Statistical analysis
Data was analyzed using the R (version 3.5.3) programming language.
Normal distribution was verified using the Shapiro–Wilk test for small
samples across all parameters. A 3x3 two-way repeated-measures ANOVA
using the Afex package was performed to determine the effect of
different treatments (CON, LOW, HIGH) over time (PRE, POST, POST30) on
all measured variables. The assumption of sphericity was assessed using
the Mauchly test. Whenever the assumption of sphericity was violated,
the degrees of freedom were corrected using the Greenhouse-Geisser
correction (GGe). Post-hoc tests were performed as pairwise comparisons
using Tukey’s adjustment within the Emmeans package to determine the
differences between single treatments at different time points.
Standardized changes in the mean of each measure were used to assess
magnitudes of effects and were calculated using Cohen’s d and then
interpreted using thresholds of 0.2, 0.5, 0.8 for small, moderate and
large,
respectively \cite{Batterham2006}.
An effect size of ±0.2 was considered the smallest worthwhile effect
with an effect size of <0.2 considered to be trivial. The
effect was considered unclear if its 95% confidence interval overlapped
the thresholds for small positive and small negative
effects \cite{Batterham2006}.
Statistical significance was set at p < 0.05 for all analyses.