A new study suggests that sitting upright （坐直）for hours at a time -- for example, when working at a computer -- may lead to chronic back pain（背疼）. Instead, the best position for your back is somewhat reclined, sitting at a 135-degree angle （即身体和大腿成135度角）rather than the 90-degree angle most office chairs are designed for.
Back pain is one of the most common causes of（表达原因的方式）work-related disability（工伤） in the U.S. and helping to identify bad seating postures（不良坐姿） may help protect the spine(保护脊椎) and prevent injury.
Overall, researchers concluded that the 135-degree reclining position（135度角坐姿） put the least stress on the spine and may reduce the risk of back pain（减少背疼的风险）. They recommend that people who sit for long periods of time（坐很长时间= sit for long time）correct (动词用法，纠正) their sitting posture and find a chair that allows them to recline.
"This may be all that is necessary to prevent back pain, rather than trying to cure pain（治疗疼痛） that has occurred over the long term（长期） due to bad postures," says Bashir. "Employers could also reduce problems by providing their staff with more appropriate seating(提供员工合适的座椅), thereby（thereby doing sth. 以此来，表示目的）saving on the cost of lost work hours."
Studying at home may lead children to increase their sedentary behavior, which can be detrimental to their physical fitness. Supposing that learners sit for long periods of time with bad seating postures at a time, with the passage of time, they are more likely to suffer back pain. In contrast to those attending a class at school, this is less likely to happen, as students have many opportunities to engage in various activities and be more physically active.