Range of motion, muscle length, and balance performance in older adults with normal, pronated, and supinated feet

[Purpose] To compare the lower limb joint range of motion and muscle length between different types of foot posture, and determine the correlation of range of motion and muscle length with balance performance. [Subjects and Methods] Ninety individuals (age, 65.2±4.6 years) were assessed using the Foot Posture Index to determine their type of foot (Normal [0 to +5], pronated [+6 to +9], and supinated [-1 to -4]; n=30 per group). The range of motion (goniometer), muscle length (goniometer and tape measure), and balance performance (functional reach test and four square step test) were measured for each participant. Data were analyzed using the Kruskal-Wallis test and Spearman's rank-order correlation. [Results] No significant differences were found in range of motion, muscle length, and balance performance among different types of foot posture, except for right and left ankle dorsiflexion range of motion. Balance performance was significantly correlated with selected muscle length and range of motion, especially in the supinated foot. [Conclusion] Range of motion and muscle length of the lower limb may be associated with balance performance in older adults with foot deformities. These findings may guide physiotherapists in choosing intervention based on specific assessments for older adults with foot deformity.