Relationship of the Functional Reach and Lateral Reach Tests in Elderly Females

Abstract

Purpose: Reduced postural stability is a risk factor for falls in elderly individuals. The functional reach and lateral reach tests are designed to assess anterior-posterior and medial-lateral stability. This study examined the relationship between these two measures of postural stability, whether the measures assess distinct components of postural stability, and inter-rater reliability. Methods: Twenty-two community-dwelling females (age=80.8 ± 6.0 years) participated in the study. Their functional reach and lateral reach were measured by 2 investigators. Pearson correlations (r) between the measures were calculated. Cronbach's alpha and factor analysis was used to examine whether the measures assess distinct components of postural stability. Inter-rater reliability was described using intraclass correlation coefficients. Results: Functional reach was correlated with left and right lateral reach (r=0.65 and r=0.52, respectively; p<0.05). The reach measures had good internal consistency but two factors were identified that contribute to postural stability (eigenvalue ≥ 1). An anterior-posterior component was associated with functional reach, height, and age. A medial-lateral component was associated with left and right lateral reach. Inter-rater reliability was high across both measures (ICC ≥0.85). Conclusion: While functional and lateral reach measures are correlated and internally consistent, they assess distinct components of postural stability. Conducting the functional and lateral reach tests together may more thoroughly assess postural stability among elderly individuals than either test in isolation.