Convergent Validity of the Lower Quarter Y Balance Test Against Two-Step and Timed Up and Go Tests in Thai Older Adults with and Without Locomotive Syndrome

Locomotive syndrome (LS) predisposes older adults to falls and functional dependency. In older adults with LS, the validity of the Lower Quarter Y Balance Test (YBT-LQ)—a dynamic balance assessment tool—remains unclear. This cross-sectional study aimed to assess the convergent validity of the YBT-LQ with the Two-Step and Timed Up and Go (TUG) tests and compare YBT-LQ performance between individuals with and without LS. Sixty Thai community-dwelling older adults (≥60 years) were equally divided into LS and non-LS groups and performed the YBT-LQ, Two-Step test, and TUG test. Correlation analyses and independent t -tests assessed relationships and between-group comparisons, respectively. The YBT-LQ exhibited moderate positive correlations with the Two-Step test ( r = 0.366, p = 0.004) and moderate negative correlations with the TUG test ( r = −0.412, p = 0.001). The LS group exhibited significantly lower YBT-LQ scores across all reach directions than the non-LS group ( p < 0.05), highlighting impaired balance in individuals with LS. The YBT-LQ is a valid and reliable tool for assessing dynamic balance and postural control, as well as identifying multidirectional stability deficits in older adults, particularly those with LS. Implementing the YBT-LQ in routine geriatric evaluations could enhance early detection and targeted interventions to reduce fall risk and improve mobility in aging populations.