Due to their profession and the tasks it entails, soldiers are exposed to high levels of physical activity and strain. This can result in overexertion and pain in the locomotor system, partly caused by carrying items of equipment. The aim of this study was to analyse the extent of muscle activity in the lower extremities caused by carrying specific items of equipment. For this purpose, the activity of selected groups of muscles caused by different items of equipment (helmet, carrying strap, backpack, and rifle) in the upper and lower leg was measured by recording dynamic surface electromyograms. Electrogoniometers were also used to measure the angle of the knee over the entire gait cycle. In addition to measuring muscle activity, the study also aimed to determine out what influence increasing weight load has on the range of motion (ROM) of the knee joint during walking. The activity of recorded muscles of the lower extremity, that is, the tibialis anterior, peroneus longus, gastrocnemius lateralis, gastrocnemius medialis, rectus femoris, and biceps femoris, was found to depend on the weight of the items of equipment. There was no evidence, however, that items of equipment weighing a maximum of 34% of their carrier's body weight had an effect on the ROM of the knee joint.

Background. The wearing of personal equipment can cause specific changes in muscle activity and posture. In the present study, we investigated the influence of differences in equipment related weight loading and load distribution on plantar pressure. In addition, we studied functional effects of wearing different equipment with a particular focus on relevant changes in foot shape. Methods. Static and dynamic pedobarography were performed on 31 male soldiers carrying increasing weights consisting of different items of equipment. Results. The pressure acting on the plantar surface of the foot increased with higher loading, both under static and dynamic conditions (p < 0.05). We observed an increase in the contact area (p < 0.05) and an influence of load distribution through different ways to carry the rifle. Conclusions. The wearing of heavier weights leads to an increase in plantar pressure and contact area. This may be caused by flattening of the transverse and longitudinal arches. The effects are more evident in subjects with flat feet deformities which seem to flatten at an earlier load condition with a greater amount compared to subjects with normal arches. Improving load distribution should be a main goal in the development of military equipment in order to prevent injuries or functional disorders of the lower extremity.