Acute effect of short foot exercise on dynamic stability and foot kinematic in trail runners: a proof-of-concept study.

BACKGROUND

Trail runners face uneven terrains requiring optimal foot stability and postural control. The short foot exercise (SFE) may acutely enhance dynamic balance and foot arch height, potentially mitigating injury risk. This study aimed to evaluate the acute effects of the SFE on postural control and kinematics during a dynamic balance test in trail runners, considering the variations in the weekly training volumes of the participants.

METHODS

Sixteen adult trail runners (mean age 36 ± 8.4 years; 50% male) with at least one year of trail running experience were evaluated. Dynamic balance was assessed using the Y-Balance Test (YBT), and kinematics of the foot arch were measured via the Arch Height Index (AHI) using a 3D motion capture system. Baseline measurements were taken, followed by an SFE protocol: the participants had to perform 12 repetitions of 5-second contractions, which they did in three sets with 2 minutes of rest between sets. Immediately afterward, YBT and AHI were reassessed.

RESULTS

YBT showed significant improvements in all reach directions after the application of the SFE (p < 0.05). In contrast, no significant changes were observed in the AHI across reach directions (p > 0.05). Yet, subgroup analysis by weekly training volume revealed that participants with higher weekly volumes experienced a significant increase in anterior AHI (mean difference = -0.54 mm; 95% CI [-1.09 to 0.01]; p = 0.027; effect size = 0.13). The SFE may acutely improve foot kinematics and dynamic balance in trail runners; however, these effects are influenced by the weekly training volume of the participants.

CONCLUSION

This study suggests that a single session of the SFE may induce acute improvements in arch height and dynamic balance in trail runners, with differential responses depending on training volume. These preliminary results highlight the potential of the SFE as an acute activation strategy for the intrinsic foot muscles, but caution should be exercised when extrapolating the results.