In conclusion, our results showed that dyspnea in morbidly obese patients remains moderately related to resting lung function and inspiratory muscle performance. This correlation is much more significant in patients with a BMI less than or equal to49 kg/m2. Inspiratory muscle impairment could in part explain dyspnea sensation in these patients but other factors are likely to contribute to this symptom, reflecting the complexity of dyspnea mechanisms. Although inspiratory muscle dysfunction remained moderate in a majority of obese patients, IME assessment in addition to standard PFTs appears useful in those with severe dyspnea or when considering bariatric surgery.