The Effect of a 6-Week Strength and Balance Training Program on Navicular Drop and Proprioception in Excessive Pronated Foot

The purpose of this study was to determine the effect of a 6-week strength and balance training program on navicular drop and proprioception in subjects with excessive pronated feet. Eleven subjects who exhibited excessive pronated feet from student population participated in this study. Navicular drop test was used to assess the subtalar joint motion. The Biodex Stability System was used to determine balance using three indices; (1) overall stability index (OSI), (2) the anterior-posterior stability index (APSI), and (3) the medial-lateral stability index (MLSI). In a randomized order, the subjects were tested balancing on each foot at the two different stability levels, namely Level 8 (more stable/less difficult) and Level 2 (less stable/more difficult). The subjects performed the following two exercises: (1) one-leg standing with flat foot for one minute and (2) one-leg standing with heel raise for one minute (6 sec up and 6 sec down). Each exercise was repeated three times on each foot. After the 6-week training period, navicular drop test and balance testing were conducted to determine if there were any changes in navicular drop and balance control. To determine treatment effect (time) and foot-side effect, means of variables (navicular drop height, OSI, APSI, and MLSI) were evaluated utilizing a repeated analysis of variance measures (ANOVA). Further analyses were made using paired t-tests. A 6-week strength and balance training program resulted in a significant improvement on the height of the medial longitudinal arch measured by the navicular drop height during one-leg standing. A significant treatment effect was also seen on balance ability during one-leg standing on the MLSI index of the BSS for the easier (more stable) balance task. This study suggests that a 6-week program of simple one-leg standing and unilateral heel-raise exercises can positively affect navicular drop height and balance ability in subjects with excessive pronated feet.