Physical training in your dreams

Scientists have come up with just about the best news that a couch potato could ever want to hear.

They say you can increase the strength of your muscles just by sitting back and imagine yourself taking exercise.

The discovery could help patients too weak to exercise to start recuperating from strokes or other injuries.

We need to encourage people to take aerobic exercise that raises their heart rate to 70% of its maximum for 20 minutes three times a week

Dr Peter Clough

If the technique works in older people, they might use it to help maintain their strength.

Muscles move in response to impulses from nearby nerve cells called motor neurons.

The firing of those neurons in turn depends on the strength of electrical impulses sent by the brain.

Dr Guang Yue, an exercise physiologist at the Cleveland Clinic Foundation in Ohio, says that this suggests you can increase muscle strength solely by sending a larger signal to motor neurons from the brain.

New Scientist magazine reports that Dr Yue and his colleagues have already found that visualising exercise was enough to increase strength in a muscle in the little finger, which it uses to move sideways.

Flexing biceps

Now his team have turned their attention to a larger, more frequently used muscle, the bicep.

They asked 10 volunteers aged 20 to 35 to imagine flexing one of their biceps as hard as possible in training sessions five times a week.

The researchers recorded the electrical brain activity during the sessions.

To ensure the volunteers weren't unintentionally tensing, they also monitored electrical impulses at the motor neurons of their arm muscles.

Every two weeks, they measured the strength of the volunteers' muscles.

The volunteers who thought about exercise showed a 13.5% increase in strength after a few weeks, and maintained that gain for three months after the training stopped.

Controls who missed out on the mental workout showed no improvement in strength.

The researchers are now repeating the experiment with people aged 65 to 80 to see if mental gymnastics also works for them.

Aerobic exercise

Dr Peter Clough, a sports psychologist from Hull University, said that it was well known that visualising playing a sport could often be a more effective way of getting better than actually practising it.

However, he said that muscle strength was only one aspect of taking exercise. Flexibility and aerobic exercise were also important parts - and these could not be achieved by simply using your imagination.

"This is an interesting theory, but sitting on the sofa thinking about taking exercise in not really a good idea.

"Simply building muscle mass might make you look good, but it is not what exercise is all about.

"We need to encourage people to take aerobic exercise that raises their heart rate to 70% of its maximum for 20 minutes three times a week - it is that which helps you to live longer."

A spokesman for Sport England said that everybody would benefit from taking exercise.

Not only was it healthy, for young people in particular it was a confidence builder, and had been shown to help reduce crime.