Validity and reliability of isometric tests for the evidence-based assessment of arm strength impairment in wheelchair rugby classification.

ABSTRACT

OBJECTIVES: The purpose of this study was to examine the validity and test-retest reliability of a battery of single-joint isometric strength tests, to establish whether the tests could be used for evidence-based classification in wheelchair rugby (WR). DESIGN: Cross-sectional. METHODS: Twenty male WR athletes with impaired arm strength and thirty able-bodied (AB) participants (15 male, 15 female) performed four isometric strength tests. Each test required three 5-s efforts and examined maximal isometric force for flexion and extension around the shoulder and elbow joint. Test validity was established by comparing differences (Cohen's effect sizes [d]) in strength between WR athletes and AB participants. Differences were also explored between male and female AB participants. Twenty AB participants returned for a second visit to establish the test-retest reliability of the test battery. RESULTS: Significantly lower force values were observed for all isometric strength measures in WR athletes compared to AB participants (p≤0.0005; d≥2.14). Female AB participants also produced significantly less force than male AB participants for all joint actions (p≤0.0005; d≥1.93). No significant differences were identified between trials for any measure of strength, with acceptable levels of test-retest reliability reported (ICCs≥0.97, SEM≤19.3N and CV≤8.4%). CONCLUSIONS: The current results demonstrated the validity of a battery of isometric strength tests, suggesting they can be used to reliably infer strength impairment in WR athletes, which is a pre-requisite when working towards evidence-based classification in Paralympic sport.