Clinical Implications of Hand Position and Lower Limb Length Measurement Method on Y-Balance Test Scores and Interpretations

Abstract

Context:  The Lower Quarter Y-Balance Test (LQ-YBT) was developed to provide an effective and efficient screen for injury risk in sports. Earlier protocol recommendations for the LQ-YBT involved the athlete placing the hands on the hips and the clinician normalizing scores to lower limb length measured from the anterior-superior iliac spine to the lateral malleolus. The updated LQ-YBT protocol recommends the athlete's hands be free moving and the clinician measure lower limb length to the medial malleolus. Objective:  To investigate the effect of hand position and lower limb length measurement method on LQ-YBT scores and their interpretation. Design:  Cross-sectional study. Setting:  National Sports Institute of Malaysia. Patients or Other Participants:  A total of 46 volunteers, consisting of 23 men (age = 25.7 ± 4.6 years, height = 1.70 ± 0.05 m, mass = 69.3 ± 9.2 kg) and 23 women (age = 23.5 ± 2.5 years, height = 1.59 ± 0.07 m, mass = 55.7 ± 10.6 kg). Intervention(s):  Participants performed the LQ-YBT with hands on hips and hands free to move on both lower limbs. Main Outcome Measure(s):  In a single-legged stance, participants reached with the contralateral limb in each of the anterior, posteromedial, and posterolateral directions 3 times. Maximal reach distances in each direction were normalized to lower limb length measured from the anterior-superior iliac spine to the lateral and medial malleoli. Composite scores (average of the 3 normalized reach distances) and anterior-reach differences (in raw units) were extracted and used to identify participants at risk for injury (ie, anterior-reach difference ≥4 cm or composite score ≤94%). Data were analyzed using paired t tests, Fisher exact tests, and magnitude-based inferences (effect size [ES], ±90% confidence limits [CLs]). Results:  Differences between hand positions in normalized anterior-reach distances were trivial (t91 = −2.075, P = .041; ES = 0.12, 90% CL = ±0.10). In contrast, reach distances were greater when the hands moved freely for the normalized posteromedial (t91 = −6.404, P < .001; ES = 0.42, 90% CL = ±0.11), posterolateral (t91 = −6.052, P < .001; ES = 0.58, 90% CL = ±0.16), and composite (t91 = −7.296, P < .001; ES = 0.47, 90% CL = ±0.11) scores. A similar proportion of the cohort was classified as at risk with the hands on the hips (35% [n = 16]) and the hands free to move (43% [n = 20]; P = .52). However, the participants classified as at risk with the hands on the hips were not all categorized as at risk with the hands free to move and vice versa. The lower limb length measurement method exerted trivial effects on LQ-YBT outcomes. Conclusions:  Hand position exerted nontrivial effects on LQ-YBT outcomes and interpretation, whereas the lower limb length measurement method had trivial effects.