Physiological and Perceptual Responses to Load Carrying in Female Subjects Using Internal and External Frame Backpacks
Final rept. Jan-Oct 1990
ARMY NATICK RESEARCH DEVELOPMENT AND ENGINEERING CENTER MA
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Eleven Female subjects ages 18-33 walked on a motor driven treadmill at 3.2 mph for 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.
- Stress Physiology
- Protective Equipment