Citation

Frost DM, Beach TA, Callaghan JP, McGill SM. J. Strength Cond. Res. 2013; 29(9): 2417-2425.

Affiliation

1Faculty of Kinesiology and Physical Education, University of Toronto, 55 Harbord Street, Toronto, Ontario, M5S 2W6, Canada 2Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada.

Copyright

(Copyright © 2013, National Strength and Conditioning Association)

DOI

10.1519/JSC.0000000000000264

PMID

24126896

Abstract

Because individuals' movement patterns have been linked to their risk of future injury, movement evaluations have become a topic of interest. However, if individuals adapt their movement behavior in response to the demands of a task, the utility of evaluations comprising only low demand activities could have limited application with regards to the prediction of future injury. This investigation examined the impact of load and speed on individuals' movement behavior. Fifty-two firefighters performed five low-demand (i.e. light load, low movement speed) whole-body tasks (i.e. lift, squat, lunge, push, pull). Each task was then modified by increasing the speed, external load, or speed and load. Select measures of motion were used to characterize the performance of each task and comparisons were made between conditions. Participants adapted their movement behavior in response to the external demands of a task (64% and 70% of all variables were influenced (p<0.05) by changing the load and speed, respectively), but in a manner unique to the task and type of demand. Participants exhibited greater spine and frontal plane knee motion in response to an increase in speed when compared to increasing loads. However, there were a large number of movement strategies exhibited by individual firefighters that differed from the group's response. The data obtained here imply that individuals may not be physically prepared to perform safely or effectively when a task's demands are elevated simply because they exhibit the ability to perform a low-demand activity with competence. Therefore, movement screens comprising only low demand activities may not adequately reflect an individual's capacity, or their risk of injury, and could adversely affect any recommendations that are made for training or job performance.

Language: en