Imagine an overheated car that has just completed a long journey. It desperately needs to cooldown. Man (and women, of course) and machine are alike in this respect. After a rigorous workout, you too must cooldown your body. The purpose of the cooldown is the reverse of a warm-up.
Right after a cardio, your heart pumps the blood furiously through your muscles. You must allow your body to redirect the blood flow back to normal and decrease your body temperature. If not, you risk fainting. Cooling down prevents your blood from accumulating in one place, such as your legs.
Why Should You Cooldown?
An ideal cooldown should last 5-10 minutes or longer if you’ve done an especially hard cardio workout. After a cardio workout, it is important to cooldown before resting. Although cooldowns probably won’t prevent the next-morning aches and pains, they can help prevent passing out. During exercise, the arteries and heart vigorously pump blood to muscles that need blood, and more blood usually ends up going to the extremities.1
The concept of the cooldown seems to have begun with a popular theory, which is now proven false, that muscles become sore soon after a cardio workout as they accumulate lactic acid. Cooling down after cardio was thought to reduce lactic acid buildup in the muscles, hasten recovery, and prevent soreness.
But, many studies suggest that post-exercise acid accumulation has little to do with impaired performance and may actually help muscle recovery.2 In reality, lactic acid is a fuel. It’s good to produce lactic acid and it’s a normal part of an exercise. It has nothing to do with muscle soreness.
However, the lactic acid theory led to the belief that by slowly lowering the intensity of your cardio workout, you can give lactic acid an opportunity to dissipate.
What Happens If You Don’t Cooldown?
The answer to this question depends on how hard your workout was. The longer and more intense the cardio, the higher the chances of post-workout dizziness. So, cooldowns can be especially beneficial after difficult training sessions. When you suddenly stop an intense cardio exercise, your blood accumulates very fast, which causes dizziness, nausea, and fainting.
People who are out of shape or at high risk for heart disease must not avoid a cooldown session as it places undue stress on the heart. After a cardio exercise, your body pumps more blood than usual to your extremities. It increases your heart rate and the blood vessels that carry blood to your muscles dilate, allowing the blood to rush in. This results in you feeling lightheaded and nauseous.
In some cases, you may also faint. A cooldown prevents that from happening and keeps your muscles moving, enough to pump blood back up from your extremities while your cardiovascular system returns to its normal state.3
Good Reason To Cooldown
Another important reason to cooldown after a cardio is to keep your muscles working at a lower intensity for a few minutes so that the blood flow to your muscles reduces gradually rather than abruptly. This helps flush out chemical byproducts of exercise, like lactate, and supply more nutrients to the muscles to help it recover, which could help with muscle building.
Is A Post-Cardio Cooldown Effective?
Some studies have revealed that cooldowns have little effect on reducing soreness after a workout.4 Contrary to popular belief, another study suggests that post-cardio cooldowns may not speed recovery or reduce muscle soreness.5 But, after an intense cardio session, a cooldown may be effective to gradually reduce heart rate and prevent post-workout dizziness.6
|↑1||Williams, Jay T., Mollie P. Pricher, and John R. Halliwill. “Is postexercise hypotension related to excess postexercise oxygen consumption through changes in leg blood flow?.” Journal of Applied Physiology 98, no. 4 (2005): 1463-1468.|
|↑2||Cairns, Simeon P. “Lactic acid and exercise performance.” Sports Medicine 36, no. 4 (2006): 279-291.|
|↑3, ↑4, ↑6||Takahashi, Tatsuhisa, Akiyoshi Okada, Junichiro Hayano, and Toshiyo Tamura. “Influence of cool-down exercise on autonomic control of heart rate during recovery from dynamic exercise.” Frontiers of Medical and Biological Engineering 11, no. 4 (2001): 249-259.|
|↑5||Law, Roberta YW, and Robert D. Herbert. “Warm-up reduces delayed-onset muscle soreness but cool-down does not: a randomised controlled trial.” Australian Journal of Physiotherapy 53, no. 2 (2007): 91-95.|