A central tenant of the corrective exercise approach is that strengthening weak muscles and lengthening short muscles will improve posture (Kendal et al 1993). For example Janda (1987) suggested that his lower cross syndrome, anterior pelvic tilt and increased lumbar lordosis, was due to tight erector spinae and hip flexors coupled with weak lower abdominals, gluteals and hamstrings.  Hyrsomallis and Goodman (2001) conducted the last significant review on this topic. They concluded that muscular strength was not related to posture based on the research up to that point. However, deeper analysis...