Do You Need to Cool Down After Exercise?
Do you need to cool down after exercise? Not for the reasons most of us were given. When researchers finally gathered every study on the question in 2018, the familiar promises — less soreness, flushed-out lactate, a better session tomorrow — mostly did not hold up. What did hold up is something coaches rarely say out loud: the five to ten minutes after you stop are when the leg muscles that were pumping blood back to your heart go quiet while the vessels they fed are still wide open. That is why a sudden stop can make you light-headed, and it is the one job a cool-down is physiologically built for. This article covers what the review found, what happens in the body when exercise ends, what the evidence says helps, and where daily support for healthy blood flow and circulation from a nattokinase supplement fits beside an active life.
In this article: What a cool-down is, and what trainers think it does · What the review found: the soreness and lactate claims · The first ten minutes: when the muscle pump switches off · What helps in those minutes · Where Great Billiom Nattokinase 10,800 FU fits
What a cool-down is, and what trainers think it does
The 2018 review in Sports Medicine by Bas Van Hooren and Jonathan Peake defined an active cool-down as "voluntary, low- to moderate-intensity exercise or movement performed within 1 h after training and competition" — in practice, "5–15 min of low- to moderate-intensity exercises" such as a jog or a gentle spin. In one survey of collegiate athletic trainers in the United States, "89% of the trainers recommended a cool-down, with 53% of these trainers recommending jogging as the preferred active cool-down method."
The belief behind that recommendation is that moving gently after hard work clears the by-products of the effort, keeps you from getting as sore, and sets you up to perform better next time. The review tested each claim against the studies that had measured it, comparing an active cool-down with simply stopping — a passive cool-down. Its authors note that "research on this topic has never been synthesized," a remarkable thing to say about something nine in ten trainers prescribe.
What the review found: the soreness and lactate claims
The verdict was unflattering. "An active cool-down is largely ineffective with respect to enhancing same-day and next-day(s) sports performance," the authors wrote, though "some beneficial effects on next-day(s) performance have been reported." On injuries, the review found no sign that an active cool-down lowers the risk. On soreness: "Most evidence indicates that active cool-downs do not significantly reduce muscle soreness, or improve the recovery of indirect markers of muscle damage, neuromuscular contractile properties, musculotendinous stiffness, range of motion, systemic hormonal concentrations, or measures of psychological recovery." An active cool-down "can also interfere with muscle glycogen resynthesis" — the refueling of the muscle you just used.
Lactate, the villain of every locker-room explanation, is the most instructive line. Active cool-downs do "accelerate recovery of lactate in blood, but not necessarily in muscle tissue," and the authors add that the practical relevance of even that is "questionable, especially because lactate is not necessarily removed faster from muscle tissue and because lactate may not be the cause of metabolic acidosis." Clearing a number from a blood test is not the same as clearing anything from your legs.
What a cool-down is supposed to do | What the 2018 review found |
Reduce next-day muscle soreness | "do not significantly reduce muscle soreness" |
Flush out lactate | Faster in blood, "but not necessarily in muscle tissue"; practical relevance "questionable" |
Improve performance later that day or the next | "largely ineffective," with some next-day benefits reported in some people |
Lower the risk of injury | No evidence found that it does |
Help the muscle refuel | "can also interfere with muscle glycogen resynthesis" |
Settle heart rate and breathing faster | Supported: heart rate was "significantly lower" 10 minutes after exercise with an active cool-down |
Keep blood moving to the legs and head after stopping | Supported mechanistically — higher leg and forearm blood flow — but whether it heads off fainting "remains unknown" |
The last two rows are the ones that survive, and they are about your circulation, not your muscles. The review puts it plainly: the period right after exercise "can be considered as a vulnerable period during which individuals can experience post-exercise syncope, with symptoms such as lightheadedness, tunnel vision, and blurred vision." An active cool-down "has been reported to result in a higher blood flow to the legs" and is thought to help by "increasing blood flow to the heart and brain due to the contractions of the muscles" and "decreasing blood pooling in the lower extremities." The authors are careful: whether that higher flow actually reduces fainting has not been shown in a trial. But the mechanism is where the cool-down's case lives.
The first ten minutes: when the muscle pump switches off
Every stride squeezes the deep veins of your calves and thighs and pushes blood uphill toward the heart. Physiologists call it the muscle pump, and during upright exercise it does a large share of the work of getting blood back from your legs. A 2014 review in the European Journal of Applied Physiology by John Halliwill and colleagues at the University of Oregon traces the idea to studies from the 1940s that "coined the term 'muscle pump' and demonstrated the profound power of skeletal muscle contractions to reduce both venous pressure and blood volume within the dependent exercising limbs, as well as the rapidity with which this beneficial effect of skeletal muscle contraction is lost when transitioning from exercise to quiet standing."
Rhythmic contractions "are capable of moving blood toward the heart against significant pressure gradients (i.e., greater than 90 mmHg) so long as venous valves are competent. Thus, with quiet standing after exercise, one can anticipate a significant rise in dependent limb venous pressure and blood volumes, and a consequent fall in venous return to the heart, when this second generator of forward blood flow is switched off." The pump stops the instant you do. The vessels do not.
That is the second half of the problem. A hard effort leaves the arteries in the muscles you used dilated for a long while afterward — what Halliwill's group, writing in Experimental Physiology, calls "a sustained postexercise vasodilatation of the previously exercised muscle," which they found is "primarily the result of histamine H(1) and H(2) receptor activation." (If that histamine surprises you, our article on exercise and histamine covers why your own body releases it during a workout.) So in the minutes after you stop, your leg vessels are still wide open and the pump that was emptying them has gone quiet. Blood settles in the legs, less of it returns to the heart, and the brain is the organ furthest uphill.
The 2014 review estimates "that between 50 and 80% of healthy individuals will develop pre-syncopal signs and symptoms if they are subjected to a head-up tilt for 15 minutes following a range of exercise activities," against roughly 8 percent for the same tilt test in the general population. Outside the laboratory, the pattern is the same: these events "occur when an individual is standing motionless during the first 5 to 10 min after exercise," and the authors suspect "the finish-line chute standstill has contributed to some cases" of collapse after races. Heat makes it worse, because the skin's vessels are open too.
If this sounds like the idle calf pump we described in our reviews of what 24 trials show about circulation while sitting and heavy legs after standing all day, it is — with one difference. At a desk or on a shift, the pump is idle while the vessels are at their resting width. After a run, the pump is idle while the vessels are wide open. The same mechanism, with the taps turned up.
What helps in those minutes
The practical answer is the one the physiology hands you: do not stand still. The American Heart Association puts it in one sentence — "Stopping suddenly can cause light-headedness because your heart rate and blood pressure drop rapidly" — and prescribes the simplest fix: "Reduce your walking speed for 5–10 minutes to allow your heart rate to slow down." The Mayo Clinic gives the same prescription in examples: "To cool down after a run, walk briskly for 5 to 10 minutes," and after a brisk walk, walk slowly for the same stretch. It notes that cooling down "may be most important for competitive endurance athletes, such as marathoners."
Halliwill's review describes the countermeasures the laboratory has tested and finds them, with one caveat, effective: physical maneuvers "designed to engage the muscle pump and augment venous return are often found to be beneficial" in holding up blood pressure after exercise. In a 1947 study of exhausted young soldiers, "alternate movement of the legs" raised blood pressure markedly; in a later case, a simple squat relieved the symptoms. The authors sum these up, "along with the advice to 'keep moving' after exercise, as a simple and effective means to avoid many cases of post-exercise syncope." The caveat is honest: an exhausted athlete cannot always rely on "fatigued muscles to protect them," and if moving is not practical, lying down with the legs raised restores the return of blood to the heart.
Where is the line for a doctor? The research above is about healthy adults, and the lightheadedness it describes passes within minutes once the legs move or the body is horizontal. Fainting outright, symptoms that arrive during exercise rather than after it, chest discomfort, or an episode that repeats are a different conversation, and they belong to a clinician rather than a blog.
Where Great Billiom Nattokinase 10,800 FU fits
A cool-down is a ten-minute decision, and nothing in a capsule replaces it: the muscle pump is muscle, and the only way to run it is to keep walking. Nattokinase belongs to a different time frame. It is an enzyme from natto, the fermented soybean dish, and its research is about supporting healthy blood flow and circulation over months rather than across the ten minutes after a run. No nattokinase trial has measured a cool-down, post-exercise recovery or lightheadedness after exercise, so this article makes no claim about the finish line on the enzyme's behalf. What the formula is built for is daily circulation support as part of an active lifestyle, and that is exactly how Great Billiom positions it: healthy blood flow, healthy blood viscosity and healthy fibrin metabolism, taken every day whether or not you trained.
Great Billiom Nattokinase delivers 10,800 FU per two-capsule serving. That matches the higher dose arm of the largest nattokinase study to date, 1,062 adults followed for 12 months in Frontiers in Cardiovascular Medicine, whose authors note plainly that it "represents a retrospective study and not a randomized control trial." Each serving also carries 180 mcg of vitamin K2 (MK-7) and 240,000 SPU of serrapeptase in delayed-release vegetarian capsules — 90 capsules, 45 servings, $19.99, or $17.99 on Subscribe & Save. The label directs two capsules daily on an empty stomach, at least an hour before or two hours after a meal; many people take theirs before bed. Nattokinase contains soy. Anyone taking an anticoagulant, antiplatelet or blood-pressure medication, anyone pregnant or nursing, and anyone preparing for surgery should talk to their doctor before starting it.
Key takeaways
A 2018 review of the research found active cool-downs "largely ineffective" for next-day performance, muscle soreness, injury and muscle-level lactate, and found they can slow the muscle's refueling (Van Hooren & Peake 2018).
What a cool-down does do is keep blood moving in the first minutes after exercise: heart rate settles faster, and blood flow to the legs stays higher than if you simply stop.
The reason that matters is the muscle pump. It stops the instant you do, while the vessels in the muscles you used stay dilated for a long while afterward — so blood settles in the legs and less returns to the heart (Halliwill 2014; Halliwill 2013).
In laboratory tilt tests, 50 to 80 percent of healthy adults show pre-fainting signs within 15 minutes of exercise, against about 8 percent at rest; real-world cases cluster in people "standing motionless during the first 5 to 10 min after exercise."
The fix is movement, not stillness: walk for 5 to 10 minutes after a run, and if you feel faint, lie down with your legs raised (AHA 2024; Mayo Clinic 2023; Halliwill 2014).
Walk the last ten minutes rather than stopping dead — that is what the evidence supports, and it costs nothing but patience. If you also want daily support for healthy blood flow and circulation as part of an active lifestyle, Great Billiom Nattokinase 10,800 FU gives you the research-matched dose with K2 MK-7 and serrapeptase in one two-capsule serving, for $19.99.
Frequently asked questions
Do you really need to cool down after exercise?
For your circulation, yes; for your muscles, the evidence is thin. A 2018 review in Sports Medicine found active cool-downs do not significantly reduce soreness or improve next-day performance, but they do keep heart rate recovery and leg blood flow higher in the minutes after stopping — the window in which lightheadedness after exercise happens.
Why do I feel dizzy after exercise when I stop?
Two things happen at once. The muscle pump in your legs, which was pushing blood back to your heart with every stride, switches off when you stand still, while the vessels in the muscles you used stay dilated afterward. Blood settles in the legs, less returns to the heart, and the brain briefly gets less than it wants.
How long should a cool-down be?
Five to ten minutes of gentle movement is what the American Heart Association and the Mayo Clinic both describe: walk briskly after a run, walk slowly after a brisk walk, swim slow laps after a swim. The physiology supports that window, since post-exercise fainting episodes cluster in the first five to ten minutes of standing motionless.
Does cooling down reduce muscle soreness or lactate?
Not meaningfully. The 2018 review found active cool-downs do not significantly reduce delayed-onset muscle soreness, and while they clear lactate from the blood faster, they do not necessarily clear it from muscle, and lactate may not be what causes the burn in the first place. The Mayo Clinic reaches the same conclusion on stiffness and soreness.
Does nattokinase help with recovery after exercise?
No nattokinase trial has measured a cool-down, post-exercise recovery or lightheadedness after exercise, so this article makes no such claim. Great Billiom Nattokinase 10,800 FU is daily support for healthy blood flow and circulation as part of an active lifestyle, taken as the label directs. For the ten minutes after a run, the evidence points to walking.
Megan Elliott, Content Editor at Great Billiom. Every claim in this article is sourced from the primary research linked above. Read our editorial standards → thegreatbilliom.com/editorial-standards
Sources
Van Hooren B, Peake JM. "Do We Need a Cool-Down After Exercise? A Narrative Review of the Psychophysiological Effects and the Effects on Performance, Injuries and the Long-Term Adaptive Response." Sports Medicine, 2018;48(7):1575–1595.
Halliwill JR, Sieck DC, Romero SA, Buck TM, Ely MR. "Blood pressure regulation X: what happens when the muscle pump is lost? Post-exercise hypotension and syncope." European Journal of Applied Physiology, 2014;114(3):561–578.
Halliwill JR, Buck TM, Lacewell AN, Romero SA. "Postexercise hypotension and sustained postexercise vasodilatation: what happens after we exercise?" Experimental Physiology, 2013;98(1):7–18.
American Heart Association. "Warm Up, Cool Down." Last reviewed January 16, 2024.
Mayo Clinic. "Aerobic exercise: How to warm up and cool down." August 31, 2023.
Chen H, et al. "Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: A clinical study with 1,062 participants." Frontiers in Cardiovascular Medicine, 2022;9:964977.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary.
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