The purpose of the study is to explore if self biofeedback program can reduce ground reaction force (GRF) from the lower extremity of the body and in the knee in particular and help obese children to avoid knee injuries.

This study will include approximately 50 patients, aged 7-12 years. All participants and their parents will sign an informed consent form before entering the study. At the beginning, participants are asked to answer a "vas scale" questionnaire for pain. Participants will be recruited from the population of overweight children from children's sports medical center 'Meir' in Kfar Saba. In the first stage the participants will be divided randomly into two groups of intervention and control. All children will take a test of 1 km and will be instructed to walk in the maximum phase before running (at the maximum it that the child can go without running) for calculating and determine the rate of 1.0 during the assessment of the intervention program for each participant. In addition, measures of the knees (valgus) will be made by a Goniometer, which is a protractor that measures angles between bones at a precise angle.

Each participant will fill a questionnaire about pain and difficulty from which he suffers in the knee. Participants will describe to the researcher the degree of pain and / or discomfort in motion (such as walking, running) and then pass a physical examination to diagnose a knee injury.

The intervention program will take four weeks while in each week their will be two exercise session and a total of 8 sessions. Each session length is about 9 minutes. Each session will include a continuous exercise in which the patient will do walking, walking pace and running (3 minutes each section). During the meeting, participant will receive biofeedback that will displayed on a computer screen that shows the forces that develop in the knee joint so that the patient can see graphically the forces that develop around the knee joint and will be guided / try to reduce the values of the graph by changing the intensity of his landing on the tracks (be guided to land more "light", "soft" landing with a smaller noise). In all training the time that the biofeedback is shown will be reduced. The control group will receive the same training program without providing biofeedback. Each participant will perform the test with his personality shoes. At the end of the intervention program will be a statistical comparative test of the GRF that developed in the knee Relative to each child Vs his original GRF and the group averages.

Inclusion Criteria:

1. Children, boys and girls, ages 7-12.
2. Children with overweight defined as BMI percentile over 85%
3. Children who are able to perform moderate physical activity.
4. Children who are able to understand and perform simple directions according to their age.

Exclusion Criteria:

1. Participant that does not wish to participate - will not be obligated to do so, and shall not participate in the study.
2. Participants with a history of chronic knee injuries
3. Participants with a background in competitive sport will not be included in the study.