PeRsonalised Exercise for Priming Post-stroke (PREPP) : Exploring intervention and outcome for clinical application

Stroke is a leading cause of disability and mortality worldwide, with more than 475,000 people currently living with lasting impairment in Australia including deconditioning and upper limb impairment. Neuroplasticity is considered a treatment target for stroke rehabilitation and recovery due to its association with improved prognosis and functional outcome. Exercise interventions may be utilised as a primer for motor rehabilitation post-stroke due to the potential to increase biomarkers of neuroplasticity such as Brain-Derived Neurotrophic Factor (BDNF). It is proposed that exercise interventions to increase BDNF concentration may be used as an adjuvant therapy to motor rehabilitation such as Constraint-Induced Movement Therapy (CIMT) to increase effectiveness. However, the optimal prescription and clinical application of exercise to increase BDNF concentrations have not been explored. The aim of this thesis was to explore exercise prescription and uptake post-stroke by 1) identifying optimal exercise training parameters, 2) investigating barriers and facilitators to the prescription and uptake of exercise in clinical practice, and 3) examining the relationship between commonly used outcome measures of neuroplasticity and upper limb function.

This thesis consists of four individual studies. The first study is a systematic review and meta-analysis that explored parameters of exercise prescription and their relationship to BDNF concentration in people with stroke. Seven electronic databases were searched for experimental or observational studies measuring changes in BDNF concentration after exercise in people with stroke. Meta-analyses demonstrated significant increases in BDNF concentration following a single session, and program, of high intensity aerobic exercise (e.g., High Intensity Interval Training [HIIT]). This study was published in the journal ‘Stroke’.

The second study was a mixed methods study that explored the barriers and facilitators to the use of HIIT post-stroke. People with stroke and health professionals who work in stroke rehabilitation were invited to complete an online questionnaire and semi-structured interview. Twenty-six people with stroke and 37 health professionals completed the questionnaire, while ten people with stroke and eight health professionals participated in an interview. People with stroke and health professionals who work with people with stroke consider HIIT to be a beneficial intervention following stroke, however its use in clinical practice is varied based upon client motivation and clinician expertise. People with stroke reported minimal support from people with stroke and health professionals, the lack of knowledge of the benefits of HIIT, and the use of the term ‘high intensity’ as the main barriers to participation. Access to health professionals, the provision of personalised education and individualisation of the protocol were reported by people with stroke as the main facilitators to participation in HIIT. Health professionals reported a lack of knowledge about how to prescribe HIIT, and participant motivation as the main barriers to the prescription of HIIT within the clinical environment. Increased education about the prescription and benefits of HIIT, obtaining medical clearance for HIIT, and comprehensive screening prior to commencing a HIIT program were the main facilitators to HIIT prescription reported by health professionals working with people with stroke.

The third study investigated an alternative to BDNF, blood lactate, as a marker of brain plasticity given the challenges associated with measuring BDNF in clinical practice, such as cost, speciality training and equipment. Due to the Covid-19 pandemic recruiting people with stroke to participate in the study was not feasible, therefore, this study was completed in a healthy population of adults. Thirty-one healthy adults were tested for BDNF, and lactate concentrate before and after a submaximal graded exercise test. A poor correlation was observed between the two biomarkers at pre- (r = -0.256, p = 0.164) and post-exercise (r = 0.112, p = 0.549). The change in concentration from pre- to post-exercise (r = 0.019, p = 0.921) was also poorly correlated. Therefore, in healthy adults, there is little evidence to suggest a relationship between BDNF and lactate.

The fourth study examined the correlation between two upper limb assessment tools to identify paretic upper limb use within an Australian clinical setting. The Motor Activity Log Amount of Use (MALAOU) and the Motor Activity Log Quality of Movement (MALQOM) 30-item scales are commonly used in clinical practice. The Rating of Everyday Arm-use in the Community and Home (REACH) scale similarly measures paretic upper limb use but is much less time intensive compared to the MALAOU and MALQOM. Ten people with stroke completed MALAOU, MALQOM and REACH assessments before and after a two-week intensive upper limb program. A moderate correlation between the MALQOM and REACH (rho = 0.717, p = 0.02) was observed at pre-intervention. No correlation was observed between any measure at any other timepoint, or when comparing the change in scores from pre- to post-intervention.

The fifth study included in this thesis is a protocol for a randomised controlled trial as a future research recommendation based upon the learnings of the other studies. The randomised controlled trial was originally planned to be completed during candidature, however due to the Covid-19 pandemic this was not feasible. This protocol, to be completed after this program of research, will explore the efficacy of a combined HIIT and Modified-CIMT upper limb function.

This work © 2024, Sarah Ashcroft.