Alteration and Recovery of Lumbar Spine Mechanics to Flexed Postures

社会已经意识到长时间坐着是不好的。虽然研究人员已经表明，长期久坐与罹患疾病和过早死亡的风险更高有关，但人们对其短期影响知之甚少。坐着涉及脊柱的大量弯曲，这直接影响到下背部的肌肉、神经和关节。这些结构的变化可能会导致伤害，从而对生活质量、工作能力和生产力水平产生重大影响。同样有趣的是，在健康人群中，一些人似乎能够无所事事地坐着，而另一些人则不能。 目前，我们知道长时间处于背部完全弯曲的姿势会导致脊柱变得更灵活，延长肌肉启动以保护关节的时间，并可能导致脊柱韧带发炎。也有证据表明，逆转上述变化所需的时间是创建这些变化所需时间的两倍多。将这些研究结果应用于坐着并不完全正确，因为大多数研究只关注最大弯曲，而坐着涉及较少的极端弯曲。同样，当检查了适当的姿势时，测试时间很短，与实际工作情况不能相提并论。到目前为止，还没有研究人员观察健康人群中久坐耐受和不耐受个体之间的差异。 为了解决这些问题，该项目将使用健康的人类受试者来调查坐着时腰部的变化及其持久性，反应的是与工作场所相关的暴露时间和座椅类型。具体地说，将测量和比较不同座椅(办公室、汽车和坐/站凳子)之间、耐坐/不耐受个体之间以及持续时间(小时、天和一周)之间背部灵活性和肌肉活动的变化。 这项研究计划的预期结果包括：(1)久坐耐受者和久坐不耐者在灵活性和/或肌肉功能方面的差异，(2)对不同座椅类型和暴露时间的灵活性和肌肉功能反应，以及(3)在短时间(几小时、一天)和中等(周)办公室坐着后灵活性和肌肉变化的持久性。 这些结果将直接导致有针对性的工作场所干预，并有能力设计适当的工作/休息战略和循证指导方针，以限制在工作场所坐着的机会。此外，它还将通过提供关于久坐的影响如何随着时间积累和持续的重要信息，为研究做出贡献。由于大多数加拿大人一天中的大部分时间都是坐着工作的，因此这项研究的结果将产生深远的影响，提高工人的生产率和表现，并最终使经济和行业受益。

Society has become aware that sitting for long periods of time is bad. While researchers have shown that sitting is linked with higher risk of developing diseases and earlier death in the long-term, relatively little is known about the short-term effects. Sitting involves a great amount of bending in the spine that directly affects the muscles, nerves and joints of the low back. Changes to these structures can lead to injury resulting in significant impacts on quality of life, the ability to work and productivity levels. It is also interesting that, within the healthy population, some individuals seem to be able to sit extensively without issue whereas others cannot. Currently, we know that long periods in a posture where the back is totally bent causes the spine to become more flexible, lengthens the time it takes for muscles to turn on to protect joints and can cause inflammation in the ligaments of the spine. There is also evidence that the reversal of the above changes takes more than twice the time it took to create them. Applying these research findings to sitting is not completely correct since most work has only looked at maximum bending whereas sitting involves less extreme bending. Similarly, when appropriate postures have been examined, the testing length has been brief and not comparable to real job situations. To date, no researchers have looked at differences between sitting tolerant and intolerant individuals in the healthy population. To address these questions, this program will use healthy, human subjects to investigate changes to the low back, and their persistence, in response to sitting with exposure times and seating types relevant to the workplace. Specifically, changes in back flexibility and muscle activity will be measured and compared between different seats (office, automobile and sit/stand stools), between sitting tolerant/intolerant individuals and between durations (hours, days and one week). The anticipated outcomes of this research program include the determination of: (1) differences in flexibility and/or muscle function between sitting tolerant and intolerant individuals, (2) flexibility and muscle function response to various seating types and exposure times and (3) the persistence of flexibility and muscle changes after short (hours, day) and medium (week) exposures to office sitting. These results will directly lead to targeted workplace interventions and the ability to design appropriate work/rest strategies and evidence-based guidelines to limit exposure to sitting in the workplace. Further, it will contribute to research by providing important information on how the effects of sitting accumulate and persist over time. Since the majority of Canadians spend most of their day sitting at work, the results of this research will have far reaching effects, improving the productivity and performance of workers, and ultimately benefiting the economy and industry.