Water is a very dangerous place for non swimmers, particularly if it is cold and an excessive amount of alcohol has been drunk. Unfamiliar surroundings, and no knowledge of local tides, can be lethal to careless individuals. Water-related fatalities are the second leading cause of accidental death in the UK and Australia, and the third in the US. The risk of drowning is 2.5 deaths per 100 000 in USA and 1 per 100 000 in the UK.
Babies are taught to swim at a very young age in some countries; this enables them to learn to swim without fear of the water. They should have had their first two combined immunizations, unless they are being breast-fed. The water temperature should be higher than normal, a minimum of 86°F or 27°C. The time spent in the water should be carefully monitored; this can vary from 10 minutes to 30 minutes but babies should not stay too long in the water as they lose heat rapidly.
Swimmers are usually taught the four swimming strokes used for competitions; the front crawl, backstroke, breaststroke and butterfly, which are swum either as a single stroke or in combination over various distances.
There are four phases of each stroke; the reach, catch, pull, and recovery. The arm action during the pull phase provides 75% of the propulsion in all strokes except the breast-stroke, where the contributions from the upper and lower limbs are equal. During reach or entry the arm reaches forwards to enter the water. In backstroke the arm entry occurs with the shoulder in the fully elevated position. Catch is similar in all competitive strokes except backstroke; the elbow flexes, the arm extends forwards at the shoulder and moves outwards in the horizontal plane whilst rotating towards the body. The pull is the propulsion phase and can vary; the swimmer either sculls or pushes the water. The arm action starts at maximum elevation and ends in extension except in breast-stroke. Recovery is the out of water phase (except breast-stroke), and the arm then returns to start position.
In breast-stroke the arms move together in pull and recovery phase and the arms do not pull below the waistline.
Swimming is a sport that attracts participants of all ages although it is largely a young sport. Competitions are organized by clubs, schools, and national associations. Short course competitions take place in a 25-metre pool, long course in a 50-metre pool. Olympic swimming competitions are over a variety of distances and strokes, and they take place in 50-metre pools. Synchronized swimming, waterpolo, and diving are also included in the Olympic programme. Swimming in the sea may be part of a triathlon race, and open sea races, including Channel swims, are also held. ‘Masters’ swimming competitions are held for those over 24 years of age whereas ‘veteran’ sports competitions in athletics are for the over 40s. Competitions for different age groups are held in most countries, and world championships also take place.
Competitive swimming is a high-intensity training and performance sport. During the school year swimming training is divided into two sessions: the first session is in the early morning before school and the second session after school. The competitive swimmer usually does an average of 12 000-18 000 metres per day. The competition programme for the season should be planned well in advance so that the swimmer can peak for a specific competition, i.e. the swimmer reduces the amount of training to get the best result.
Swimming is a relatively injury-free sport and was found to be the safest of eleven sports surveyed by Weightman and Brown in 1975. It is non-load-bearing and does not involve antigravity work, resulting in fewer injuries. The injuries that do occur are usually due to overuse, doing too much too quickly, or breaking the rules.
To ignore warning signs of strong currents, king waves or rip tides may have lethal consequences. Diving into the shallow end of a pool or into a wave or sea where rocks are submerged may result in severe injuries. Pools should have the depth clearly marked so that swimmers do not dive into shallow water. Pools used for competition should be marked 2 metres from the wall at each end to judge when to turn. Flags are placed above the pool 5 metres from the end of the pool for the backstroke turn. There are rules against running around the pool. Pool discipline should be maintained, particularly out of the pool to prevent people slipping or jumping into the pool on top of other swimmers. There should also be strict discipline in the pool when swimming lengths. Hyperventilation before trying to swim a long distance under water should be forbidden, as it increases the risk of hypoxia (lack of oxygen), and may result in loss of consciousness and death by drowning. The hyperventilation removes carbon dioxide and hence delays the stimulus to breathe when breathholding.
Swimming programmes are helpful for both the mentally and the physically handicapped as they weigh less in water, and this makes it easier for them to move their muscles, enabling them to improve muscle tone and co-ordination of movement. Pregnant women can swim during their pregnancy while many other sports are not suitable. Swimming is also useful in rehabilitation of injured athletes. Patients with rheumatoid arthritis can improve their aerobic capacity by swimming in warm water. Asthmatics should be encouraged to swim, as swimming is the sport that is least likely to precipitate an asthmatic attack, and the fitter they are the fewer attacks they have; swimming improves their breathing. Asthma is not a handicap in achieving excellence in sport as shown by the number of Olympic gold medal swimmers who were asthmatics.
Water aerobics is becoming a popular method of keeping fit, with less potential for injury than high impact aerobics. Running in the water is a useful method for athletes to keep fit, if they are injured and unable to cope with full weight-bearing on hard surfaces. Hydrotherapy is also an effective rehabilitation after injury. Swimming is thus a sport that can be enjoyed by many different groups.
SHU KAWAHARA
shu@mercy.co.jp
Telephone No. +81-50-5539-9816
FAX : +81-34-578-9623
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