Performance when Breathing Through Different Respirator Inhalation and Exhalation Resistances During Hard Work

Respirator inspiratory and expiratory breathing resistances impact ventilation and performance when studied independently. However, it is less clear as to how various combinations of inhalation and exhalation resistance affect user performance. The present study investigated the performance of 11 individuals during constant load, demanding work to exhaustion while wearing respirators with eight different combinations of inhalation and exhalation resistance. Exercise performance time, performance rating, minute volume, and peak inspiratory and expiratory airflow were recorded at the end of each test trial, and independent correlations with inhalation resistance and exhalation resistance were assessed. The combined impacts of respirator inhalation and exhalation resistances were quantified as the total external work of breathing (WOB _tot ) and correlations between the test variables and WOB _tot were also examined. Significantly linear decreases in performance were found with increased inhalation resistances independent of exhalation resistance (R² = 0.99; p < 0.001) and with increased WOB _tot (R² = 0.92; p < 0.001). Performance also decreased with increased exhalation resistance but no significant relationships were found. Minute volume decreased linearly with increased inhalation resistance independent of exhalation resistance (R² = 0.99; p < 0.001), but the linear decrease observed between minute volume and WOB _tot was weak (R² = 0.36; p < 0.05). These findings suggest that WOB _tot serves as a reliable estimate of the combined impacts of respirator inhalation and exhalation resistances on user performance during hard work, but that inhalation resistance alone serves as a better predictor of ventilation during respirator wear.

Keywords:

• breathing resistance
• performance
• respirator
• work of breathing

Notes

^A Significantly different from other inhalation resistance conditions.

^B Numbers in parenthesis represent number of observations.

^C Independent of exhalation resistance conditions.

^D Independent of inhalation resistance condition.

^A Numbers in parentheses represent number of observations.

^B Significantly different from 0.71 through 1.67 J · L^{− 1} conditions.

^C Significantly different from the 0.71 J · L^{− 1} condition.