Loads Carried by Soldiers: Historical, Physiological, Biomechanical and Medical Aspects

Abstract : Loads currently recommended by the U.S. Army Infantry school are 33 kg for an approach march load (45% of body weight) and 22 kg for a combat load (30% of body weight). Methods of reducing loads include the use of lightweight technology, load tailoring, auxiliary transport systems, doctrinal changes, and physical training. Specific physiological factors involved in load carriage include aerobic capacity and muscle strength. The specific muscle groups involved in load carriage have been examined using correlational approaches, EMG analysis and strength changes after marching. Most of the functional muscle groups of the lower body (hip extensors, knee flexors and extensors, ankle plantar flexors), are involved in load carriage performance. It also appears that the trunk extensors may be important. A combination of jogging, interval training and resistance training will improve load carriage performance over short distances. Marching with loads in combination with other military training appears to increase VO2 max in recruits. The energy cost of load carriage is minimized if the load is placed as close to the center of mass of the body as possible. Self pacing results in a lower energy cost than a forced pace. Loads carried on the feet increase the energy cost of 0.7 to 1.0% for every additional 0.1 kg. Lower extremity injuries are those most commonly experienced in load carriage.