Validity and reliability of the Valkyria Trainer Balance^® portable force platform in its isometric mode

BACKGROUND: Isometric maximal voluntary force (IMVF) is essential for individuals' health and physical performance. Therefore, there is a need for valid and reliable devices to assess IMVF. OBJECTIVE: To determine the validity and reliability of the Valkyria Trainer Balance^® portable force platform in its isometric mode. METHODS: Fifty-eight physically healthy individuals (30 men and 28 women) participated in the study. A repeated measures design was used to compare the inter-day test-retest reliability of peak force. The validity of the Valkyria Trainer Balance^® force platform was determined by comparing the peak force with the ArtOficio^® force platform. The analysis consisted of the intraclass correlation coefficient (ICC), standard error of measurement (SEM), and coefficient of variation (CV). A CV ≤ 10% and ICC ≥ 0.80 were considered acceptable reliability, while a ≤ 5% and ICC ≥ 0.90 were regarded as high reliability. RESULTS: CV the peak force showed high test-retest inter-day reliability (CV = 4.3% and ICC = 0.99). When comparing both force platforms, there was a 1.1% difference between the two devices. CONCLUSIONS: The results of this study demonstrate that the Valkyria Trainer Balance^® force platform is valid and reliable for assessing IMVF in physically healthy individuals.