The effect of subtalar joint position on dorsiflexion of the ankle/rearfoot versus midfoot/forefoot during gastrocnemius stretching.

BACKGROUND: Limited ankle joint dorsiflexion passive range of motion (PROM) has been associated with common chronic lower extremity conditions, and clinicians often instruct patients in stretching exercises to increase dorsiflexion. However, little is known about how subtalar joint (STJ) position affects dorsiflexion at the midfoot/forefoot versus ankle/rearfoot during gastrocnemius stretching. The purpose of this study was to determine if more dorsiflexion occurs at the ankle/rearfoot and less at the midfoot/forefoot during gastrocnemius stretching with the STJ positioned in supination versus pronation.

METHODS: In this repeated measures design, 27 participants (23 females, 4 males; mean age = 31.3 years, SD = 10.7) with current or recent history of lower extremity chronic conditions and less than 10 degrees ankle dorsiflexion measured with the knee in extension on the involved side(s) performed five 30-second gastrocnemius stretching trials in pronation and supination on each side in a randomly determined sequence. A 7-camera Vicon Motion Analysis System and an AMTI force plate were used to measure midfoot/forefoot dorsiflexion, ankle/rearfoot dorsiflexion, knee extension, and normalized vertical ground reaction force.

RESULTS: Two-way repeated measures ANOVA revealed a significant increase in midfoot/forefoot dorsiflexion when stretching in pronation compared to supination (P < .001). ANOVAs also demonstrated significantly more extension of the knee when stretching in supination compared to pronation (P < .001), and increased normalized vertical ground reaction force when stretching in supination compared to pronation (P = .032). With the numbers available, no significant difference in ankle/rearfoot dorsiflexion when stretching in supination compared to pronation could be detected (P > .05).

CONCLUSION: Gastrocnemius stretching in pronation resulted in more dorsiflexion at the midfoot/forefoot than stretching in supination.

CLINICAL RELEVANCE: Clinicians may want to consider STJ position during gastrocnemius stretching to either facilitate or limit recruitment of dorsiflexion motion at the midfoot/forefoot.