Incentive spirometry uses a medical device to help open the airways and improve the functioning of the lungs following surgery. The devices do not build respiratory muscle strength. In fact, they have been found to offer inadequate training resistance (Dekhuijzen et al., 1990; 1991; Larson et al., 1988). Incentive spirometers are also strongly affected by how much air moves through the device and how quickly the air moves. Resistive training can involve breathing through a device with small openings that become progressively smaller (Jederlinic, 1984) or breathing through a device with many small holes. As the device dial is turned, the number of open holes decreases. This type of resistive training is impacted by the user’s breathing pattern or airflow rate, while respiratory strength training is not affected by flow rate (Larson et al., 1988). Respiratory strength training devices load the respiratory muscles at measurable intervals and help to build muscle strength. Each of these device types is useful in the right context, and depending on the desired outcome, i.e., incentive spirometry should be used to open the airways after surgery, and pressure threshold trainers should be used to build muscle strength.