From: https://www.shape.com/fitness/tips/post-workout-cool-down-benefits-dynamic-stretches

One of the biggest culprits for skipping your workout? Not having enough time. That not only translates to missed classes and training sessions, but it usually means that when you do manage to get to the gym, you’re more inclined to cut corners (like reps, sets, stretches, warm-ups, and cooldowns) to save some precious time.

But when it comes to your post-workout cooldown, you’re really doing your body a disservice by bypassing it. Coming down from, say, a run or a Tabata circuit by slowing your movements and slowly bringing down your heart rate can help you recover more easily, and increase heart health over time, according to a research published in the Journal of Exercise Physiology Online.

Read on to learn about a few more reasons why you shouldn’t skip your post-workout cooldown.

It controls your post-workout blood flow.

Exercise helps get your blood flowing, so abruptly stopping can actually cause your blood pressure to drop rapidly. When blood pressure drops too quickly, it can cause you to feel light-headed, which is why Heather Henri, M.D., an associate professor of medicine at Stanford University, recommends cooling down for about six minutes after you’ve completed a workout. Fainting is also a risk, as this impact on blood flow could cause blood to pool in your lower extremities, which delays its return to your heart and brain, according to research done by the American Council on Exercise. Cooldowns also reduce the concentration of lactic acid. Using active recovery (here are some active recovery exercise examples) to slowly reduce effort, you can actually increase power and endurance during your next round, too. This is exactly why you shouldn’t totally rest between sets during your workout.

It safely slows down your heart rate.

Your internal body temperature rises during a workout, which means your blood vessels are dilated and your heart is beating faster than normal. It’s important to gradually, and safely bring your heart rate back down after a workout, says Dr. Henri. Skipping the cooldown and dropping the heart rate suddenly can put added stress on your heart, according to research published in the journal Frontiers of Medical and Biological Engineering. Try slowing down your movements from, for example, a faster dance cardio flow to a slower one, a run to a walk, or a plyometric exercise to a movement with both feet on the ground, suggests Deborah Yates, a certified group fitness director for the Bay Club in Silicon Valley.

It prevents injury.

Incorporating a cooldown after your workout can help prevent injuries, and that goes for fitness rookies and seasoned athletes alike. Sprains, strains, and tears in the lower back, hip flexors, knees, hamstrings, and quadriceps are some of the most commonly injuries, says Yates. So, you’ll want to focus on elongating your muscle fibers, which have been under tension during your workout, to achieve your full range of motion. This can be done through hip, lower-back, and spine stretches such as a runner’s lunge or side bend, as well as core-balancing poses such as a standing half lotus and standing bow pose, says Yates.

It increases your flexibility.

The best time to work on your flexibility is when your body is fully warm and you’re breaking a sweat. But instead of hopping off the treadmill and going directly into a toe touch, experts suggest doing some dynamic stretches first. This can decrease your risk of injury, relieve back pain, and improve athletic performance, said Tanja Djelevic, Crunch fitness trainer, in “6 Active Stretches You Should Be Doing.” Taking time for this kind of cooldown can also increase your flexibility and mobility over time, which is thought to help avoid muscle tears, back pain, and joint issues. (Still wondering which is more important, mobility or flexibility? Find out. The answer might surprise you.)