The Effects of Military Style Ruck Marching on Lower Extremity Loading

Load carriage while performing prolonged marches may play a role in military overuse injuries. It is known that both external load carriage and muscular fatigue can contribute to increases in ground reaction forces and loading rate and play a role in stress injuries. The purpose of this study is to determine whether or not a prolonged military style ruck march will cause changes in vertical ground reaction force and loading rate. 15 healthy members of the Army ROTC and Army National Guard performed vertical jumps, had ankle dorsiflexion, plantarflexion, inversion and eversion strength measured, and walked across a force plate before and after a 4-mile ruck march wearing full combat gear and a 16kg rucksack. Paired t-tests were used determine if the ruck march caused significant changes in these measures. The pre and post march values of peak vertical ground reaction force (p\u3c0.005), loading rate (p=0.003), plantarflexion (p=0.006), and dorsiflexion (p=0.01) strength all changed significantly. It would appear that a relatively short ruck march can elicit significant increases in both vertical ground reaction force and loading rate, while significantly reducing plantar and dorsiflexion strength, all of which are likely factors in the high rate of overuse injuries among military personnel