Objective: To assess which subjective scale, the visual analogue scale (VAS), the Borg CR10 (Borg) scale, or the Likert scale (LS), if any, is decidedly more reproducible and sensitive to change in the assessment of symptoms.
Design: Prospective clinical study.
Setting: Exercise laboratory.
Participants: Twenty-three physically active male subjects (mean +/- SD age of 30 +/- 4 years old) were recruited.
Intervention: Each subject attended the exercise laboratory on four occasions at intervals of 1 week. Three subjective scales were used: (1) the VAS (continuous scale); (2) the Borg scale (12 fixed points); and (3) the Likert scale (LS; 5 fixed points). Four identical submaximal tests were given (2 min at 60% maximum oxygen uptake [VO(2)max] and 6 min at 70% VO(2)max). Two tests were undertaken to assess the reproducibility of scores that were obtained with each subjective scale. Two other tests were undertaken to assess the sensitivity of each scale to a change in symptom perception: a double-blind treatment with propranolol, 80 mg, (ie, active therapy; to increase the sensation of breathlessness and general fatigue during exercise) or matching placebo. The subjective scale scores were measured at 1 min 30 s, 5 min 30 s, and 7 min 15 s of exercise. Reproducibility was defined as the proportion of total variance (ie, between-subject plus within-subject variance) explained by the between-subject variance given as a percentage. Sensitivity was defined as the effect of the active drug therapy over the variation within subjects.
Results: Overall, the VAS performed best in terms of reproducibility for breathlessness and general fatigue, with reproducibility coefficients as high as 78%. For sensitivity, the VAS was best for breathlessness (ratio, 2.7) and the Borg scale was most sensitive for general fatigue (ratio, 3.0). The relationships between the respective psychological and physiologic variables were reasonably stable throughout the testing procedure, with overall typical correlations of 0.73 to 0.82
Conclusion: This study suggests that subjective scales can reproducibly measure symptoms during steady-state exercise and can detect the effect of a drug intervention. The VAS and Borg scales appear to be the best subjective scales for this purpose.