Oxygen Consumption and Blood Pressure Are Not Influenced by Use of a Backpack Hip Strap

Several studies have explored the effect of backpack carriage on physiologic responses while walking, but few have focused specifically on the influence of the use of a hip strap on these responses. The aim of this study was to investigate the effect of a backpack hip strap on physiologic responses when walking at a moderate intensity while carrying a backpack with a standardized relative load of 30% of the wearer's body mass.

Twenty-three healthy, active participants carrying backpacks walked on a treadmill at a speed and grade that elicited 40-50% of their heart rate reserve. Participants completed 2 counterbalanced 30-min trials, one with the hip strap in the strapped condition and one with the hip strap unfastened. Metabolic, heart rate, blood pressure, and muscle oxygen saturation (SmO₂) responses were recorded during both trials. For each variable, 5-min intervals were averaged at baseline, 5, 10, 15, 20, 25, and 30 min. A repeated measures ANOVA test was used to evaluate the differences between the conditions at each time point. Data reported are the values from the final 5-min interval (30 min) and are reported as mean±SD.

No differences were found between strapped and unstrapped trials for oxygen consumption (strapped 21.9±4.2 mL·kg^-1·min^-1; unstrapped 22.0±4.4 mL·kg^-1·min^-1, P=0.842), Δmean arterial pressure (strapped +5±17 Δmm Hg; unstrapped +12±14 Δmm Hg, P=0.128) or muscle oxygen saturation of the quadriceps (strapped 86±15%; unstrapped 90±12%, P=0.359) and calf (strapped 73±19%; unstrapped 81±12%, P=0.888).

These results suggest that wearing a hip strap does not influence physiologic responses up to 30 min of moderate intensity walking while carrying 30% of the wearer's mass.