Purpose: The relation between balance and impact was suggested in reports indicating gymnasts land with greater impact when landing on soft mats compared to hard surfaces.  This suggested a relation between balance and impact.  The was the second report in this series which examined the effect of footwear on balance.

Synopsis: Balance was tested in younger men. Shoe sole hardness was positively related to stability and thickness was negatively related to stability.

Significance:  The importance of this report was related to data indicating that footwear in common use presented a public health hazard.  This report was largely responsible for the movement to thinner and firmer materials in athletic footwear, particularly shoes in sports that have a high ankle sprains frequency, most notably basketball and football.  This was the first report to indicate that in young men, balance is positively related to sole hardness and negatively related to sole thickness.  This was the first report to suggest that the cause of the instability was oscillatory medial-lateral movement caused by these resilient materials.  Balance was better when barefoot in a younger compared to older cohort, but continued to be poor - only better than one shoe condition.