Effect of an Arm-Span-Adjusted Hand Position on Closed Kinetic Chain Upper Extremity Stability Test Performance and Muscle-Related Body Composition Associations

Background: The Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST) is used to assess upper-extremity performance in a closed kinetic chain position. The standard hand placement of 36 inches may favor individuals with larger body dimensions. Methods: Sixty-five healthy adults (44 males, 21 females; 18–33 years) performed the CKCUEST under two conditions: the standard position and a modified position with hand distance set at 50% of arm span. The mean number of touches, standard score, and power score were calculated for each condition. Reliability and the effects of sex and body composition were also examined. Results: Performance was significantly better in the modified position for mean touches (24.4 ± 4.47 vs. 23.0 ± 4.62, p = 0.001), standard score (0.4 ± 0.07 vs. 0.3 ± 0.06, p = 0.001), and power (81.1 ± 18.29 vs. 77.1 ± 22.00, p = 0.001). Both conditions showed excellent reliability (ICC = 0.944–0.946). Females performed significantly fewer touches than males in the standard position (p = 0.001), whereas this difference was not significant in the modified position. Several anthropometric and body composition variables significantly predicted performance. Conclusions: An arm-span-adjusted hand position improves CKCUEST performance and may provide a fairer assessment across individuals with different body dimensions.