Fire-fighters' Self-contained Breathing Apparatus (SCBA): The effects of SCBA mass upon exercise duration during treadmill walks in the laboratory

摘要

The present study investigated the wear duration of two fire-fighters' Self-contained Breathing Apparatus (SCBA). Ensemble E#1 had a mass of ～16 kg, and a maximum air capacity of 1,980 litres (@ 180 bars). Ensemble E#2 had a mass of ～11.5 with a maximum air capacity of 1,620 litres (@ 180 bars). The exercise duration (T_(lim)) of 10 professional fire-fighters, exercising at a group mean of 70% VO_(2 max) was monitored during two treadmill walks. One walk was performed in each ensemble. Volunteers' baseline characteristics were: age 38 (± 8) yrs; height 178 (± 7) cms, mass 85 (± 14) kg, peak oxygen uptake in SCBA (VO_(2pBA)) 45 (± 8) ml.kg~(-1).min~(-1). It was hypothesised that wearing the lighter SCBA (E#2), would reduce the volunteers' ventilatory demands and enable them to exercise for the same duration as they could in the heavier SCBA (E#1), despite its reduced air capacity. Results showed that despite the reduced ventilatory demands of E#2 (59.2 (± 20) vs. 67.2 (± 20) l.min~(-1), p < 0.001), the exercise duration (T_(lim)) was significantly shorter (1,684 (± 494) secs vs. 1,824 (± 514) secs, p < 0.005). There is a strong positive association between volunteers' VO_(2pBA) (ml.kg~(-1).min~(-1)), and both minute ventilation (V_E), and T_(lim). Test results show that fire-fighters with a VO_(2pBA) < 35 ml.kg~(-1).min~(-1) struggled to complete the exercise protocol. Furthermore, four of the volunteers would not have been able to exercise at this intensity for the 20 minutes deemed necessary by their employers. The present study shows that during steady-state treadmill walks, reducing the mass and capacity of fire-fighters' SCBA by 28% and 18% respectively, results in a 12% fall in ventilatory demand, and an 8% reduction in T_(lim).