The short answer
For the kind of stretching most people mean — holding a position until a muscle feels long, then coming out of it — somewhere between twenty and sixty seconds per stretch is where the useful range sits. Below about fifteen seconds you're mostly just moving. Beyond a minute or two the extra return gets small enough that it's usually better spent on a different body part.
That's it. That's the finding. Everything else is detail.
Why the numbers vary so much
Because "stretching" describes at least four different activities, and they have different clocks:
- A quick reset at a desk. Ten to twenty seconds. The goal isn't lasting change, it's interrupting a position you've held too long.
- A general mobility session. Twenty to forty-five seconds per stretch, which is what most of Lucy's routines use.
- Working on a genuinely restricted joint. Longer holds, repeated, over months. This is a project, not a session.
- Warming up before sport. Mostly movement rather than holds — long static stretches immediately before explosive work can temporarily reduce power.
Most advice arguments online are two people describing different activities at each other.
Total time matters more than any single hold
The more useful number isn't how long one stretch lasts — it's how much time a muscle group gets across a week. Five thirty-second holds spread over the week tends to beat one long session, partly for physiological reasons and mostly for a very human one: you'll do the short ones.
This is why Lucy counts stretches in seconds rather than reps, and why every duration in a routine can be nudged up or down before you start. Thirty seconds is the default because it's long enough to be worth doing and short enough not to be a negotiation.
What the hold should feel like
A four or five out of ten. Present, unmistakable, slightly boring. Not something you have to breathe through.
Two signs you've gone too far:
- You're holding your breath. Discomfort you have to brace against is past the point of usefulness.
- The stretch has become sharp, or has moved into a joint. Stretch belongs in the meat of a muscle, not in a knee or a lower back.
If you're shaking, you're not stretching any more — you're doing an isometric hold at an awkward angle.
Both sides, roughly the same
When a stretch is one side at a time, do both, and give them similar time. It's tempting to spend longer on the tight side, and that's not wrong — but the difference should be one extra round, not five minutes versus thirty seconds.
Lucy handles this by counting each side separately and telling you when to switch, which mostly exists so you can shut your eyes and stop doing arithmetic about your own body.
The version to remember
Twenty to sixty seconds. Four to five out of ten. Breathe. Both sides. Come back in a couple of days.
If you want a number to hold onto: thirty seconds, most days, is a completely respectable stretching practice, and it beats the perfect one you're planning to start next month.
Lucy is a stretching app, not a clinician. If a stretch causes sharp pain, numbness or anything that travels down a limb, stop — and read our Fitness & Safety Disclaimer.
