# MScope: A Reliable Battery for Functional Status Assessment in Multiple Sclerosis
## 4 Discussion
These findings may be attributed to a possible lack of familiarity with the tests, which could have contributed to the significant differences found between the measurements taken on different days for certain tests. However, it is also essential to consider that other factors may have contributed to these differences. These may include the natural variability in biological measurements, changes in environmental factors, and neuromuscular fatigue that patients may experience after their first laboratory visit. The neuromuscular evaluations conducted as part of this study encompassed a range of assessments, including handgrip strength, isometric peak force during the squat exercise (measured with a dual force plate system and a force sensor), and isometric peak force during unilateral and bilateral knee extension exercise (measured with a force sensor). Neuromuscular evaluations demonstrated excellent intra-day reliability, with ICC values exceeding 0.75 (ranging from 0.912 to 0.989) for both measurements. This high level of consistency indicates that these measures are reliable for assessing neuromuscular function of the lower limbs and demonstrated strong consistency within the same day. Regarding the test-retest reliability, the results were generally good to excellent. The ICCs for the majority of the variables ranged from 0.797 to 0.955, indicating a reasonable degree of consistency between the testing sessions (see Table 2). This finding supports the stability of neuromuscular measures over time, with non-significant differences in the Bland-Altman test. However, the heteroscedasticity analysis (Supplementary File S2) revealed significant differences between measurements 1 and 2 for the MVICSQ and UMVICLEXT_L variables, suggesting that variability in these measurements may be influenced by the magnitude of the recorded values. This should be considered when interpreting the reliability of these assessments, although this may be explained by fatigue induced by the maximum isometric tests performed only 72 h apart. Although neuromuscular capacity assessments have been frequently included in various intervention studies with MS patients, commonly through measurements such as one-repetition maximum (1-RM), maximal concentric isokinetic torque, mechanical power across different loads, or MVIC, the simplest approach for generally untrained MS patients remains assessing isometric strength at a specific joint angle. However, only one study has specifically examined the reliability of MVIC measurements in the leg extension exercise at 90\({}^{\circ}\) knee flexion, demonstrating high repeatability (ICC = 0.973) and a minimum detectable change of 13.2 kg [45]. Furthermore, the study reported a strong correlation between MVIC and 1-RM (R\({}^{2}\) = 0.804) with a 13% absolute percentage error in predicting 1-RM based on MVIC [45]. This reliability was consistent across MS types and independent of neurological disability scores [45]. Notably, our study results align with these findings and with prior studies conducted in different populations that have investigated the reliability of similar assessments. For example, [PERSON] et al. [46] reported high reliability (ICC = 0.97) for isometric squat tests in healthy adults. However, the handgrip strength test remains the most commonly administered strength assessment for patients with neurological disorders such as MS [47]. In the case of PwMS, it has proven to be a reliable measure, with reliability estimates of 0.98 for MVIC and 0.84 for time to fatigue [47]. These findings align closely with the results observed in our study. These studies, in conjunction with others focusing on handgrip strength, indicate that these assessments can be reliable tools for evaluating muscle function in diverse populations, including healthy individuals and those with specific health conditions, such as MS [48].