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Soccer Hamstring Injuries Are Up, But Preventing Them Is Complicated

This is Strength in Numbers, a new column exploring the science of sports and athleticism — including technology, sports nutrition, injury treatment and prevention, neuromuscular training, brain health, doping, recovery and more! As this feature takes shape, I welcome your feedback, suggestions and news tips. Email me, leave suggestions in the comments section or tweet to me @CragCrest.

The injury report, hamstring edition

Jan Ekstrand thinks every hamstring injury is preventable. “All of them?” I asked him during a Skype conversation last week. “Yeah, I think so,” he replied.

Ekstrand, director of the Football Research Group, coauthored a recent report in the British Journal of Sports Medicine that found “hamstring injury has been the single most common injury type in professional [soccer] for many years.” The BJSM study, which tracked soccer players from 36 clubs in 12 European countries between 2001 and 2014, also found that hamstring injuries have risen among pro soccer players. During the 13-year study period, average rates of hamstring injuries climbed 2.3 percent from year to year, and the most pronounced bump happened during practice — hamstring injuries acquired during training rose by 4 percent per year.

That’s odd because other types of injury, like ankle sprains and medial collateral ligament strains, have decreased. It’s the hamstring that we can’t seem to get right. But why?

One possible reason is that the intensity of play has increased. “Hamstring injuries are most common during high velocity activities — it’s the sprinter’s injury,” Ekstrand said, noting that the number of fast sprints in soccer matches also rose during the study period. Sprinting isn’t going to suddenly disappear from soccer, so Ekstrand’s thoughts have turned toward other approaches to prevention. An exercise program called the Nordic hamstring protocol has been shown to decrease the risk of acute hamstring injuries in soccer by at least 50 percent, by strengthening the hamstring muscles in their “eccentric” phase.

The Nordic hamstring protocol is quick and simple. But it doesn’t work if you don’t do it, and a study Ekstrand and his colleagues published a few months ago found that very few teams in the UEFA Champions League have adopted the program.1 There’s no single reason why, he said. Some teams don’t use it because it’s not soccer-specific. “The mantra among many coaches is, to increase performance, everything in training should be sport-specific,” Ekstrand said. The Nordic exercise, which requires kneeling on the ground and leaning forward, is unlike anything you see in a typical soccer match.

I read Ekstrand’s study and felt the twinge of my own hammy, which has been ailing me since I was a high school middle-distance runner. I don’t remember how it happened, but sometime during my first track season I tweaked my left hamstring. I’ve spent years trying to make it right again; I only recently began testing the Nordic hamstring protocol, but since I incorporated a similar eccentric hamstring exercise — the hamstring push up — into my routine, my problem hamstring has given me far less grief.

We all want to find the one magic thing that will prevent our tweaks and pangs, but Ekstrand said that the right formula will vary according to individual circumstances. He did offer one piece of advice that applies to everyone though: Don’t rely on a single exercise for prevention, you have to look at your life as a whole. “When you’re stressed, you get tense in the muscles,” he said. In some cases, the best prevention may be some extra rest or relaxation.

Training is important, but so is recovery. Increasing the training load without adequate recovery — in my case by upping my running mileage too quickly — is a classic way that athletes set themselves up for injury.

Meldonium is dope

Maria Sharapova made meldonium famous when she announced that she’d tested positive for the drug in the Australian Open (the World Anti-Doping Agency added meldonium to its List of Prohibited Substances and Methods on Jan. 1).

Sharapova, though, is not alone. As of March 29, there have been 123 “adverse analytical findings” for the substance, according to WADA spokesperson Ben Nichols. And a new paper in the British Journal of Sports Medicine reports that meldonium was detected in nearly 9 percent of the urine samples tested during the Baku 2015 European Games and the pre-competition tests leading up to the games, which took place about six months before meldonium was banned. The drug turned up in 66 of the total 762 samples and 3.5 percent of athletes who were drug tested declared ahead of time that they were taking meldonium, including six gold medalists, five silver medalists and two bronze medalists.

Sport climbing 4 2 50.0% 0
Sambo 9 3 33.3 0
Canoe/kayak 48 15 31.3 2
Gymnastics 26 7 26.9 1
Wrestling 64 11 17.2 4
Volleyball 21 3 14.3 2
Taekwondo 36 5 13.9 6
Archery 11 1 9.0 0
Basketball 11 1 9.0 0
Athletics 40 3 7.5 2
Aquatics 137 9 6.6 2
Boxing 53 2 3.8 1
Karate 28 1 3.6 0
Triathlon 33 1 3.0 0
Cycling 90 2 2.2 1
Badminton 11 0 0.0 0
Fencing 24 0 0.0 2
Football 4 0 0.0 0
Judo 53 0 0.0 0
Shooting 45 0 0.0 0
Table Tennis 14 0 0.0 0
Total 762 66 8.7 23
Meldonium use by athletes at the Baku 2015 European Games

Pre-competition urine samples included; only declarations of meldonium use from June 8-28, 2015 counted.

Source: British Journal of Sports Medicine

When caught, Sharapova said that she’d taken the drug for a decade for “medical reasons.” But what those reasons are, exactly, is murky — something about magnesium deficiency, heart problems and her family history of diabetes. It’s possible that Sharapova and these other elite athletes need an obscure heart drug to compete. Or they could just be cheaters who won’t go down without elaborate explanations.

Speaking of doping excuses…

One of the most tired excuses that athletes give for a positive doping test is that they unwittingly ingested a banned drug in a dietary supplement. (An associate of San Francisco Giants outfielder Melky Cabrera went so far as to create a fictitious company and supplement to blame for the synthetic testosterone found in one of Cabrera’s drug tests.) Yet sometimes it’s true: On Monday the U.S. Anti-Doping Agency announced that Yoel Romero, a UFC athlete from Miami, had accepted a six-month sanction after testing positive for the growth hormone ibutamoren. Romero received the light ban (he could have gotten two years) after USADA tests confirmed that a supplement he’d been taking contained an undeclared ingredient: Ibutamoren.

The product was likely Shed RX2, a supplement marketed as “an extremely powerful herbal diuretic” that could help the body dramatically eliminate excess water retention and “help maintain muscle performance and muscle fullness.” Here’s the thing: if the supplement really helped muscle performance, it would probably be banned3. And if it didn’t, then it was nothing more than a risky placebo — most purported health and performance-enhancing benefits from supplements are nothing more than unproven marketing claims.

As I’ve written previously, there’s no good reason for athletes to take supplements. That’s especially the case for U.S. Olympic athletes like Romero who, by now, have surely come across the US Anti-Doping Agency’s years-long campaign to inform them of the risks of ingesting a banned substance via a supplement.

Since the beginning of the year, USADA has added least 16 supplements to its “High Risk Dietary Supplement List,” including Shed RX, Get Ripped, which could contain banned stimulants; and HGH X, which turned up ostarine, a type of banned anabolic agent, in a recent test.

Thanks to the Dietary Supplements and Health Education Act, dietary supplements don’t require evaluation or proof that they’re safe before they’re sold. The FDA has the power to regulate the manufacturing and packaging of supplements, but Utah Senator Orrin Hatch (his state is a hotbed for supplement manufacturing) has repeatedly lobbied against tightening oversight.4 Every time the FDA warns about one dodgy supplement, it seems another turns up elsewhere.

If all of that weren’t bad enough, athletes who buy or promote supplements may also be enabling dodgy pyramid schemes, as Mina Kimes explained recently in ESPN Magazine. This may be a situation where it’s wise to heed the advice of recently departed former first lady Nancy Reagan, “Just say no.”


  1. The Nordic protocol has been incorporated into FIFA’s 11+ program, a 20-minute warm-up created to prevent injuries, which has been very successful in youth and amateur players, Ekstrand said.

  2. USADA declined to name the supplement, but it appears to be Shed RX, which was added to the USADA “High Risk Dietary Supplement List” on April 1 with a note that testing of the product revealed the presence of ibutamoren, which is what Romero tested positive for.

  3. The World Anti-Doping Agency aims to include any substance or method that satisfies two of the following three criteria: it has potential to enhance or enhances sports performance, it poses a health risk to the athlete or its use violates the “spirit of sport,” as outlined in its Code.

  4. For a fascinating accounting of the recurring fight to keep supplements unregulated, see Catherine Price’s terrific book, Vitamania.

Christie Aschwanden was a lead science writer for FiveThirtyEight. Her book “Good to Go: What the Athlete in All of Us Can Learn from the Strange Science of Recovery” is available here.