School of Physiotherapy (Faculty of Health) & Division of Geriatric Medicine (Faculty of Medicine), Dalhousie University, Halifax, NS B3H 4R2, Canada.
Geriatric Medicine Research, Dalhousie University & Nova Scotia Health, Halifax, NS B3H 4R2, Canada.
Sensors (Basel). 2023 Jan 4;23(2):587. doi: 10.3390/s23020587.
Objective monitors such as the activPAL characterize time when the thigh is horizontal as sedentary time. However, there are physiological differences between lying, bent-legged sitting, and straight-legged sitting. We introduce a three-monitor configuration to assess detailed sedentary postures and demonstrate its use in characterizing such positions in free-living conditions. We explored time spent in each sedentary posture between prolonged (>1 h) versus non-prolonged (<1 h) sedentary bouts. In total, 35 healthy adults (16♀, 24 ± 3 years; 24 h/day for 6.8 ± 1.0 days) wore an activPAL accelerometer on their thigh, torso, and shin. Hip and knee joint flexion angle estimates were determined during sedentary bouts using the dot-product method between the torso−thigh and thigh−shin, respectively. Compared to lying (69 ± 60 min/day) or straight-legged sitting (113 ± 100 min/day), most time was spent in bent-legged sitting (439 ± 101 min/day, p < 0.001). Most of the bent-legged sitting time was accumulated in non-prolonged bouts (328 ± 83 vs. 112 ± 63 min/day, p < 0.001). In contrast, similar time was spent in straight-legged sitting and lying between prolonged/non-prolonged bouts (both, p > 0.26). We document that a considerable amount of waking time is accumulated in lying or straight-legged sitting. This methodological approach equips researchers with a means of characterizing detailed sedentary postures in uncontrolled conditions and may help answer novel research questions on sedentariness.
目的监测器，如 activPAL，将大腿处于水平位置的时间定义为久坐时间。然而，躺着、曲腿坐和直腿坐之间存在生理差异。我们引入了一种三监测器配置来评估详细的坐姿，并展示其在自由生活条件下用于描述这些姿势的用途。我们探索了在长时间（>1 小时）和非长时间（<1 小时）坐姿之间，每种坐姿所花费的时间。共有 35 名健康成年人（16 名女性，24 ± 3 岁；24 小时/天，持续 6.8 ± 1.0 天）在大腿、躯干和小腿上佩戴 activPAL 加速度计。使用躯干-大腿和大腿-小腿之间的点积法，分别在坐姿期间确定髋关节和膝关节的弯曲角度估计值。与躺着（69 ± 60 分钟/天）或直腿坐（113 ± 100 分钟/天）相比，大多数时间用于曲腿坐（439 ± 101 分钟/天，p < 0.001）。大部分曲腿坐时间都积累在非长时间坐姿中（328 ± 83 分钟/天，比长时间坐姿多 112 ± 63 分钟/天，p < 0.001）。相比之下，长时间/非长时间坐姿之间的直腿坐和躺着时间相似（两者，p > 0.26）。我们记录到，大量的清醒时间是在躺着或直腿坐中积累的。这种方法为研究人员提供了一种在不受控制的条件下描述详细坐姿的手段，可能有助于回答关于久坐的新研究问题。
