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The biomechanical and neuromuscular responses to shoe-surface instability

Apps, C (2017) The biomechanical and neuromuscular responses to shoe-surface instability. Doctoral thesis, Liverpool John Moores University.

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Abstract

Unstable shoes are a unique category of footwear that provide a training stimulus during casual wear. Reported therapeutic benefits have led to their commercial success, although enhancing muscle activations and balance, normally associated with instability training devices like wobble boards, are not as effective. Therefore, the aim of this thesis was to develop and evaluate an unstable shoe that provides continually unpredictable perturbations. The notion was that a more challenging, and varied instability, alike uneven terrain, would provide an enhanced training stimulus. The first study investigated if the developed shoe with irregular midsole deformations (IM) was more demanding, alike uneven terrain, it was compared to an irregular surface (IS) and a stable shoe-surface during treadmill walking and running. Generally, IM increased instability compared to the control, demonstrated by a more cautious gait pattern and posture at initial contact, and subjectively perceived as less stable whilst walking and running. Certain responses in IM were similar to IS, such as the increased variability of frontal ankle motion and maximum sagittal knee angle in stance phase. This is proposed to benefit IM wearers by improving the level of functional joint variability. The second study assessed if the varied instability of IM would be more de-stabilising than an unstable shoe (US) by comparing joint stability strategies during walking and running. Results revealed joint stiffness reorganisations between the ankle and knee in IM and US during loading. Further joint stiffness re-distributions and increased ankle co-contraction were found in IM compared to US, indicating additional adaptations are required for stability. The third study revealed IM may similarly be beneficial in gym training, as adaptations were also triggered in forward and lateral lunge movements to maintain stability. Increased gastrocnemius medialis and peroneus longus activations were required for the push-off phase in lunges, which related to ankle position. Investigating short-term training effects after regular IM wear was not feasible with the prototype developed, so instead a 6-week IS walking intervention was undertaken, as similar responses were found to IM during locomotion in the first study. Results showed no significant improvements to ankle muscle strength and postural balance compared to a control group, who did not undertake a training intervention. This research revealed IM provided an innovative stimulus that increased instability compared to an US and simulated certain responses to an IS. Unpredictable instability provided by footwear may have potential use for injury prevention and rehabilitation interventions, but future work needs to assess which populations it benefits.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: unstable footwear; perturbations; kinematics; movement variability; electromyography; joint stability; lower-limb
Subjects: Q Science > QP Physiology
R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Date Deposited: 16 Jun 2017 11:24
Last Modified: 16 Jun 2017 11:24
Supervisors: Lake, MJ and O'Brien, T and Sterzing, T
URI: http://researchonline.ljmu.ac.uk/id/eprint/6690

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