Local and non-local effects (on the posterior chain) of four weeks of foot exercises: a randomized controlled trial

Abstract

This study investigated the local, remote, and contralateral effects of a four-week intrinsic foot muscle exercise intervention in recreationally active participants on foot parameters, flexibility, and performance of the posterior chain (PC). Twenty-eight healthy participants (12f, 16m) were randomly assigned to a control group or performed 2 × 6 min of foot exercises twice daily unilaterally at least five days/week for four weeks. At baseline (M1), after the intervention (M2), and after a four-week wash-out period (M3), we assessed bilateral Foot Posture Index-6, medial longitudinal arch mobility, single-leg stance balance, range of motion (ROM) (first metatarsophalangeal joint and ankle), and flexibility and performance of the PC. The FPI-6 score changes over time differed significantly between groups for both legs, improving by 26% in the trained- (p < .001) and 11% in the untrained leg (p = .02) in the intervention group from M1 to M2. Improvements were maintained at M3 for the trained leg (p = .02). Ankle range of motion and balance of the trained leg improved from M1 to M2, yet only became significant at M3 (ROM: p = .02; balance: p = .007). The other parameters did not change significantly. A four-week foot exercise intervention might have local but no remote effects in healthy young adults.German Clinical Trial Register (DRKS00027923) (24/08/2022).

Keywords: Dorsal chain; Force transmission; Intrinsic foot muscles; Plantar foot sole; Superficial backline.

Fig. 1

The foot exercise intervention: Starting with (A) a warm-up sequence, followed by either (B) hallux- and lesser toe extension or (C) the short-foot exercise and (D) toe grip exercise.

Fig. 2

CONSORT study flow diagram.

Fig. 3

The effect plots of the linear regression results for the results of (A) the Foot Posture Index-6 for the trained and (B) the contralateral leg, (C) the single leg stance balance, and (D) the range of motion of the ankle. Displayed p-values denote significant differences between groups in the changes between time points. Note the y-axis does not start at 0.