The Effect of a Backpack Hip Strap on Energy Expenditure While Walking.

Objective To examine the effect of backpack hip strap use on walking energy expenditure while carrying a loaded backpack. Background Previous studies have demonstrated that energy cost increases as the mass of the load carried increases. However, few investigations have focused on backpack carriage design. Methods Fifteen young, healthy, male subjects walked at a self-selected pace for 10 minutes in two backpack loading conditions: with a hip strap (strapped) and without a hip strap (nonstrapped). Oxygen consumption (VO2), rating of perceived exertion (RPE), respiratory exchange ratio (RER), and heart rate (HR) were monitored throughout each 10-minute trial. Change scores from the 4th to 10th minute were calculated for each variable. A t test was used to evaluate the difference between conditions for each variable. Results The changes in VO2 (-0.62 ± 0.40 vs. 0.33 ± 0.23, p = .04) and RPE (1 ± 0.25 vs. 2 ± 0.21, p < .01) from the 4th to the 10th minute were different for the strapped versus nonstrapped condition. There was no difference in the change in RER (0.04 ± 0.01 vs. 0.03 ± 0.01, p > .05) or HR (3.53 ± 0.93 vs. 4.07 ± 1.39, p > .05) for the strapped versus unstrapped condition. Conclusions Wearing a hip strap reduced the energy expenditure and perceived exertion in as little as 10 minutes of walking compared to the nonstrapped condition. Future work should consider the effect of a hip strap on these variables while hiking for extended periods. Application Wearing a hip strap may increase the comfort and reduce the energy required of wearing a backpack. This is useful information for backpack designers, military personnel, and recreational hikers.