“Swimming is sometimes described as the perfect exercise for people with asthma,” says Greg Smith, CEO of the Asthma Foundation of NSW. A foundation study of 73 kids who joined a swimming programme found that half reported a change in the amount or type of asthma medication they needed. Two-thirds of these children reported they needed less medication to stay healthy. The air just above the surface of the water is moister and less likely to cause the airway muscles to constrict and bring on an attack, Smith says.
“Swimming is a good whole-body exercise that has low impact for people with arthritis, musculoskeletal or weight limitations,” says Robert Robergs, director of the exercise physiology labs at the University of New Mexico. Water’s buoyancy helps cushion joints and bones. Immersed to the waist, your body bears 50% of its weight; to the chest, 25%; to the neck, 10%.
A study at Indiana University found long-term swimmers aged over 40 who swam more than four times a week showed fewer signs of ageing than the general population. Study leader Dr Joel Stager says that the subjects displayed lower blood pressure, blood triglycerides and cholesterol; better pulmonary function; and better muscle mass.
Swimming uses all the major muscle groups and water provides 12 times the resistance of air, which boosts muscle strength. It’s not so wonderful for building bone density, however; for that you need weight-bearing exercise.
Chlorine affects lungs
A study by the Sports Science Institute of South Africa found a big increase in exercise-induced breathing problems in swimmers who used chlorinated pools.
Earlier this year, researchers in Brussels found that infants taking indoor swimming lessons were more likely to develop asthma and recurrent bronchitis. It’s believed that chlorine-related gas is particularly damaging to the lungs of very young children.
Chlorine quickly kills most germs that cause skin rashes and swimmer’s ear, but it takes longer to kill diarrhoea-causing cryptosporidium. And if levels of chlorine are too low, chloramines form from the reaction between chlorine, urine and sweat. Chloramines can cause skin, eye and respiratory irritation.
“Most of the ‘ideal’ ranges for chlorine in public pools are simply too low,” says Tom Griffiths, president of the Aquatic Safety Research Group at Penn State University. Heavily used pools may need three to four parts per million (ppm) to prevent chloramine reactions.
Swimming is a great way to get fit, but it may not speed up weight loss. Exercise physiologist Robert Robergs explains that scientists believe water submersion sets off a complex nerve pathway that lowers metabolic rate. As a result, you burn fewer kilojoules. And there’s another possible catch, according to Professor Louise Burke of the Australian Institute of Sport: “Swimming can increase appetite in some people and lead to eating more than you think.”
Swimming is a good fitness choice for just about everyone, but especially people who find other forms of exercise painful. If you want to lose weight, though, you may need to up the pace: a 70kg swimmer doing a vigorous freestyle can burn 35kJ a minute, Robert Robergs’ findings notwithstanding.
Some experts suggest people with asthma avoid pools with chlorine concentrations too far above 0.5ppm. So how do they get protection against chloramines? “Use a pool with a non-chlorine shocking agent like monopersulphate-based oxidisers,” says Griffiths.
He also recommends pools where water is replaced regularly. If indoors, they should have UV light treatment systems and good ventilation that brings in fresh air and blasts out chloramines at busy times.