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

Halder, Amitava LU ; Kuklane, Kalev LU ; Miller, Michael LU ; Nordin, Axel LU ; Unge, Jeannette LU and Gao, Chuansi LU (2020) In Fire Technology
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... (More)
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 (Less)
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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Stairclimbing capacity, Oxygen uptake, Maximum-intensity work, Physical fitness, Muscle fatigue, Electromyography, Blood lactate, Stairclimbing duration
in
Fire Technology
publisher
Kluwer
external identifiers
  • scopus:85083567149
ISSN
0015-2684
DOI
10.1007/s10694-020-01013-w
language
English
LU publication?
yes
id
5d550d9f-5f8c-4271-982a-fdf2f5bcbb09
date added to LUP
2020-07-24 01:03:20
date last changed
2020-10-07 07:02:09
@article{5d550d9f-5f8c-4271-982a-fdf2f5bcbb09,
  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, <br>
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<br>
reached 44.8 (7.3) mL min−1 kg−1, which was 92.3 (9.7)% of V˙O2max<br>
when the HRhighest peaked at 174 (11) b min−1. However, the mean V˙O2<br>
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 &lt; .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},
  author       = {Halder, Amitava and Kuklane, Kalev and Miller, Michael and Nordin, Axel and Unge, Jeannette and Gao, Chuansi},
  issn         = {0015-2684},
  language     = {eng},
  month        = {07},
  publisher    = {Kluwer},
  series       = {Fire Technology},
  title        = {Physiological Capacity During Simulated Stair Climbing Evacuation at Maximum Speed Until Exhaustion},
  url          = {http://dx.doi.org/10.1007/s10694-020-01013-w},
  doi          = {10.1007/s10694-020-01013-w},
  year         = {2020},
}