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. (C) 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.