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The impact of thoracic load carriage up to 45 kg on the cardiopulmonary response to exercise

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Abstract

Purpose

The purposes of this experiment were to, first, document the effect of 45-kg thoracic loading on peak exercise responses and, second, the effects of systematic increases in thoracic load on physiological responses to submaximal treadmill walking at a standardized speed and grade.

Methods

On separate days, 19 males (age 27 ± 5 years, height 180.0 ± 7.4 cm, mass 86.9 ± 15.1 kg) completed randomly ordered graded exercise tests to exhaustion in loaded (45 kg) and unloaded conditions. On a third day, each subject completed four randomly ordered, 10-min bouts of treadmill walking at 1.34 m s−1 and 4 % grade in the following conditions: unloaded, and with backpacks weighted to 15, 30, and 45 kg.

Results

With 45-kg thoracic loading, absolute oxygen consumption (\( \dot{V}{\text{O}}_{2} \)), minute ventilation, power output, and test duration were significantly decreased at peak exercise. End-inspiratory lung volume and tidal volume were significantly reduced with no changes in end-expiratory lung volume, breathing frequency, and the respiratory exchange ratio. Peak end-tidal carbon dioxide and the ratio of alveolar ventilation to carbon dioxide production were similar between conditions. The reductions in peak physiological responses were greater than expected based on previous research with lighter loads. During submaximal treadmill exercise, \( \dot{V}{\text{O}}_{2} \) increased (P < 0.05) by 11.0 (unloaded to 15 kg), 14.5 (15–30 kg), and 18.0 % (30–45 kg) showing that the increase in exercise \( \dot{V}{\text{O}}_{2} \) was not proportional to load mass.

Conclusion

These results provide further insight into the specificity of physiological responses to different types of load carriage.

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Abbreviations

f B :

Breathing frequency

EELV:

End-expiratory lung volume

EILV:

End-inspiratory lung volume

FEV1 :

Forced expired volume in 1 second

FPE:

Fire protective ensemble

FVC:

Forced vital capacity

IC:

Inspiratory capacity

PaCO2 :

Partial pressure of arterial carbon dioxide

PETCO2 :

Partial pressure of end-tidal carbon dioxide

RER:

Respiratory exchange ratio

\( \dot{V}_{\text{A}} \) :

Alveolar ventilation

\( \dot{V}{\text{CO}}_{2} \) :

Carbon dioxide production

\( \dot{V}{\text{O}}_{2} \) :

Oxygen consumption

VT :

Tidal volume

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Acknowledgments

Technical assistance from Bradley Welch is appreciated. Cameron Ehnes was supported by the Undergraduate Research Initiative program at the University of Alberta.

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Authors and Affiliations

  1. Faculty of Physical Education and Recreation, University of Alberta, 4-427 Van Vliet Complex, Edmonton, AB, T6G 2H9, Canada

    Devin B. Phillips, Cameron M. Ehnes, Michael K. Stickland & Stewart R. Petersen

  2. Department of Medicine, University of Alberta, Edmonton, AB, T6G 2J3, Canada

    Michael K. Stickland

  3. G. F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, AB, T5K 0L4, Canada

    Michael K. Stickland

Authors
  1. Devin B. Phillips
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  2. Cameron M. Ehnes
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  3. Michael K. Stickland
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  4. Stewart R. Petersen
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Corresponding author

Correspondence to Stewart R. Petersen.

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There are no conflicts of interest.

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Communicated by Susan Hopkins.

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Phillips, D.B., Ehnes, C.M., Stickland, M.K. et al. The impact of thoracic load carriage up to 45 kg on the cardiopulmonary response to exercise. Eur J Appl Physiol 116, 1725–1734 (2016). https://doi.org/10.1007/s00421-016-3427-6

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  • DOI: https://doi.org/10.1007/s00421-016-3427-6

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