Single joint assessment of isometric plantarflexor force characteristics using portable force plates: A systematic...

The aim of this systematic review was to (1) identify differences in isometric force plate testing procedures for the ankle plantarflexors and (2) determine the reliability of existing methods to inform minimum reporting standards. A systematic search of PubMed, Web of Science, Google Scholar, MEDLINE and CINAHL was conducted from inception to 2025, for peer-reviewed studies using portable force plates to assess isometric plantarflexor force. PRISMA guidelines were followed. Two independent reviewers assessed methodological quality using the COSMIN Risk of Bias tool and Mixed Methods Appraisal Tool, with discrepancies resolved collaboratively. Twenty studies met the inclusion criteria, revealing methodological variations in task familiarisation, participant instructions, joint angles, sources of compliance, statistical analyses and force plate considerations. Within-session peak force demonstrated good to excellent reliability (ICC ≥ 0.91, 95% CI range 0.84-0.99) based on eleven studies of adequate quality. Evidence for between-session reliability is limited, with three studies identified: two of doubtful quality and one of adequate quality. No researchers have examined the reliability of plantarflexor force-time values. Across the included studies, portable force plates provide reliable within-session peak plantarflexor force data across testing positions. Future research should explore between-session reliability and temporal variables using standardised protocols.