Weight loss reduces dyspnea on exertion in obese women

Abstract

During submaximal exercise, some otherwise healthy obese women experience breathlessness, or dyspnea on exertion (+DOE), while others have mild or no DOE (−DOE). We investigated whether weight loss could reduce DOE. 29 obese women were grouped based on their Ratings of Perceived Breathlessness (RPB) during constant load 60W cycling: +DOE (n=14, RPB≥4, 34±8yr, 36±3kg/m2) and −DOE (n=15, RPB≤2, 32±8yr, 36±4kg/m2) and then completed a 12-week weight loss program. Both groups lost a moderate amount of weight (+DOE: 6.6±2.4kg, −DOE: 8.4±3.5kg, p<0.001). RPB decreased significantly in the +DOE group (from 4.7±1.1 to 3.1±1.6) and remained low in the −DOE (from 1.5±0.7 to 1.6±1.1) (interaction p<0.002). Most physiological variables measured (i.e. body composition, fat distribution, pulmonary function, oxygen cost of breathing, cardiorespiratory measures) improved with weight loss; however, the decrease in RPB was not correlated with any of these variables (p>0.05). In conclusion, moderate weight loss was effective in reducing breathlessness on exertion in obese women who experienced DOE at baseline.

Exertional dyspnoea in obesity

“…These results would suggest that breathlessness is dependent only on minute ventilation (and V′O 2 ). However, as we have shown in several studies, not all obese adults experience dyspnoea on exertion [7,24,43,44,58]. In our studies, the prevalence of DOE in otherwise healthy obese adults is ∼37-44%, as defined by a rating of perceived breathlessness (RPB) ⩾4 (i.e.…”

“…V′O 2 : oxygen uptake; PaCO 2 : arterial carbon dioxide tension. Reproduced from [24] with permission from the publisher.…”

“…These data indicate that weight gain occurs fairly evenly across the whole body and not just in certain areas. Likewise, weight loss does not change fat distribution since fat mass is lost from all body regions, including chest, abdominal, visceral, subcutaneous and peripheral areas [24].…”

“…We tested the effects of weight loss (via caloric reduction diet only) and improved cardiorespiratory fitness (via aerobic exercise training without weight loss) on DOE in otherwise healthy obese women [8,24]. Both treatments by themselves markedly ameliorated breathlessness during submaximal cycling exercise at 60 W; however, the mechanism of this improvement is unclear as there were no significant correlations with any accompanying physiological changes in body composition, fat distribution, pulmonary function, work of breathing or cardiorespiratory measures [16,24]. It is possible that the improvement in DOE could be due to psychophysiological mechanism(s), which should be investigated in future studies.…”

Introduction to Special Issue “Non-homeostatic Control of Respiration”

“…Air hunger provoked activation in a cortico-limbic circuitry including the anterior insula, anterior cingulate and prefrontal cortices. Bernhardt and Babb (2014) report that even mild weight loss reduces breathlessness on exertion in obese individuals. This observation is highly relevant, as exerciseinduced dyspnea is one of the major factors that reduce motivation of subjects with obesity for exercising.…”