Differentiating maximal and submaximal voluntary strength measures for the purposes of medico-legal assessments and para sport classification: A systematic review.

Measurement of maximum voluntary muscle contractions are effort-dependent - valid measurement requires maximal voluntary effort (MVE) from participants. Submaximal efforts (SMEs) yield invalid and potentially misleading results. This is particularly problematic in medico-legal and Para sport assessments where low strength scores may confer a personal advantage. Therefore, objective methods for accurately differentiating MVE and SME are required. This systematic review aimed to identify, appraise and synthesise evidence from scientific studies evaluating the validity of objective methods for differentiating MVE from SME during maximal voluntary contractions. Four electronic databases were searched for original research articles published in English and secondary references appraised for relevance yielding 25 studies for review. Methods were categorised based on eight distinct underlying theories. For isokinetic strength assessment, methods based on two theories - Strength-measure Ratios and Inter-Trial Strength Consistency - correctly classified 100% MVE and > 92% SME. Consequently, research evaluating the relative suitability of these methods for translation into practice is warranted. During isometric strength assessments, methods based on Deceptive Visual Feedback and Force-length properties warrant further investigation. Both methods yielded statistically significant differences between MVE and SME, with minimal overlap in values, but their sensitivity and specificity have not been evaluated.