Abstract: The author made careful observations and measurements on the facade and flank X-ray photographs of the tibia of 45 boys including the ordinary group, weight-lifting group and jumping group in accordance with their sports'specialities. Statistical analyses of the related indices were taken.
As far as the thickness of substantia compacta of tibia wall is concerned, the medial wall is larger than the lateral one and margo anterior is larger than posterior wall. Both the medial wall of weight-lifting athletes and the margo anterior of jumping athletes become thick. A biomechanic explanation is given for these changes.

Key words: Tibia; Substantia compacta; Anthropometry; Biomechanic mechanism