Episode 61
Ground Reaction Forces in 28 Yoga Poses

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Jules Mitchell and I talk about ground reaction forces (GRFs) in 28 Hatha yoga poses. Why do we need to know about GRFs? Because when we measure those forces it helps us understand how yoga poses impact bones and possibly bone mass.

• What is Ground Reaction Force (GRF)? In biomechanics it's the force exerted from the ground to the body when they make contact.

• Newton's 3rd law: for every action there is a reaction.

• Running is a high impact sport that is good for bone density (2.5-3x bodyweight).

• When bones are exposed to compressive forces the bones deposit more bone minerals and become denser.

• Producing muscle force also loads bone.

• Using a force plate, researchers measured GRFs in the hands and feet during sun salutations, warrior poses and arm balances.

• The 28 yoga poses produced forces less than 2x body weight which means that yoga can be categorized as a low impact exercise, similar to walking in terms of GRFs.

Read our review of this study over at Yoga Research and Beyond