['Recent research has shown that distinct dimensions in the perception of dyspnea can be differentiated; however, most studies to date have only used a global rating scale for the measurement of this sensation.', 'This study examined the different influence of sensory and affective aspects of perceived dyspnea on the commonly used Borg scale, which measures the global perception of dyspnea.', 'Dyspnea was induced in 16 healthy volunteers (mean age 26.2 +/- 6.3 years) by breathing through an inspiratory resistive load (3.57 kPa/l/s) in two experimental conditions (attention and distraction). After each of the two conditions the experienced intensity (i.e., sensory dimension) and unpleasantness (i.e., affective dimension) of dyspnea were rated on separate visual analog scales (VAS), followed by a global rating of dyspnea on the Borg scale. Hierarchical multiple linear regression models were calculated to analyze the predictive validity of VAS ratings of intensity and unpleasantness on the Borg scale ratings.', 'When subjects attended to their breathing, only VAS intensity scores showed a significant influence on Borg scale ratings (p < 0.05). In contrast, only the VAS unpleasantness scores showed a significant influence on Borg scale ratings (p < 0.05) when subjects were distracted.'] Do sensory and affective aspects of dyspnea contribute differentially to the Borg scale 's measurement of dyspnea?