Bend and stretch. For such a seemingly simple activity, stretching remains one of the most contentious parts of any workout. After all, most of what we used to know about stretching has now been proven flat-out wrong — or at least seriously called into question.

“Honestly, I don’t think we’ve heard the last of the arguments about whether to stretch or not to stretch — or even when to stretch” since the research is constantly evolving, says Janet Hamilton, an exercise physiologist and certified strength and conditioning specialist with Running Strong in Atlanta.

So unless you like to spend your time combing through research journals, you could easily be stretching the wrong way — and potentially stunting your fitness gains as a result. Consider these the new(est) rules of stretching:

Don’t Stretch as a Warmup.

Stretching used to be a warmup non-negotiable. Now research shows that pre-workout stretching can impede exercise performance and results — especially if held for longer than 60 seconds. For example, in one study published in the Journal of Strength and Conditioning Research, when young men stretched before performing squats, their lower-body strength and stability took a nosedive, meaning they couldn’t bang out their best reps.

[See: 7 Exercises Men Should Do Every Day.]

“When you stretch, you decrease muscles stiffness, reducing stability and force production, which will then decrease mechanical efficiency,” explains Michael Silverman, director of rehabilitation and wellness at Northern Westchester Hospital in New York. He notes that it will even increase oxygen demand. Translation: You’ll have to breathe faster and heavier to get through any given workout.

Pre-workout stretching doesn’t seem to prevent injury, either, according to a recent Applied Physiology, Nutrition, and Metabolism review. That may come down to the fact that stretching introduces “slack” in your muscles and tendons, decreasing the stability you need to stay safe when strength training, running, cycling or enjoying any other workout, Silverman says.

Do Warm Up (Sans Stretching).

To prepare your body for exercise, Hamilton recommends performing some easy-paced cardio or drills (think: skips, butt-kicks, bodyweight squats and lunges or incline pushups) that mimic the movements that you’ll perform during your workout. “I encourage my athletes to think of warming up and stretching as distinctive entities,” she says.

Don’t Stretch Immediately After Your Workout.

Naturally, most exercisers who learn that pre-workout stretching is a no-no move their stretches to the end of their workouts. But it might not be the best fit there, either. For example, one Cochrane review of previous research concluded that stretching doesn’t reduce post-exercise muscle soreness. And a 2016 review published in the Strength and Conditioning Journal shows that finishing up your workout with stretching may actually impede muscle recovery.

Why? Contrary to conventional wisdom, during stretches, the flow of blood to the muscles is actually decreased, preventing oxygen from reaching your muscle cells and exercise byproducts from escaping them, explains lead author William A. Sands, a certified strength and conditioning specialist and sport technologist with the U.S. Ski and Snowboard Association.

[See: 7 Exercises Trainers Wouldn’t Be Caught Dead Doing.]

Do Cool Down (Sans Stretching).

After your workout, Sands recommends slowing your heart rate and getting blood where it needs to be immediately after your workout with five to 10 minutes of easy aerobic exercise, which research shows is more effective at helping people bounce back after tough workouts. If you’re sore in the days following your workout, try walking, swimming or performing light bodyweight exercises to gently take your body through its full range of motion, Hamilton says. If you’re craving a feel-good stretch, perform it after these low-key activities when exercise by-products are already out of your system.

Do Stretch Throughout the Day.

With all of these “don’ts,” you might think you don’t need to — or shouldn’t — stretch at all. But a 2017 review in Human Movement Science suggests that chronic stretching may still improve muscle performance by increasing flexibility. While the researchers note the review was anything but definitive, it raises the possibility that stretching (just not immediately before or after your workouts) could improve your workout performance and results.

No matter your workout routine, like most Americans, you probably spend a good amount of time sitting. “Doing so places your joints in extreme angles at times,” says Hamilton, noting that sitting for hours on end shortens the hip flexors, inactivates the glutes and can cause the spine to hunch forward. In one 2014 study of office workers, performing stretches focused on the neck, shoulders, low back, hands and wrists significantly decreased aches and pains.

[See: 8 Ways to Stay Healthy at Work.]

Break up time spent sitting with regular stretch breaks, making sure to hit all of your major muscles from head to toe, including your glutes, hamstrings, quads, lats, chest and shoulders. Move through each stretch until you feel a good “pull” in your muscle, but not so far that it hurts. Perform each stretch slowly and under control, and never bounce to go deeper into a stretch, Hamilton says. Doing so can trigger your muscles to tense up, rather than relax.

More from U.S. News

7 Exercises You Can Do Now to Save Your Knees Later

How to Know if You’re Exercising Too Much

7 Signs You Should Stop Exercising Immediately

The New Do’s and Don’ts of Stretching originally appeared on usnews.com