Test–Retest Reliability and Concurrent Validity of FysioMeter C-Station Assessing Lower-Limb Muscle Strength via Isometric Mid-Thigh Pulls

The isometric mid-thigh pull (IMTP) is a reliable method to assess lower limb isometric muscle strength. A portable device (FysioMeter C-station) could serve as a suitable alternative. The reliability and concurrent validity of the FysioMeter C-station have not been evaluated for the IMTP unilateral test. The aims of this study were to (1) examine the between-session reliability of the unilateral IMTP test for the left and the right legs using the C-station, and (2) explore the concurrent validity of these measures when compared to gold standard force plates (AMTI). Twenty healthy, recreationally active males (age: 23 ± 4 years, height: 1.81 ± 0.60 m, weight: 79.6 ± 10.8 kg) participated and completed test sessions one week apart. The participants performed the following: (i) three bilateral IMTPs on dual force plates (AMTIBI); (ii) three unilateral IMTPs on each leg on a single force plate (AMTIRIGHT, AMTILEFT); and (iii) three unilateral IMTPs on each leg on the C-station (CSRIGHT, CSLEFT). The peak force was measured in all the testing modalities and an Intraclass Correlation Coefficient (ICC) and Pearson Correlation Coefficient (PCC) were used to evaluate the reliability and validity. The C-station showed good between-session reliability for CSLEFT (ICC = 0.84) and CSRIGHT (ICC = 0.85). A strong concurrent validity (PCC ≥ 0.82) was found for the C-station compared to the gold standard (AMTI). The C-station appears to be reliable for measuring unilateral IMTP in recreationally active males. Furthermore, strong concurrent validity of the C-station compared to the gold standard was demonstrated.