Strength for Task Training: a novel intervention to improve locomotor ability following stroke
Many people with stroke have ongoing difficulty with locomotor abilities to the extent that it limits their participation in meaningful community life. Deficits in locomotor ability are strongly related to muscle weakness following stroke. Whilst the majority of physical therapy time is spent on the rehabilitation of locomotor abilities, the most effective rehabilitation method has yet to be determined. The need to develop efficacious rehabilitation strategies to address locomotor disability following stroke is paramount. Therefore, the primary aim of this thesis was the development of a novel intervention to improve locomotor ability in people following stroke. Systematic reviews of the evidence base were undertaken, evaluating two rehabilitation interventions; strength training and task-specific training. It was identified that strength training results in considerable increases in muscle strength. Yet despite the strong relationship between strength and locomotor ability, gains in strength following strength training translate poorly into improvements in locomotor ability. In considering task-specific training, the findings indicate that it improves locomotor ability; however gains are modest at best. These reviews suggested that the limited outcomes seen may relate to a failure to train people with stroke at sufficient intensity and dose, and with specificity to locomotor disability. A narrative review of the neuroscience literature in relation to the neural control of walking and neural plasticity elucidated a role for strength training to act as a priming intervention prior to task-specific training in people with stroke. Collectively this information informed the development of a novel intervention to improve locomotor ability following stroke; Strength for Task Training (STT). The key features of STT are that strength training is utilised to systematically prime the central nervous system prior to task-specific training and that strength training and task-specific training are conducted in an evidence based manner to maximise gains in locomotor ability. As part of the development of the STT intervention and preparation for evaluation, the selection of valid and reliable outcome measures was considered. The identification of suitable measures of the neural plasticity underlying recovery proved challenging. Therefore, a feasibility assessment of potential outcome measures was undertaken, identifying two possibilities; Transcranial magnetic stimulation (TMS) derived measures of corticomotor excitability and serum measurement of the neurotrophin, brain derived neurotropic factor (BDNF). In order to establish the test-retest reliability of these measures, two repeated measures studies were undertaken. These studies established the excellent test-retest reliability of TMS-derived measures when taken during treadmill walking. However, BDNF proved a less reliable measure. The final study of this thesis was a mixed methods pilot study which evaluated the feasibility of the research protocol for testing the STT intervention in a randomized controlled trial and the acceptability of the STT intervention to people with stroke and physiotherapists. This pilot study established the feasibility of the sampling and recruitment strategy, the integrity of the trial protocol and the feasibility, acceptability and safety of the STT intervention. The rigorous implementation of this mixed methods pilot study enabled refinement of both the study protocol and intervention, safeguarding the success of future evaluation in a large randomised controlled trial and translation of this novel intervention into clinical practice.