Do you need to cool down?
"Make sure you cool down after a tough workout to help your recovery."
This is another bit of fitness advice you were probably given as a kid, but is there any truth to the importance of a workout cool down? Yes, there actually is a pretty decent benefit, but it's not what most people think it is.
The commonly held belief is that by gradually decreasing the intensity of the workout or performing post-workout stretches you will flush out the lactic acid that built up in your muscles. The thought was that removing this lactate build up will reduce soreness the next day and improve your recovery so you can perform better the next time. Unfortunately, it turns out that lactic acid has nothing to do with delayed-onset muscle soreness.
Soreness is typically caused by actual damage to the muscle cells. I know this sounds bad but it's a actually a good thing. This is how your body adapts. When you overload your muscle fibers and cause this kind of breakdown, your body repairs and strengthens the muscles so that they can handle the load in the future. This is really how exercise makes you stronger. It's also why proper rest is just as important as the workout itself. If you keep breaking down the muscles without ever giving your body the chance to rebuild them, your strength will never increase. This is why overtraining actually decreases your strength and performance.
While there is a type of cool down that will help reduce delayed-onset muscle soreness (and I'll get to that), the common types of cool downs won't help reduce soreness the next day (however, those same studies did show that a warm up will help). Other studies have also shown that a cool down does little to improve performance on subsequent activities. Lactate may hamper performance in the short term (this is a defense mechanism to prevent damage during extreme exertion), but your body will flush it out of your system long before it could do any harm whether you cool down or not. If a cool down doesn't help like we thought it would, then why bother? Is there any point to cooling down?
Cool down for a healthier heart
There are real benefits of cooling down, especially after a tough workout, and they are far more important than just saving yourself from a little muscle pain. Exercise stresses the heart to make it stronger, and a simple cool down afterwards will help your heart come back down from this stressed state much faster.
Your heart pumps oxygen-rich blood throughout your body and returns the waste carbon dioxide to the lungs so it can be expelled. During exercise, blood flow and respiration increase not only to delivery more oxygen to cells in need, but more importantly, to flush out the increasingly large amounts of waste carbon dioxide being produced. The contracting muscles in your extremities actually help to propel this waste-laden blood back to the lungs so carbon dioxide can be removed. Flushing this waste product from your body is what actually helps you get your heart rate and breathing back under control. That's why you still breath heavy after you stop. Your body doesn't really need more oxygen at that point, it needs less carbon dioxide. So when you see football players breathing pure oxygen on the sidelines after a play, it's really more for a psychological benefit than a physical one.
The purpose of a cool down is to use your muscles to help drive this carbon-dioxide laden blood out of your system. If you skip a cool down, this carbon-dioxide rich blood will pool in the dilated blood vessels in your muscles (mostly in your legs) which can make you feel faint and dizzy, but most importantly, it means your heart will need to work harder to move this blood back through your circulatory system. The real point of a cool down is to help get your heart rate back down to its resting rate as quickly as possible to reduce the strain on the organ. Studies have shown that a cool down will lower your heart rate faster than stopping cold. Just walking around at a leisurely pace for a few minutes afterwards will pump that blood out of your legs and drop your heart rate.
Heart Recovery Rate
One of the ways to test your heart health is to measure your Heart Recovery Rate. Basically measure your heart rate at the end of a tough activity and then measure it 2 minutes later. The difference between the two numbers is your Recovery Rate. The higher your number, the healthier your heart. It's a good way to track your cardiovascular improvements over time but it can also serve as a way to take a general assessment of your heart health.
If your Recovery Rate is:
Less than 22: Your heart's age is slightly older than your calendar age.
22–52: Your heart's age is about the same as your calendar age.
53–58: Your heart's age is slightly younger than your calendar age.
59–65: Your heart's age is moderately younger than your calendar age.
66 or more: Your heart's age is a lot younger than your calendar age.
We have been working to integrate heart rate monitors into our lolo apps recently so I've been doing a great deal of heart rate testing (doing the tests myself and monitoring others). I can confirm that everyone's heart rate recovered much faster (thus giving them a higher Recovery Rate score) when they continued walking at a slow pace verses when they stopped immediately and sat down.
Why does lowering your heart rate matter?
Aside from the fact it will make you feel better faster after a tough workout, a cool down is good for your heart. When it comes right down to it, you only get so many heartbeats in your lifetime. The average human's heart beats 2.6 billion times over the course of his or her life. While exercise increases your heart rate in the short term, it lowers your resting heart rate in the long term which places less overall strain on your heart and drastically increases your lifespan. A cool down isn't going to make a huge difference in the total numbers, but why not give your heart a break? It also provides the nice benefit of preventing you from feeling dizzy or light headed after a tough workout, and it makes it much easier to get your breathing back down to normal.
My stance on simple things like walking a few minutes to cool down is if it really has no downside, but it seems to provide a possible decent long-term upside then why not do it? There are some other cool down alternatives that I'll suggest shortly, but I recommend incorporating a short walk either before or after each one of them to quickly help your heart drop down to its resting rate.
Cool down cross training
You've already gone through all the effort to suit up and workout, so why not throw in a few more minutes that can add some additional benefit to your health? I still recommend incorporating a few minutes of walking to help your heart recover, but these are some additional types of training that are best done at the end of your workout or as a cool down.
Stretching: This is probably the most common way to cool down. As I talked about in the article about Performance Stretching, static stretching does offer myriad physical and psychological benefits, and working your muscles while they're already warm is a great way to maximize the effectiveness. However, I haven't been able to find any studies that suggest it helps lower your heart rate immediately after an activity. I would suggest walking for a few minutes to help your heart recover before moving into your stretch routine. You'll likely need to walk around to find a place to stretch anyway, so this minor delay shouldn't be a problem.
Core Training: The muscles in your core support you through all your life's activities and yet so many people tend to ignore this important training. People like doing crunches to try and get a six pack, but the rest of their core muscles go ignored. I recommend tacking a complete core program like the one found in Easy Abs to the end of your workout. It only takes a few minutes a day to make a big difference. Since most of the exercises involve lying on your back, it's also a nice way to continue burning some calories without further taxing your arms and legs. While some of the exercises will help drain the carbon-dioxide rich blood out of your legs, I still recommend walking around a few minutes afterwards to complete your cool down.
Foam Roller Stretching: Foam roller stretching actually has been shown to reduce delayed-onset muscle soreness when performed after an intense workout. It also improves flexibility, vascular health, and breaks up painful scar tissue in the muscle. It's a great way to improve the health and performance of your muscles, but once again, I would recommend walking around a bit to help your heart recover before starting your stretching routine.
Don't just sit down
I understand the urge to sit down and relax at the end of a tough workout, but the benefits to your heart from a quick cool down shouldn't be ignored. Most people skip the cool down because even jogging at half speed sounds unpleasant at that point. No need to do anything so strenuous. All you need to do is walk for a few minutes so your muscles can pump the spent blood back through your system to give your heart a break, get your breathing back under control, and quite possibly add years to your life.