Relationship of ankle strength and hypermobility to squatting skills of children with Down syndrome.

We used ankle goniometric and force measures to determine the relative contribution of hypermobility and strength to heels-down squatting (HDS) in four groups: eight children with Down syndrome, eight hypermobile children, six retarded children, and seven children with normal development. Analysis of variance and across group correlations revealed force as a major but not sole contributor to HDS; hypermobility was found not to have significant influence. Heels-down squatting may be a compensatory mechanism resulting from underdeveloped balance or irregular activation of agonist-antagonist relations around the ankle joint.