Static Stretching: Dr. Anthony Blazevich

Based on Episode 119 of the Just Fly Performance Podcast, a conversation between host Joel Smith and sports scientist Dr. Anthony Blazevich.

Static stretching has spent two decades as the villain of the warm-up, and Dr. Anthony Blazevich thinks the case against it is far weaker than coaches assume. Blazevich, a biomechanist at Edith Cowan University and one of the field’s leading researchers on muscle, tendon, and stretching, has run much of the actual science here. His summary is not a defense of five-minute hamstring holds; it is a plea to stop arguing from emotion and look at what the evidence really shows, which is that the danger is narrow, brief, and mostly erased by a proper warm-up.

Key Takeaways

• The force loss is real but brief. Prolonged static stretching weakens a muscle for only about five to fifteen minutes, and short holds barely touch it.
• A full warm-up erases the deficit. When athletes stretch and then complete a normal warm-up, the negative effect disappears and can even turn slightly positive.
• The injury argument cuts both ways. Dynamic stretching replaced static stretching without a single prospective study showing it lowers injury risk.
• Activating a muscle before you stretch it works better. Loaded, active stretching produces roughly three times the range-of-motion gain of passive stretching, and raises tendon stiffness at the same time.
• If it makes an athlete feel ready, that counts. Stretching reliably improves an athlete’s sense of preparedness and calms the nervous system.

The force loss is real, but it lives in a narrow window

Blazevich does not deny that heavy stretching can make you weak. He explains the mechanism through what he calls a spinal amplifier: an inward current in the motor nerves that normally boosts every contraction, and that prolonged stretching switches off.

Static stretching for four or five minutes turned off these inward currents. We now believe that the loss of muscle force and loss of neural drive is a result of switching off this amplification system that occurs in your spinal cord.

The critical detail is duration. The effect is large only after minutes of stretching a single muscle, and it does not last.

If you do too much stretching, you are weaker, you will perform worse for about five to fifteen minutes. But here’s the thing, it only lasts about five to fifteen minutes. It doesn’t happen if you only stretch a muscle for, say, thirty seconds.

As he points out, almost no athlete warming up for sport holds a single muscle for more than about thirty seconds total, which is well below the dose that causes a meaningful problem.

A full warm-up erases the deficit

The reason the laboratory horror stories rarely play out on the field is that athletes do not stretch and then immediately compete. They stretch, then run drills, then build from general to specific over twenty to sixty minutes. Blazevich’s randomized trials tested exactly that sequence.

Our recent randomized control trial, as well as at least three other well-controlled trials, have shown that when we do this, there is no effect of static stretching at all. In fact, if there is an effect, it’s a slight positive effect on speed and power output of a muscle.

He is fond of the counterexample that most coaching arguments ignore. Elite performance and static stretching are not mutually exclusive.

When I was at Brunel University, the Jamaican track and field team used to train there in the summers, and you’d have Usain Bolt warming up doing static stretching. Well, he runs pretty quick.

The injury argument cuts both ways

Much of the case against static stretching rests on injury prevention, but Blazevich argues the field quietly reversed a decision without evidence. Dynamic stretching was removed decades ago on the belief that it caused injury, then reinstated on no better footing.

We removed dynamic stretching under the belief that it caused injury, and not one single study prospectively has ever examined the effect of dynamic stretching on injury risk.

Meanwhile, he notes, several reviews now find at least a small reduction in muscle injury risk from pre-exercise static stretching in running-based sports. He is careful not to oversell it, and he still uses dynamic stretching in his own warm-ups. His point is narrower: the confident, emotional case that static stretching is harmful does not match a literature that mostly says we do not know much.

Activate the muscle, then stretch it

Where Blazevich is genuinely enthusiastic is active or loaded stretching, in which you contract a muscle hard and then drive it into a stretch. In his lab this is effectively eccentric training, and the range-of-motion results are dramatic.

When we activate the muscle and then force it into a stretch over a period of weeks, we get massive increases in range of motion, but they seem to occur with an increase in tendon stiffness. Stretching doesn’t have to occur at the expense of tissue stiffness if stiffness is what you want.

Getting both more range and more stiffness at once is unusual, and it reframes flexibility as a nervous-system skill rather than a change in the tissue itself. Blazevich frames the whole thing as a learning process.

Stretching is a learning effect. It’s how you tolerate the stretch load that matters. You can pretty much do the splits now, your brain just won’t let you.

The same logic explains why PNF and other active methods tend to beat passive holds: the extra feedback from contracting the muscle simply teaches the brain and spinal cord to allow more range, faster.

If stretching helps an athlete feel ready, let them

Finally, Blazevich refuses to strip a tool from athletes over a rounding error. Stretching has measurable effects on the nervous system beyond the muscle, and on how prepared an athlete feels.

If athletes were allowed to do any kind of stretching at all, whether it was dynamic or static, they always felt more prepared for their sport. So that psychological element, we think, is really important.

He adds that a calm, general stretch after training lowers sympathetic tone, gives a team time to reflect, and may nudge an athlete toward recovery, benefits that have little to do with lengthening a muscle and everything to do with keeping a person training and in a good frame of mind.

Frequently asked questions

Is static stretching bad before training or competition?
Not in the doses athletes actually use. Blazevich’s research shows prolonged static stretching of a single muscle for several minutes can reduce force for about five to fifteen minutes, but short holds of around thirty seconds, followed by a full warm-up, show no negative effect and sometimes a small positive one.

Why does static stretching make you feel weak?
Blazevich attributes it to switching off a spinal-cord amplification system. Inward currents in the motor nerves normally boost each contraction, and several minutes of stretching turns them off for five to fifteen minutes, lowering neural drive and force.

Does stretching prevent injury?
The evidence is mixed and often overstated. Several reviews find a small reduction in muscle injury risk from pre-exercise static stretching in running-based sports, while dynamic stretching, which replaced it, has never been shown prospectively to reduce injury at all.

What is loaded or active stretching?
It is stretching in which you first contract the muscle hard and then drive it into the stretch, which in practice is a form of eccentric training. Blazevich found it produces about three times the range-of-motion improvement of passive static stretching and increases tendon stiffness at the same time.

Should athletes stretch after training?
It will not undo muscle damage, but it can lower sympathetic tone, reduce soreness in some studies, and improve how recovered an athlete feels. Blazevich treats post-training stretching as a good practical opportunity to calm down and check the body rather than a proven recovery method.

About the authors

Dr. Anthony Blazevich is a professor of biomechanics and a sports scientist at Edith Cowan University in Perth, Australia. He is one of the field’s leading researchers on muscle and tendon mechanics, muscle architecture, stretching, and the neurophysiology of force production, and his work on muscle-tendon compliance and static stretching is widely cited across strength and conditioning.

Joel Smith is the host of the Just Fly Performance Podcast and the founder of Just Fly Sports, a former collegiate strength and track and field coach focused on speed, power, and athletic development. Listen to the full episode with Dr. Anthony Blazevich on Just Fly Sports.