Physiological and Perceptual Responses to Load Carrying in Female Subjects UsingInternal and External Frame Backpacks

摘要

Eleven Female subjects (ages 18-33) walked on a motor driven treadmill at 3.2 mphfor one hour carrying 33% of their body weight. The grade of the treadmill alternated every 15 minutes from 0 to 3%. Each subject carried an internal frame backpack for one trial and an external frame backpack for another trial on a separate day. The variables measured during the two load-carrying experiments included oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (R), minute ventilation (VE), and the ratings of perceived exertion for the chest (RPE-Chest), shoulders (RPE-Shoulders), and legs (RPE-Legs). There were no statistically significant differences found between the two packs for any of the metabolic, cardiorespiratory, or perceptual variables measured. The grade of the treadmill had a significant effect on VO2; R; VE, and HR regardless of the type of pack carried. Minute ventilation was the only physiological response to load carrying that was significantly influenced by exercise time. The values for RPE-Chest, RPE-Shoulders, and RPE-Legs were significantly increased by exercise time and treadmill slope, regardless of the type of pack frame carried. It was concluded that when a load is carried on the back, differences in backpack frame designs are not great enough to produce significant differences in the energy cost or perception of carrying a moderately heavy load.