Studies were carried out to examine methods of measuring leg densities and to learn whether physical activity affects the composition of the leg. Sixty five female college students were tested to determine the center of mass of the leg and then the leg weight was determined using a single or double scale method. The center of mass was found to fall 43% of the distance distal from the trochanter. This was below the upper patella landmark used in the single scale method. It was indicated that the more dense the leg, the higher the center of mass. A second study measured the changes in leg densities and size following a five week training period. Seven males and seven females used a strength training apparatus. The results showed strength and girth changes occurred with females reducing the girth and both males and females increasing strength. The habituation to exercise may have played a part in the changes. Strength increases change much faster than size or weight. Females changed strength at a faster rate than males and subjects exercising very little had similar leg compositions when compared to heavy exercisers.