Effects Of Modern Military Footwear On The Metabolic Demands Of Walking

Abstract

Quantifying the metabolic costs of carrying or wearing various military uniform components is essential for accurate assessment of the metabolic cost of warfighters performing military tasks under scenarios and environmental conditions. PURPOSE: Evaluate the metabolic demand of walking at incremental speeds in a controlled laboratory environment while wearing military-issued combat boots compared to athletic sneakers. METHODS: In this randomized, cross-over study, nineteen active military-age men (age, 24 ± 5 years; height, 177 ± 6 cm; body mass, 80 ± 13 kg) performed an incremental treadmill walking test in combat boots and athletic sneakers on separate visits. Treadmill speed started at 4.18 km/h for 3 min, then increased by 0.23 km/h every 2 min. Tests were terminated when volunteers either completed the highest treadmill speed (7.08 km/h), reached volitional fatigue, or exceeded a respiratory exchange ratio of 1.0. Volunteers exhaled into a laboratory metabolic cart that measured expired gases. Metabolic demand was quantified as the average oxygen uptake (V̇O2) over the final minute of each walking speed. RESULTS: Across all speeds, walking in combat boots resulted in significantly higher V̇O2 than walking in athletic sneakers (0.63 ± 1.05 mL·kg-1·min-1; p = 0.01). Regression analysis determined a V̇O2 difference between footwear of 0.31 mL·kg-1·min-1 at 4.18 km/h that increased by 0.22 mL·kg-1·min-1 with each 1 km/h increase (R2, 0.68). Regressing walking V̇O2 when wearing combat boots on walking V̇O2 while wearing athletic sneakers revealed both a positive offset and slope (Trendline, V̇O2boots = 0.04 + 1.04·V̇O2sneakers; R2, 0.97). CONCLUSIONS: The metabolic demand of walking in military combat boots is greater and more pronounced at increased walking speeds than when wearing common athletic sneakers. The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government.