title: The effects of thoracic load carriage on maximal ambulatory work tolerance and acceptable work durations.
abstract: OBJECTIVE
  Torso loads restrict chest-wall movement and ventilation, particularly during heavy exercise. Therefore, the differential impact of load carriage and chest-wall restriction was investigated during progressive treadmill exercise. In addition, acceptable work durations were derived across a wide range of submaximal, loaded exercise intensities.
  
  
  METHODS
  Twelve males participated in two research phases. Phase 1: Three incremental treadmill tests until exhaustion [control (clothing only), load carriage (clothing plus 22-kg vest), and clothing with chest strapping]. Phase 2: Five steady-state exercise trials (clothing plus 22-kg vest) at intensities from 30 to 80 % of peak aerobic power to determine maximal acceptable work durations.
  
  
  RESULTS
  Maximal work tolerance [control 17.21 min (±0.93); loaded 13.44 min (±0.68); strapped 17.00 min (±0.83)] and the mass-specific peak aerobic power [control 61.61 mL kg(-1) min(-1) (±2.28); loaded 45.42 mL kg(-1) min(-1) (±1.41); strapped 59.99 mL kg(-1) min(-1) (±1.61)] were reduced only when loaded (P < 0.05). Peak minute ventilation was retained, although loading and chest strapping reduced the breathing reserve. The lower and upper acceptable work duration derivations when working at the 30 % intensity were 133.40 min (±23.77) and 220.10 min (±48.69), but at 80 % intensity, both durations were reduced to <7 min.
  
  
  CONCLUSIONS
  Thoracic loading significantly reduced exercise tolerance and the breathing reserve, but did not modify peak minute ventilation or the absolute peak aerobic power. Chest strapping, as used herein, exerted minimal impact. However, the projected maximal acceptable work durations were much less than derived using previously published methods.
authors.affiliation: Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia. peoples@uow.edu.au.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Peoples
authors.affiliation: Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Lee
authors.affiliation: Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Sean R
authors.initials: SR
authors.lastname: Notley
authors.affiliation: Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Nigel A S
authors.initials: NA
authors.lastname: Taylor
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance; D006801:Humans; D008297:Male; D012132:Respiratory Muscles / Q000502:physiology*; D060726:Torso / Q000502:physiology*; D014939:Work of Breathing
keywords: Chest strapping; Chest wall; Diaphragm; Fatigue; Load carriage; Loaded breathing; Maximal voluntary ventilation; Oxygen consumption