Load And Speed But Not Footwear Affect Heart Rate And Perceived Exertion During Walking

PURPOSE: To assess heart rate (HR) and rating of perceived exertion (RPE) responses to various load carriage and footwear configurations at incremental walking speeds. METHODS: Nine subjects (male n = 7; age = 32 ± 9 y; height = 174.6 ± 5.1 cm; body mass (BM) = 75.44 ± 13.50 kg; O2max = 45.4 ± 3.5 mL·kg-1.min-1) walked on a level motorized treadmill for three min at 0.67, 1.12, and 1.56 m.s-1 in each combination of two footwear conditions (sneakers, military boots) and three backpack load conditions (0, 22.5, 45% BM) randomized. During the last 30 s of each stage, HR and RPE (Borg 6-20 scale) were assessed. Separate three-way repeated measures ANOVAs were used to evaluate changes in HR and RPE across footwear, load, and speed iterations (alpha = 0.05). RESULTS: No 3-way interactions were observed for HR (p = 0.98) or RPE (p = 0.71). A speed by load interaction effect was observed such that HR progressively elevated as speed and load increased (0.67 m·s-1: 0% BM = 82 ± 12 bpm, 22.5% BM = 89 ± 16, 45% BM = 99 ± 17; 1.12 m·s-1: 0% BM = 86 ± 11, 22.5% BM = 98 ± 15, 45% BM = 107 ± 18; 1.56 m·s-1: 0% BM = 100 ± 15, 22.5% BM = 116 ± 20, 45% BM = 135 ± 26; all p ≤ 0.04). A speed by load interaction effect was also observed for RPE whereby RPE became higher as speed and load increased (0.67 m·s-1: 0% BM = 7 ± 1, 22.5% BM = 8 ± 1, 45% BM = 9 ± 2; 1.12 m·s-1: 0% BM = 8 ± 1, 22.5% BM = 10 ± 2, 45% BM = 12 ± 1; 1.56 m·s-1: 0% BM = 10 ± 2 bpm, 22.5% BM = 12 ± 1, 45% BM = 15 ± 2; all p ≤ 0.01). Footwear did not influence HR (p = 0.59) or RPE (p = 0.66). CONCLUSION: Increases in walking speed and load carriage independently raise HR and RPE while footwear appears inconsequential. The combination of increased speed and load simultaneously elevates HR and RPE beyond increasing either independently. The views expressed in this abstract are those of the authors and do not reflect the official policy of the U.S. Government, Department of Energy, Department of the Army, Department of Defense, or CoachMePlus. Funding provided through the Medical Technology Enterprise Consortium (#W81XWH-22-9-0014). Supported by: Experiential Learning Network (ELN) University at Buffalo