Why stretching before a workout can backfire

For decades, gym class taught us to sit and hold a long stretch before doing anything active. But research on static stretching — holding a muscle at length for 30–60 seconds — shows that doing it right before strength or power activity can temporarily reduce how much force you produce. The effect, sometimes called stretch-induced strength loss, is modest and short-lived, but it's the opposite of what a warm-up is for.

The likely reason is twofold: a long hold briefly reduces the muscle-tendon unit's stiffness (which you actually want for springy, forceful movements), and it may dial down neural drive to the muscle for a few minutes. So the pre-run hurdler's stretch isn't priming you — it can leave you slightly weaker and slower right when you need output.

What works better is a dynamic warm-up: active movements like leg swings, lunges, and bodyweight squats that raise muscle temperature, rehearse the motion, and wake up the nervous system without the prolonged hold. Static stretching still has value — for building flexibility and range of motion — but it pays off most after training or in a separate session, not as the on-ramp to lifting or sprinting.

One more myth worth retiring: stretching does not reliably prevent injuries. A proper warm-up lowers injury risk, but simply touching your toes beforehand isn't the protective ritual it was sold as.