Background/Aims For people living with acquired brain injury from stroke or trauma, clinical practice guidelines recommend high-intensity physical rehabilitation to optimise motor outcomes. There is an acknowledged evidence–practice gap between routine clinical practice and the amount, intensity and type of active upper limb rehabilitation recommended in research-informed guidelines. The aims of this study were to identify methods used to facilitate high doses of upper limb practice in published trials, understand stakeholder perspectives of the barriers and enablers to these methods in hospital settings, and to synthesise findings to form an evidence-based action plan for rehabilitation professionals, service providers and adults living with an acquired brain injury. Methods A rapid systematic literature review and a series of qualitative interviews with service users and rehabilitation clinicians explored the evidence on intensity and the experience of high intensity rehabilitation following brain injury and stroke. Triangulating this mixed method evidence, recommendations were generated on how to increase upper limb rehabilitation intensity during inpatient therapy. Results There was consensus in the literature that high-dose motor training improves a person's ability to move their hand and arm after brain injury and stroke. Trials mostly delivered therapy programmes as a replacement to usual care; however, it was unclear how high-intensity therapy was integrated into usual rehabilitation. Methods employed to increase the intensity of upper limb rehabilitation included strategies to optimise engagement (eg encourage independent practice and more practice); clinician-related processes (eg self-auditing, use of groups); environmental factors (eg equipment, dedicated space); and organisational influences (eg professional development, dedicated research positions and mentoring). Qualitative data showed that barriers and facilitators stem from service user factors (eg cognitive ability, advanced age, cultural mores) as well as clinician factors (eg quality of the therapeutic relationship, type and quality of therapist instructions). Organisational factors such as a strong research culture and a commitment to evidence-based practice positively influenced outcomes. Conclusions There is capacity to increase the intensity of upper limb rehabilitation by optimising organisational support and systems, as well as greater service user engagement in therapy processes. Implications for practice Rehabilitation clinicians have long understood that dose is a critical component of motor training. Findings may assist with structuring upper limb rehabilitation programs and addressing clinician factors to increase the intensity of therapy.