Asymmetrical loading during non-visual navigation

Since previous studies showed that loading influences posture and gait, the aim of the present study was to determine the effect of asymmetrical loading on locomotion. The following questions were posed: is there a habituation to asymmetrical loading and what is the effect of immediate unloading? Nine healthy subjects (4 males and 5 females) were tested. They had to memorize visually a triangle drawn on the floor and then to walk clockwise and counterclockwise along it in darkness and blindfolded under the following conditions: baseline, loading of right shoulder with 20% of the body weight, after 30 min of habituation to the weight, and immediately after unloading. The turns in degrees around the angles and the distance of the path in cm were measured. The present study demonstrated that asymmetrical loading, which leads to changes in the somatosensory afferentation, affects the human locomotor pattern. There is a habituation effect as well as an unloading effect. There was also a difference between the changes in clockwise and counterclockwise locomotion. Several hypotheses are discussed to explain the results obtained under all conditions.