What’s New in Sports Recovery Research
The mental side of soreness, the downside of ice baths, and the genetics of tendon injuries were hot topics at this year’s ACSM conference
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The publication earlier this year of science journalist Christie Aschwanden’s book, Good to Go: What the Athlete in All of Us Can Learn from the Strange Science of Recovery, has sparked lots of conversation. Aschwanden casts a skeptical eye on the proliferating technology of modern sports recovery—the cryosaunas, the infrared pajamas, the sensory deprivation tanks—but she doesn’t dismiss it entirely. Perhaps, she suggests, the benefits of some of this technology are as much mental as physiological—if that’s even a meaningful distinction. Chilling in an ice tub may cool off your mind as well as your muscles, and that too may prime you for the next day’s workout.
It was hard not to think of Achwanden’s insights while scrolling through the presentations at this year’s American College of Sports Medicine conference in Orlando, many of which grappled with the challenges of keeping athletes healthy and strong. I’ve already written about some of the most notable findings from the conference on strength and hydration; here are some of the highlights related to athletic recovery and injuries.
Soreness Is (Partly) in Your Mind
The usual explanation of delayed-onset muscle soreness (DOMS) is something like this: when you do exercise that’s unfamiliar or harder than usual, you inflict microscopic tears in your muscle fibers. Over the next 24 to 48 hours, a cycle of inflammation and repair leads to soreness that can persist for several days. But it has long been clear that this explanation doesn’t tell the whole story. For example, if you exercise your right leg only, your left leg will be less likely to get sore after future workouts, which suggests that the perception of soreness isn’t just about what’s happening in your muscle fibers.
In this spirit, an ACSM presentation from a team led by Einat Kodesh of the University of Haifa in Israel explores the potential role of mental traits in post-exercise soreness. They had 32 volunteers complete a series of psychological questionnaires and pain tests, then perform an exercise designed to induce DOMS. A day later, another questionnaire found that 17 of the subjects had developed DOMS, while 15 hadn’t.
Sure enough, there were some notable psychological differences between those who did and didn’t get sore. The DOMS sufferers had reported higher levels of anxiety, depression and stress before any exercise took place. The higher a subject’s anxiety, the more intense their subsequent muscle soreness was likely to be. Less surprisingly, the pre-exercise pain tests, which basically involved poking the subjects with a blunt needle to see how much pressure it took to make them hurt, also successfully predicted who was likely to develop DOMS.
The message here isn’t that pain and soreness are all in your head, or that admitting you feel sore is a sign of weakness. But it is a reminder that recovery is a murkier and less objective concept that we like to think. When we try to understand athletes’ obsession with things like ice baths, if we focus only on what’s happening in the muscle fibers, then we’re not necessarily seeing the whole picture.
Ice Baths Block Workout Gains
Still, we can’t simply ignore what’s happening in the muscle fibers. Over the last decade, sports scientists have been debating a controversial claim: that by enhancing or accelerating post-exercise recovery, we risk wiping out some of the benefits of the workout. According to this argument, the inflammation, oxidative stress, and repair processes triggered by a hard workout are precisely the signals that tell your body to adapt and get stronger. If you repeatedly suppress those signals by, say, taking an ice bath or popping high-dose antioxidants, you may feel better the next day, but you’ll be less fit a month later.
There’s enough evidence to say that this trade-off between recovery and adaptation is real—in theory. But it’s less clear whether it has any practical significance. For example, it may be that any hypothetical lost adaptation is more than balanced out by the fact that athletes who recover better are able to sustain higher workloads. For now, this remains an open question—which is why a study from Luc van Loon’s group at Maastricht University in the Netherlands, led by Cas Fuchs, is of particular interest.
Fuchs and his colleagues had 12 volunteers do a strength-training session, then hop into an ice tub—or actually, half an ice tub. One leg was submerged in cold water at 46 degrees Fahrenheit (8 Celsius), while the other leg was submersed in tepid water at 86 degrees Fahrenheit (30 Celsius), for 20 minutes. Then they chugged a recovery shake with 45 grams of carbohydrate and 20 grams of protein, the latter of which contained a tracer that allowed the researchers to determine how much of the protein was incorporated into new muscle. Over the following two weeks, the researchers took frequent blood samples and muscle biopsies to track their progress.
Sure enough, the rate of muscle protein synthesis was significantly lower in the cooled leg than in the leg that got the lukewarm bath, with a difference over the course of two weeks of about 13 percent. Now, lab measures like muscle protein synthesis are still not the same as measuring actual differences in strength over a longer period of time. It’s awfully suggestive, though, and bolsters the case that ice baths—and, presumably, other recovery enhancers—may come with a hidden cost to fitness gains.
You Have Your Parents’ Tendons
A study from Ritsumeikan University, home to one of the top collegiate running programs in Japan, looked at injury risk in 24 elite long-distance runners. The researchers weren’t concerned with mileage levels, shoe type, stretching routines, or any of the usual factors we associate with running injuries. Instead, they were focused on spit.
Over the past decade or so, a series of studies have suggested that certain gene variants can affect the structure of your collagen fibrils, the basic building blocks of tendons and ligaments. Some versions of these genes make you less likely to develop problems like Achilles tendinopathy; others make you more likely. Researchers have found, for example, that rugby players who make it to the elite level are more likely to have the tendon-protective gene variants, presumably because those who don’t are more likely to have their careers derailed by injury.
In the new Japanese study, the athletes were asked about their history of tendon and ligaments inflammations and injuries during their university career, then gave a spit sample for DNA analysis. The injury data was compared to five specific variants in four different genes that have previously been associated with tendon and ligament structure. For three of the five variants, those with the “bad” version were indeed significantly more likely to have suffered tendon and ligament injuries. (The fourth variant didn’t have any predictive value in this group, and the fifth didn’t yield any information because all the runners in the study had the same version of the gene.)
Given previous research, these results aren’t particular surprising. The question is what you do with this information. There are companies that offer personal genetic testing that includes some of these gene variants (COL5A1 was the best predictor in this study), so you can find out your status and…do what, exactly?
In a review of the field a few years ago, some of the leading researchers suggested that, rather than getting a DNA test, you should simply be aware of whether you have a personal or family history of tendon and ligament injuries. Either way, it’s worth thinking about what you would change in your training if you suddenly discovered that your tendons were, say, 10 or 20 percent more likely to get inflamed compared to the average person. If you think you would start doing more stretching or strengthening or icing or “listening to your body” or whatever, then my question is simple: why aren’t you doing that already?
My new book, Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance, with a foreword by Malcolm Gladwell, is now available. For more, join me on Twitter and Facebook, and sign up for the Sweat Science email newsletter.