Respiratory symptom perception differs in obese women with strong or mild breathlessness during constant-load exercise.

BACKGROUND

During constant-load exercise, some otherwise healthy obese women report substantially more dyspnea on exertion (DOE) than do others. The objective of this study was to investigate whether qualitative differences exist between the sensations of dyspnea felt by these women.

METHODS

Seventy-eight women were categorized based on their ratings of perceived breathlessness (RPBs) (Borg 0-10 scale) after 6 min of 60-W cycling. Thirty-four women rated RPB ≥ 4 (+DOE) (34 ± 7 years, 36 ± 5 kg/m² BMI), and 22 women rated RPB ≤ 2 (-DOE) (32 ± 7 years, 37 ± 4 kg/m² BMI). Twenty-two women rated RPB as 3 (RPB = 3) (34 ± 7 years, 34 ± 4 kg/m² BMI) and were grouped separately to allow for a better delineation of the +DOE and the -DOE groups. After the exercise test, subjects were asked to pick three of 15 statements that best described their respiratory sensations.

RESULTS

The +DOE and the -DOE groups were characterized differentially (P < .05) by the respiratory clusters "Breathing more" (82% of -DOE vs 41% of +DOE), "Shallow" (36% vs 6%), and "Heavy" (14% vs 53%). All four descriptors in the cluster "Work/Effort" were chosen more frequently by women in the +DOE group than by women in the -DOE group. Although relative exercise intensity was higher in the +DOE women (75% ± 13% vs 67% ± 10% of oxygen uptake at peak exercise, 41 ± 10 L/min vs 31 ± 8 L/min as % maximal voluntary ventilation, 83% ± 7% vs 76% ± 7% of peak heart rate), none of these variables was significantly associated with RPB.

CONCLUSIONS

Not only is the intensity of dyspnea significantly different between the +DOE and the -DOE groups, but so are the self-reported qualitative aspects of their dyspnea. Women in the +DOE group reported an increased sensation of the work of breathing relative to women in the -DOE group, which may be associated with the elevated RPB.