***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE To investigate the effect of sitting posture on lung capacity and expiratory flow ( LC-EF ) and lumbar lordosis . DESIGN Repeated measures on 1 group of subjects in 4 postures . SETTING Laboratory . PARTICIPANTS Seventy able-bodied volunteers . INTERVENTIONS Postures were assumed r and omly : normal , with full ischial support and flat lumbar support ; slumped , with the pelvis positioned in the middle of seat while leaning against the backrest ; against the back part of the seat without ischial support ( WO-BPS ) , with partially removed ischial support and an enhanced lumbar support ; and st and ing . MAIN OUTCOME MEASURES For LC-EF , forced vital capacity , maximum forced expiratory flow , forced expiratory volume in 1 second , and peak expiratory flow ; and lumbar lordosis . RESULTS All LC-EF measures in st and ing were significantly superior to those in slumped and normal sitting , and 4 measures were significantly higher than in WO-BPS . In slumped sitting , LC-EF significantly decreased from that in normal sitting . WO-BPS sitting significantly increased 4 of the LC-EF measures from those in the normal sitting . Lumbar lordosis was the highest in st and ing and progressively decreased in WO-BPS , normal , and slumped sitting . CONCLUSIONS Slumped sitting significantly decreased LC-EF and lumbar lordosis . Because it increases the lumbar lordosis and promotes LC-EF , the WO-BPS posture may be a better seating option for people sitting for a prolonged time BACKGROUND Individuals may respond differently to various chair design s and the factors that influence these sitting behaviours are not well understood . There is very little information in the scientific literature regarding the observation and documentation of gender differences in seated postures . In particular , anecdotal observations of potential gender-specific sitting behaviours led us to test the influence of gender on the postural responses to different seated conditions . METHODS Sixteen healthy university students ( 8 males and 8 females ) were tested on four different chair configurations .  Upper body kinematics ( spine angles and centre of mass ) and seat pressure profiles ( centre of pressure , peak pressure ) were obtained during each testing session . FINDINGS Regardless of the chair used or the task performed , average lumbar and trunk angles were significantly more flexed for males than for females ( P=0.047 and P=0.0026 , respectively ) . Males exhibited average lumbar spine and trunk angles of 65.4 degrees ( SD 16.2 degrees ) and 29.8 degrees ( SD 28.3 degrees ) , respectively , while female lumbar spine and trunk angles were 49.6 degrees ( SD 23.1 degrees ) and -3.3 degrees ( SD 20.4 degrees ) , respectively . The pelvis was posteriorly rotated for males ( 7.6 degrees ( SD 8.2 degrees ) ) and anteriorly rotated for females ( -5.5 degrees ( SD 9.3 degrees ) ) ( P=0.0008 ) . Significant gender * chair interactions of the location of the individual on the chair seat were most marked for the pivoting chair with a back rest . Females positioned their centre of mass and hip joints anterior to the chair pivot point while males ' centre of mass ( P=0.0003 ) and hip joints ( P=0.0039 ) were located posterior to the pivot point . Females also sat with their centre of mass closer to the seat pan centre of pressure than males when a back rest was present ( P=0.0012 ) . INTERPRETATION Males and females may be exposed to different loading patterns during prolonged sitting and may experience different pain generating pathways . Therefore , gender-dependent treatment modalities and /or coaching should be implemented when considering methods of reducing the risk of injury or aggravation of an existing injury STUDY DESIGN R and om allocation of subjects into a placebo-controlled , crossover study . OBJECTIVES To investigate the effect of changing thoracic and scapular posture on shoulder flexion and scapular plane abduction range of motion in asymptomatic subjects , and in subjects with subacromial impingement syndrome . BACKGROUND Changes in upper body posture and concomitant imbalance of the muscle system have been proposed as one of the etiological mechanisms leading to subacromial impingement syndrome . Although clinicians commonly assess posture and devise rehabilitation programs to correct posture , there is little evidence to support this practice . METHODS AND MATERIAL S Selected postural , range of movement , and pain measurements were investigated in 60 asymptomatic subjects and 60 subjects with subacromial impingement syndrome , prior to and following thoracic and scapular taping intended to change their posture .  RESULTS Changing posture had an effect on all components of posture measured ( P<.001 ) and these changes were associated with a significant increase ( P<.001 ) in the range of motion in shoulder flexion and abduction in the plane of the scapula . Changing posture was not found to have a significant effect on the intensity of pain experienced by the symptomatic subjects , although the point in the range of shoulder elevation at which they experienced their pain was significantly higher ( P<.001 ) . CONCLUSIONS The findings of this investigation suggest that changing 1 or more of the components of posture may have a positive effect on shoulder range of movement and the point at which pain is experienced 
    Output:
    
Incorrect sitting posture contributes to many disorders , especially in the cervical and lumbar spine .
It also determines the work of the respiratory system .
Most authors suggest that maintenance of the physiological curvature of the spine is crucial for the biomechanics of the sitting position , as well as the location of the head and position of the pelvis .