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 (AMTI_BI); (ii) three unilateral IMTPs on each leg on a single force plate (AMTI_RIGHT, AMTI_LEFT); and (iii) three unilateral IMTPs on each leg on the C-station (CS_RIGHT, CS_LEFT). 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 CS_LEFT (ICC = 0.84) and CS_RIGHT (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.