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The impact of ambulatory gradients on the oxygen cost of torso load carriage for people of varying body size

Journal Article


Abstract


  • Introduction: The oxygen cost of torso-borne loads is independently

    influenced by body mass and the ambulatory gradient.

    Although the effects of variations in gradient and loading are well

    known, the interaction of those factors across individuals of widely

    varying body mass has yet to be studied. Since contemporary workforces

    are morphologically diverse, it is important to understand

    the impact of load carriage on people varying in body mass.

    Methods: Ambulatory oxygen consumption (open-circuit

    respirometry) was measured in 65 men (23.0 y [SD 3.0]; 80.5 kg [SD

    1.7]: range 56.0–109.8 kg), matched for height-adjusted adiposity

    (sum of six skinfolds: 59.3 mm [SD 25.4]) and height-adjusted body

    mass (65.9 kg [SD 22.0]), and grouped into five mass categories

    (55–65 kg [N = 12]; 66–76 kg [N = 15]; 77–87 kg [N = 19]; 88–98 kg

    [N = 12]; and 99–110 kg [N = 7]). On separate days, participants

    completed two, 15-min treadmill walks (4.8 km h−1) separated by

    5-min rests: unloaded (battle dress and running shoes) and torso

    loaded (25-kg weighted vest). A different treadmill gradient was

    investigated each day (0%, 5% and −5%).

    Results: As reported elsewhere, lighter individuals used less

    oxygen when performing the same task, although the relative

    increase in oxygen consumption for level walking varied inversely

    with body mass when loaded (29% [lightest], 23%, 21%, 19%, 16%

    [heaviest]). That pattern remained identical during both inclined

    (29% [lightest], 26%, 23%, 22%, 20%) and declined walking (28%

    [lightest], 25%, 20%, 21%, 14%). Indeed, the ambulatory gradient had

    no differential impact on the metabolic responses of participants of

    varying body mass.

    Conclusions: Regardless of the ambulatory gradient, the relative

    impact of load carriage was always greater for the smaller

    individuals, even though the metabolic cost of unloaded walking

    was lower. The latter is true for all locomotor activities during

    which the body mass remains unsupported. The mass-dependency

    of the former observation results from the fact that the relative

    impact of carried loads is always a function of the ratio of the added

    mass to the mass of each individual. The fact that this relationship

    did not vary during either inclined or declined walking is signifi-

    cant, since it demonstrates the consistency of the mass-dependent

    nature of load carriage across ambulatory gradients.

UOW Authors


  •   Bowes, Heather (external author)
  •   Burdon, Catriona (external author)
  •   Taylor, Nigel A.S.. (external author)

Publication Date


  • 2017

Citation


  • Bowes, H. M., Burdon, C. B. & Taylor, N. A.S.. (2017). The impact of ambulatory gradients on the oxygen cost of torso load carriage for people of varying body size. In Fourth International Congress on Soldiers’ Physical Performance, 28 Nov-1 Dec 2017, Melbourne, Australia. Journal of Science and Medicine in Sport, 20 (Supp 2), S40-S40.

Start Page


  • S40

End Page


  • S40

Volume


  • 20

Issue


  • Supp 2

Place Of Publication


  • Australia

Abstract


  • Introduction: The oxygen cost of torso-borne loads is independently

    influenced by body mass and the ambulatory gradient.

    Although the effects of variations in gradient and loading are well

    known, the interaction of those factors across individuals of widely

    varying body mass has yet to be studied. Since contemporary workforces

    are morphologically diverse, it is important to understand

    the impact of load carriage on people varying in body mass.

    Methods: Ambulatory oxygen consumption (open-circuit

    respirometry) was measured in 65 men (23.0 y [SD 3.0]; 80.5 kg [SD

    1.7]: range 56.0–109.8 kg), matched for height-adjusted adiposity

    (sum of six skinfolds: 59.3 mm [SD 25.4]) and height-adjusted body

    mass (65.9 kg [SD 22.0]), and grouped into five mass categories

    (55–65 kg [N = 12]; 66–76 kg [N = 15]; 77–87 kg [N = 19]; 88–98 kg

    [N = 12]; and 99–110 kg [N = 7]). On separate days, participants

    completed two, 15-min treadmill walks (4.8 km h−1) separated by

    5-min rests: unloaded (battle dress and running shoes) and torso

    loaded (25-kg weighted vest). A different treadmill gradient was

    investigated each day (0%, 5% and −5%).

    Results: As reported elsewhere, lighter individuals used less

    oxygen when performing the same task, although the relative

    increase in oxygen consumption for level walking varied inversely

    with body mass when loaded (29% [lightest], 23%, 21%, 19%, 16%

    [heaviest]). That pattern remained identical during both inclined

    (29% [lightest], 26%, 23%, 22%, 20%) and declined walking (28%

    [lightest], 25%, 20%, 21%, 14%). Indeed, the ambulatory gradient had

    no differential impact on the metabolic responses of participants of

    varying body mass.

    Conclusions: Regardless of the ambulatory gradient, the relative

    impact of load carriage was always greater for the smaller

    individuals, even though the metabolic cost of unloaded walking

    was lower. The latter is true for all locomotor activities during

    which the body mass remains unsupported. The mass-dependency

    of the former observation results from the fact that the relative

    impact of carried loads is always a function of the ratio of the added

    mass to the mass of each individual. The fact that this relationship

    did not vary during either inclined or declined walking is signifi-

    cant, since it demonstrates the consistency of the mass-dependent

    nature of load carriage across ambulatory gradients.

UOW Authors


  •   Bowes, Heather (external author)
  •   Burdon, Catriona (external author)
  •   Taylor, Nigel A.S.. (external author)

Publication Date


  • 2017

Citation


  • Bowes, H. M., Burdon, C. B. & Taylor, N. A.S.. (2017). The impact of ambulatory gradients on the oxygen cost of torso load carriage for people of varying body size. In Fourth International Congress on Soldiers’ Physical Performance, 28 Nov-1 Dec 2017, Melbourne, Australia. Journal of Science and Medicine in Sport, 20 (Supp 2), S40-S40.

Start Page


  • S40

End Page


  • S40

Volume


  • 20

Issue


  • Supp 2

Place Of Publication


  • Australia