A young woman doing a lunge stretch by the side of a river under a gray cliff.
Physically warming up dilates your blood vessels, allowing more to flow into your muscles and preparing them to work. Silviarita / Pixabay

A million and one pieces of advice on stretching have already spread the internet thin. Don’t fret—this one is different. Instead of giving generic advice on the potential benefits or drawbacks of various stretching methods, we’ve compiled the best science-backed evidence out there on how to warm up your muscles, in order of your desired fitness level. Don’t worry, we know you are reading this on the way to the gym.

If you’re a casual exerciser, especially anything that doesn’t require a lot of flexibility

Congratulations—this whole thing doesn’t really matter for you. As long as you do a short aerobic exercise like jogging or a quick, light jaunt on a rowing machine, you’re golden. Here’s what Jay Hoffman, an exercise physiologist at the University of Central Florida, has to say about it: “Prior to working out performing some dynamic warm-up, like jogging, serves to increase body temperature. This is the goal of the warm-up, period.” Physically warming up dilates your blood vessels, allowing more to flow into your muscles and preparing them to work.

So, increase your body temperature with a slow aerobic activity, upping the intensity over the course of five to 10 minutes. Then kick things into high gear.

I’m a casual exerciser, but I want to increase my flexibility

Like the previous category, you should do a light aerobic warm up, but don’t really need to do a specific stretch routine beforehand. After your workout is over, , that’s when to invest your time in static stretching. Exercise causes your blood vessels to open, making your muscles warmer and limber. This means you will be less stiff and therefore less likely to pull something as you stretch. Hold each stretch for 15 to 30 seconds and repeat them 2-4 times as a cool-down phase.

I’m fairly serious about my regular exercise routine and want to optimize my workouts

The bottom line is that you still need to up your body temperature, but you can do that in any number of ways. Though not unanimous, the weight of evidence suggests that dynamic stretching, not static, is superior. Static stretches can decrease your muscular output (TK description), and though that might only matter for people lifting heavy weights, it’s probably not what you’re going for at the beginning of your workout. If you’re feeling tight, personal trainer Jessi Haggerty suggests rolling them out with a foam roller and doing some active stretching on those areas. Then, she says, “you can always build something more sports-specific into the beginning of your workout. For example, walking or running at a slower pace if you’re going for a long run, or starting off your strength training circuit with lighter weights or bodyweight exercises and build up from there.”

So to repeat: no static stretching at the beginning. Light aerobic activity for a few minutes to get the blood moving, then dynamic stretches on tight muscles plus or minus a foam roller. Cool down with stretches and/or another roll session.

I am an elite athlete

You should really be going to see a trainer to get a tailored regimen, not to a website that can only hand out broad advice, but we’ll roll with it.

A meta-analysis of more than a hundred studies on stretching found that static movements reduced muscle strength by 5.5 percent, whereas dynamic stretching increased it by 2 percent. These are tiny numbers that probably don’t matter at all to the recreational athlete, but they’re enough that if you’re seriously involved in sports of some kind you should pay attention. Here’s Hoffman again to back us up: “Stretching is best performed after the workout, but some individuals prefer to do it before with a foam roller as part of their warm-up routine. Not a big deal, I just wouldn’t perform any static stretching for a competitive athlete prior to a power event.”

Find a short series of dynamic stretches, like walking lunges or bear crawls, that works for you and make a habit of doing it prior to the workout but after a bit of aerobic exercise. Proper mobility is important, but you don’t want to risk reducing your peak power by stretching your hamstrings. Do that afterwards.

I scrolled to the bottom hoping for a piece of blanket advice

Jog or lightly row on the machine for 5 to 10 minutes. Then do a handful of dynamic stretches that get your muscles mobilized, like this routine suggested by the American Council on Exercise. Foam roll tight muscles if desired. Then workout. Then do some static stretches as a cool down. Done.