The Nordic curl is billed as the ultimate hamstring saviour, but is its reputation deserved? Peta Bee finds out

Hamstrings are as large as they can be limiting. Running the length of the thigh from the back of the knee to the hip, the stringy muscles and tendons are engaged in bending the knee and straightening the hip, relied upon heavily for any movement involving power and speed.

With each running stride or jump, the strain on the hamstring is considerable and, if insufficiently prepared, they will buckle beneath it, a pull or tear being the painful consequence.

Statistics show that hamstring strains are the most common non-contact injury in elite sport and, for athletes in all events, hamstring protection is paramount. Yet it remains a neglected focus for some. “It’s very overlooked for many athletes,” says physiotherapist Philip Coleman of the Running Physio clinic in Newbury.

“In sports like football, where hamstring injuries are rife, it has become a prime area of attention in training, but while many sprinters do have adequate hamstring-strengthening programmes, others don’t. And many distance runners think they are immune from tears, which is completely wrong.”

Power of the Nordic curl

What, then, should we be doing to power up the mass of muscle and tendons at the back of the legs? If there is one exercise that is touted as a hamstring savior over any other, it is the Nordic curl.

Professional football clubs have invested thousands of pounds in equipment designed to help players execute this simple strengthening move correctly and sports scientists have devoted more research time to it than any other lower-limb exercise.

“It is not a new exercise, but has really come into prominence over the last few years as its value has been better understood,” says Sammy Margo, a spokesperson for the Chartered Society of Physiotherapy. “We now know that it can be hugely important in preventing hamstring injuries if it is done in a considered and graded way.”

HOW IT WORKS

Margo says that the effectiveness of the Nordic curl comes down to its eccentricity. “Eccentric loading of a muscle occurs when it strengthens and lengthens at the same time,” she explains. “It creates more force through a muscle than concentric, or shortening, moves and that ultimately creates strength.”

Studies have shown that eccentric muscle moves like the Nordic curl are also effective at boosting coordination between brain cells and muscles, improving proprioception in the process. “There are benefits to it over other hamstring strengthening moves,” Margo says. “It engages the whole of the upper body and core muscles, which makes it a tremendous all-round exercise.”

Care needs to be taken to progress gradually, she adds. “If you rush into the exercise or allow too little recovery time between sessions, it could increase vulnerability of the hamstring, so be cautious.”

HOW TO DO THE NORDIC CURL

Kneel on the ground, with someone sitting behind to hold your ankles. As slowly and smoothly as possible, lean forward so that your chest approaches the ground.

Use your hamstrings to control your forward momentum until you can no longer resist gravity. Put out your arms at that point to halt your fall.

When your chest touches the ground, push yourself upright to repeat the exercise initially 8-12 times.

nordic-curl

WHAT THE SCIENCE SAYS

Dozens of recent studies suggest that almost two thirds of hamstring injuries among sports people could be prevented if they practice the ‘curl’ on a regular basis.

One trial involving Danish footballers that was conducted five years ago assigned participants to either a regime of normal strength training (not including the Nordic move) or a programme that focused heavily on the hamstring curl.

During the season that followed, those who had practised the Nordic curl experienced 70 per cent fewer injuries than the control group. Among players who had previously suffered hamstring problems, the injury rate dropped by 85 per cent.

In April, a study published by the American College of Sports Medicine analysed the hamstring muscle fibre lengths of 28 healthy men before asking them to embark on either a six-week training schedule of moves with lengthening muscle contractions – including the Nordic curl – or a programme of shortening contractions.

Previous trials had suggested that shorter muscle fibres increase the risk of hamstring injury in elite athletes and this was no different. However, the researchers stressed the need to keep up the Nordic curl work. “It works great, unless the athlete stops doing the exercises in-season or goes on holiday at the end of the season,” they wrote. “Then, all of the hard work is for nothing, with significant reductions in muscle fibre length and potential increases in injury risk.”

ENTER THE NORDBORD

Leicester City, Swansea, Liverpool and Chelsea players are among those who use a revolutionary piece of equipment called the NordBord.

Developed by scientists at Queensland University of Technology, it measures eccentric and isometric muscle strength in the hamstrings.

“We’ve shown with our research that athletes who are weak at this exercise are significantly more likely to sustain a hamstring strain,” explains Dr Tony Shield, who initially invented and built the portable prototype with a former student.

Not yet available commercially, the equipment has nonetheless been snapped up by professional sports teams. “It measures the force generated by the hamstring during a Nordic hamstring stretch and correlates the muscle’s strength in relation to a player’s body mass,” says Carl Wells, head of sports science at St George’s Park, the FA’s national performance centre in Burton Upon Trent where it is used regularly.

“We find it incredibly useful. Players hop on to it after training, performing 8-10 repetitions of the exercise.”

WHAT’S THE ALTERNATIVE?

Not everyone is convinced the Nordic curl is the ultimate saving grace. Coleman recommends a modified hamstring exercise using an exercise ball.

“There are downsides to the Nordic curl in that it works both legs together,” he says. “Many athletes have a weaker side and, using a Swiss ball, you can isolate an under-developed hamstring much more easily.”

To do it, lie on the floor with both feet on top of a large exercise ball, your upper back and shoulders on the floor, and your arms out to the sides. Raise your hips and your lower back off the ground so they form a straight line with your legs. Keeping your abdominal muscles tight, pull the ball toward your bottom by digging your heels into the ball until your feet are flat and your knees and butt are high in the air. Pause, then push the ball away from you until your legs are straight. You can isolate one hamstring by lifting one leg off the ball and pulling the ball with your other leg.