Stretching before exercising could actually CAUSE an injury

Stretching before exercising could actually CAUSE an injury - and make you slower 

• Static stretching – where limbs are extended and held in a position for a period of time – is particularly bad
• Stretching loosens the muscles and tendons, making them less powerful and more prone to injury

By Anna Hodgekiss

PUBLISHED: 06:43 EST, 4 April 2013 | UPDATED: 13:49 EST, 4 April 2013

We’ve long been told that stretching before exercise is the best way to prevent injury, but experts are now warning it could do more harm than good.

Not only could certain warm-up exercises prevent you from performing to the best of your ability, they could also make you more prone to injury.

It’s now thought that static stretching – where the limbs are extended and held in a position for a period of time to make our joints and muscles more flexible – is particularly bad. 

The authors of both reports say the reason may be because stretching loosens the muscles and tendons.

Not only could certain warm-up exercises prevent you from performing to the best of your ability, they could also make you more prone to injury

While this loosening makes them more flexible, it makes them less able to ‘spring’ into action.

It also gives the muscles and joints less support, increasing the risk of injury.

The process has been likened to having loose elastic on a waistband. While it may be more flexible, but it's also less effective at its job.

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To avoid injury, tendons need to be very elastic. But stretching makes them less elastic, so they are less able to deal with the large energy load placed on them by exercise. 

Stretching can even affect other parts of the body, too. Previous research from the University of Texas has found that stretching one muscle can also impair another muscle that was not stretched - e.g. stretching a muscle in your left leg could weaken a muscle in your right leg -possibly by affecting the nervous system.

The new conclusions were drawn researchers at the University of Zagreb analysed 104 studies of stretching, the New York Times reported.

They found that competitive athletes who did static stretching reduced the strength in their muscles by almost 5.5 per cent. 

Muscle power fell even more if the stretch was held for more than 90 seconds.

The ability to lift weights also reduced by 8.3 per cent after static stretching

If the stretch is held for less than 45 seconds, the negative effect is reduced, but stretched muscles are generally less strong, they say. 

Other types of exercise were also affected. The ability to run fast or jump as high as you can was also reduced by three per cent after stretching.

This means that all-important tennis serve or sprint start could be missing that added bit of ‘oomph’, say the researchers.

Another study, published this month in The Journal of Strength and Conditioning Research, concluded that young, fit men who stretched before lifting weights could manage 8.3 per cent less weight after the static stretching.

It may also lead to people feeling ‘weaker and wobblier’ during the workout.

The answer, say the researchers, is to warm up doing the movements you will use during exercise. That means jacks, high leg kicks and jogging on the spot.