Stretching — and when to stretch — wouldn't seem like a hotly debated topic. Conventional wisdom says you stretch to warm up before a workout and to cool down after. Right? But the actual truth lies somewhere in the middle.

Dr. Scott Rand, sports medicine specialist with Houston Methodist, says that effective stretching is something that many of us do poorly and at the wrong time.

"Stretching before a run, for example, is something a lot of runners do very badly, but then they don't stretch afterwards," Dr. Rand says. "I've been a runner for most of my adult life, and I can tell you that most runners don't stretch the way they should, including me."

Types of stretching

"There are several different types of stretching," says Dr. Rand. "Stretching simply means I'm creating tension on a muscle. The muscles and the tendons can get tight, and the little ratchet that makes your muscles contract and relax can get stuck — and by stretching we release that a little bit, and the muscles elongate — and they're less likely to be damaged when you put force across them."

What most people think of when they think of stretching — holding a pose to create tension in a muscle — is called static stretching. Many moves that come to mind, like a calf stretch or shoulder stretch, are considered static. When completing a static stretch, you take a muscle to its end range point and hold it for 30 seconds or more.

Static stretches can be active, where you apply force for more intensity; or passive, where you use a device like a resistance band or towel, or someone helps you with the stretch.

Dynamic stretching, the other main form of stretching, is about active movement. It emphasizes full range of motion in dynamic stretches — think arm circles, walking lunges or even high knees. These are usually repeated several times for the benefit.

Proprioceptive neuromuscular facilitation (PNF), according to Dr. Rand, is another type of stretching where the muscle is stretched to the limits that it can go, and then you fire the muscle and make it go in the other direction. This type is usually performed with the aid of a physical therapist or athletic trainer.

Should you warm up before working out?

Yes, absolutely. But you can skip that middle school gym warmup where you were encouraged to touch your toes or hold static stretches no matter the upcoming activity. Static stretching before a workout when your muscles are "cold," or inactive, can cause injury since it is easier for cold muscles to contract and overstretch. This is the mistake that many fall prey to.

"You don't stretch to warm up," Dr. Rand says. "The ideal time to stretch is when your exercise is over, when you finish your run or finish your exercise."

To warm up before a workout, Dr. Rand says you want to focus on dynamic stretching movements. Dynamic stretching can help raise your body's temperature, activate muscles and get blood flowing to them, priming your body for the workout you're about to complete.

Think of your warmup as a rehearsal for the workout you're about to do. For example, if you're doing an arm workout, you'll want to do dynamic movements such as arm circles or arm swings. Other types of dynamic stretching movements include torso twists, high kicks, butt kicks, squats, walking lunges, mountain climbers and inchworms.

A warmup for a strength session could be as simple as completing a round of the movements you'll do without the weights. If you're going for a longer-distance run or bike ride, you could also jog slowly or cycle at a slower pace or lower resistance.

A warmup can last anywhere from five to ten minutes. If you're pressed for time with your workout, doing some dynamic movements to get the blood flowing is better than going into your workout completely cold. Warmups can help protect you from injury and can be a good way for you to get into the right mindset for your workout.

Is it better to stretch before or after exercise?

You can receive the full benefits of static stretching after a workout by being able to hold the stretch for longer, as well as being able to hold a deeper stretch thanks to your warm muscles.

"If you work out any part of your body — let's say your back or your biceps — then you should stretch them after you're done with that workout," Dr. Rand says. "Doing that myofascial release type of stretching after you're done with your workout decreases the amount of what's called delayed onset muscle soreness" (DOMS).

DOMS are tiny tears that happen in the muscles that cause the stiffness or soreness that usually sets in a day or two after a workout. While DOMS is a natural process that indicates your body is getting stronger, it doesn't feel great. Carving out time to stretch after a workout can help decrease how much DOMS affects you.

"All of the research in endurance-type exercise says that spending a minimum of five minutes doing some stretching for the muscles you've just worked at the end really helps you to be able to move better later on in the day, decreases DOMS, improves mobility and makes things hurt a whole lot less," Dr. Rand says.

Can we use tools to help us stretch?

Foam rollers and massage guns have become popular tools to help with workout recovery and to aid with muscle tightness or knots.

"I often try to get runners to use foam rollers after exercise for the hamstrings and their glutes," Dr. Rand says. "Nobody really wants to do that because let's be honest, it hurts. But it will hurt less the more often you do it, and it will hurt less later on if you commit five minutes to do those stretching exercises."

Dr. Rand says that those who are very flexible can receive benefit from form rollers to aid in getting enough range of motion to get an effective stretch. He also says that massage sticks and massage guns can be efficient in getting muscles to release knots. However, he says that there are caveats in using massage guns.

"You wouldn't use them over bony prominences, and you wouldn't use them over injured muscles," Dr. Rand says. "If I've got a big, deep thigh bruise, adding a massage gun to that to make the bruise even bigger doesn't make a whole lot of sense. You also have to have enough soft tissue to be able to tolerate the percussion."

Dr. Rand says that people will often have pain in the side of the hip over the trochanter, the bony prominence where the femur and hip bone attach. He says to avoid using a massage gun there, even if the trochanter hurts, as the correct place to massage would be the muscles behind that area and lower in the leg.

When shouldn't we stretch?

In general, we think of stretching as beneficial to either help prime us for movement or to recuperate. However, it can do damage at certain times.

"You shouldn't stretch when you have a specific injury and there are certain types of injuries that really need to be rested," Dr. Rand says. "If you get a significant tendon or muscle strain, say you strain a calf muscle or quadricep or something like that. Stretching that injured muscle perpetuates the injury. The general rule, whether it's a significant tendon or muscle injury, is that you rest until you are pain-free and you regain your flexibility and strength."

Is it worth it to stretch?

If you're that person who goes from full-blown workout to the couch, you may want to reconsider.

"It doesn't take 30 minutes to do it," Dr. Rand says. "You don't have to spend as much time stretching as you spend exercising, but if you'll invest a little bit of that time, it really does pay big dividends. Stretching is important from a pain relief and simple body mechanics standpoint."