PURPOSE: The use of respiratory and chemical protective equipment may be essential for firefighters, military, or homeland security personnel in accomplishing their unique missions. The purpose of this study was to measure the effect of this equipment on exercise capacity, which has not been previously quantified.
METHODS: Healthy volunteers performed maximal, symptom-limited cardiopulmonary exercise testing (CPET) using the modified Balke protocol. Each participant performed three exercise tests, at least one week apart. During the first test, subjects wore a standard military uniform (long sleeve shirt, pants, and boots). During the second and third tests, subjects wore an M-40 chemical protective mask with or without the addition of full chemical protective gear (charcoal-lined suit, protective hood, rubber boots and gloves), in randomized sequence. Parameters measured during each exercise study at peak exercise included exercise capacity (VO2max), time to exhaustion (TTE), O2 pulse, minute ventilation (VE), tidal volume(Vt), and estimated stroke volume (SV).
RESULTS: Twenty-two healthy active duty soldiers completed the study. There were 12 males and 10 females, with mean age of 36 years (range 18-45), and mean body mass index (BMI) of 25.3. When compared to baseline exercise performance, subjects demonstrated significant reduction in VO2 (3.27 vs 2.69 L/min, p<0.01), TTE (763 vs 707 seconds, p<0.01) O2 pulse (19 vs 15.4 Liters/min, p < 0.01), VE (127 vs 92 Liters/minute, p < 0.01), Vt (2.66 vs 2.14 Liters, P, 0.01)and SV (125 vs 102 milliliters, p<0.01) while exercising with the chemical protective mask. The addition of the full chemical protective suit resulted in further significant decrease in TTE (707 vs 502 seconds (p<0.05), but in none of the other measured parameters. Peak heart rate was similar during each exercise sequence (176 +/− 3.4 beats/minute).
CONCLUSION: Exercise capacity is significantly reduced while wearing a chemical protective mask. As expected, most of this exercise limitation is ventilatory in nature.
CLINICAL IMPLICATIONS: These results may be valuable for future planners of emergency and military operations.
DISCLOSURE: Veeta Vaughn, None.