 A cool down is a part of pretty much every structured cycling workout. You start with easy riding in the beginning to warm up and then you do your intervals or your hard group ride or your race or whatever it is you're looking to achieve that day and then you ride easy again at the end of the ride to cool down. Even if you have absolutely no plan when you head out the door to go for your ride, it's natural to end the ride with a couple minutes of easy pedaling. But is there actually a physiological reason for doing this? Although it may seem odd, would you be just as well off if you jumped off the bike immediately after your hard effort and skipped the cool down completely? Well, I don't know if your body would be better off, but my average speed and average power are definitely higher when I don't do a cool down, which gets more kudos on Strava. So I think we can go ahead and wrap this video up. This is what we're going to be getting into today by taking a look at what the science has to say on this topic, and a good place to start would be by examining the reasons that people give for why a cool down is necessary. Now, there are a wide range of justifications that people give for cooling down, but probably the most common are that it aids with recovery and reduces soreness, clears blood lactate, and helps with injury prevention. Let's start with this recovery claim. This study tested a number of different recovery interventions on netball players to see if they performed better in sprints in the following day after exercise. One of the recovery methods that was tested was active recovery. Now, I know, netball players are not trained cyclists, and I'll be addressing that in a minute. It's also interesting to note that a lot of these studies that test active recovery or cool down also test a variety of other recovery methods. I won't get into how those methods fared in this video, but perhaps that'll be a topic for another video. Back to the study though. They actually found that active recovery had no effect on performance the following day, and muscle soreness was actually higher when subjects cooled down. And this is not the only study that comes to this conclusion. Similar studies find the same thing, like this study that found that active recovery had no effect on performance, muscle damage, doms, or perceived physical state. It would seem from these studies that a cool down is actually not all that important for recovery. And in fact, if you are worried about recovery after a hard workout, then you may actually want to spend more time on the warm up for the workout and not the cool down. For example, this study looking at the effect of warm up and cool down on muscle soreness had subjects do either just a warm up, just a cool down, a warm up and a cool down, or neither in combination with 30 minutes of backwards downhill treadmill walking. Yes, walking backwards downhill for 30 minutes is certainly an odd exercise for the study to choose. But it was probably an exercise that the subjects bodies weren't used to, meaning that they would get more sore from doing it. And then they could see which one of these interventions would make the subjects less sore. And sure enough, what they found was that the warm up did reduce perceived muscle soreness. However, the cool down had no apparent effect, and similar conclusions have been found in similar studies as well. At this point, it may seem safe to conclude that adding a cool down is not helping you recover, but there is a problem with a lot of these studies that I alluded to earlier. And that's that they're generally done on untrained individuals. It isn't too much of a surprise that adding a cool down didn't help these individuals with their recovery because it's further adding to a training stress that they're already not used to. For example, if you took a couch potato and had them ride for 45 minutes, that's 45 minutes longer than they usually ride, and they're probably going to be sore the next day. If you then go ahead and add a 15 minute cool down onto that, then they've significantly increased their training load right there. And they're probably just going to be more sore, even if that cool down was done at an easier pace. Now, to be fair, this wouldn't explain why a warm up is helpful, but a cool down isn't, but I'm trying to play devil's advocate here. For a more experienced cyclist who's used to riding at a higher volume and intensity, adding a cool down is not a significant addition to their training load. So maybe a cool down would be helpful for this person. And there are studies on more highly trained athletes like distance runners and elite level BMX racers that do hint that active recovery may aid in recovery. This study looking at the effect of active recovery on weight lifters found that active recovery does not seem to enhance recovery, although there is a lot of individual variability here. This would mean that active recovery may be beneficial for some people, but not for others. Certainly not any rock solid evidence so far, but another reason that athletes and coaches give for why a cool down is important is that it helps clear lactate that has accumulated over the course of a hard workout. Let's investigate that. As this review article on whether or not we need a cool down puts it, high intensity exercise can lead to an accumulation of metabolic byproducts in the muscles such as lactate, which has traditionally been associated with fatigue. As a result, the rate at which lactate concentration is reduced has frequently been used as an objective indicator of recovery from exercise. There's quite a bit of confusion out there about whether lactate is good or bad, and perhaps that's a topic for another video. Actually, I'm more confused why we started talking about milk all of a sudden. For the purposes of this video, just know that recent research does show that lactate production doesn't cause acidosis, but actually slows it. That being said, lactate production coincides with cellular acidosis and remains a good indirect marker for cell metabolic conditions that induce metabolic acidosis. I got a little bit into the weeds there, but essentially your lactate levels are still relevant when we're talking about acute fatigue. So then, could doing something to clear this lactate at the end of a workout like a cool down be beneficial for recovery? Is doing a cool down even clear lactate any faster? This study looked at the removal of blood lactate with active and passive recovery after a 200 meter swimming trial, and sure enough, they did find that when subjects performed active recovery, the blood lactate removal was quicker. Similar results have been found in other studies as well using other forms of exercise. Okay, so it looks like doing a cool down does in fact help clear lactate faster, but the question still remains, does this actually help with recovery or performance in any way? This review article on the topic is skeptical, stating that after high intensity exercise, rest alone will return blood lactate to baseline levels well within the normal time period between training sessions. Going back to this review, they echo this, stating that blood lactate returns to resting levels within 20 minutes to two hours anyway. No one schedules training sessions that close together, so this whole discussion about faster lactate clearance may be largely irrelevant. It's important to remember that what we're after here is better performance. And of those studies that showed a faster removal of blood lactate with a cool down, subsequent performance was not always improved. The jury is still out on this one, but it seems as though faster lactate clearance once your workout is already done, is unlikely to be a huge concern from a recovery standpoint, because whether it's 20 minutes or two hours, your lactate levels will be at resting level for a considerable amount of time before your next workout. All right, what about injury prevention? This is probably a less common reason for cooling down, although plenty of people do use it as part of the justification for it. Well, cohort studies on runners did not find that a cool down reduced the incidence of injuries. The same has been found in triathletes, and even though more research needs to be done here, the evidence just isn't there to say that cooling down will help with injury prevention. I've got to say this reminds me a lot of the research on stretching, and just like with the cool down, stretching after exercise is commonplace. Or at least a lot of people think it should be, whether or not they actually do it is a whole another question. The video I did on stretching is a couple years old at this point, so let me jog your memory. Studies done on how stretching affects exercise performance have found that stretching before exercise does not improve performance and actually may even reduce the amount of force your muscles are able to produce. When stretching is done after exercise, it doesn't appear to improve recovery, and the practice of stretching in general doesn't even seem to be particularly effective at preventing most types of injuries. Well, it looks like your high school gym teacher was wrong. So, do cool downs fall in the same category? This review provides us with this evidence heat map for cool downs. In green are the number of studies showing benefits. In blue are the ones showing no effect, and in red are the ones showing harm. As we can see, there's a lot of evidence that a cool down will clear blood lactate faster, but what is unclear is whether or not this is actually aiding in recovery. Most studies looking at delayed onset muscle soreness find no effect, and the same goes with same day and next day performance. It does appear that a cool down does not help with muscle glycogen resynthesis, which makes sense. They conclude by stating that few of the proposed benefits are actually supported by research. Again though, more research needs to be done on trained athletes. Is doing a cool down going to make you less sore for your ride the following day? Probably not. So, does this mean that you should scrap cool downs all together and just jump off the bike immediately when you're done with your last hard effort? No, not necessarily. I do think that there's still some practical applications to a cool down. First of all, a cool down is generally a good mental breather at the end of a workout. You can breathe a sigh of relief that you made it through and reward yourself with some easy pedaling before you call it done. Also, if you're riding outside, most people are not doing their last hard interval right up to their doorstep and then stepping off the bike. They need to ride home first and riding home at an easier pace after the hard work is done just makes sense. Doing a hard workout does not mean that every minute of the workout needs to be hard and in fact in the vast majority of cases, it shouldn't be. Even if you're riding on the indoor trainer, I would still add in a cool down just as a means to get in some more volume. Getting volume in can be difficult when you're riding indoors and adding in a cool down is a relatively mentally easy way to do that. The positive takeaways that I get from this research are this. First, if you're strapped for time and you need to shorten your workout just to fit it in, then the first place that you should take away time is from the cool down because it appears to be the least necessary part of the workout. And the final point is that if you're a racer, doing a cool down like you're supposed to when you cross the finish line rarely actually happens. A lot of times you're talking with your competitors about how the race went or you go and check your placing and your finish time or maybe you flop on the ground hardly able to move. Yeah, that or just head straight to the beer tent. Either way, at least now you can take comfort in the fact that that cool down was probably not super critical. I can't believe I'm saying that, but as always, I'm just here to report on the science. Thanks for watching. If you enjoyed this video, be sure to give it a like, subscribe for more science based cycling videos just like this one, and share this video with your cycling friends. I'll see you in the next one.