# Stretched to the limit: why hamstring fails are curse of the Premier League

Academics and medics are working to understand why hamstring injuries are keeping players sidelined for longer.

## Introduction

The sight of a player pulling up with a hamstring injury has become all too familiar in the . Weary muscles are being stretched to the limit by an expanding calendar, but dealing with more games is not the only challenge for medical departments.

It is not that there has been a sudden explosion. It can simply seem that way when high-profile players such as the Arsenal forwards  and Kai Havertz are long-term absentees. Using figures up to and including game week 26, that ended last Sunday, the Premier Injuries website says 100 of the 418 injuries this season related to hamstrings (24%), compared with 120 from 457 (26%) at the same stage last year.

However, the data also shows hamstring injuries are keeping players out for longer. Of those 100 injuries this season, nine kept a player out for up to 13 days, 40 for 14 to 30 days, and 51 led to more than 30 days on the sidelines. Last season’s corresponding 120 injuries led to 49 absences of more than 30 days.

Meanwhile the volume is greater in the modern game. A study overseen by Prof Jan Ekstrand of Linköping University in Sweden, covering seasons 2001-02 to 2021-22, looked at 54 teams in 20 European countries and found the rate of hamstring injuries doubled from 12% to 24%.

No one anticipates an imminent improvement. A slight dip in the overall figures is no cause for cheer when there is concern about hamstring injuries becoming more serious. Surgery has become more common and specialists have their hands full with damage flaring in increasingly tricky parts of the muscle.

“Last year we had a lot of hamstring failures,” says Fearghal Kerin, a physiotherapist who recently left Chelsea. “It would traditionally have been considered to be hamstring tightness. We don’t really see a return in 10 days any more.”

The physical burden on players is regularly brought up. Space has to be made for new or enlarged tournaments and there is little time to rest between games. “People just basically play, recover, play, recover,” says Maheta Molango, the Professional Footballers’ Association chief executive. Kerin points to the disruption caused by the pandemic and the 2022 World Cup taking place in winter. Additional added time caused by the video assistant referee system is another factor.

“Every team now has a high line,” Kerin says. “It effectively means any ball in behind comes with an immediate turn and 30-to-40-metre sprint. Think about what’s going to cause a hamstring injury or a player to pick up enough sprint metres that will increase the risk. Then combine that with a pressing style. Then you have fixture congestion and players who are faster, stronger and more powerful. You’ve got a perfect scenario for repeat and high-grade hamstring injuries.”

A big discussion point is the emergence of a new trauma within the hamstring. “We are seeing more injuries below the tendon or that involve that challenging area at the bottom of the hamstring called the T-junction,” Kerin says. “We’ve got the main tendons at the top and bottom but within the muscle we’ve got what’s called the intramuscular tendon. There’s a classification scale – A, B, C – and the injuries there are a C-type. They typically take longer and are of higher risk of recurrence.”

Players becoming stronger could be the cause. A theory is that a player’s ability to produce more force is greater than their ability to absorb it. “What we’re now talking about is: ‘Can we get the tendon stronger?’” Kerin says. “There’s been a lot of research last year about specific exercises that can increase the size of the tendon and its ability to transmit these higher forces. That research is novel but it’s a central theme.”

There is the question of whether to reduce the load on the tendon or increase its ability to do the job. For Nick Metcalfe, a chiropractor who works with clubs and players, the challenge is to look deeper during treatment. He cites a study indicating that many hamstring injuries occur because of an over-stretch instead of a sprint mechanism.

“Maybe it’s not just the hamstring that’s under trauma,” Metcalfe says. “Maybe there’s some nerve involvement. That’s kind of the downstream effect from the pelvis. Ninety-one per cent of hamstring experts agree that nerve flexibility in the back of the leg is an important consideration. But the T-junction is more complex. It’s got two nerve supplies. Maybe it’s not just a hardware problem, maybe it’s also a software problem.”

“I would call it neuromuscular coordination,” Schilders says. “When a player gets fatigued, he doesn’t run the way he normally runs. The T-junctions are mainly acceleration injuries. It’s very important that you listen to your players. If they accelerate and they feel a pop, you have to look for a tear. There’s a tear until proven otherwise.”

Schilders delivered a lecture on T-junction injuries at a conference in Bologna this past week. “It has been a bit of an under-recognised injury,” he says. “It’s not unusual to be sent a scan which has been sent to three other people and nobody picks up the T-junction injury. Often it’s more severe than what is thought. And there’s also the fact that you have different types of T-junction injuries.”

Prof Rowena Johnson, chair of education at the Royal College of Radiologists, works closely with Schilders and was with him in Bologna. “An MRI is a static examination that doesn’t give you any dynamic information,” she says. “It can underestimate the severity. We’re trying to improve the imaging to reduce that risk.”

Schilders says: “The one thing that is always very important with hamstring surgery and professional football is you have to make sure that you do nerve preservation. There are quite a few nerves running around your T-junction.” Johnson says that performing an ultrasound on a player with a recurrent injury can help locate nerves deep within scar tissue.

“Unfortunately a lot of players we see have been around the houses,” she says. “It’s a niche area to treat. Sometimes they haven’t quite gotten to the bottom of what’s caused their symptoms and why they keep breaking down.”

The mind drifts back to a young Michael Owen tumbling as he chased a through ball during a game between Leeds and Liverpool at Elland Road in 1999. Owen was all about pace. His fall was dramatic. These days it is more common to see a player simply feel a twinge during a run.

It can be deceptive. Nicolas Jackson needed treatment on a hamstring problem during the first half of  but was not substituted until the 50th minute. “One challenge is how they feel initially doesn’t necessarily correlate exactly with what you see in the scan,” Kerin says. “Often the worse the injury the better the player can feel at the time. Their pain perception is not as bad because the tendon is not intact.”

Kerin suggests that Owen would undergo surgery now, adding that not operating is the riskier move and can lead to a lengthier absence. The medics are doing all they can. It is up to the people running the sport to lift the load on them and the players.
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