Local and remote effects on the posterior chain of four weeks of minimalist shoe walking or intrinsic foot muscle exercises in healthy participants

Introduction Intrinsic foot muscle exercises (FE) and wearing minimalist shoes (MS) were shown to be beneficial for foot health in specific populations (e.g. runners) [1]. There are also a few studies reporting potential non-local positive effects along the posterior chain (PC) [2]. For healthy, recreationally active participants, there is little evidence concerning local and remote effects along the PC. Further, it is unclear whether these potential effects remain after a phase without training. This study assessed the local and remote effects along the PC of four weeks of FE or MS walking and the potential remaining effects after a four-week wash-out period.

Materials and Methods Forty-two recreationally active participants (19 female, 26±5 years) were randomly allocated to either a control group (no intervention), the MS- (~5000 steps/day), or the FE group (five exercises, 3x10 repetitions, held for 5s, with randomly allocated foot). Both interventions were performed at least five days/week. The following local and non-local outcomes were assessed at baseline (M1), after the four-week intervention (M2), and after a four-week wash-out period (M3): Foot Posture Index-6 (FPI-6), Arch Rigidity Index, single-leg stance balance, ankle- and PC Range of Motion (ROM) (knee-to-wall test and modified sit-and-reach test), and PC performance (Bunkie Test, standing 90:20 isometric PC test, concentric isokinetic hamstrings measurement). For the MS study, we fitted multiple hierarchically built mixed models to the data. For the FE study, we calculated two linear regression models, with one of the models evaluating the interaction between group and measurement. We compared the two models with a likelihood-ratio test using analysis of variance (ANOVA). The analyses for the FE study were performed for each leg separately.

Results Statistics showed a significant improvement in the FPI-6 score by 17% (t(51)=-6.05, p<.001), and balance by 14% (t(49)=-2.56, p=.01) from M1 to M2 after MS, which was maintained at M3 (FPI 6: t(51)=-2.73, p=.009; balance: t(49)=-2.25, p=.03). After FE, the FPI-6 improved from M1 to M2 for the trained leg (26%, t(52)=-5.27, p<.001), also maintained at M3 (t(52)=-2.35, p=.02). Interestingly, FPI-6 also improved from M1 to M2 in the untrained leg (11%, t(52)=-2.38, p=.02). Further, balance and ankle ROM slightly improved from M1 to M2 (trained leg) (balance: 14%; ankle ROM: 15%) but only significant at M3 (balance: t(50)=-2.84, p=.007; ankle ROM: t(50)=2.49, p=.02) in the FE group. All other results were not significant (p<0.05).

Conclusion Although four weeks of MS walking or FE had local benefits on foot health (i.e., foot posture, balance), we found no remote effects of active foot strengthening interventions on the PC. The effects might have been greater in orthopedic patient populations with e.g. flat foot disorders. Future studies should consider a longer intervention duration.

Publication History

Article published online:
21 May 2025

• Literature

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