The Influence of the Self-Contained Breathing Apparatus (SCBA) on Ventilatory Function and Maximal Exercise

Abstract

Our previous work showed that breathing low density gases during exercise with the self-contained breathing apparatus (SCBA) improves maximal ventilation (VE) and maximal oxygen consumption [Formula: see text] This suggests that the SCBA limits exercise by adding a resistive load to breathing. In this study we compared [Formula: see text] with and without the various components comprising the SCBA to determine their impact on [Formula: see text] Twelve males performed 4 randomly ordered incremental exercise tests to exhaustion on a treadmill: (1) low-resistance breathing valve only (CON); (2) full SCBA (SCBA); (3) SCBA regulator only (REG); and (4) carrying the cylinder and harness assembly but breathing through a low-resistance breathing valve (PACK). Compared to CON, [Formula: see text] was reduced to a similar extent in the SCBA and REG trials (14.9% and 13.1%, respectively). The PACK condition also reduced [Formula: see text] but to a lesser extent (4.8 ± 5.3%). At [Formula: see text][Formula: see text] was decreased and expiratory mouth pressure and external breathing resistance (BR) were increased in both the SCBA and REG trials. There was a significant correlation between the change in maximal [Formula: see text] and [Formula: see text] with the SCBA. The results show that the SCBA reduces [Formula: see text] by limiting [Formula: see text] secondary to the increased BR of the SCBA regulator. Key words: ventilation, breathing resistance, expiratory flow limitation, [Formula: see text]