## 4 Discussion  
To the best of the authors' knowledge, this is the first study about the test-retest reliability of the CST and 1 min-STST in Long COVID patients, additionally establishing the MDC in both tests. Given the diverse characterisation of the effects of COVID-19 and their great impact on the quality of life, it is very important to determine the reliability and reproducibility of the tests that evaluate effort tolerance, in order to implement efficient and safe physical exercise protocols, with the aim of accurately objectifying the changes and adaptations that such protocols may generate. The evaluations were carried out in both tests with at least 7 days between evaluations; this period was established as the most adequate in test-retest reliability studies [34]. Some reliability studies, such as that of [PERSON] et al. [35], used the correlation coefficient; however, we conducted our test-retest reliability analysis using ICC, as recommended by [PERSON] et al. [36], since it is considered to be a more accurate method. The CST proved to be a reliable and reproducible tool, showing excellent test-retest reliability within the session (ICC (95% CI) 0.96 (0.93 to 0.98)). Several studies have also demonstrated the reliability of CST, both in a healthy population [18; 37] and in people with chronic respiratory diseases [38; 39]. The 1 min-STST also presented excellent test-retest (ICC (95% CI) 0.98 (0.96 to 0.99)), even better than that of the CST in this population. This test has also proved to be a valid and reliable tool in people with different pathologies [40; 41; 42; 43]. Therefore, these tests may be valid and adequate to assess exercise tolerance in this and other populations. The Bland-Altman plots showed a disagreement ranging from 13.3 to \(-\)8 steps for reliability in the CST and from 3.1 to \(-\)2.2 stands in the 1 min-STST. The 6 MWT is the most widely used method for the evaluation of exercise tolerance, although it has some drawbacks, such as the need for a long corridor in order to be carried out [12]. Therefore, we believe that the CST and 1 min-STST are adequate and simple alternatives that can be easily used in contexts where time and space are limited, since they do not require expensive and sophisticated equipment to evaluate the exercise capacity, thus they can be conducted in home environments, which is undoubtedly an added value. Moreover, a recent study has pointed out that both tests are significantly correlated with the 6 MWT in patients who were recovering from the effects of COVID-19 [17], thus both alternative tests are solid and recommendable. Furthermore, due to their ease of completion, both face-to-face and remotely [11; 44], especially in the case of the 1 min-STST, which has been recommended by the literature in tele-rehabilitation programmes, these instruments are very valid in situations such as the one caused by the COVID-19 pandemic, where lockdowns were established and the  
Figure 1: Bland-Altman plot Inter-rater reliability; The bias and limits of agreement (black lines) are displayed for CST (**A**) and 1 min-STST (**B**). The mean score is represented on the x-axis and the difference between sessions (mean of the differences) is represented on the y-axis (mean difference \(\pm\) 1.96 SD). mobility of the population was restricted [45; 46; 47; 48]. On the other hand, COVID-19 sequelae monitoring programs advocate for the assessment of physical capacity [49]. Given the significant number of patients exhibiting these sequelae, primary care has been compelled to accommodate this patient population [50]. These low-cost tools have already been employed in primary care-based rehabilitation programs, demonstrating their ability to detect post-intervention differences [46]. In summary, our data contributes to the clinicians' ability to use these tools with knowledge of their reliability, particularly in understanding the MCID. This knowledge will assist primary care professionals and tele-rehabilitation practitioners in determining the effectiveness of their interventions.