Abstract
BACKGROUND: The randomization method (RM) is used as a gold standard for creating equal groups in most independent-group design studies.
OBJECTIVE: To identify whether the fatigue index (FI)-based matching method could be an alternative for the RM in the context of forming equal independent study groups using relative maximal isometric squat strength(R-MISS) recovery data as the dependent variable.
METHODS: Baseline R-MISS values of 30 resistance-trained male participants were assessed. FI was calculated during an exhaustive training intervention (ETI), including four sets of submaximal isometric squat contractions. Maximal isometric squats were performed 30 seconds, and 2, 4, 6, 8, 10, 12, and 14 minutes after the ETI to assess the recovery levels of R-MISS. For the statistical analyses, low- and high-endurance groups, and two equal-endurance groups (each including 15 participants) were retrospectively formed based on FI scores.
RESULTS: The results of the repeated-measures analysis of variance revealed that recovery moments greatly differed (8 minutes) between the high- and low-endurance groups but were similar between the two equal-endurance groups(difference of 2 minutes). Simulations performed using the resampling procedure revealed that the FI-based matching method was more successful than the RM(71.6% vs. 56.2%) in the context of forming equal study groups.
CONCLUSIONS: These results indicate that the FI-based matching method is a better alternative to the RM for preventing an unequal distribution of participants among independent groups in R-MISS recovery-related studies.