The effect of wearing military loads on ventilatory function and soldier performance

  • Nicola Carol Dawn Armstrong

Student thesis: Doctoral Thesis


This work aimed to provide an evidence-base to inform the evaluation of future soldier systems so that they minimise breathing restriction. The hypothesis that restrictions to ventilatory function observed with torso-borne load carriage would limit exercise and the performance of military tasks was tested.
Four separate studies were conducted to quantify the effect of wearing body armour with backpack loads on infantry soldiers at rest and whilst marching. Load redistribution was also assessed as a potential intervention. The load configurations examined ranged from no load to 50 kg. Ventilatory function, maximum inspiratory / expiratory pressures (PImax and PEmax respectively, to estimate respiratory muscle fatigue (RMF)), shoulder pressure / force and cardiopulmonary parameters were measured pre / post and during the loaded marches. The marches were between 40 and 180 minutes in duration and included light to heavy exercise intensities. Military task performance was measured using cognitive performance tests and the time to complete a 2.4 km best effort test.
Wearing military loads caused a restrictive ventilatory impairment of up to 20 % depending on the load carried. Soldiers developed a rapid / shallow breathing pattern whilst marching with load which led to RMF. PImax and PEmax were reduced post-exercise following short duration tasks in Assault Order loads (PImax: 8 %, PEmax: 17 %) and following long duration moderate intensity marches in body armour (PImax: 7 to 13 %, PEmax: 10 to 19 %). Expiratory flow limitation was evident in 72 % of participants tested during heavy exercise.
Accuracy during working memory and response inhibition tasks reduced with load and time by up to 20 %. Load redistribution improved accuracy during cognitive tasks but did not affect physiological parameters.
The study hypothesis was accepted. The restriction to breathing caused by military loads limited performance during heavy exercise. RMF was evident during long duration marching although this did not limit performance.
Date of AwardJan 2020
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorMike Tipton (Supervisor) & Mitch Lomax (Supervisor)

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