Maximum Hand-Rung Coupling Forces in Children: The Effects of Handhold Diameter

In: Human factors: the journal of the Human Factors Society, Volume 55, Issue 3, p. 545-556

Abstract

Objective: To quantify the effect of handhold size (diameter) on the maximum breakaway strength between a hand and handhold for children. Background: Falls from playground equipment are a major cause of childhood injury and death. It is unclear if recommendations for handholds on playground equipment are too broad. Methods: Breakaway strength was defined as the maximum quasistatic force that can be exerted on a grasped object before the object is forcibly pulled from the grasp. Hand anthropometry, grip, and breakaway strengths were measured for 397 children between the ages of 6 and 11 years. Three cylindrical handhold diameters were tested. Results: Breakaway strength was significantly affected by handhold size, gender, and hand dominance. Significant covariate predictors for breakaway strength included grip strength, age, and hand breadth. Breakaway strength was reduced for the largest diameter (3.81 cm) for children of all ages. Conclusion: Handhold design factors significantly affect the breakaway strength of children. Application: The results can be used as a basis for design recommendations for hand rungs used by children to reliably support their bodyweight.