Presenter Information

Hannah E. HabighorstFollow

Presentation Type

Poster

Faculty Mentor’s Full Name

Matthew Bundle

Faculty Mentor’s Department

Health and Human Performance

Abstract

DOES THE METABOLIC COST OF LOAD CARRIAGE DIFFER BETWEEN MALES AND FEMALES?

Habighorst HE, Baker RL, Berglund KM, Gutierrez SA, Dierman AR, Christman EE

Department of Health and Human Performance

PURPOSE: The scientific understanding of energy use during load carriage suggests that the additional metabolic increment necessary to support an external load is determined by the load’s percentage of the subject’s body weight. Accordingly, for comparison purposes experimental undertakings often adjust the mass of an external load to represent a constant fraction of each subject’s mass. However, in occupational and applied settings, individuals are frequently asked to support similar absolute loads irrespective of their body weight. Here, we evaluated whether the energy requirements in male and female subjects differed during treadmill walking across a range of speeds, while supporting a common 20.5kg external load. METHODS: We measured VO2 during three, 5min trials, administered with a 20.5kg pack, on a level treadmill at 1.7, 1.8, 1.9 ms-1, from 20 subjects(age = 22.1±2.4yrs), who had been assigned as sex-matched pairs on the basis of mass (10 males, Mb = 72.6±6.3kg; 10 females, Mb = 72.8±6.2kg; difference between pairs = 0.6±0.5kg, max 1.4kg). RESULTS: Measured values of VO2 in females were 24.7±4.2, 28.9±3.7, and 30.8±3.3ml kg-1 min-1 at 1.7, 1.8, and 1.9 m s-1, respectively, these values in males, although lower, were indistinguishable (min p-value=0.08) and were 23.1±3.3, 25.8±3.7, and 30.1±4.6 ml kg-1 min-1 at the same speeds. Nonetheless, our data provide 27 points of comparison, with identical loads, at similar speeds (3 of 10 female subjects were unable to complete the 1.9 ms-1 trial); in 8 of these 27 points of comparison females were more economical than their matched pair. CONCLUSION: Our data lend support to the presence of a sex based difference in load carriage economy, warranting further study. We note also that the similar rates of energy expenditure between the sexes observed here, translate to higher relative intensities for females due to their likely lower mass-specific aerobic capacities (i.e. VO2max).

Category

Health and Medical Science

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Apr 27th, 3:00 PM Apr 27th, 4:00 PM

DOES THE METABOLIC COST OF LOAD CARRIAGE DIFFER BETWEEN MALES AND FEMALES?

UC South Ballroom

DOES THE METABOLIC COST OF LOAD CARRIAGE DIFFER BETWEEN MALES AND FEMALES?

Habighorst HE, Baker RL, Berglund KM, Gutierrez SA, Dierman AR, Christman EE

Department of Health and Human Performance

PURPOSE: The scientific understanding of energy use during load carriage suggests that the additional metabolic increment necessary to support an external load is determined by the load’s percentage of the subject’s body weight. Accordingly, for comparison purposes experimental undertakings often adjust the mass of an external load to represent a constant fraction of each subject’s mass. However, in occupational and applied settings, individuals are frequently asked to support similar absolute loads irrespective of their body weight. Here, we evaluated whether the energy requirements in male and female subjects differed during treadmill walking across a range of speeds, while supporting a common 20.5kg external load. METHODS: We measured VO2 during three, 5min trials, administered with a 20.5kg pack, on a level treadmill at 1.7, 1.8, 1.9 ms-1, from 20 subjects(age = 22.1±2.4yrs), who had been assigned as sex-matched pairs on the basis of mass (10 males, Mb = 72.6±6.3kg; 10 females, Mb = 72.8±6.2kg; difference between pairs = 0.6±0.5kg, max 1.4kg). RESULTS: Measured values of VO2 in females were 24.7±4.2, 28.9±3.7, and 30.8±3.3ml kg-1 min-1 at 1.7, 1.8, and 1.9 m s-1, respectively, these values in males, although lower, were indistinguishable (min p-value=0.08) and were 23.1±3.3, 25.8±3.7, and 30.1±4.6 ml kg-1 min-1 at the same speeds. Nonetheless, our data provide 27 points of comparison, with identical loads, at similar speeds (3 of 10 female subjects were unable to complete the 1.9 ms-1 trial); in 8 of these 27 points of comparison females were more economical than their matched pair. CONCLUSION: Our data lend support to the presence of a sex based difference in load carriage economy, warranting further study. We note also that the similar rates of energy expenditure between the sexes observed here, translate to higher relative intensities for females due to their likely lower mass-specific aerobic capacities (i.e. VO2max).