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Article: Bone Density

With water exercise on the rise, researchers are spending more time studying its effects on the body.  We see how beneficial water based exercised (WBE) are with the brain, such as by aiding in the fight against dementia (see article in the April 2019 Winged M).  Studies show that WBE can support the body by relieving pressure placed on joints from normal wear and tear, as well as relieving symptoms of arthritis.  It can also aid in lowering blood pressure by relaxing the blood vessels so that they can carry more blood throughout the body, resulting in less strain to the heart as it pumps that blood out to the more distal extremities. 

What about bone density?  For a long time, it was believed that water-based exercise did little to nothing for bone density.  Luckily, researchers have not given up on this question and results from studies are in favor of water exercise helping and maintaining and building bone density.

To make bones stronger, you must increase the load applied to the bone.  Your bone density increases in response to external stresses like exercise, thereby making your bones stronger.  While aerobic land exercises, such as running, tennis and dancing can provide this bone-strengthening load we seek, land-based exercises can often cause unwanted and painful stress to our joints.  However, with WBE, the resistance of the water just from physical movement places a demand on the skeletal system and in turn placing a load on the bones.  Once the bones are subjected to stress they are forced to respond and increase muscle tension.  This process results in stronger and denser bones.

Studies show that the impact on the bottom of the pool in chest-deep shallow water aerobics and water running adds to the bone loading capacity.  The impact is less compared to land-based exercise due to buoyancy, but it still provides stress to the bones and increases their strength.  In a study done in Brazil in 2018, researchers trained a group of postmenopausal women in a 30-minute-high-intensity jump-based aquatic program for 24 weeks.  Their data showed that this type of aquatic exercise program is able to improve bone mineral density and functional fitness parameters. 

Deep water aerobics holds value as well.  Since bone density increases when you build strength, studies were done to see if the same can happen in the pool.  In the deep water, the resistance property of this environment provides training all the way around your body.  Whatever directions you move, you are moving against the water pressure that is approximately 12 times more resistant than air.  By incorporating aqua dumbbells in your workout, and pushing and pulling them under the water you cause resistance, which is similar to lifting heavy weights on land.  You can also use noodles, aqua gloves, paddles, and kickboards to achieve the same resistance that weights provide on land.  You can also do a wall workout in the deep water where you push yourself off the wall or out to do pushups.

It is still believed that land-based exercise provides the greatest impact on bone health with exercises that include sudden impact and weight-bearing functional strength training.  However, research finds that water-based exercises are useful for promoting bone health and you are not cheating your bones by being in the water like we once believed.