Effect of repetitive exercise testing on breathlessness in humans

Area of Science:

• Exercise Physiology
• Respiratory Medicine
• Psychophysics

Background:

• Conflicting reports exist regarding the reproducibility of the visual analogue scale (VAS) and modified Borg scale for breathlessness assessment.
• Understanding the reliability of these subjective measures during exercise is crucial for clinical and research applications.

Purpose of the Study:

• To investigate the reproducibility of the visual analogue scale (VAS) for breathlessness during repetitive exercise testing.
• To determine the influence of testing frequency on the reliability of breathlessness perception.

Main Methods:

• Healthy subjects performed a progressive exercise test 10 times, either daily (Group A) or weekly (Group B).
• Breathlessness was assessed every minute using the VAS.
• Change point regression analysis was used to identify reproducible thresholds.

Main Results:

• Both groups showed a significant increase in the mean intercept of the breathlessness/ventilation (VAS/V(I)) relationship after 10 occasions.
• Reproducible VAS/V(I) intercept values were achieved after approximately the fifth testing occasion in both groups.
• The slope of the VAS/V(I) relationship remained highly reproducible and unchanged with repeat testing.

Conclusions:

• Breathlessness scores decrease with repetitive testing, particularly within the first five sessions, suggesting a physiological adaptation.
• The high reproducibility of the VAS/V(I) slope indicates distinct mechanisms contributing to breathlessness sensation.
• A common underlying physiological mechanism may influence both breathlessness perception and exercise heart rate during repetitive testing.