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Thelen DG, Schultz AB, Alexander NB, Ashton-Miller JA.Thelen DG, et al.J Gerontol A Biol Sci Med Sci. 1996 Sep;51(5):M226-32. doi: 10.1093/gerona/51a.5.m226.J Gerontol A Biol Sci Med Sci. 1996.PMID: 8808994