| dc.description.abstract | The human foot is a versatile mechanical system, actively modulated by neuromuscular contributions from intrinsic and extrinsic foot muscles spanning its plantar surface. These contributions play a fundamental role in human bipedal proficiency, particularly during push-off phases of gait. However, our understanding of the mechanisms underlying healthy foot function remains incomplete. This thesis aims to provide deeper insights into the neuromechanical function of the foot and its capacity to support human movement.
Adequate muscle strength appears to be critical for effective propulsion and maintaining healthy foot function, yet musculoskeletal issues, including weakness and pain, frequently impair foot function. Chapter 4 investigates the effects of popular foot-strengthening exercises (FSEs) on neuromuscular activation compared to everyday functional movements. Electromyographic (EMG) recordings from eighteen healthy adults revealed that targeted exercises elicited muscle activation levels comparable to, or exceeding, those observed during dynamic tasks. These findings underscore the efficacy of specific exercises in rehabilitation programs aimed at enhancing foot muscle strength and function.
Building on this, Chapter 5 examines the force-generating capacity of foot muscles and their role in modulating forefoot stiffness during gait. Torque-angle relationships, derived from supramaximal tibial nerve stimulations, demonstrate how intrinsic and extrinsic muscles interact with the foot’s passive structures to regulate stiffness. Muscle contributions dominated torque responses at metatarsophalangeal joint positions critical for gait, indicating that these muscles are well-suited to provide meaningful mechanical contributions during locomotion, augmenting foot function beyond passive structural support.
Recognising the limitations of direct in-vivo measurements due to the foot's anatomical complexity, Chapter 6 introduces a neuromusculoskeletal modelling approach to estimate underlying foot function. Utilising the experimental torque-angle data from Chapter 5, an optimisation framework was developed to estimate in-vivo muscle-tendon unit (MTU) parameters, including optimal fibre length, maximal isometric force, and tendon slack length. Results from the optimisation suggest that traditional cadaver-based parameters do not accurately reflect in-vivo muscle function in healthy young adults. Together, the studies presented in this thesis provide novel insights into the active role of foot muscles in modulating mechanical function, with significant implications for rehabilitation, foot-strengthening programs, and the advancement of neuromusculoskeletal foot models. | en_GB |
