Warming the Intrinsic Foot Muscles: A Specific Warm-Up for Dynamic Stability in a Pilot Study.

Background Optimizing the intrinsic foot muscles (IFMs) is a key aspect of athletic conditioning for enhancing dynamic balance and preventing injury. However, conventional warm-up strategies often neglect the IFMs in favor of proximal muscle groups, leaving their specific contribution under-investigated. This randomized crossover pilot study primarily tested whether localized warming of the IFMs using capacitive and resistive electric transfer (CRET) improves dynamic balance on the modified Star Excursion Balance Test (mSEBT) compared with warming the posterior calf. Secondary objectives were to assess changes in deep tissue temperature and weight-bearing ankle dorsiflexion. Methods Nine healthy adult males participated in this randomized crossover trial. Participants received a two-minute CRET intervention applied to the IFMs, and in a separate session, after a one-week washout period, to the posterior calf muscles. The primary outcome was the normalized reach distance in the three directions (anterior (ANT), posteromedial (PM), and posterolateral (PL)) of the mSEBT. Secondary outcomes included deep tissue temperature and ankle dorsiflexion range of motion, measured with the weight-bearing lunge test (WBLT). Data were analyzed using nonparametric tests. Results Deep tissue temperature and ankle dorsiflexion (WBLT) significantly increased after both the IFM and posterior calf interventions. However, a significant and selective improvement in mSEBT performance was observed only in the PL reach distance following the IFM intervention (p=0.029). The posterior calf intervention did not yield a significant improvement in the PL direction. No significant changes were found in the ANT or PM directions under either condition. Conclusions IFMs are a viable target for pre-activity thermal interventions. The selective improvement in the PL direction suggests that heating the plantar foot enhances the neuromuscular control required for challenging, multiplanar balance tasks, an effect that extends beyond simple increases in flexibility. This finding implies that our intervention specifically benefited the foot and ankle complex, which is heavily taxed in the PL direction. This approach offers a focused warm-up strategy to optimize performance and potentially mitigate injury risks.