PURPOSE: To compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects.SCOPE: Nine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions.RESULTS: Perturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait.CONCLUSIONS: Healthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.
Het ondergaan van een eenzijdige beenamputatie is een drastische chirurgische ingreep. Mensen, die na een amputatie in staat zijn om te lopen met een prothese, zijn functioneel onafhankelijker, en hebben een hogere kwaliteit van leven dan mensen die in een rolstoel belanden. Het is daarom niet verrassend dat het herwinnen van de oopvaardigheid één van de voornaamste doelen is tijdens de revalidatie. Doel van het onderzoek was om inzicht te krijgen in de factoren die het herwinnen en onderhouden van de loopvaardigheid van mensen na een beenamputatie beïnvloeden. Gebaseerd op de resultaten van het onderzoek kan geconcludeerd worden dat de fysieke capaciteit hierbij een belangrijke rol speelt. Een relatief kleine verbetering in de capaciteit kan al resulteren in significante en klinisch relevante verbeteringen. Hoewel geavanceerde prothesen de mechanische belasting van het lopen met een beenprothese verminderen, kan een ineffectieve balanscontrole deze positieve resultaten weer tenietdoen. ABSTRACT Undergoing a lower limb amputation is a life-changing surgery. The ability to walk greatly influences the subject's functional independence and quality of life. Not surprisingly, regaining walking ability is one of the primary goals during prosthetic rehabilitation. The primary aim of the research performed was to enhance our understanding of some of the factors that influence the ability to regain and maintain walking after a unilateral lower limb amputation. Based on the results we can deduce that a person's physical capacity plays an important role in their walking ability. Relatively small improvements in capacity could lead to significant and clinically relevant improvements in people's walking ability. Furthermore, results show that sophisticated prosthetic feet can reduce the mechanical load experienced when walking with a prosthesis. Interestingly, inefficient balance control strategies can undo any positive effect of these prostheses.
Progressive disability develops with older age in association with underlying disease, comorbidity and frailty. Physical performance characteristics are important to improve the physical condition of older persons and therefore may be able to prevent or delay the onset of (progressive) disability. However lack of understanding of the physiology and etiology of functional decline leading to disability causes a problem in the development of effective preventive interventions. The aim of the present review is to determine which physical performance characteristics are determinants of disability in the older general population.
