Effect of respirator inspiratory resistance level on constant load treadmill work performance

Respirator inspiratory resistance can affect performance times, especially when the experiment is optimized to elicit respiratory stress. Twelve subje cts performed on a treadmill at constant speeds and grades chosen to result in performance times of 5-15 min. Six levels of inspiratory resistance wer e used, ranging from 0.78 to 7.64 cm H2O.sec/L. The results showed that per formance times decrease linearly with resistance level, and no threshold re sistance value is apparent. Inspiratory resistance also induces hypoventila tion, with lower minute volumes and lower oxygen consumption values at high er resistances. These trends are also linear. From these results, there is no value for inspiratory resistance that can be given as a design goal. Oth er parameters such as weight and space may dictate filter resistance values , and these, in turn, will lead to determined performance degradations.