Sports science findings you should know
9+ ideas to boost your training & recovery
There's a lot of bad sports science advice out there. I often see ideas being shared that have been pretty thoroughly debunked. In the past few years, I've read a number of books on a variety of sports science topics. Here are some of the most important concepts I've learned.
1. Don't ice your injuries
There are two ideas that especially motivated me to write this article. Here is the first one: using ice to treat injuries is not supported by modern science.
...the icing age really took hold in sporting circles around the time that physician Gabe Mirkin wrote about the familiar term RICE (Rest, Ice, Compression, Elevation) in his 1978 tome, The Sports Medicine Book. Mirkin didn’t invent the acronym or the sequence of actions, which had been mentioned in medical journals as early as 1906, but he helped popularize it within the sports medicine community...
...There’s no question that icing can reduce pain, at least temporarily, he told me, but it comes at a cost. “Anything that reduces your immune response will also delay muscle healing,” Mirkin says. “The message is that the cytokines of inflammation are blocked by icing—that’s been shown in several studies.” He now believes that instead of promoting healing and recovery, icing might actually impair it...
That's right, even the guy who popularized the acronym RICE doesn't believe in icing injuries anymore. Cut out those carbs and manage injuries with PEACE and LOVE instead:
Roughly, the modern theory is: icing reduces swelling by causing blood vessels to constrict. However, blood flow is what the body needs to heal itself. The "good stuff" (cells or nutrients or whatever) that are causing the area to heal are carried in by blood cells and the "bad stuff" is being carried away by the blood as well. Icing reduces the swelling temporarily, but it doesn't cause you to heal faster.
Source: Good to Go by Christie Aschwanden, Chapter 4
2. Static stretching doesn't reduce injury risk
Here's the second big one: don't do static stretches. The best science we have says that static stretching doesn't do anything to make you less likely to get injured while working out. To be fair, dynamic warmups have become relatively popular nowadays, but static stretching is still surprisingly common given that it's never been shown to be helpful. (In doing some research for this post, I found this article published by Harvard Health in 2022 on "The importance of stretching". So, yes, people are still on the pro-stretching train.) Static stretches have never been shown to reduce injuries:
“If injuries usually occur within the normal range of motion,” McGill University sports doctor Ian Shrier asked in a widely cited editorial in the British Journal of Sports Medicine in 2000, “why would an increased range of motion prevent injury?”
Literally hundreds of studies have tried to answer that question, and the Centers for Disease Control and Prevention reviewed 361 of them in 2004 in search of an answer. “Stretching was not significantly associated with a reduction in total injuries,” they concluded...
...warming up—for example with a gentle jog and some movement drills within the expected range of motion—reduces injury risk whether you stretch or not.
...Most muscle injuries occur within the normal range of movement during “eccentric” contractions (while the muscle is lengthening, for instance when you’re lowering a biceps curl). In other words, you’re most likely to pull your hamstring while sprinting or changing direction, not while trying to do the splits (unless you’re a ballerina or a hockey goaltender, in which case static stretching is in fact important).
Using static stretching to increase your range of motion before a workout doesn't help, because injuries generally happen within your normal range of motion. It's also well-known that static stretching will make you temporarily weaker. Static stretches really shouldn't be part of anyone's warm-up routine.
The excellent site PainScience.com (written by an ultimate player!) has an extensive review on stretching (and I mean extensive), including this subtitle: "Stretching science has shown that this extremely popular form of exercise has almost no measurable benefits". Stretching won't fix your muscle pain and won't decrease your injury risk. Do your PT exercises (strengthening, not stretching).
Sources: PainScience.com; Which Comes First, Cardio or Weights? by Alex Hutchinson, Chapter 6
3. Over-hydration is an issue, too
Staying healthy during workouts is not just about drinking lots and lots of water. I'm happy to see knowledge of this concept growing recently, although I do still see comments from time to time suggesting nothing is more important than drinking copious amounts of water.
It's (perhaps surprisingly) much easier to die from over-hydration (hyponatremia) than dehydration. Here's what Christie Aschwanden says in Good to Go:
Low blood sodium causes cells in the body to swell, and when this happens in the brain the results can be deadly....
There’s never been a case of a runner dying of dehydration on a marathon course, but since 1993, at least five marathoners have died from hyponatremia they developed during a race. In addition, scores of other athletes have become gravely ill but survived. In 1998, Kelly Barret, a forty-three-year-old pediatric dentist and mother of three, became the first runner to die in the Chicago Marathon, and it was likely hyponatremia that killed her.
Don't let anyone tell you that you need to drink a certain amount of water, no matter what. Here, as in other things, it's OK to trust your body: if you feel thirsty, drink; if you're not thirsty, drinking lots of water isn't necessary.
A common variant of this advice is that you should hydrate early, because you don't want to wait until it's too late. In the sport science community, there was previously an idea that if you lost 2% of your body weight, performance would be negatively effected. But there's no strong evidence for that idea, either. Top marathoners consistently lose weight during performance:
The results are consistently the opposite of what you would expect: the fastest finishers tend to be the most dehydrated. For example, among 643 finishers in the 2009 Mont Saint-Michel Marathon in France, sub-three-hour finishers averaged a loss of 3.1 percent of their starting weight; finishers between three and four hours averaged 2.5 percent; and those clocking more than four hours were the only ones to obey the 2 percent rule, losing on average 1.8 percent. The results don’t prove that drinking makes you slower, but they certainly raise further questions about the claim that any loss greater than 2 percent slows you down.
As for the relatively common sight of athletes needing assistance or even collapsing after the finish of a long race, there are several reasons to be suspicious of the idea that these athletes are paying the price for insufficient hydration...studies have found no difference between the typical dehydration levels of collapsed athletes and those who walk away from the finish line untroubled.
Sources: Endure by Alex Hutchinson, Chapter 9; Good to Go, Chapter 2
4. Try motivational self-talk
In Play On (read my review here), Jeff Bercovici writes that motivational self-talk is one of the key changes he personally made after researching his book:
Before I learned what a powerful performance tool it can be, I never gave much thought to the particulars of my internal monologue. Now I do. I’ve discovered that I perform best when challenging and exhorting myself rather than encouraging, praising, or criticizing. Self-talk is particularly handy in lonelier pursuits like running and cycling.
In Endure (read my review here) Alex Hutchinson writes positively of self-talk as well:
If I could go back in time to alter the course of my own running career, after a decade of writing about the latest research in endurance training, the single biggest piece of advice I would give to my doubt-filled younger self would be to pursue motivational self-talk training—with diligence and no snickering.
He covers some of the studies in support of self-talk as a training method:
The self-talk group learned to use certain phrases early on (“feeling good!”) and others later in a race or workout (“push through this!”), and practiced using the phrases during training to figure out which ones felt most comfortable and effective. Sure enough, in the second cycling test, the self-talk group lasted 18 percent longer than the control group, and their rating of perceived exertion climbed more slowly throughout the test.
Here's my explanation of why it works: I practice motivational self-talk by, for example, visualizing running on the track and telling myself "you know these feelings. push through these feelings". On the track, I use those phrases and am able to push through and run faster. But now, I've actually worked out harder than I otherwise would have. I don't need to just rely on mental games to perform better—my body is getting stronger as a totally normal effect of recovering from a challenging workout.
Sources: Play On by Jeff Bercovici, Endure
5. Breathe with your mouth closed
James Nestor and his book Breath (read my review here) have gone somewhat viral in the last few years. Although the book gets into some theories that seem a little wacky to me, the basic idea—breathe through your nose, not your mouth—is well-supported by science.
For example, the relevant article on Healthline.com says mouth breathing increases your risks of dental issues (bad breath, tooth decay, gingivitis) and sleeping issues (sleep apnea, snoring). According to the article, nose breathing works because:
Your nose is designed to help you breathe safely, efficiently, and properly. It can do this due to its ability to:
Filter out foreign particles. Nasal hair filters out dust, allergens, and pollen, which helps prevent them from entering your lungs.
Humidify inhaled air. Your nose warms and moisturizes the air you breathe in. This brings the air you inhale to body temperature, making it easier for your lungs to use.
Produce nitric oxide. During nasal breathing, your nose releases nitric oxide (NO). NO is a vasodilator, which means it helps to widen blood vessels. This can help improve oxygen circulation in your body.
Even if you don't care too much about some of the other benefits, nose breathing is useful because sleep quality is perhaps the most important factor in post-workout recovery. As Christie Aschwanden says in Good To Go,
Insofar as there exists any magical secret for recovery, sleep is it.
The benefits of sleep cannot be overstated. It’s hands-down the most powerful recovery tool known to science. Nothing else comes close to sleep’s recovery-enhancing powers. You could add together every other recovery aid ever discovered, and they wouldn’t stack up. Going to sleep is like taking your body to the repair shop.
As she reports, being well-rested improves your reaction times and makes you less susceptible to falling ill (and that's not just due to nasal breathing—the study participants were directly exposed to a cold virus). Sleep is when the muscles rebuild themselves and the mind consolidates things it has learned.
Nasal breathing may have been hyped up a bit beyond its usefulness in the past few years, but nose breathing means better sleep means better recovery is legit, as best I can tell.
Sources: Breath by James Nestor, Good to Go
6. The Placebo Effect is an effect
There are lots of things we can do to try to improve our training and recovery. The book Good to Go covers the science behind a number of interventions that are intended to help us recover faster. Ice baths, hot baths, massage, specially formulated meals, Tom Brady pajamas...all are supposed to help us recover more quickly, but none of them are backed up by solid science.
But that actually doesn't mean that they're useless. Most of you are probably familiar with the term 'placebo effect', but just in case: "The placebo effect is a beneficial health outcome resulting from a person’s anticipation that an intervention will help." People taking fake pills that they think will treat their condition do better than people who are given no intervention at all.
But here's the funny part: the "beneficial health outcome" is real, even though the treatment is "fake". There are many interventions that don't have solid science backing them up. But if you can find a ritual that works for you, that feels really good and that you truly believe in, you probably do get an actual benefit from it. It can be an effective part of your routine, even if it's never been "proven effective" in a randomized, controlled, double-blind study. The placebo effect is an effect. Even knowing about placebo effects won't keep them from working—just tell yourself "this may not work for everyone, but I have the right genes/body type/etc that it works for me."
Here's a study that really highlights how the placebo effect is an effect:
It’s hard, of course, to have a “placebo-controlled” ice bath study, since you can’t disguise the fact that you’re immersing yourself in freezing water. But researchers at Australia’s Victoria University found a way around this problem in a 2014 study. They compared fifteen-minute post-cycling-workout soaks in either cold water, lukewarm water, or lukewarm water with the addition of a special “recovery oil.” “We made sure that we put the recovery oil in the water in plain sight of the participants,” recalls David Bishop, the study’s senior author, “and we gave them a glossy summary of some made-up research about scientifically proven benefits of ‘recovery oils.’”
Over the following two days, the researchers tested their subjects’ leg strength—which, in the end, is the most important recovery outcome. Sure enough, the ice bath significantly outperformed the lukewarm bath throughout the two-day recovery period. But the recovery oil was just as good, and perhaps even marginally better than the ice bath—even though the oil was, in fact, a liquid soap called Cetaphil Gentle Skin Cleanser. This, you might think, debunks the value of ice baths once and for all—except for the fact that the athletes who had either ice or oil really did seem stronger in the two days following the workout.
That being said, I prefer trying to find low-cost solutions, since any money I save can be used on something else...getting a $60 massage after every workout is going to get expensive quickly, no matter how much you believe in it. Self-massage with a lacrosse ball works quite well for me!
Sources: Endure, Chapter 13; Good to Go, Chapter 11
I'm intrigued, but not yet completely convinced
Here are three more ideas that have attracted my notice lately (and that I've experimented with myself), but I haven't seen enough to make me completely convinced.
7. Eat more cartilage
In Play On, Jeff Bercovici says of collagen/bone broth: "Yes, it’s a huge fad, but it’s the rare nutrition fad with data to back it up." Sadly, he doesn't actually give us a well-researched discussion of what that science is. And I haven't taken the time to look carefully into the primary sources myself. The page on collagen on Healthline.com, for example, is mildly supportive but definitely stresses that more research is needed.
Nevertheless, it seems that:
(a), It's logical enough — the "humans have been eating cartilage for hundreds of thousands of years and our bodies have evolved to use it" argument,
(b), It's easy enough — I just eat the cartilage off chicken bones, and,
(c), It's harmless enough — at best it actually works, at worst I eat some crunchy stuff that generations of humans have proved is safe to eat.
The idea is that collagen contains some of the ingredients our body uses to build muscles, ligaments, and cartilage. Eating it give our body more of those building blocks to work with:
The science behind it seems to be absurdly simple in the way science rarely is. Eating collagen supplies proteins that enable the body to form its own new collagen, which is not only the major component of tendons and ligaments but also of the tissue matrix that binds individual muscle fibers to each other, allowing them to transfer force without tearing. Studies have shown gelatin supplementation during injury rehab results in faster return-to-play after ACL reconstructions and Achilles tendon ruptures.
I still want to understand the research better, but there might be something here.
Source: Play On
8. It's OK to put your knees over your toes
When I started lifting weights as a teenager, it seemed like everyone knew you don't put your knees over your toes. That advice seems to be changing. I expect many of my blog readers have already heard of the Knees Over Toes Guy, but perhaps a few haven't.
Basically, this theory says that having your knees over your toes will happen in the course of normal athletic motions. Given that, it's important to train your strength through those motions. (That being said, it's always important to ease yourself gradually into any new workouts.) Putting your knees over your toes helps strengthen the knee itself and the muscles near it that help keep it safe.
As (weak) proof of the claim that "having your knees over your toes is normal", here's a screenshot I took from an ultimate game that I had open in my browser. It took me about 15 seconds of watching to find this shot. KOT is especially common when changing direction (including slowing down):
Even PainScience.com has suggested that these ideas are at least plausible, writing that:
I’ve called VM isolation a “pernicious myth,” [by "VM isolation", he means "training the part of the quadriceps closest to the knee"] based on evidence like Mirzabeigi et al — one of many studies over the years that strongly suggested VM isolation was either impossible (or only possible in the sense that what you see at Cirque du Soleil is possible, but out of the reach of the average person). In 2002, Malone, Davies, and Walsh wrote, “The concept of VM isolation through specific exercise should no longer be part of our lexicon.” Such professional opinions have been common for a decade and they are still out there.
We were wrong-ish.
More recent evidence has mostly changed my mind.
He points out a number of exercises proven to help train this muscle near the knee; one is a core movements in the Knees Over Toes Guy program:
just the right exercises do indeed preferentially engage the VM...[for example:]
—squats with a wedge (standing on a wedge so that the toes are pointing down)
Anecdotally, me and a few others I've talked to believe these movements have helped strengthen and rehab our knees.
Sources: PainScience.com, Knees Over Toes Guy (YouTube channel, subreddit, etc)
9. Sit more actively to burn more calories
In Exercised (my review here), Daniel Lieberman writes about the harm that prolonged periods of sitting have on our body. He offers a couple recommendations. First, to get up and move around every so often. Barring that, even just fidgeting can be beneficial:
...the more I read these worrisome statistics, the more I have tried to modify my habits. I have been striving to get up more regularly to do little errands and pet my dog. I also have been using my standing desk more often...
...These activities aren’t serious exercise, but experiments that ask people to interrupt long periods of sitting even briefly—for example, just a hundred seconds every half hour—result in lower levels of sugar, fat, and so-called bad cholesterol in their blood. In turn, less circulating blood sugar and fat prevent inflammation as well as obesity. In addition, small and occasional bouts of moving stimulate muscles to quench inflammation and reduce physiological stress.
Another way to sit actively is to fidget, or do what researchers drily term “spontaneous physical activity.”...studies have found that simply fidgeting while seated can expend as much as twenty calories an hour as well as promote beneficial levels of blood flow to restless arms and legs.
His second recommendation, which I find even more interesting, is to sit in ways that we use our muscles:
More truthfully, the problem isn’t sitting itself, but hours upon hours of inactive sitting combined with little to no exercise. If our ancestors from generations ago behaved like today’s hunter-gatherers and farmers, then they likely sat for five to ten hours a day, as much as some but not all contemporary Americans and Europeans. But they also got plenty of physical activity when not sitting, and when these chairless ancestors plunked themselves down, they didn’t rest in supportive chairs with seat backs; instead, they squirmed as they squatted, kneeled, or sat on the ground, using about the same degree of muscle activity in their thighs, calves, and backs as when they stood. [emphasis added by me]
...I was also surprised to read there is no good evidence...that we can lessen the incidence of back pain by using special chairs or getting up frequently. Instead, the best predictor of avoiding back pain is having a strong lower back with muscles that are more resistant to fatigue
This is another idea I put in the "easy enough, might as well try it" bin. Since reading the book, I always try to sit in ways that keep my muscles activated—sitting up so my back muscles activate, lifting myself up a bit if I'm lying on my side, etc. I try to avoid sitting in a way that's so comfortable that I never have to move. I avoid sinking into the couch: there were no couches in the ancestral environment.
Edit (2023-08-31)
Based on a recent Reddit thread, I'd like to add:
10. We don't know exactly what causes (or how to avoid) cramps
Exercise-induced cramps are intense, painful contractions that usually strike when fatigued and/or overheated. They are most common in the legs, especially the calves and hamstrings, more rarely the quadriceps. Fatigue and heat are major factors, but not dehydration and electrolyte shortage (that’s a myth).58 What actually does cause them is still unclear (shocker), along with much else about them.
Since the best we can say is that fatigue and heat factor in, the most universal advice we can give is: find ways to be less fatigued (at any given point in your game/tournament). Some universal tips: better rest, less stress in your life, getting in better shape, and good nutrition.
Putting ice packs on your body can theoretically help with the heat factor as well, although I'm not sure if it's been researched systematically. In Endure, Alex Hutchinson also suggests consuming ice/slushies instead of just drinking cold water—because it takes energy to melt ice, some of the heat generated by your body will be used up melting the ice instead of increasing the temperature in your cells. (Now that's some sports science...10th grade chemistry applied to working out!)
PainScience.com says that whether electrolytes help with cramps still hasn't been systematically researched (oddly):
If electrolyte loss caused cramps, we would fully expect supplementation to help — and people sure do. Oddly, this wildly popular belief remains ignored by science.
So there's nothing wrong with experimenting to see if there's any diet changes that'll help reduce your cramps, whether Gatorade, pickle juice, bananas or something else. It may be placebo effect, or it may be a successful n=1 science experiment, but if you find something that works there's no reason not to stick with it.
As mentioned by PainScience, there seems to be a genetic element to cramping. So you may be stuck with more cramps than some of your friends get, no matter what you do. (But given that those genes still exist, they are probably helping you out at the same time, in some other subtle way.)
What I think is highly unlikely to help is stretching beforehand (whether earlier in the week, or earlier in the day) — a response that was popular in the Reddit thread I've linked above. Given what we know about cramps and what we know about stretching, I see no reason stretching would help.
Edit (2023-09-06)
One more myth based on the same Reddit thread linked in #10 above:
11. Lactic acid isn't what makes your muscles sore
But there's some nuance to that.
Lactic acid definitely isn't what makes your muscles sore the day after a tough workout (this is officially known as "Delayed Onset Muscle Soreness", a.k.a DOMS). The Healthline.com article on DOMS doesn't even give this theory the time of day. They bring it up for the sole purpose of shooting it down:
You don't need to "clear" your muscles of lactic acid to feel better the next day.
When it comes to fatigue while working out, though, lactic acid is involved—although it's not the only factor. We've injected lactic acid into muscles, and it doesn't—by itself—make people fatigued:
In a 2014 study, Markus Amann and Alan Light, along with colleagues at the University of Utah, tried injecting three different metabolites associated with intense exercise—lactate, protons, and adenosine triphosphate, or ATP—into the thumb muscles of ten lucky volunteers. The concentrations they used varied from the “normal” concentrations that are always circulating in the body to the higher levels associated with moderate, vigorous, and extreme exercise. On their own, none of the three metabolites had any discernible effect. The same was true when they were injected in pairs, despite the fact that lactate plus protons is what makes lactic acid.
But when they injected all three metabolites together, the volunteers suddenly had the bizarre sensation of extreme fatigue and discomfort—concentrated in their thumbs. At low doses, the sensations reported by the volunteers were mostly things like “tired” and “pressure”; as the doses increased, the sensations ramped up in intensity and shifted to pain-related words like “ache” and “hot.” The results suggest that lactic burn isn’t literally the feeling of acid dissolving your muscles; instead, it’s a cautionary signal created in the brain by nerve endings that are triggered only in the presence of three key metabolites.
So lactic acid isn't the one and only cause of the fatigue that makes us have to slow down in an intense workout. But it is one of the factors causing those feelings in our muscles. In our quest to bust myths, it's perhaps also worth mentioning that it isn't even actually lactic acid in our muscles—as you may have noticed if you carefully read the previous quote. It's lactate. It tends to naturally turn into lactic acid when extracted from our bodies. Early researchers didn't know this and didn't realize that what they saw under their microscope was different from what was present when the sample was still inside our bodies. I'm not a chemist and I won't pretend I really understand this, but read Chapters 2 & 6 of Endure for more information.
Edit (2024-02-28):
12. You don’t need to do a cool down
See my article here: Cool it with the cool downs.