New research shows aqua-aerobics is safe in pregnancy

Women often turn to water workouts, such as aqua-aerobics, during their pregnancy to reap the benefits of exercise while enjoying buoyancy support for their growing bodies. But amid unclear guidelines, there's been concerns pregnant women risk overheating while exercising in warm water. New research from a Melbourne physiotherapist aims to set the record straight, writes Karen Keast.

As the director of Aquamums, physiotherapist Mandy Brearley has run aqua exercise classes for pregnant women in Melbourne for more than 20 years.

While Ms Brearley is well versed in the benefits of moderate intensity exercise for women during pregnancy, she was concerned at inconsistent guidelines surrounding the appropriate pool temperature for pregnant women when exercising.

Guidelines from the Royal Australian and New Zealand College of Obstetricians and Gynaecologists in 2003 stated pregnant women must not exercise in water above 28ºC while current British guidelines from the Royal College of Obstetricians and Gynaecologists advise pregnant women against exercising in water over 32º.

The American College of Obstetricians and Gynaecologists and updated Australian and New Zealand guidelines have not specified a water temperature for exercise during pregnancy.

The lack of consistency prompted Ms Brearley to embark on a study designed to provide pregnant women and health professionals with solid evidence outlining a safe water temperature for pregnant women participating in aqua-aerobics.

"Health professionals are aware that pregnant women mustn't overheat - it can be harmful to the developing foetus," she says.

"Some studies in North America had shown that just being in very hot water can cause an increase in body temperature and perhaps harm to the foetus but those temperatures in spas are 39ºC and 40º.

"So there is a perception that warm water can overheat the body but looking at the literature, there hadn't been any studies published on the thermoregulation of pregnant women in various temperatures of water," she adds.

"My question was - is it okay to exercise in community swimming pools that are heated around 30º to 32º, is that safe?"

As part of her Masters Degree in Physiotherapy (Research), Ms Brearley and her small research team studied the body temperature response of 109 healthy women in their second and third trimesters of pregnancy after they participated in standardised aqua-aerobics classes at seven indoor community pools, heated between 28.8º to 33.4º, spanning 18 weeks.

The tympanic temperature of participants was measured at rest pre-immersion, after 35 minutes of moderate intensity aqua-aerobic exercise, after a further 10 minutes of light exercise while in the water, and then after leaving the facility.

Researchers found the body temperature of participants increased only slightly - at an average of just 0.16º.

"Exercise causes an increase in body temperature because of the heat that's produced by the working muscles," Ms Brearley says.

"There was a small increase in body temperature related to the exercise but we found it didn't matter whether the water was 28º or up to 33º, the body temperature response was the same."

While the temperature rise is significant statistically, it's not an increase that places pregnant women at risk of overheating, Ms Brearley says.

"If the body temperature rises more than 1.5º above the resting body temperature then that would be something that you would be concerned about."

The results of the observational study, recently published in the Australian Physiotherapy Association's (APA) Journal of Physiotherapy, show healthy pregnant women are able to safely exercise in community pools heated up to 33º.

Ms Brearley says it's a good result for mothers and their babies.

"There are so many physiological benefits of the water on the pregnant body," she says.

"The buoyancy of the water helps support the body and as the baby is getting bigger and everything is getting bigger and heavier the water reduces weight, so there's a great reduction of weight bearing through the joints and especially through the lumbar spine and the pelvic girdle joints.

"A lot of women have trouble with their pelvic girdle joints during pregnancy so the buoyancy takes the load off and enables a really low impact, safe exercise option.

"Women can exercise very comfortably in this medium right up to full term, and you are still getting the full benefits of exercise right to the very end of the pregnancy, whereas on land it might be becoming a bit awkward and a bit uncomfortable."

There are other benefits to aqua-aerobics. The hydrostatic pressure of the water works to reduce swelling in the ankles, assists carpal tunnel syndrome and varicose veins.

It also increases the blood flow to the baby through the placenta while water works to dissipate exercise-induced body heat away from the body and into the water, at a faster rate than exercising in air.

"Exercising in the water is the best thing to do. It's absolutely fantastic for pregnant boosts the circulation, improves cardiovascular fitness and that's all good for the foetus.

"Exercising in water is a really good option."

Ms Brearley says the study, the first research of its kind, provides evidence that will help to support or inform guidelines for water temperature in aerobic exercise during pregnancy.

"This will also help other health professionals to be confident that if they're doing classes or working with pregnant women that these temperatures are perfectly safe," she says.

"However, everybody is an individual and there are individual differences in thermoregulation so you still need to watch out for individual cases, and make sure that people are comfortable and not feeling too hot and ensuring that they are hydrating as well.

"In doing moderate intensity aqua exercise in these temperatures, there's no risk whatsoever. It's fantastic for the baby."

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