Presentation Type
Poster Presentation
Category
STEM (science, technology, engineering, mathematics)
Abstract/Artist Statement
Axially loaded weight may impose a metabolic demand equivalent to that of fat mass (FM). As males (M) typically have a lower body fat percentage than females (F), differences in the metabolic demand of load carriage may be resolved by accounting for FM in pack loads. PURPOSE: To determine whether normalizing pack load to FM will equalize metabolic cost across sex during load carriage. METHODS: Twenty-eight participants (14M, 23±5 y, 1.81±0.07 m, 78.7±10.0 kg, 12.7±5.4% body fat, VO2peak 4.18±0.54 L·min-1; 14F, 22±4 y, 1.68±0.07 m, 63.7±8.1 kg, 22.6±5.2% body fat, VO2peak 2.76±0.47 L·min-1) were recruited. Preliminary visits included measures of height, body weight, body composition (air displacement plethysmography (ADP); bioelectrical impedance (BIA)), isometric mid-thigh pull peak power, and treadmill VO2peak. An average of ADP and BIA body fat percentages was used to calculate experimental pack loads. Participants performed 2 trials of treadmill walking at 1.34 m·s-1 and 10% grade for 10 minutes while measuring expired gases, heart rate (HR) and rating of perceived exertion (RPE). Trials were separated by 15 minutes of rest. Load order was randomized between 30% of body mass (30%BM) and 30% of body mass minus absolute FM (SubFM). RESULTS: VO2 was higher (M30%BM 2.47±0.38 L·min-1, F30%BM 2.02±0.26 L·min-1, MSubFM 2.18±0.25 L·min-1, FSubFM 1.64±0.25 L·min-1, p< 0.001), and HR was lower (M30%BM 145±23 bpm, F30%BM 164±17 bpm, MSubFM 132±21 bpm, FSubFM 143±18 bpm, p=0.045) in M than F across load conditions. Percentage of VO2peak was lower in M than F across load conditions (M30%BM 60±9%, F30%BM 74±6%, MSubFM 53±7%, FSubFM 60±6%, p< 0.001). Mean sex differences in percentage of VO2peak between loads was 13.8% in the 30%BM condition (p< 0.001) and 7.1% in the SubFM condition (p=0.010). CONCLUSIONS: Normalizing pack weight to FM reduces but fails to completely normalize sex differences in the metabolic cost of load carriage.
Mentor Name
Dustin Slivka
An Exploratory Analysis Of The Role of Sex In Load Carriage
UC North Ballroom
Axially loaded weight may impose a metabolic demand equivalent to that of fat mass (FM). As males (M) typically have a lower body fat percentage than females (F), differences in the metabolic demand of load carriage may be resolved by accounting for FM in pack loads. PURPOSE: To determine whether normalizing pack load to FM will equalize metabolic cost across sex during load carriage. METHODS: Twenty-eight participants (14M, 23±5 y, 1.81±0.07 m, 78.7±10.0 kg, 12.7±5.4% body fat, VO2peak 4.18±0.54 L·min-1; 14F, 22±4 y, 1.68±0.07 m, 63.7±8.1 kg, 22.6±5.2% body fat, VO2peak 2.76±0.47 L·min-1) were recruited. Preliminary visits included measures of height, body weight, body composition (air displacement plethysmography (ADP); bioelectrical impedance (BIA)), isometric mid-thigh pull peak power, and treadmill VO2peak. An average of ADP and BIA body fat percentages was used to calculate experimental pack loads. Participants performed 2 trials of treadmill walking at 1.34 m·s-1 and 10% grade for 10 minutes while measuring expired gases, heart rate (HR) and rating of perceived exertion (RPE). Trials were separated by 15 minutes of rest. Load order was randomized between 30% of body mass (30%BM) and 30% of body mass minus absolute FM (SubFM). RESULTS: VO2 was higher (M30%BM 2.47±0.38 L·min-1, F30%BM 2.02±0.26 L·min-1, MSubFM 2.18±0.25 L·min-1, FSubFM 1.64±0.25 L·min-1, p< 0.001), and HR was lower (M30%BM 145±23 bpm, F30%BM 164±17 bpm, MSubFM 132±21 bpm, FSubFM 143±18 bpm, p=0.045) in M than F across load conditions. Percentage of VO2peak was lower in M than F across load conditions (M30%BM 60±9%, F30%BM 74±6%, MSubFM 53±7%, FSubFM 60±6%, p< 0.001). Mean sex differences in percentage of VO2peak between loads was 13.8% in the 30%BM condition (p< 0.001) and 7.1% in the SubFM condition (p=0.010). CONCLUSIONS: Normalizing pack weight to FM reduces but fails to completely normalize sex differences in the metabolic cost of load carriage.