Tired of tough aerobic workouts, exercisers are opting for something altogether gentler. Core stability tones and strengthens muscles - and gives a leaner silhouette. Eleanor Bailey reports
Regular exercisers love mid-February. lt is the time after the mad January rush when the gym becomes deliciously empty again. But while an element of the newly resolved will merely have slunk back to their normal slothful selves, a lot of new exercisers are forced to give up because of early injury. Their low level of fitness meant their bodies were simply not strong enough to cope with a tough workout.

Damage to limbs and back through exercise is a common problem which confirms to people that exercise is unpleasant and dangerous. Fortunately something is now being done about it. The rules of physiotherapy are being taken into the gym and they call it "core stability".

Core stability is the buzz phrase of more and more fitness instructors who want to do something about the grisly four out of five aerobic exercisers who have had or will suffer from back pain. Its principle is that we need a core strength in the muscles that support the back and limbs before we let our bodies do anything.

"If people were more aware of their posture and core stability we would see fewer injuries, particularly from exercises that involve repetitive movement," explains chartered physio- therapist Sarah Ashwell. "Imagine that your spine is like the mast of a ship and that the core muscles are the ropes. Learning to control these muscles enables you to move your limbs as biomechanically perfectly as possible and so helps to prevent over-strain or over-use."

Likely to add to its attraction is the news that core stability exercise also helps create the kind of body shape we yearn for. Rather than building bulk, it encourages a long and lean shape. It even pays particular attention to the abdominal muscles at the bottom of the stomach - this is to build strength but also means it is tackling one of the most loathed lumps of the female body.

A new book was published at the beginning of this month all about core stability. Abdominal Training by Physiotherapist Christopher Norris, Director of Sports Injury Clinic Norris Associates coins the acronym "FLAT": Functional Load Abdominal Training, which he has developed from physiotherapy exercises designed to rehabilitate the spine after injury.

The exercises concentrate on side and deep abdominal muscles the obliques and transverses, unlike more superficial stomach exercises like sit-ups. Norris's exercises involve a lot of sucking in of the stomach, careful tilting of the pelvis and finding and optimising the hollow at the base of the spine, all of which develops the strong base. "These exercises have been part of physiotherapy and sports science for 40 years," says Norris, but now these are catching on in fitness and more and more fitness professionals are taking an interest.

While Norris's book is aimed at the less fit, core stability trunk training has also been shown to help athletes. American research confirmed that athletes accelerating at the end of a race and those who propelled themselves faster from the starting blocks tended to have better "core stability".

"These exercises are very safe and so people can start doing them from day one, with supervision," says Norris. "The more careful use of the abdominal muscles also means that they end up with flatter tummies and stronger muscles, not bulkier ones."

Sarah Jennings, who has studied Pilates and now does core stability exercises in addition to running and swimming, explains how she felt better with a more centred approach. "I had been doing a lot of weights on and off for a few years and I was really thinking that it was too extreme. My neck and shoulders were very tight and stiff and I didn't feel in balance. Core stability has sound principles that really make sense to me. It makes you much more aware of your body and what is good exercise and what is over-straining. There is a lot of squeezing and thinking about the muscles you are targeting rather than blindly straining, and it doesn't make muscles bulky in the way other exercise can. Having said that, I wouldn't do just core stability stuff because it doesn't get you sweaty enough. I think it is a good base. It makes you stronger and healthier."

Pilates, the increasingly popular exercise which involves small movements and weights, has many of the same principles, with its precision, careful muscle targeting and body control. This exercise form works on the basis that once the centre of the body is soundly centred then everything else can follow and you are more fit to do the exercise you want. Having said that, some people suspect that part of the popularity of these safe, thoughtful exercises has a lot to do with the fact that they don't involve getting out of breath.

'Abdominal Training' by Christopher M. Norris is published by A & C Black and costs pounds 10.99.

Key Exercises for Core Stability

1 Pelvic Tilting

Lie on your back with bent knees and feet and knees shoulder width apart. Tighten the abdominals and buttock muscles and tip pelvis backwards, flattening the small of the back. Repeat, holding still at the half way point.

2 Abdominal Hollowing

Kneel on all fours with hands and knees shoulder width apart; let tummy muscles relax completely. Pull them up and tighten, hollowing the tummy. Repeat.