We quantified lumbar lordosis and thoracic kyphosis in standing posture by three-dimensional measurement and investigated their gender differences and changes with pelvic forward tilt. Subjects were healthy young adults (25 men and 25 women). The subjects maintained a quiet standing and a standing with maximum pelvic forward tilt for 10 seconds each, with eyes closed. Three-dimensional spatial coordinates of 6 body parts were identified: the 7th cervical vertebra (C7), maximum backward point of

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... thoracic kyphosis, maximum forward point of lumbar lordosis, 1st sacral vertebra (S1), right anterior superior iliac spine, and right posterior superior iliac spine. The lumbar lordosis and thoracic kyphosis were identified using a conformateur. The curvature degree was evaluated by the relative distance from the lumbar lordosis point or thoracic kyphosis point to the straight line between C7 and S1. In quiet standing, the lumbar lordosis was significantly greater in women and the thoracic kyphosis in men. With the pelvis tilt forward, the lordosis increased, and the kyphosis decreased, significantly in both men and women. No gender differences were found in these changes. In women, there was a moderate correlation between the lumbar lordosis and thoracic kyphosis in both quiet and pelvic tilt standing (quiet r = 0.600; pelvic tilt r = 0.572; ps < 0.01), suggesting that their curvatures would change with related to each other. In men, no correlation was found between them, suggesting the independence of each curvature.