Can swimming and water exercise really build bone?

People frequently ask me if swimming or other water exercise can help build or maintain bone density. I’ve always thought (and so have other researchers) that water exercise wouldn’t be the best possible exercise for bone — after all, swimming is low-impact, and the water supports your body weight. I could see how the full-body muscle movement in water exercise might reduce the “use-it-or-lose-it” peril of sedentary living, but could this form of exercise really stimulate the bones to build new bone?

Well, I have good news for all you swimmers: Studies from all around the world suggest that you not only can maintain bone density with aquatic exercise, you can also build bone.

How water exercise helps after menopause

Several studies over the years that have found that water exercise does indeed offer benefits for bone building in postmenopausal women — but not in terms of bone density increase. Rotstein and colleagues (2008) followed a group of 35 postmenopausal women for seven months as they participated in hour-long water exercise three times a week. They found that the mineral content of the women’s bones improved — meaning, the bones were stronger — but their bone density wasn’t noticeably greater.

This has been a fairly constant theme in research of water exercise and bone health: Swimmers’ bone densities are found to be comparable to sedentary control subjects, but their rate of bone turnover is significantly higher (Gómez-Bruton et al., 2013), meaning their bones became more resistant to fracture and able to repair themselves more effectively.

Personally, I’m happy for women to have stronger bones even if they’re not dense — I’ve long maintained that strong bones are the key to avoid debilitating fractures. Brazilian researchers, however, have been getting great results on both fronts by using a high-intensity interval-training method in their water exercise studies.

In 2014, one study (Moreira et al. 2014) found that high-intensity water exercise for 6 months reduced bone resorption markers even though bone density didn’t change — not that different from what earlier research found. More recently, however, Aboarrage and colleagues (2018) trained study participants in a high-intensity aquatic exercise protocol that included a form of interval training using jumping and hopping performed for 20 minutes in warm water that was about chest deep.

This new study offers a different twist: By using exercise that encouraged jumping in water and fairly high exertion, the water exercisers increased bone density throughout the body, and specifically in the spine and femur. As an added bonus, the exercise group also had greater leg strength and agility after the six-month time frame than the controls.

Swimming builds better bones

For those who prefer water exercise, this is great news! You’re not shortchanging your bones by swimming or doing water aerobics. And if, for one reason or another, you can’t perform other types of exercise due to severe joint pain or poor balance — or perhaps you’re recovering from a fracture to an arm or a leg — exercising in water is one way to keep your muscles strong without overloading your joints or risking a fall. So, I for one am going to let go of the mentality that water exercise isn’t useful for promoting bone health. Jump in, the water’s fine — and it’s good for your bones!