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Title: The interactive effect of cooling and hypoxia on forearm fatigue development
Authors: Lloyd, Alex
Hodder, S.G.
Havenith, George
Keywords: Combined stressors
High altitude
Issue Date: 2015
Publisher: © Springer-Verlag
Citation: LLOYD, A., HODDER, S.G. and HAVENITH, G., 2015. The interactive effect of cooling and hypoxia on forearm fatigue development. European Journal of Applied Physiology, 115(9), pp.2007-2018.
Abstract: Purpose: To examine the effect of separate and combined exposure to hypoxia [normoxia (F<inf>I</inf>O<inf>2</inf> = 0.21) vs. moderate altitude (F<inf>I</inf>O<inf>2</inf> = 0.13)] and temperature [thermoneutral (22 °C) vs. cold (5 °C)] on muscle fatigue development in the forearm, after repeated low-resistance contractions. Methods: Eight males were exposed for 70 min to four separate conditions in a balanced order. Conditions were normoxic-thermoneutral (N), hypoxic-thermoneutral, normoxic-cold and hypoxic-cold. After 15-min seated rest, participants carried out intermittent dynamic forearm exercise at 15 % maximal isometric voluntary contraction (MVC) for eight consecutive, 5-min work bouts. Each bout was separated by 110 s rest during which MVC force was collected. Results: When exposed to hypoxia and cold independently, the exercise protocol decreased MVC force of the finger flexors by 8.1 and 13.9 %, respectively, compared to thermoneutral normoxia. When hypoxia and cold were combined, the decrease in MVC force was 21.4 % more than thermoneutral normoxia, reflecting an additive effect and no interaction. EMG relative to force produced during MVC, increased by 2 and 1.2 μV per kg (36 and 23 % of N) for cold and hypoxia, respectively. When the stressors were combined the effect was additive, increasing to 3.1 μV per kg (56 % of N). Conclusion: When compared to exercise in thermoneutral normoxic conditions, both cold and hypoxia significantly reduce brief MVC force output. This effect appears to be of mechanical origin, not a failure in muscle fibre recruitment per se. Additionally, the reduction in force is greater when the stressors are combined, showing an additive effect.
Description: The final publication is available at Springer via http://dx.doi.org/10.1007/s00421-015-3181-1
Version: Accepted for publication
DOI: 10.1007/s00421-015-3181-1
URI: https://dspace.lboro.ac.uk/2134/17889
Publisher Link: http://dx.doi.org/10.1007/s00421-015-3181-1
ISSN: 1439-6319
Appears in Collections:Published Articles (Design School)

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