Effects of Backpack on Lower and Upper Body Reaching Ability

Abstract

PURPOSE: Backpack carriage is well known to negatively affect metabolic performance during marching/hiking. However, reaching performance with lower and upper body has not been examined during load carriage with a backpack, yet this might be important during specific conditions. METHODS: Lower extremity reaching during backpack carriage was tested using the Y-Balance Test (a variation of the Star Excursion Balance Test measuring leg reach in posterolateral, posteromedial and anterior directions), and upper extremity reaching was tested using the Functional Reach Test (FRT). Subjects were healthy males (n=6) and females (n=6), ages 19-47, who wore a military (MOLLE II) backpack and performed in bare feet using the dominant leg and arm for reaching. During both tests, subjects were tested without the backpack, and then (in random order) with the backpack empty (0), or with a load of sand equivalent to 10, 30, and 50% of their bodyweight. Three trials were completed for each reach condition and the results averaged. Mean values were analyzed with paired t-tests and Bonferroni corrections. RESULTS: Data presented as mean reach in cm ± SD; * = sig diff from No backpack (p < 0.0125 t-test). Backpack load resulted in reductions in leg (lower body) reach in all three directions. Backpack load resulted in an increase in arm (upper body) reach at the heaviest (50%) load, although the empty backpack (0%) resulted in a decrease in arm (upper body) reach. CONCLUSIONS: Backpack loads of 10%-50% of an individual’s bodyweight decreased reach performance with the lower extremity, but increased upper extremity reaching with the heaviest load.Table: No title available.