By observing children's entry or exit from a basic education school, any adult who is not familiar with this image, immediately will note that many children must carry "too much weight" in the backpack and that this "overload" could harm their health in the medium and long term. Carrying school supplies and other assets by pre puberty students is a problem that concerns the whole school community. Although every year, at the beginning of the school year, several attention calls to the problem appear in media and some organizations disseminate several recommendations to alleviate the problem, in practice, nothing concrete is done to change this situation. Before advancing in the text it should be defined, in a very simplified way, what is meant by "normal gait". In this thesis, "normal gait", is defined as being made without overload with self-selected speed; as opposed to "normal gait" we have "pathological gait." One concern of education community is to know what is the maximum load limit that a child can carry, ie, when the load leads to a pathological gait, impacting on the normal development of the child. This is the problem that we propose to study in this thesis. Neuromuscular system controls human movement. Gait is described as a set of repeated movement cycles determined by a multifactorial set considered determinate to the same pattern. When is wanted to make a gait assessment it is important to include more than one analysis technique, been used in this work some like kinematics, muscle activity (EMG), energy cost and thermography. When the motion is not carried out with the minimum possible energy expenditure, there are changes in its kinematic pattern, in muscle activation and temperature detected at the body surface.