SINGAPORE - Swimming can burn calories, is easy on the joints, builds muscular strength and endurance and improves cardiovascular fitness.
But, like any other exercise which involves physical exertion, swimming demands a lot of the cardiovascular and musculoskeletal systems of the body, said Ms Ho Jiaying, a senior physiotherapist at Singapore General Hospital.
For someone who has never swum seriously before, it is a good idea to get a medical review before starting a rigorous and competitive regimen, say doctors and physiotherapists.
A medical review can help to identify cardiovascular diseases, relevant medical conditions and musculoskeletal problems which may be made worse by exercise, said Associate Professor Ching Chi Keong, a senior consultant at the department of cardiology and director of cardiac electrophysiology and pacing at National Heart Centre Singapore.
In such cases, pre-existing medical conditions could increase the risk of injuries or sudden death.
Such a review for swimmers would look for conditions that could make swimming risky, especially on a competitive level. These include asthma, diabetes, heart murmurs and heart conditions such as hypertrophic cardiomyopathy, which is a thickening of the heart muscle, coronary artery disease or long QT syndrome (LTQS).
Abnormal cardiac electrical activity
It is estimated that about one in 5,000 people has LQTS, a disorder of the heart's electrical activity which could cause a sudden, abnormal and life-threatening heart rhythm.
The QT is the interval between the start of the Q wave and the end of the T wave in the heart's electrical cycle, during which the heart contracts and beats, then becomes "charged" up to repeat this.
In people who are known to have LQTS, 10 to 12 per cent may suffer a heart event that is triggered by swimming, said Prof Ching.
LQTS is diagnosed through an electrocardiogram (ECG), which measures the electrical activity of the heart, medical history (for instance, of fainting episodes) and a family history of LQTS, said Prof Ching.
However, its diagnosis is not straightforward.
About 10 to 15 per cent of LQTS patients may have a normal QT interval, while 2 to 3 per cent of the healthy population may have a prolonged QT interval, said Prof Ching.
Moreover, there are 13 types of LQTS.
But, just to be on the safe side, anyone with a family history of this condition should have a thorough check-up before starting on any swimming exercise programme.
A sports physical would also flag previous orthopaedic injuries, such as sprains, fractures and dislocations, back and neck injuries and any previous surgery, said Ms Ho.
The physical examination would assess cardiovascular fitness through the pulse rate, blood pressure, an electrocardiogram, and a test for measuring the person's maximum intake of oxygen during exercise.
There would also be neurological assessments on reflexes, strength and coordination.
One could also expect musculoskeletal assessments on core stability, range of motion in the joints, muscle flexibility and strength in the back, hips, legs and, in particular, the shoulders for swimmers.
This is because shoulder injury is one of the most common problems found in swimmers, said Ms Ho.
Shuttle swim test
Swimming-specific performance and endurance tests may also be performed, she said.
One is a shuttle swim test, where the swimmer swims a 10m distance within a progressively decreasing time frame.
The timing is indicated by an audio cue where the interval between successive signals is reduced approximately every minute.
The first level of the test requires a swimming velocity of 0.9m/s, which is increased by 0.05m/s with each subsequent level.
It is designed to test the aerobic fitness of competitive water polo players.
There is also a swimming beep test, a variation of the popular running beep test.
It is based on a 1.5km swim. The distance is broken down into 15 x 100m laps. Each 100m is then broken down into 8 x 12.5m swims.
The speed level changes with every 100m.
The first 3 x 100m is set at a very slow rate, to be used as a warm-up and to help the person get used to the test.
The time between beeps reduces as the test goes along.
The swimmer's score is the level and number of laps reached before he is unable to keep up with the beeps.
The results of a sports physical will provide a more complete picture of a person's current general health, fitness level and physical well-being.
They will help in providing the necessary treatment and education to enhance a person's swimming performance and reduce his risk of injuries, said Ms Ho.
Who should go for physicals?
Based on the Singapore Sports Safety Committee's recommendation in 2007, sports physicals should be done according to a person's risk of sudden death or serious injuries, which would include any early warning signs, or a family history of medical conditions as well as the level of competition.
A sports physical is compulsory if one is a professional athlete. It should be done annually.
Annual tests are also strongly recommended if one is an athlete for one's country, school or club.
If one is just swimming for recreation, then a sports physical is voluntary.
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