Evaluating the relationship between gait and clinical measures of plantar flexor function

Individuals with plantar flexor weakness often require rehabilitation and/or orthoses, which should be personalized based on level of weakness. While plantar flexor weakness can be measured via peak plantar flexion moment during gait (MGAIT), motion analysis systems are often not clinically available. Clinical measures, such as the single-leg heel rise (SLHR) test and isometric muscle test, may provide surrogate measures of plantar flexor function during gait. However, it is currently unknown if a relationship(s) exists between such measures. This study evaluated the relationship between gait and clinical measures of plantar flexor function for typical individuals. Twenty-four participants underwent an instrumented gait analysis, from which MGAIT was calculated. Next, participants performed an isometric plantar flexor test, from which the maximum plantar flexion moment (MISO) was calculated. Finally, participants performed a SLHR test, from which maximum plantar flexion moment (MSLHR) and total work (Wtot_SLHR) were calculated. Via Pearson correlations, MSLHR was most strongly correlated to MGAIT (r = 0.56; p = 0.005). Wtot_SLHR was significantly correlated to MGAIT (r = 0.47; p = 0.019). MISO was not significantly correlated to MGAIT (r = 0.19; p = 0.363). MSLHR and/or Wtot_SLHR may provide clinically-feasible surrogate measures of plantar flexor function during gait.