LLOYD MAIN TEXT- ACCEPTED.pdf (932.01 kB)
Download file

The interactive effect of cooling and hypoxia on forearm fatigue development

Download (932.01 kB)
journal contribution
posted on 16.06.2015, 13:37 by Alex LloydAlex Lloyd, Simon HodderSimon Hodder, George HavenithGeorge Havenith
Purpose: To examine the effect of separate and combined exposure to hypoxia [normoxia (FIO2 = 0.21) vs. moderate altitude (FIO2 = 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.

History

School

  • Design

Published in

European Journal of Applied Physiology

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.

Publisher

© Springer-Verlag

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2015

Notes

The final publication is available at Springer via http://dx.doi.org/10.1007/s00421-015-3181-1

ISSN

1439-6319

Language

en