Measures of trunk muscle strength and their measurement properties: a protocol for a systematic review and narrative synthesis of clinical measures

INTRODUCTION: Spinal musculoskeletal conditions, including low back and neck pain, are leading causes of disability globally. The trunk muscles, which comprise muscles in the thoracic and lumbar regions, are essential for functional activities, necessitating mobility, motor control and strength. To investigate the effectiveness of interventions directed at improving trunk muscle strength, it is essential to have valid, reliable and responsive performance-based outcome measures (PBOM). While isokinetic dynamometry is considered the gold-standard PBOM, the associated costs, size/weight and operational complexity of this equipment preclude its use in a clinical setting. There is, therefore, a need to evaluate the measurement properties of alternative accessible measures of trunk strength. This systematic review therefore aims to investigate the measurement properties of PBOM of trunk muscle strength measures appropriate for use in a clinical setting. METHODS AND ANALYSIS: This protocol has been designed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols. CINAHL, Web of Science, Pedro, MEDLINE, EMBASE, SPORTDiscuss will be searched systematically from the database start date up to 16 April 2020, along with reference checking and the grey literature searching. Eligibility criteria include studies investigating measurement properties of PROM for trunk muscle strength for use in a clinical setting in adults with and without spinal musculoskeletal complaints. Two independent reviewers will determine the eligibility of the studies through screening process of titles, abstract and the full text. Both reviewers will assess the risk of bias using COnsensus-based Standards for the selection of health status Measurement Instruments risk-of-bias tool and then extract the data from included studies. The overall quality of the included studies will be evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. A narrative synthesis will be carried out if meta-analysis is not applicable. Findings from this systematic review will aid clinicians and practitioners working in the field for example, sport, in using the most appropriate PBOM to measure trunk muscle strength. ETHICS AND DISSEMINATION: No research ethics application is needed as there are no patient data in this study. The results of this study will be submitted to a peer reviewed journal and presented at conferences. PROSPERO REGISTRATION NUMBER: CRD42020167464.