The other day I was at my local sports club playing squash, and at the end of the session, the instructor made a big deal out of cooling down so we "won’t be sore tomorrow." While it’s not the first time I’ve heard this advice, I always wonder where the instructors learn this bit of incorrect information. I know they all mean well, but there is now quite a bit of research that shows that a cool down after exercise doesn't prevent muscle soreness. That's not to say the cool down has no purpose, it's just that preventing soreness and speeding recovery isn't it.

A cool down often feels good, and the psychological relief of riding easy, or walking around after a tough workout, can do wonders for your mental well-being. But many well-designed studies found no amount of cool down will prevent muscle soreness after exercise. In fact, studies show that a proper warm up before exercise is more likely to reduce your post-exercise muscle soreness.

So does the cool down have any benefits? Well, yes, there is one major benefit: a few minutes of cooling down after maximal efforts can help prevent an athlete from feeling dizzy or possibly passing out. What this means is that you may not want to end your workout (or a spin class) with an all-out sprint, maximal effort or a tabata session and then jump off the bike and touch your toes. I once attended an exercise class where the instructor had us do just that. It's a risky move when you consider the varying fitness levels and health conditions that may be lurking in an exercise class. And for any athlete racing in competitions, it makes sense to keep moving around slowly for several minutes after you cross the finish line.

So far, the research has pretty well debunked the following so-called benefits of cooling down 

after exercise.

According to the current research, cooling down has little effect on:

• Reducing muscle soreness after exercise
• Aiding recovery
• Increasing flexibility
• Increasing strength gains
• Preventing injuries

The benefit of cooling down after hard exercise is mainly that it prevents the blood from pooling in the extremities after maximal efforts, which can cause dizziness and fainting. By exercising at a slower intensity for several minutes after a hard effort, sprint or maximal effort, you'll allow your circulatory system to gradually return to a resting state while maintaining proper blood pressure.

When an athlete faints or collapses after max efforts (or when crossing the finish line), the most common cause is stopping so suddenly that the blood pools in the extremities (usually the legs), and the brain is deprived of oxygen for a moment. It’s called postural hypotension, and is the same mechanism that causes you to feel dizzy if you stand up too quickly when you have low blood pressure. Other less likely culprits for dizziness include severe dehydration, a lack of sodium (hypernatremia), heat illness or heart attack — all of which are fairly rare.

The treatment for postural hypotension is to simply lay the person down, and raise her feet above her heart until the blood and oxygen get back to the brain. If that doesn't solve the problem, then something more serious could be going on, and medical help should be sought immediately.

Other common words of wisdom about the cool down say that it will help you will recover faster and prevent soreness. The idea that cooling down will reduce or prevent muscle soreness has not been found to be true with research. In fact, what has been discovered is that muscle soreness after exercise is caused by micro tears in the muscle fibers. Ironically, this is also how a muscle gets stronger. After the small tears are produced, the muscle tissue repairs and rebuilds itself (hypertrophy) and in doing so, gets bigger.

So by all means, continue to cool down after exercise if you like. Just understand what a cool down can and can not do for you.