This weekend, the German Bundesliga returns to action after its month-long winter break. After a grueling World Cup year with a shortened summer vacation for many players, the chance to rest was a long time coming. "The load on players is too high," Joachim Löw, head coach of the German men's national team, said back in October. "The high demands on teams in national leagues and of course the Champions League, it's too much. If you look at the players, they need more of a break."
The idea that there might be too much soccer also manifested in a different way in October, just across the North Sea. Raheem Sterling, England's then-19-year-old wonderkid, bowed out of a European Championship qualifier against Estonia because he felt tired. He was roundly criticized for lacking commitment and physical fitness. But among the voices rising to Sterling's defense was fellow England international Frank Lampard's. Perhaps this is because Lampard is aware of something many fans and pundits don't often consider: at the elite level, the game is constantly increasing in speed and intensity. Lampard is going into his 20th year as a professional. He's lived the changes.
You don't have to dig deep to find people to tell you about how advances in fitness changed soccer. But with prominent coaches and players and even some team doctors suggesting this increased physicality has come at an exhausting price, it makes one wonder, has the game crossed some kind of threshold? Has the physical load on players become too much?
Löw obviously has his mind made up, and he's not alone. "We have to do something for the regenerative potential in those players," says Dr. Thorsten Rarreck.
Rarreck served as club doctor at Schalke, one of Germany's biggest clubs, for 13 years before leaving last fall. When I ask him what can be done, Rarreck tells me that he would recommend reducing the length of games, or dividing them into three thirds rather than two halves, or increasing squad sizes from 25 to 30, or increasing the number of substitutions from three to five or six. He says this with a laugh because none of it will happen.
Advances in physical training (and possibly, to some extent, doping) have created a situation in which elite soccer is more physically demanding than ever before.
"The profile of the football game has changed," says Oliver Schmidtlein, a former physiotherapist for Bayern Munich and the German national team. According to Schmidtlein, the time from when a player gains ball possession to when he is engaged by a defender has dropped considerably over the last 15-20 years, from several seconds to "less than two seconds, average, which means there is a lot more man-to-man or body-to-body contact within the game."
The players run farther, too: "Three kilometers more per game, and 10 matches more per season, and they have lots of rapid and explosive movements in the match, and so the charge on the players is much higher than it was 10 years ago," says Rarreck.
So the game is faster, and more intense. But what does that mean for players, exactly? It's hard to say. Some might speak up about fatigue, as Sterling did, but more are likely to play through it, which they're incentivized to do, both through their million-dollar contracts and competition inside a team for places in the starting lineup.
One way to objectively judge whether the game's increased physicality has affected players is to look at how injuries have changed over time. If the soccer is more physically demanding, one would think injuries would have increased as well. (I've been under the impression that injuries have been increasing in frequency for some time, but maybe I watch too many Arsenal and Dortmund games.)
Lucky for us, scientists have studied this question for more than a decade. The results—at face value, anyway—are underwhelming. According to the findings of a multi-year study funded by UEFA, the European governing body of soccer, the injury rate among Europe's elite teams (a sample of those participating in the Champions League), hasn't changed significantly since the study began, in 2001. A closer look, however, reveals the type of injury suffered by elite players has changed dramatically.
Ankle injuries, for example, have fallen significantly. The UEFA Study's lead researcher, Dr. Jan Ekstrand, a Swedish orthopedic surgeon and professor of sports medicine at Linköping University, says the rate of ankle injuries dropped 50 percent since the 1980s, a decrease that continued throughout the study period. There are several possible explanations—like changes in shoes and refereeing—but the drop is mostly due to breakthroughs in medicine. According to Ekstrand, thanks to years of study and collaboration, "medical people [now] have a knowledge of how to diagnose, treat, rehabilitate, and prevent ankle sprains. Ankle sprains are not a problem anymore."
Muscle injuries are a different story. They've become more frequent, "especially hamstring injuries, which have increased about three percent every year since we started, in 2001," says Ekstrand. Three percent might not sound like much, but it's a bigger return than you get on the money in your savings account, and it adds up. According to some of Dr. Ekstrand's published research, in 2011, hamstring injuries accounted for nearly "one third of all time-loss injuries in men's professional football."
Most hamstring injuries are overuse injuries, and they occur most frequently at the ends of a half, when players are fatigued. Muscle injury rates are also higher when there's less time between matches.
What can be done? Outside of simply playing less soccer, both Rarreck and Schmidtlein advocate for individualized "prehab" regimens, and agree that the one-size-fits-all approach to physical training and prevention should no longer be an option at the highest level. Rather, players need to be individually tested on measurables—like flexibility, speed, and endurance, among others—so that a club's staff can establish a baseline from which to judge a player's progress and, if injured, rehabilitation.
"I think it's really necessary to have evidence-based systems that provide information to the therapists and trainers, so they have a profile about each individual player," Schmidtlein says. "Players that, for example, play for FC Bayern and other top clubs, like Arsenal, you need to look at these players individually and have programs for them individually. Of course, there are clubs like Arsenal who have that and do that, but there are still many, many, many clubs that do not have any system like this at all. So these clubs are only reactive."
A proactive approach to injury prevention and recovery would be a positive step forward, but establishing a baseline for each player isn't the same as measuring load. And measuring individual variables like total distance traveled during a season or number of sprints, can be helpful, but even those numbers do not tell whole story. The total physical load on players is a combination of all of these, plus metrics about the heart, training time, type of training (contact, non-contact), and more.
The ability to measure the physical load endured by players over the course of a season—both in training and during games—represents a possible next step in injury reduction, especially when it comes to overuse injuries. By measuring load, it is theoretically possible to establish a cutoff line: cross that line and the likelihood of injury increases. In baseball, this sort of thing is already in practice. Since the 80s, teams have kept track of the number of pitches thrown by pitchers, with the general understanding that once someone throws more than 100—even fewer for young players—the risk of injury increases.
All the top clubs in Europe have turned to wearable technology as a means to measure training load. Those funny little vests that you see players wear in training—not the pinnies, but the smaller, tighter ones—have sensors in them that can track just about every performance metric you can think of: heart rate, distance covered, number and duration of sprints, the list goes on. Preventing injuries to star players would bring the kind of cost savings and bumps in win percentages that make club executives lick their lips.
But there are some problems.
All of the sensor companies sell their products as tools for injury prevention. But they're selling clubs on possibility more than usability. "It's commonly said that [wearable technology] measurements also help avoiding injuries," says Ekstrand. "There's no proof of this at all in the literature. There are no studies showing this. And the reason is that there's no consensus of how to measure load."
Clubs collect massive reams of data, but nobody knows which data are important. "Further," continues Ekstrand, "it's not possible for one club to get any robust data about correlation between load and injuries, because if you look for example at hamstring injuries, the club can expect in their first quarter with 25 players to have about six to eight hamstring injuries. To get any robust data, you need 10 times as many injuries and ten times as many measurements. So the data from one club is not enough."
According to Ekstrand, soccer clubs still refuse to share this kind of data, which means nobody, not even the clubs themselves, really has usable information. It also means the legion of amateur statisticians out there who would kill for a chance to try and solve the load problem can't help. The analytics community has been trying to break open soccer, like it did baseball, for years now, and this biometric data seems more ripe for meaningful analysis than the spatial and tactical data the community is at work crunching right now.
But until the data is available and the relevant metrics are identified, the line between what's physically possible and what's healthy will remain unknowable. What is knowable is that the game won't just slow down on its own. But if there aren't enough highly skilled, elite athletes healthy enough and with enough energy to maintain that level of intensity? Well, that's a different story.
A technological solution might remain a distant goal, but in the mean time, Ekstrand remains confident the medical teams can continue to find better treatments for soccer injuries. "I have mentioned that there has been a huge development in football medicine and research over the last 15 years," Ekstrand says just before our interview is over. "And this is mainly due to the international organizations—FIFA and UEFA—[which] have really thought about the health of players and have supported and funded research to preserve the health of the players and avoid injuries. And I would say that football—soccer—is the leading sport in the world when it comes to sports-specific medical research. Are you going to publish this in the US?"
"Yes," I say.
"No problem for me to have that statement. It might embarrass American football, but they have to respond then."