1) Burr, D. B., Martin, R. B. and Martin, P. A. (1983) : Lower extremity loads stimulate bone formation in the vertebral column. Implications for osteoporosis. Spine 8 (7) , 681-686.
2) Chow, R. K., Harrison, J. E., Brown, C. F, and Hajek, V. (1986) : Physical fitness effect on bone mass in postmeanopusal women. Arch. Phys. Med. Rahabil., 61, 231-234.
3) Dalen, N, and Olsson, K. E. (1974) : Bone mineral content and physical activity. Acta Orthop. Scand., 45, 170-174.