Introduction: The Y-Balance Test (YBT) is a dynamic balance test assessing range of motion, flexibility, neuromuscular control, and strength. The YBT is used to evaluate individuals for increased injury risk, deficiencies, and progress of rehabilitation. Due to the higher cost associated with materials in a YBT kit, a modified YBT (mYBT) was created using three cloth measuring tapes, and three blocks of wood to help mitigate financial barriers. In previous studies the mYBT has demonstrated adequate agreement of composite scores with the Upper Quarter Y-Balance Test (UQYBT). The purpose of this study was to determine the agreement of composite scores between the mYBT and Lower Quarter Y-Balance Test (LQYBT) and the intra- and inter-rater reliability for both methods. Methods: A convenience sample of healthy university students and faculty/staff completed a testing protocol to compare LQYBT and mLQYBT composite scores. The protocol was repeated a week later. Results: The intraclass correlation (ICC) values for interrater scores were excellent for the LQYBT (right ICC2,1 = 0.98, left ICC2,1 = 0.996) and mLQYBT (right ICC2,1 = 0.999, left ICC2,1 = 0.999). The ICC values for intrarater reliability were excellent for the mLQYBT (right ICC2,1 = 0.92 for both raters, left ICC2,1 = 0.93 for both raters). The intrarater reliability for the LQYBT was good-excellent for rater 1 (right ICC2,1 = 0.89, left ICC2,1 = 0.93) and excellent for rater 2 (right ICC2,1 = 0.94, left ICC2,1 = 0.95). There was a strong positive correlation (Pearson product moment coefficients) between the LQYBT and mLQYBT composite scores (right limb = 0.94, left limb = 0.95). There were wide limits of agreement for both limbs with 17.08 cm (-8.85-8.23) on the right and 15.13 cm (-8.26-6.87) which were wider than the intrarater (2.16-3.34 cm) and interrater (0.36-1.31 cm) SEM ranges for both limbs and methods. The limits of agreement also exceeded the MDC range for intrarater (5.99-9.26 cm) and interrater (1.00-3.63 cm) on both limbs and methods. Conclusion: The results of this study do not support the interchangeable use of the mLQYBT with the LQYBT.
Lawson et al. (Sun,) studied this question.