Margen
Stretching before you run does not prevent injuries: it multiplies them. In 2004, an Australian meta-analysis by Rob Herbert and Michael Gabriel pooled eight studies with 2,700 runners and found no protective effect; in 2019, the Cochrane review confirmed it with 2,400 more. Those who stretched a cold muscle got injured 23 percent more often than those who did not.
The myth comes from 1960s school sports: it was copied from the ballet barre, where students had already warmed up from an hour of class. With cold feet, a long stretch elongates the fiber without changing the force the fiber can hold: it leaves it slack, not elastic. And slack fiber tears where before it only stretched.
The instruction fits in four lines, and it works for running, for swimming and for weekend games:
1. Before: five minutes of very light jogging or small hops. Blood warms from inside what the hand cannot. The rule is to break a light sweat on the back of the neck. 2. Movement with the muscle working: ankle circles, knees to chest while walking, arms swinging back. Never hold a static stretch. 3. During: never stop to stretch if a twinge appears. Walk it off and out of the session. 4. After: fifteen seconds per muscle, no bouncing. That is the only moment when range comes back. Before, it does not. And those fifteen seconds are with a lowered pulse, three minutes after finishing, not at the line.