Physiological Capacity During Simulated Stair Climbing Evacuation at Maximum Speed Until Exhaustion
| Autor: | Kalev Kuklane, Jeannette Unge, Chuansi Gao, Axel Nordin, Amitava Halder, Michael Miller |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
Lactate threshold 020101 civil engineering 030229 sport sciences 02 engineering and technology Perceived exertion Oxygen uptake 0201 civil engineering Sharp rise Combinatorics Leg muscle 03 medical and health sciences 0302 clinical medicine Healthy volunteers Blood lactate General Materials Science Safety Risk Reliability and Quality Stable state |
| Zdroj: | Fire Technology. 57:767-790 |
| ISSN: | 1572-8099 0015-2684 |
| DOI: | 10.1007/s10694-020-01013-w |
| Popis: | 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 $$ ( {\dot{V}}{\text{O}}_{2} ) $$ ( V ˙ O 2 ) 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, $$ {\dot{V}}{\text{O}}_{\rm 2max} $$ V ˙ O 2 max 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% $$ {\dot{V}}{\text{O}}_{\rm 2max} $$ V ˙ O 2 max . 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 $$ {\dot{V}}{\text{O}}_{\rm 2highest} $$ V ˙ O 2 highest reached 44.8 (7.3) mL min−1 kg−1, which was 92.3 (9.7)% of $$ {\dot{V}}{\text{O}}_{\rm 2max} $$ V ˙ O 2 max when the HRhighest peaked at 174 (11) b min−1. However, the mean $$ ( {\dot{V}}{\text{O}}_{2} ) $$ ( V ˙ O 2 ) 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 $$ {\dot{V}}{\text{O}}_{\rm 2} $$ V ˙ O 2 steady state was slowly reached. EMG amplitudes of four major leg muscles increased and the median frequencies of two muscles decreased significantly (p −1) is possible to sustain 2–6 min. These overall results offer useful and vital information to consider when designing underground emergency evacuation facilities. |
| Databáze: | OpenAIRE |
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