A four-week minimalist shoe walking intervention influences foot posture and balance in young adults-a randomized controlled trial

INTRODUCTION

Minimalist shoes (MS) are beneficial for foot health. The foot is a part of the posterior chain. It is suggested that interventions on the plantar foot sole also affect the upper segments of the body. This study aimed to investigate the local and remote effects along the posterior chain of four weeks of MS walking in recreationally active young adults.

METHODS

28 healthy participants (15 female, 13 male; 25.3 ± 5.3 years; 70.2 ± 11.9 kg; 175.0 ± 7.8 cm) were randomly assigned to a control- or intervention group. The intervention group undertook a four-week incremental MS walking program, which included 3,000 steps/day in the first week, increasing to 5,000 steps/day for the remaining three weeks. The control group walked in their preferred shoe (no MS). We assessed the following parameters in a laboratory at baseline [M1], after the four-week intervention [M2], and after a four-week wash-out period [M3]: Foot parameters (i.e., Foot Posture Index-6, Arch Rigidity Index), static single-leg stance balance, foot-, ankle-, and posterior chain range of motion, and muscle strength of the posterior chain. We fitted multiple hierarchically built mixed models to the data.

RESULTS

In the MS group, the Foot Posture Index (b = -3.72, t(51) = -6.05, p < .001, [-4.94, 2.51]) and balance (b = -17.96, t(49) = -2.56, p = .01, [-31.54, 4.37]) significantly improved from M1 to M2, but not all other parameters (all p >.05). The improvements remained at M3 (Foot Posture Index: b = -1.71, t(51) = -2.73, p = .009, [-4,94,0.48]; balance: b = -15.97, t(49) = -2.25, p = .03, [-29.72, 2.21]).

DISCUSSION

Walking in MS for four weeks might be advantageous for foot health of recreationally active young adults but no chronic remote effects should be expected.

Clinical Commentary: A Criteria-Based Testing Protocol for Return to Sport Post Hip Arthroscopy for Impingement

Overall, 84%-87% of athletes will return to sport following hip arthroscopy; however, some literature suggests that only 57% of athletes return to their preinjury level, and only 16.9% report optimal performance. This discrepancy may be due to a lack of consistency within the definition of return to sport as well as a lack of consistency within rehabilitation programs when determining return to sport readiness. Athletes who are returning to sport must demonstrate adequate range of motion, strength, and the ability to perform multi-directional movements without the risk of reinjury. There has yet to be a comprehensive, criteria-based, return to sport testing protocol that utilizes objective measures to ensure athletes are ready for return to sport. The goal of the authors was to create a criteria-based testing protocol for return to sport following hip arthroscopy utilizing components best supported in the literature. The following parameters were identified as key areas to assess for within a return to sport testing protocol: range of motion, strength, functional testing, self-reported outcomes including psychological readiness and time. The purpose of this clinical commentary is to propose a criteria-based testing protocol to be used following hip arthroscopy for impingement from early rehabilitation through return to previous level of sport. Criteria are presented clearly to promote objective progression through rehabilitation while still being mindful of the biological healing time required for safe and efficient progression. It is the authors' hope that in identifying and establishing a criteria-based testing protocol a higher percentage of athletes will be able to return to sport.

Level of Evidence

5.

Comparison between the Original- and a Standardized Version of a Physical Assessment Test for the Dorsal Chain - A Cohort-Based Cross Sectional Study

This cohort-based cross-sectional study compares the original (OV) and a newly developed standardized version (SV) of the Bunkie Test, a physical test used to assess the dorsal chain muscles. Twenty-three participants (13 females, 10 males; median age of 26 ± 3 years) performed the test, a reverse plank, with one foot on a stool and the contralateral leg lifted. In the SV, the position of the pelvis and the foot were predefined. The test performance time (s) and surface electromyography (sEMG) signals of the dorsal chain muscles were recorded. We performed a median power frequency (MPF) analysis, using short-time Fourier transformation, and calculated the MPF/time linear regression slope. We compared the slopes of the linear regression analysis (between legs) and the performance times (between the OV and SV) with the Wilcoxon test. Performance times did not differ between SV and OV for either the dominant (p = 0.28) or non-dominant leg (p = 0.08). Linear regression analysis revealed a negative slope for the muscles of the tested leg and contralateral erector spinae, with a significant difference between the biceps femoris of the tested (-0.91 ± 1.08) and contralateral leg (0.01 ± 1.62) in the SV (p = 0.004). The sEMG showed a clearer pattern in the SV than in the OV. Hence, we recommend using the SV to assess the structures of the dorsal chain of the tested leg and contralateral back.

Myofascial Treatment Techniques on the Plantar Surface Influence Functional Performance in the Dorsal Kinetic Chain

Prior studies have shown that self- and manual massage (SMM) increases flexibility in non-adjacent body areas. It is unclear whether this also influences performance in terms of force generation. Therefore, this study investigated the effect of SMM on the plantar surface on performance in the dorsal kinetic chain. Seventeen young participants took part in this within-subject non-randomized controlled study. SMM was applied on the plantar surface of the dominant leg, but not on the non-dominant leg. A functional performance test of the dorsal kinetic chain, the Bunkie Test, was conducted before and after the intervention. We measured the performance in seconds for the so-called posterior power line (PPL) and the posterior stabilizing line (PSL). The performance of the dominant leg in the Bunkie Test decreased significantly by 17.2% from (mean ± SD) 33.1 ± 9.9 s to 27.4 ± 11.1 s for the PPL and by 16.3% from 27.6 ± 9.8 s to 23.1 ± 11.7 s for the PSL. This is in contrast to the non-dominant leg where performance increased significantly by 5.1% from 29.7 ± 9.6 s to 31.1 ± 8.9 s for the PPL and by 3.1% from 25.7 ± 1.5 s to 26.5 ± 1.7 s for the PSL. SMM interventions on the plantar surface might influence the performance in the dorsal kinetic chain.