There is a popular consensus that "bad posture" causes back pain. You can find claims all over the internet, clinical offices and infomercials that you should work on your posture to reduce pain. Many professional schools teach this notion. It is common practice in physiotherapy and other practices to stretch and strengthen various muscles to address postural pain, yet there is little current clinical evidence to support this notion.
"Bad posture" may have aesthetic disadvantages, impacts to our self-confidence and changes in how others perceive us, yet very few studies show that it leads to more pain.
Like many things in our pop culture certain ideas become so ingrained that even when evidence suggests otherwise, we find it hard to change our beliefs.
Most current clinical research has difficulty correlating "bad posture" with pain. Numerous studies have examined if subjects with certain postures are more likely to have back pain as a result of their posture.
Spinal alignment such as increased or decreased spinal curvature, pelvic rotation and leg length discrepancy do not seem to make you more likely to experience pain compared to someone with "normal posture".
People who work in occupations which require frequent awkward posture do not seem to develop more pain than their counterparts who do not.
It is often more likely the reverse -- that pain leads to bad posture. Most people who are experiencing pain, shift or move away from the painful side. The theory is that as a result of pain you may be experiencing is causing you to modify your posture. This can lead to pain not only in the joint affected but also other body joints.
Research does point to an important postural fact: When loading your body with weight or when performing difficult and complex movements it is important for the movement to be executed with good form. Alignment tends to matter with heavy squats, lifting, repeated movements. The take away point is not so much to worry about posture, but rather think about how you move. Improve your quality and quantity of movement. Ensure that you are mastering a movement before adding resistance to the movement (lifting heavy weight or doing prolonged gardening).
You should frequently change postures while working. Do not stay in the same position for too long. Take a call while walking, read while lying on your stomach, stand while writing, sit while doing computer work, stand while doing computer work, perform simple movements or stretches as a break from desk work.
Bellow is the list of references supporting the discussion above.
1. Grundy, Roberts (1984) Does unequal leg length cause back pain? A case-control study. Lancet. 1984 Aug 4;2(8397):256-8. http://www.ncbi.nlm.nih.gov/pubmed/6146810
2. Pope, Bevins (1985) The relationship between anthropometric, postural, muscular, and mobility characteristics of males ages 18-55. Spine (Phila Pa 1976). 1985 Sep;10(7):644-8. http://www.ncbi.nlm.nih.gov/pubmed/4071274
3. Grob, Frauenfelder et al. (2007), The association between cervical spine curvature and neck pain. Eur Spine J. 2007 May; 16(5): 669–678. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2213543/
4. Nourbakhsh, et al. (2002) Relationship between mechanical factors and incidence of low back pain. J Orthop Sports Phys Ther. 2002 Sep;32(9):447-60. http://www.ncbi.nlm.nih.gov/pubmed/12322811
5. Dieck, et al. (1985) An epidemiologic study of the relationship between postural asymmetry in the teen years and subsequent back and neck pain. Spine (Phila Pa 1976). 1985 Dec;10(10):872-7. http://www.ncbi.nlm.nih.gov/pubmed/2938272
6. Franklin, et al. (1988) An analysis of posture and back pain in the first and third trimesters of pregnancy. J Orthop Sports Phys Ther. 1998 Sep;28(3):133-8. http://www.ncbi.nlm.nih.gov/pubmed/9742469
7. Lederman (2010) The fall of the postural–structural–biomechanical model in manual and physical therapies: Exemplified by lower back pain. CPDO Online Journal (2010), March, p1-14. http://www.cpdo.net/Lederman_The_fall_of_the_postural-structural-biomechanical_model.pdf
8. Chaleat-Valleyed, et al. (2011) Sagittal spino-pelvic alignment in chronic low back pain. Eur Spine J. 2011 Sep;20 Suppl 5:634-40. http://www.ncbi.nlm.nih.gov/pubmed/21870097;
9. Smith, O-Sullivan, et al. (2008) Classification of sagittal thoraco-lumbo-pelvic alignment of the adolescent spine in standing and its relationship to low back pain. Spine (Phila Pa 1976). 2008 Sep 1;33(19):2101-7. http://www.ncbi.nlm.nih.gov/pubmed/18758367.
10. Christensen, et al. (2008) Spinal curves and health: a systematic critical review of the epidemiological literature dealing with associations between sagittal spinal curves and health. J Manipulative Physiol Ther. 2008 Nov-Dec;31(9):690-714. http://www.ncbi.nlm.nih.gov/pubmed/19028253
11. Papageorgeoui, et al. (1997) Psychosocial factors in the workplace--do they predict new episodes of low back pain? Evidence from the South Manchester Back Pain Study. Spine (Phila Pa 1976). 1997 May 15;22(10):1137-42. http://www.ncbi.nlm.nih.gov/pubmed/9160473
12. Hodges, Moseley (2003) Experimental muscle pain changes feedforward postural responses of the trunk muscles. Exp Brain Res (2003) 151:262–271 http://cdns.bodyinmind.org/wp-content/uploads/Hodges-et-al-2003-Exp-Brain-Res-experimental-lbp.pdf