The effect of different Masai Barefoot Technology (MBT) shoe models on postural balance, lower limb muscle activity and instability assessment

Abstract

Unstable shoe constructions may counteract balance deficits and underutilization of lower limb muscles. The Masai Barefoot Technology (MBT) concept has been widely analysed in terms of footwear-induced instability. However, previous experiments investigated predominately one specific MBT shoe model. Therefore, the purpose of this experiment was to evaluate the effects of differently shaped MBT soles on stance biomechanics. Mean velocity of centre of pressure (CoP) displacement, root mean square (RMS) tibialis anterior (TA), peroneus longus (PL), gastrocnemius medialis (GM), vastus lateralis (VL) and biceps femoris (BF) activity, as well as subjective perception of instability were recorded in 31 young asymptomatic adults during standing with three different MBT models and a standard control shoe. Statistical analysis included repeated-measures ANOVAs with Bonferroni–Holm adjusted post-hoc tests. MBT footwear, regardless of shape and structure, significantly increased postural sway compared to the control condition. Additionally, there were significant differences between the MBT shoe types. These results coincided with those obtained from instability assessment testing. No significant effects of MBT footwear were detected for the GM and BF muscles. A consistent increase in TA, PL and VL RMS activity was only found for one MBT model. On a muscular level, within-MBT differences were statistically less pronounced than for CoP and for instability rating measures. These findings suggest that specific variations in MBT sole construction criteria differently challenged the postural control system without forfeiting the principal feature of simulating a less firm surface for the user. Further investigations are warranted to examine the framework of instability within the MBT concept, as well as associated intrinsic and extrinsic influences related to rehabilitation and prevention programmes.