For a nation that is supposed to love it, we are appallingly bad at swimming. Statistics from the Department of Culture, Media and Sport suggest that 12 million Britons are habitual swimmers, with 22 per cent of adults and 50 per cent of children regularly taking a dip in their local pool - and more than 19,000 expected to take the plunge in next month's Swimathon (see panel, facing page). However, according to the Amateur Swimming Association (ASA), another 12 million are unable to swim at all and many of those who learnt at school have techniques so poor that they are likely to cause muscle strains, neck and back pain.

Swimming is compulsory on the national curriculum at Key Stage 2 (ages 7-11) and although schools have the option to introduce it, Ofsted has found that most lessons take place in Year 5, when children are 9 and 10. As a result, one child in five leaves primary school unable to swim the 25m specified by the Government as a target. Swimming is relegated to optional status at state secondary schools, so those who haven't managed to swim the length of a small pool by the time they are 11 are unlikely to catch up. “After primary school, many people feel embarrassed that they can't swim,” says David Sparkes, chief executive of the ASA. “And that puts a barrier in people's minds.”

Such a narrow window of opportunity for learning means that those who can swim may never master it well. Steven Shaw, a former competitive swimmer and teacher of the Alexander Technique, says that examples of appalling style can be spotted in pools around the country. He says that swimming badly will hinder your progress and enjoyment and can result in pain. Classic mistakes made by recreational swimmers include: holding the head too high in the front crawl, which strains the neck and back muscles; hunching the shoulders in breaststroke, which causes poor posture and shallow breathing; and a lack of rotation in the hips during backstroke decreases shoulder mobility and is a potential cause of neck and upper-back pain.

“Breast-stroker's knee” is a common injury

“Craning the neck and snatching it out of the water to breathe in the breaststroke puts cumulative strain on the spine and can lead to a type of whiplash injury,” says Shaw, the author of Master the Art of Swimming. “Likewise, ‘breaststroker's knee', the most common knee injury in swimming, is the result of repeated stress on the medial collateral ligament when people perform the narrow whip kick.” Shaw advocates a wider breaststroke kicking action to increase hip mobility and to minimise the risk of knee injury.

Even the butterfly, widely regarded as the most difficult stroke, can become less challenging when tweaks are made to technique. “Swimming continuous butterfly seems out of reach to many people because it leaves them exhausted,” he says. “But, with the right technique, it is not necessarily any more challenging.” He says that most people try to kick their legs too ferociously, which interrupts the flowing action of the arms, and to breathe on every stroke, rather than alternate strokes, which causes hyperventilation.

In general, physiotherapists rate swimming and aqua workouts as the best exercise for those with joint problems or injuries - but only when it is done well. “Water acts as a giant cushion and is much kinder to joints and tendons because it supports your body weight,” says Sammy Margo, the spokeswoman for the Chartered Society of Physiotherapists. “Equally, bad swimming can aggravate existing injuries and trigger new problems.” If you get into “a bad groove” when you swim, “you will cause abnormal biomechanics, with subsequent wear and tear, mainly to the neck and shoulders, though also to the knees and back”, she says.

A study at the Chiropractic and Osteopathic College of Australasia in 2005 identified some of the problems experienced by regular swimmers. These were low back injuries, as a result of repetitive stress during turns and the strain of poor head position; shoulder injuries, owing to lack of flexibility and overuse; and spinal problems, caused by poor head positioning when turning to breathe in front crawl.

Huge benefits in tweaking technique

Sometimes, all that is needed to minimise these risks are slight tweaks to technique, but the benefits are immense. A study published in the European Journal of Applied Physiology earlier this year indicated that improving the technique of a group of swimmers resulted in them expending less energy per length but completing a set distance more speedily.

Other studies that have compared elite and recreational swimmers have revealed how the top performers' superior technique enables them to use oxygen 50 per cent more efficiently, so they swim faster for longer. Shaw says that, done properly, swimming can be therapeutic. When the butterfly is mastered, for instance, it mobilises the spine and is “a great stroke for people with sciatica and stiff or tense backs who often experience relief from their pain when they swim this way”. Breaststroke improves mobility of the hips, ankles, wrists and spine.

Stephanie West, a spokeswoman for the ASA, says the association has launched schemes to help people improve their swimming. Everyday Swim is a national campaign run in conjunction with Sport England that aims to increase participation by 2 per cent this year. Likewise, the ASA Kelloggs Swim Active programme offers free instruction at selected pools to families with young children. If you've never learnt, contact your local council for information on adult and children's beginner sessions in your area.

“It is amazing how quickly a fear of the water or bad swimming habits can be overcome with the right instruction,” West says. “The health benefits of regular swimming include aerobic fitness and overall muscle toning and strengthening. Often all it takes to get the most out of swimming is a little effort and direction.”

For more details on the Everyday Swim campaign and the Swim Active programme, log on to www.britishswimming.org

Take the plunge

Fancy a challenge to test your swimming technique? Join Swimathon, the world's largest swimming fundraising event, on April 17-20, at more than 500 public and private swimming pools across the UK. More than half a million people have taken part in Swimathon during its 22-year history, swimming a total of more than 570,000 miles, the equivalent of circling the Earth 23 times.

More than 19,000 UK swimmers are expected to take part this year to raise money for the Marie Curie Cancer Care and the Swimathon Foundation, the charity that promotes and arranges the annual fundraising event. There are events for all abilities and you can also enter teams of 2-5 people to spread the distance you swim over several days. What's stopping you diving in?

Visit www.swimathon.org for details.

Gadgets for the fast lane

Finis Tempo Trainer, £19.15

This “personal pace coach” works like a metronome during piano practice. This small waterproof electronic device works best when worn underneath a cap or placed under a goggle strap near the temple. It produces a small beep, which helps to keep your stroke pace consistent and will even alert you when you start to slow down or lose rhythm. It allows you to set your own personal goals, monitoring your improvement as you go. It is also ideal for runners and cyclists.

Stockists www.swimtec-uk.com

Suunto Memory Belt, from £100

Heart monitors are a useful means of assessing how hard you are exercising. They work by measuring your heart rate using a strap worn over your chest, which transmits the information to a watch. Suunto has designed a waterproof model, which records and stores your heart's activity during swimming. The collected data can then be downloaded on to a PC after your session for analysis. Alternatively, the monitor can transmit the data in real-time to a pool-side trainer, who can tell if you need to work harder.

Stockists www.sunto.com

Freelap Stopwatch, £115, Timing pole H2O, £120

Timing lengths in the pool with a conventional stop- watch would be a logistical nightmare for the solo swimmer, but Freelap has designed a system that uses transmitters to register your speed and the number of laps swum. A timing pole is placed at either end of the pool, which sends a signal within a 2m radius to a waterproof stopwatch worn on the wrist. The time for each length is automatically updated every time you pass the end of the pool, and is displayed on the watch and stored for downloading on to Freelap's software after the workout.

Stockists www.hssports.co.uk

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