Strains

Acute vs chronic

Strain compares this week's load to your last four weeks. The ratio is the single best predictor of injury in endurance sport.

The ratio

acute      this week's load
chronic    trailing 4-week average
ratio      0.8–1.3  safe
flag       > 1.5    back off

Why it matters

A ratio above 1.5 means you're asking for trouble. Pulse flags it the morning it happens, not the week after.