Physiological Capacity During Simulated Stair Climbing Evacuation at Maximum Speed Until Exhaustion

Research output: Contribution to journalArticle

Abstract

Stair-ascending at maximum ability is required during emergency evacuations to reach a safe refuge from deep underground structures. We hypothesized that an ascent can last maximum 5 min at the individual’s maximum step rate (SR), and oxygen uptake (V˙O2) would not reach a stable state. This study explored stair-ascending endurance and some physiological constraints of performance. Eighteen healthy volunteers with mean (standard deviation, SD) age 26.7 (4.0) years, height 172.2 (10.7) cm, weight 68.0 (11.3) kg, BSA 1.8 (0.2) m−2, V˙O2max 48.5 (5.4) mL min−1 kg−1, and HRmax 192 (9) b min−1 ascended on a stair machine at a SR equivalent to their 100% V˙O2max. The mean (SD) ascending duration was 3.47 (1.18) min, supporting the hypothesis. The calculated vertical height covered was 85.5 (32.1) m. The V˙O2highest reached 44.8 (7.3) mL min−1 kg−1, which was 92.3 (9.7)% of V˙O2max when the HRhighest peaked at 174 (11) b min−1. However, the mean V˙O2 reached a relatively steady state after the sharp rise. The post-ascent blood lactate, respiratory exchange ratio, and perceived exertion values recorded were high, 14.4 (4.0) mmol l−1, 1.20 (0.09), and 18.2 (0.7), respectively, indicated that exhaustion was reached. The ascending SR rate was above the lactate threshold; therefore, the attainment of V˙O2 steady state was slowly reached. EMG amplitudes of four major leg muscles increased and the median frequencies of two muscles decreased significantly (p < .01) indicating local muscle fatigue (LMF). Leg LMF and hyperventilation resulted in speedy exhaustion leading to termination. These results infer that stair ascending at maximum ability (122 steps min−1) is possible to sustain 2–6 min. These overall results offer useful and vital information to consider when designing underground emergency evacuation facilities

Details

Authors
Organisations
External organisations
  • Institute for Safety (IFV), Netherlands
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Health Sciences

Keywords

  • Stairclimbing capacity, Oxygen uptake, Maximum-intensity work, Physical fitness, Muscle fatigue, Electromyography, Blood lactate, Stairclimbing duration
Original languageEnglish
JournalFire Technology
Publication statusPublished - 2020 Jul 22
Publication categoryResearch
Peer-reviewedYes