Neuromuscular Impairment Following Backpack Load Carriage

• Authors: Sam D. Blacker , Joanne L. Fallowfield , James L.J. Bilzon , Mark E.T. Willems
• Languages of publication: EN

Abstracts

EN

Load Carriage using backpacks is an occupational task and can be a recreational pursuit. The aim of this study was to investigate the mechanisms responsible for changes in neuromuscular function of the m. quadriceps femoris following load carriage. The physiological responses of 10 male participants to voluntary and electrically stimulated isometric contractions were measured before and immediately after two hours of treadmill walking at 6.5 km•h-1 during level walking with no load [LW], and level walking with load carriage (25 kg backpack) [LC]. Maximal voluntary contraction force decreased by 15 ± 11 % following LC (p=0.006), with no change following LW (p=0.292). Voluntary activation decreased after LW and LC (p=0.033) with no difference between conditions (p=0.405). Doublet contraction time decreased after both LW and LC (p=0.002), with no difference between conditions (p=0.232). There were no other changes in electrically invoked doublet parameters in either condition. The 20:50 Hz ratio did not change following LW (p=0.864) but decreased from 0.88 ± 0.04 to 0.84 ± 0.04 after LC (p=0.011) indicating reduced Ca2+ release from the sarcoplasmic reticulum during excitation contraction coupling. In conclusion, two hours of load carriage carrying a 25 kg back pack caused neuromuscular impairment through a decrease in voluntary activation (i.e. central drive) and fatigue or damage to the peripheral muscle, including impairment of the excitation contraction coupling process. This may reduce physical performance and increase the risk of musculoskeletal injury.

Keywords

EN

Load Carriage; Neuromuscular Impairment; Fatigue; Exercise Induced Muscle Damage

• Publisher: De Gruyter Open
• Journal: Journal of Human Kinetics
• Year: 2013
• Volume: 37
• Issue: 1
• Pages: 91-98

Dates

published

1 - 06 - 2013

online

05 - 07 - 2013

Contributors

author

Sam D. Blacker

• University of Chichester, Department of Sport and Exercise Sciences, West Sussex, PO19 6PE, UK, Phone [phone], Fax [phone]

author

Joanne L. Fallowfield

• Institute of Naval Medicine, Alverstoke, Hampshire, UK

author

James L.J. Bilzon

• University of Bath, Department for Health, Bath, UK

author

Mark E.T. Willems

• University of Chichester, Department of Sport and Exercise Sciences, West Sussex, UK

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Identifiers

DOI

10.2478/hukin-2013-0029