Increased sensations of intensity of breathlessness impairs maintenance of intense intermittent exercise

Tom K K TONG*, Frank H K FU, Bik Chu CHOW, Binh Quach, Kui Lu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

To identify the reserve of an individual's tolerance of the sensation of breathlessness and metabolic stress in maintaining intense intermittent exercise at exhaustion under conditions of normal breathing, the contribution of the effect of modest inspiratory load on these two responses to the change in the exercise sustainability (Exsus were examined. Seven men repeatedly performed 12 s exercise at 160% maximal aerobic power output followed by passive recovery for 18 s under normal and ventilatory muscle loaded (VML) breathing conditions until exhaustion. In the VML trial, ventilatory muscle work at exhaustion was double that of the normal control. The control Exsus was reduced [mean (SEM)] [31.7 (6.6)%] while the slope of the time course for the rating of the perceived magnitude of breathing effort (RPMBE/Time), which reflected the intensity of breathlessness, was increased [164.8 (32.2)%] from control and the RPMBE at exhaustion was higher than corresponding control value [144.4 (21.8)%]. Moreover, increases in plasma ammonia and uric acid concentrations, which indicated metabolic stress, were increased [168.1 (28.0)% and 251.7 (57.4)%, respectively], with no change in total oxygen uptake from control when the control exercise was repeated with an identical duration of VML exercise. It was found that the reduction in Exsus in the VML trial was correlated to the increase in their sensations of the intensity of breathlessness (RPMBE/Time: r = 0.81; RPMBE at exhaustion: r = 0.97, P < 0.05). The reduction in Exsus, however, was not correlated to the increase in metabolite concentrations. These findings implied that there was no substantial reserve of tolerance of the sensation of breathlessness relative to that of metabolic stress in subjects maintaining intense intermittent exercise at exhaustion under normal conditions of breathing.

Original languageEnglish
Pages (from-to)370-379
Number of pages10
JournalEuropean Journal of Applied Physiology
Volume88
Issue number4-5
DOIs
Publication statusPublished - Jan 2003

Scopus Subject Areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)

User-Defined Keywords

  • Inspiratory resistive loading
  • Metabolic stress
  • Sensation of breathlessness

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