Effects of cognitive and physical loads on local dynamic stability during gait.

The objective of this study was to examine the main and interactive effects of cognitive and physical loads on soldiers' gait characteristics. Twelve young healthy male participants volunteered to take part in the study. They were instructed to walk on the treadmill at their comfortable speed under different combinations of physical and cognitive loads. The physical load was applied by carrying backpack load that was set at 0 kg, 8.5 kg, and 20 kg, respectively. The cognitive task was to speak out the name of the months in a reverse order as accurately as possible, starting from any random month specified by the experimenter. Gait characteristics were assessed using local dynamic stability measures. Only physical load had significant effects on local dynamic stability. No interactive effects between cognitive and physical loads were found. The findings from this study can aid in better understanding gait characteristics of load-carrying soldiers. In addition, practical implications can also be derived from the results of this study. For instance, in order to prevent unnecessary fall accidents in military training and combat, measures should be taken to reduce the backpack load for soldiers.

[1]  K. Aminian,et al.  Relationships between dual-task related changes in stride velocity and stride time variability in healthy older adults. , 2006, Human movement science.

[2]  J. Steele,et al.  Does load position affect gait and subjective responses of females during load carriage? , 2012, Applied ergonomics.

[3]  J. G. Hollands,et al.  Engineering Psychology and Human Performance , 1984 .

[4]  Thurmon E Lockhart,et al.  Differentiating fall-prone and healthy adults using local dynamic stability , 2008, Ergonomics.

[5]  Paul J Amoroso,et al.  Hospitalizations for fall-related injuries among active-duty Army soldiers, 1980-1998. , 2002, Work.

[6]  R. L. Attwells,et al.  Influence of carrying heavy loads on soldiers' posture, movements and gait , 2006, Ergonomics.

[7]  K. Holt,et al.  How do load carriage and walking speed influence trunk coordination and stride parameters? , 2003, Journal of biomechanics.

[8]  C. Bard,et al.  Attentional demands for static and dynamic equilibrium , 2004, Experimental Brain Research.

[9]  J. Knapik,et al.  Load carriage using packs: a review of physiological, biomechanical and medical aspects. , 1996, Applied ergonomics.

[10]  Michael Roan,et al.  The effect of evenly distributed load carrying on lower body gait dynamics for normal weight and overweight subjects. , 2010, Gait & posture.

[11]  S. Birrell,et al.  The effect of military load carriage on 3-D lower limb kinematics and spatiotemporal parameters , 2009, Ergonomics.

[12]  Joo Chuan Yeo,et al.  Effects of load carriage and fatigue on gait characteristics. , 2011, Journal of biomechanics.

[13]  Karen L Troy,et al.  Effects of an attention demanding task on dynamic stability during treadmill walking , 2008, Journal of NeuroEngineering and Rehabilitation.

[14]  Jonathan B Dingwell,et al.  Intra-session reliability of local dynamic stability of walking. , 2006, Gait & posture.

[15]  S. Simon,et al.  Biomechanical and metabolic effects of varying backpack loading on simulated marching , 2000, Ergonomics.

[16]  M. Willems,et al.  Neuromuscular and cardiovascular responses of Royal Marine recruits to load carriage in the field. , 2012, Applied ergonomics.

[17]  Leif Hasselquist,et al.  Effects of carried weight on random motion and traditional measures of postural sway. , 2006, Applied ergonomics.

[18]  Rodney X Sturdivant,et al.  Metabolic effects of soldier performance on a simulated graded road march while wearing two functionally equivalent military ensembles. , 2007, Military medicine.

[19]  T. Crowder,et al.  Effects of heavy load carriage during constant-speed, simulated, road marching. , 2007, Military medicine.

[20]  Stewart A Birrell,et al.  The effect of load distribution within military load carriage systems on the kinetics of human gait. , 2010, Applied ergonomics.

[21]  Scott A. England,et al.  The influence of gait speed on local dynamic stability of walking. , 2007, Gait & posture.

[22]  J. Dingwell,et al.  Nonlinear time series analysis of normal and pathological human walking. , 2000, Chaos.

[23]  W. Sparrow,et al.  Ageing effects on the attention demands of walking. , 2002, Human movement science.

[24]  J. Dingwell,et al.  Kinematic variability and local dynamic stability of upper body motions when walking at different speeds. , 2006, Journal of biomechanics.