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A contribution to understanding the impact of variations in body mass on fractionating the metabolic burden of military load carriage

Journal Article


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Abstract


  • Purpose: The oxygen cost associated with load carriage is

    dependent upon both its mass and its placement about the

    body. For occupations in which load carriage is routinely performed,

    and involves identical loads for all individuals, the relative

    metabolic cost varies inversely with body mass. However, whilst

    we understand the average impact of varying load placement, our

    appreciation of its impact on a morphologically diverse, contemporary

    workforce is very limited.

    Methods:The relationship between load placement and body

    mass was evaluated 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

    (59.3 mm [SD 25.4]) and height-adjusted body mass (65.9 kg [SD

    22.0]). Participants were grouped into mass categories (55–65 kg

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

    99–110 kg [N = 7]) and walked at 4.8 km h−1 (0% gradient) for five,

    15-min stages, separated by 5-min rests. Each stage involved a

    unique load configuration presented in a balanced order: unloaded

    (battle dress and running shoes); head loading (1.38-kg helmet);

    torso loading (25-kg weighted vest); hand loading (2 kg each wrist);

    and foot loading (2 kg each foot [boot plus ankle]). Data were collected

    using open-circuit respirometry, sampled over the last 5 min.

    Results: Within each condition, gross oxygen consumption

    increased in parallel with body mass (p < 0.05). However, when

    net data were normalised for the external load (change score

    divided by the added mass), a body mass-dependency of the

    oxygen cost was not realised within any condition. When

    averaged across the mass categories, the oxygen consumed

    per kilogram of mass carried was greater for foot loading

    (44.8 mL kg−1 min−1 [±2.0]; p < 0.05) compared to all other locations

    (head: 7.0 mL kg−1 min−1 [±4.9]; torso: 8.6 [±0.3]; hands: 8.0

    [±1.3]). The gross oxygen costs of torso (1211.8 mL min−1 [±21.0])

    and foot loading (1179.8 mL min−1 [±20.7]) were both greater than

    the other three conditions (unloaded: 999.2 mL min−1 [±20.5];

    head: 1005.8 mL min−1 [±19.2]; hands: 1038.4 mL min−1 [±19.0];

    p < 0.05), but did not differ from one another (p > 0.05).

    Conclusion:Whilst the relative impact of fixed load carriage was

    greater for smaller individuals, no relationship was found between

    body mass and the nett mass-specific, ambulatory oxygen cost of

    these added loads, regardless of their location. This is important,

    for it shows that whilst loads have greater impact on smaller individuals,

    that impact appears not to be position dependent.

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. A. & Taylor, N. A.S.. (2017). A contribution to understanding the impact of variations in body mass on fractionating the metabolic burden of military load carriage. In Fourth International Congress on Soldiers’ Physical Performance, 28 Nov-1 Dec 2017, Melbourne, Australia. Journal of Science and Medicine in Sport, 20 (2), S75-S76.

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=6237&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/5183

Start Page


  • S75

End Page


  • S76

Volume


  • 20

Issue


  • 2

Place Of Publication


  • Australia

Abstract


  • Purpose: The oxygen cost associated with load carriage is

    dependent upon both its mass and its placement about the

    body. For occupations in which load carriage is routinely performed,

    and involves identical loads for all individuals, the relative

    metabolic cost varies inversely with body mass. However, whilst

    we understand the average impact of varying load placement, our

    appreciation of its impact on a morphologically diverse, contemporary

    workforce is very limited.

    Methods:The relationship between load placement and body

    mass was evaluated 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

    (59.3 mm [SD 25.4]) and height-adjusted body mass (65.9 kg [SD

    22.0]). Participants were grouped into mass categories (55–65 kg

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

    99–110 kg [N = 7]) and walked at 4.8 km h−1 (0% gradient) for five,

    15-min stages, separated by 5-min rests. Each stage involved a

    unique load configuration presented in a balanced order: unloaded

    (battle dress and running shoes); head loading (1.38-kg helmet);

    torso loading (25-kg weighted vest); hand loading (2 kg each wrist);

    and foot loading (2 kg each foot [boot plus ankle]). Data were collected

    using open-circuit respirometry, sampled over the last 5 min.

    Results: Within each condition, gross oxygen consumption

    increased in parallel with body mass (p < 0.05). However, when

    net data were normalised for the external load (change score

    divided by the added mass), a body mass-dependency of the

    oxygen cost was not realised within any condition. When

    averaged across the mass categories, the oxygen consumed

    per kilogram of mass carried was greater for foot loading

    (44.8 mL kg−1 min−1 [±2.0]; p < 0.05) compared to all other locations

    (head: 7.0 mL kg−1 min−1 [±4.9]; torso: 8.6 [±0.3]; hands: 8.0

    [±1.3]). The gross oxygen costs of torso (1211.8 mL min−1 [±21.0])

    and foot loading (1179.8 mL min−1 [±20.7]) were both greater than

    the other three conditions (unloaded: 999.2 mL min−1 [±20.5];

    head: 1005.8 mL min−1 [±19.2]; hands: 1038.4 mL min−1 [±19.0];

    p < 0.05), but did not differ from one another (p > 0.05).

    Conclusion:Whilst the relative impact of fixed load carriage was

    greater for smaller individuals, no relationship was found between

    body mass and the nett mass-specific, ambulatory oxygen cost of

    these added loads, regardless of their location. This is important,

    for it shows that whilst loads have greater impact on smaller individuals,

    that impact appears not to be position dependent.

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. A. & Taylor, N. A.S.. (2017). A contribution to understanding the impact of variations in body mass on fractionating the metabolic burden of military load carriage. In Fourth International Congress on Soldiers’ Physical Performance, 28 Nov-1 Dec 2017, Melbourne, Australia. Journal of Science and Medicine in Sport, 20 (2), S75-S76.

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=6237&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/5183

Start Page


  • S75

End Page


  • S76

Volume


  • 20

Issue


  • 2

Place Of Publication


  • Australia