The Reliability and Validity of the Modified Butterfly Agility Test.

Background: No gold standard criteria exist for return to sport decision-making. The Butterfly Agility Test (BAT) has been shown to be a valid and reliable test for assessing various aspects of athletic performance; however, the space required to conduct it may be prohibitive for clinical environments and it has not been validated among an athletic population.

Purpose: To determine the reliability of the modified BAT (mBAT) and the number practice trials required to optimize its reliability. A secondary purpose was to assess the preliminary validity of the mBAT associated with the Y-Balance Test (YBT) and its relationship with player position among competitive soccer athletes.

Study design: Multi-phase reliability and validity study.

Methods: Phases I and II involved 25 healthy adults (72% female, mean age = 23.4 years) and 45 competitive soccer athletes (55% female, mean age = 18.2 years), respectively. In Phase I, subjects performed 10 consecutive trials of the mBAT to assess test-retest and inter-rater reliability of the mBAT. In Phase II, subjects completed two consecutive trials of the mBAT and YBT during the pre-season period. Intraclass correlation coefficients were used to assess the reliability of the mBAT and repeated measures analysis of variance (ANOVA) was used to assess differences between trials in Phase I. In Phase II, Pearson's product-moment correlation coefficient was used to assess the relationship between mBAT and YBT performance and an ANOVA was used to assess differences in mBAT and YBT performance between player positions.

Results: In Phase I, the mBAT demonstrated excellent reliability (ICC = 0.92-1.00). In Phase II, female collegiate athletes performed better than male high-school athletes on the mBAT (p = 0.01). No significant relationships were found between the mBAT or YBT with player position (p > 0.26).

Conclusion: The mBAT is a reliable physical performance test and three practice trials are recommended prior to recorded trials. The validity of the mBAT for distinguishing athletic performance remains inconclusive, although it appears the mBAT measures a distinct aspect of physical performance compared to the YBT. Although this data is preliminary, the mBAT shows promise as a useful tool for clinicians, trainers, and coaches to assess physical performance among competitive soccer athletes. Larger prospective studies are warranted prior to utilizing the mBAT for clinical decision-making.

Level of evidence: 3b.