Strain Score captures cumulative load from movement and cardiovascular stress across the day. Higher strain reflects more work for your autonomic and musculoskeletal systems; it is meant to sit beside recovery so you can balance push days with enough restoration.
Exercise dominates, but sustained non-exercise stress that elevates heart rate and movement also contributes. The score is normalized to your recent baseline so meaningful spikes stand out without punishing everyday life noise.
After high-strain days, expect recovery to need more sleep and easier movement the next day. Chaining hard strain on low recovery is where injury risk and performance debt accumulate; use the pair of scores to modulate rather than max out every week.
Sleep Score describes last night; Recovery Score estimates today's readiness; Strain Score sums today's load. Together they outline whether your rhythm is sustainable.