces — but because reduced pain doesn’t mean reduced damage.

What Happens When You Run Through It

Compensatory mechanics. When something hurts, your body automatically changes your gait to reduce load on the painful area. You shorten your stride, shift weight to the other leg, change your foot strike. These compensations reduce pain in the moment but create abnormal stress on structures that weren’t designed for it. A sore left knee leads to overloading the right hip, which leads to a second injury.

Inflammatory cycling. Tendons and ligaments heal through a controlled inflammatory process. Running on an inflamed tendon restarts the inflammatory cycle before it can complete. The tendon never gets past the early healing phase. What should have been 10 days of recovery becomes a chronic condition that persists for months.

Structural progression. A mild stress reaction (bone bruising) becomes a stress fracture. A small tendon strain becomes a partial tear. Minor injuries don’t stay minor under continued loading — they progress. The tissue is already compromised and each run adds more damage than a healthy structure would experience.

The Endorphin Trap

Running produces endorphins — your body’s natural painkillers. This is why pain often decreases after the first 10-15 minutes of running. The tissue is still being damaged, but your brain has turned down the volume on the pain signal.

This creates a dangerous feedback loop: you start the run hurting, the pain fades, and you conclude that running didn’t make it worse. But the next morning, the pain is back — often worse than before. The endorphins wore off. The damage didn’t.

When to Stop

During a run: If pain changes your gait at any point — you’re limping, favoring one side, shortening your stride involuntarily — stop. Walk home. That run is over.

Between runs: If pain is present at rest (sitting, walking), take at least 2-3 days off before attempting to run again. Pain at rest means the inflammatory response is active even without the running stimulus.

Trending worse: If pain has been present for 3+ runs and is getting worse, not better — stop running and see a healthcare provider. This is not going to resolve on its own with continued training.

The Math of Rest

Two days off for a mild issue costs you two days. That’s roughly 2% of a month’s training — negligible.

Running through that same issue for two more weeks often turns it into a 4-8 week forced break. That’s 30-60% of your training cycle — devastating to race preparation.

The equation is clear: early rest is always cheaper than delayed rest. The runners who take a few days off at the first sign of trouble miss the least total training time. The runners who push through miss the most.

What Pacewright Does

The algorithm can’t see your pain. But it can respond to the downstream effects:

If you mark a run as missed due to injury, the algorithm adjusts upcoming workouts and tracks the time off for return-to-training ramping.

If your RPE suddenly spikes on what should be easy runs, the training load calculation reflects the increased stress. The algorithm may flag the ACWR change.

When you return, the system builds a 4-week ramp back to full training — starting at 50-60% volume and progressing only if your RPE data suggests you’re recovering well.

But the first and most important decision is yours: to stop when something is wrong, before it becomes something worse.

Healthcare provider note: If anything in this article conflicts with guidance from your healthcare provider, follow your provider’s advice — they know your situation, we don’t.