The human body is remarkably adaptable to the stresses placed upon it. Have you ever noticed that the skin on your hands is much thinner than the skin on your feet? You've probably noticed that this isn't the case with babies. Have you ever noticed what the skin on the hands of construction workers looks like? It's usually much thicker.
And this is true for all tissues; the human body adapts very well... when given time. Muscles become bigger when we do weight training, bones become stronger, ligaments thicken, cartilage increases in volume, and it even seems that the discs between the vertebrae benefit from the mechanical stress we put on them.
But of course, even at the gym, you need to take breaks. And this also applies to the mechanical stresses of everyday life.
Changing posture is a break
Imagine sitting still, tied down, unable to move, for 12 hours straight...
Even if you've never experienced it, you probably imagine it as something unpleasant, not being able to move.
And for good reason: there is no position that is comfortable when held for a long time [1].
This is probably why, when we sit, we all move unconsciously: we lift one buttock, slouch a little, lean forward slightly, rest our arms on the desk...
All of this causes pressure to be distributed to different areas, a little more on the buttocks, then a little more on the thighs, then a little more on the arms... We have many different strategies for taking “breaks” from constraints.
And the further we get into the day, the more we feel the need to take these “breaks.” As a result, office workers stand up more often at the end of the day or when they have been doing physically demanding activities [2].
Should we change our posture?
At one time, it was recommended to maintain a so-called optimal posture calculated based on knowledge of the mechanics of the average individual. This applied to both sitting and standing, and we even gave advice on the correct movements to use when lifting objects from the floor.
The problem is that despite numerous studies, these strategies do not seem to have had a significant effect on reducing the risk of pain [3]. In recent years, there has been a change in mindset. One author recommends changing the way we advise people to lift loads [4]:
- - First, train people so that their bodies are able to cope with the strain more effectively, just as we would train someone to lift as much weight as possible in a CrossFit session.
- - Then, change the way you lift according to the desired effects. Lean forward if you need to conserve energy, or use the most comfortable technique if you experience pain or discomfort.
And in this paradigm, changing your posture regularly is an excellent way to achieve maximum comfort.
Does it work?
Allowing people to choose their own posture for lifting a load off the ground optimized lifting speed without significantly changing back mechanics [5]. This may not have any implications in real life, but lifting faster means less fatigue.
Different ways to lift: von Arx et al 2021. From stoop to squat: A comprehensive analysis of lumbar loading among different lifting styles. Frontiers in Bioengineering and Biotechnology, 9.
With regard to sitting positions among workers, standing up from time to time during the day reduced the risk of discomfort at the end of the day in one study [6]. Researchers wanted to test the effect of placing electrodes on the back to activate patients' muscles regularly. They found that this reduced muscle stiffness [7].
However, interventions to promote smaller changes in posture have not yet been proven effective, and researchers recommend reserving these interventions for people who experience pain at rest that is improved by movement [8].Among the interventions that vary sitting postures regularly, the use of balls or ball chairs is often recommended. The results in studies are rather mixed in terms of both pain prevention and treatment, and this does not seem to be a very effective idea [9-11].
In summary, small, repeated adjustments to your posture are an option but should not be the focus of your attention until we know more about the effects of these strategies. Major changes, such as switching from sitting to standing, are more likely to make you feel better at the end of the day.
Conclusion
Move! We don't have any magic advice, but changing your position, varying your posture, movements, and positions are common-sense tips that can be recommended today while we wait for future studies to shed more light on what is best to do.
Sources :
[1] Greene, R. D. et al. Transient perceived back pain induced by prolonged sitting in a backless office chair: are biomechanical factors involved? Ergonomics 62, 1415–1425 (2019).[2] Ten Broeke, P. et al. Temporal dynamics of sitting behavior at work. Proc. Natl. Acad. Sci. U. S. A. 117, 14883–14889 (2020).
[3] Rodrigues Ferreira Faisting, A. L. & de Oliveira Sato, T. Effectiveness of ergonomic training to reduce physical demands and musculoskeletal symptoms - An overview of systematic reviews. Int. J. Ind. Ergon. 74, 102845 (2019).
[4] Washmuth, N. B., McAfee, A. D. & Bickel, C. S. Lifting techniques: Why are we not using evidence to optimize movement? Int. J. Sports Phys. Ther. 17, 104–110 (2022).
[5] Von Arx, M. et al. From stoop to squat: A comprehensive analysis of lumbar loading among different lifting styles. Front. Bioeng. Biotechnol. 9, (2021).
[6] Davis, K. G. & Kotowski, S. E. Postural variability: An effective way to reduce musculoskeletal discomfort in office work. Hum. Factors 56, 1249–1261 (2014).
[7] Kett, A. R., Milani, T. L. & Sichting, F. Sitting for too long, moving too little: Regular muscle contractions can reduce muscle stiffness during prolonged periods of chair-sitting. Front Sports Act Living 3, 760533 (2021).
[8] O’Sullivan, K., O’Keeffe, M., O’Sullivan, L., O’Sullivan, P. & Dankaerts, W. The effect of dynamic sitting on the prevention and management of low back pain and low back discomfort: a systematic review. Ergonomics 55, 898–908 (2012).
[9] Elliott, T. L. P., Marshall, K. S., Lake, D. A., Wofford, N. H. & Davies, G. J. The effect of sitting on stability balls on nonspecific lower back pain, disability, and core endurance: A randomized controlled crossover study: A randomized controlled crossover study. Spine (Phila. Pa. 1976) 41, E1074–E1080 (2016).
[10] Kingma, I. & van Dieën, J. H. Static and dynamic postural loadings during computer work in females: Sitting on an office chair versus sitting on an exercise ball. Appl. Ergon. 40, 199–205 (2009).
[11] Schult, T. M. et al. Sitting on stability balls: biomechanics evaluation in a workplace setting. J. Occup. Environ. Hyg. 10, 55–63 (2013).