Change in biomechanics of sitting posture affects the pulmonary function

ABSTRACT The objective of this study was to characterize the postures induced by two different chair-desk systems and analyze their effects on lung function. This was a cross-sectional, descriptive study of single subject with intra-series type analysis (A-B, B-A) during consecutive days of data collection. Fifteen volunteers participated using two chair-desk systems: conventional (A) and experimental (B). Postural evaluation was performed in both systems using photogrammetry. These images were analyzed using AutoCAD® 2010, estimating the average position of the joint angles of individuals in each system. These values were analyzed verifying the averages in each posture. Postural and respiratory data were compared by checking whether the different positions adopted by the participants resulted in changes in the spirometry values. Conventional chair-desk system promoted two different postural patterns, considering that one presented joint angles similar to experimental system, with similar spirometry results and the other presented body angles according to the reference of standards and spirometry results significantly lower in FEV1, FEV1/FVC and FEFmax. Experimental system differed from values of literature in standing posture only in FEFmax, suggesting similarity of postural situation. It was concluded that the experimental furniture proved a tool capable of benefiting respiratory function in sitting posture and may be an option to benefit people in special conditions such as pregnant women, obese individuals and people with chronic pulmonary diseases.摘要 本研究旨在表征两种不同桌椅系统所诱导的身体姿态，并分析其对肺功能的影响。本研究为横断面描述性研究，采用系列内（A-B、B-A）分析范式，于连续多日内开展数据采集工作。共有15名志愿者参与，分别使用两种桌椅系统：常规桌椅系统（A）与实验桌椅系统（B）。采用摄影测量法对两种系统下的受试者姿态进行评估，通过AutoCAD® 2010对采集到的影像进行分析，估算每名受试者在各系统下的关节角度平均位置，并对上述数值展开分析以验证不同姿态下的平均指标。通过比对受试者采取的不同姿态是否会引发肺量测定参数变化，对姿态数据与呼吸数据进行对比分析。常规桌椅系统可诱导两种不同的姿态模式：其中一种的关节角度与实验桌椅系统相近，对应的肺量测定结果也相似；另一种的身体角度符合标准参考值，但一秒用力呼气容积（Forced Expiratory Volume in 1 second，FEV1）、一秒率（FEV1/FVC）与最大呼气流量（Maximum Expiratory Flow，FEFmax）的测定结果显著更低。实验桌椅系统仅在站立姿态下的最大呼气流量（FEFmax）与文献报道值存在差异，提示其姿态状态与标准情况较为接近。研究结论表明，实验桌椅系统可作为改善坐姿下呼吸功能的有效工具，有望为妊娠女性、肥胖人群及慢性肺部疾病患者等特殊群体提供获益选择。