Preliminary Study: Immediate Effect of the Slow Deep Breathing Exercise and Sustained Maximal Inspiration with Volume-Oriented Incentive Spirometry on the Diffusing Lung Capacity in Healthy Young Participants

Slow-deep breathing exercise (SDBE) while using a volume-oriented type of incentive spirometry (VIS) device (SDBE/VIS) is one of the techniques in chest physical therapy designed to improve lung volume and oxygenation. However, the immediate effect of SDBE/VIS paired with a sustained maximal inspiration (SMI) on diffusing lung capacity (DLC), has not been documented. This preliminary study aimed to evaluate the immediate effect of SDBE/VIS paired with the SMI technique on DLC in healthy participants. Twenty healthy sedentary adults (11 males and 9 females) aged 20 to 23 years were recruited into this cross-over study and randomly assigned to one of 2 ordered groups; SDBE/VIS paired with SMI followed by SDBE/VIS alone or SDBE/VIS alone followed by SDBE/VIS with SMI. During each of the 2-testing sessions, the participants performed 3 sets of 5 SDBE/VIS trials which were controlled by ensuring that each participant reached their maximal vital capacity; derived from their pulmonary function test. The DLC for carbon monoxide (DLCO), alveolar volume (VA), and total lung capacity (TLC) was assessed prior to (baseline) and after each of the 5 experimental trials. A 3-min rest period was given between each set of 5 trials and 1 week between testing sessions. The results demonstrated that SDBE/VIS paired with the SMI technique significantly increased both the DLCO (mL/min/mmHg and %) and VA (L and %) when compared to the baseline values. Whereas, SDBE/VIS without using the SMI technique did not alter the DLCO, VA or the DLCO/VA. However, both SDBE/VIS with and without the SMI technique showed a significant increase the TLC (L and %), with the TLC from SDBE/VIS paired with SMI was significantly higher than when the SDBE /VIS was performed without using the SMI technique. Thus, it appears that performing SDBE/VIS exercised paired with the SMI technique has a significant and positive effect on DLC.