2.5.2. Study II: between-day reliability

A one-way repeated measures analysis of variance for all outcome variables was used to determine potential differences between testing days. Tukey's honestly significant difference corrected post-hoc comparisons were performed to determine where any potential differences between days may have occurred. To measure the internal consistency, variability, and reliability of HRV measures when quantified with the cyton board between days, Cronbach's alpha (α), between-day within-subject coefficient of variation, ICC, SEM, and typical error of the measurement (TEM) values were calculated. A threshold of <70%, 70–80%, 80–90%, and >90% were utilized to classify unacceptable, acceptable, good, and excellent Cronbach's Alpha metrics, respectively [48, 49]. Moreover, consistent with previous physiological research [50, 51, 52, 53, 54, 55], coefficient of variation values were deemed acceptable/reasonable (<20%) or good (<10%) and were calculated using published reliability guidelines [56]. The ICC thresholds for the between-day reliability were consistent with those used for the concurrent validity aspect of this investigation [46, 47]. The SEM [56, 57] and TEM [46] metrics were calculated as previously outlined. Data are presented as log transformed mean ± standard deviation or 95% CI, where appropriate. Significance was set a priori at alpha = 0.05.