Source notes

Stretching before exercise can have different effects depending on how it fits into the warm-up. In healthy, active people, weighted estimates from the available studies showed a larger immediate performance reduction after at least 60 seconds of static stretching per muscle group than after shorter amounts: about 4.6% versus 1.1%. Static stretching means holding a muscle in a lengthened position. Dynamic stretching, which uses controlled movement, showed a small average performance improvement. These findings concern performance soon after a stretching session, not the long-term effects of flexibility training.

Timing changes the interpretation. Tests usually took place only three to five minutes after stretching, and most studies did not include subsequent dynamic activities. The few that did include them found no clear performance effect. Results also varied by the task and the muscle length used during testing. The overall averages therefore do not mean that every brief stretch makes every kind of exercise performance worse.

How Does This Show Up in Real Life?

A prolonged stretch immediately before a maximal strength test is a different situation from a short stretch followed by movement practice before sport. The authors recommend considering stretching within a complete warm-up, including dynamic activity afterwards, rather than judging it in isolation. They suggest allowing time after longer static stretches when immediate maximal performance matters. All the stretching methods examined could improve range of motion, but evidence did not clearly rank one method as best. Injury prevention requires a separate judgment: static and contract-relax stretching showed no clear overall benefit for all injuries or overuse injuries. Some evidence suggested fewer acute muscle injuries, particularly in activities involving sprinting, but study designs made it difficult to isolate stretching's contribution. More flexibility alone does not establish protection from injury.

The studies differed in stretch duration, intensity and performance tests, and some protocols poorly reflected real warm-ups. Missing reports of nonsignificant results limited calculations. Evidence for dynamic stretching and injury prevention was absent, and contract-relax evidence was relatively sparse. Range-of-motion improvements were generally temporary, often lasting less than half an hour; these acute findings cannot establish durable training adaptations.

This evidence supports a more specific question than whether stretching is good or bad: what kind, how much, and before which task? It is useful for interpreting immediate trade-offs in a warm-up, with greater caution needed for claims about injury prevention or lasting improvements.