Think back to elementary school physical education. Chances are, your instructor warmed up the class with a number of static stretches… like touching your toes and holding it for 30 seconds. Now, a growing body of evidence suggests that static stretching has the opposite effect that we intend; it decreases speed, reduces strength and increases injury risk.

The New York Times recently cited two studies in the case against static stretching. One study, published in The Journal of Strength and Conditioning Research, has demonstrated the negative impact of static stretching on weight lifting. A separate article published in The Scandinavian Journal of Medicine and Science in Sports has added additional fuel to the fire by analyzing more than 100 previous studies.

Here are a few of the key findings.

According to researchers, static stretching reduces strength by almost 5.5%. In a different study involving squats, static stretching was found to reduce strength by 8.3% - and was linked to increased feeling of instability. Researchers noted that the impact is greatest when muscles are stretched for 90 seconds or more - and somewhat reduced for stretches under 45 seconds.

But it doesn’t end there. Power is a measure of a muscle’s ability to produce for during contractions, and muscle power generally falls by about 2% after static stretching. Explosive muscular power - like bursting into a full sprint - was reduced by 2.8%.

While reducing output by a few percentage points doesn’t sound like a big deal, every pound or nanosecond counts - especially in the world of competitive sports. When races are won by hundredths of a second, reducing power by 2% is a game changer.

The bottom line: Skip static stretches. Instead of warming up by holding poses for a given length of time, most trainers recommend dynamic stretching. Dynamic stretching involves moving your muscles - like arm circles or jumping jacks - to properly warm up your body for a given exercise.