Effect of Forward Shoulder Posture on Forced Vital Capacity- ACo-relational Study

Forward shoulder/rounded shoulder posture is one of the numerous deviations from the normal or standard posture. Forward shoulder is described as abduction and elevation of the scapula and a forward position of the shoulder, giving an appearance of a hollow chest^2,3.The etiology of FSP have been attributed to several factors that include muscle weakness and shortening. It can result from shoulder being pulled forward by overdeveloped, shortened and tight anterior shoulder girdle muscles, such as serratus anterior, pectoralis major, pectoralis minor and upper trapezius muscles. FSP can also be caused by weakness and lengthening of the muscles that function to pull the scapula towards the spine, such as the middle and lower trapezius muscles. Presence of excessive habitual flexion of the back will lead to shortening of pectoral muscles and fix the shoulders in forward position leading to FSP⁴. Muscles that become tight tend to pull the body segments to which they are attached, creating postural deviation. The respiratory pump is comprised of the muscles of respiration and the thorax is made up of the ribs, scapulae, clavicle, sternum and the thoracic spine. Muscular effort is required to enlarge the thoracic cavity and lower the interthoracic pressure. Muscles attached to the rib cage can influence the mechanics of breathing to some degree³. Optimal breathing capability derives from a posture of optimal muscle balance. A balanced musculature is most efficient in terms of energy expenditure. Imbalance of musculature resulting from tightness, weakness or paralysis may adversely affect the volumes and pressures that can be attained or maintained. Weakness of upper back erector spainae, middle and lower trapezius muscle interferes with the ability to straighten the upper back, thus limiting the ability to raise and expand the chest and maximize the lung capacity².The aim of this study was to know weather there is any effect of forward shoulder posture on forced vital capacities.

15 non smoking male subjects with a mean age of 35.26(SD ±15.38) diagnosed to have Forward shoulder posture (FSP) were taken for the study. FSP was assessed by plumbline method and by measurement of interscapular distance (ISD). Forced Vital Capacity (FVC) of these subjects was recorded by spirometer.

The mean values of FVC, plumb line and ISD were as follows FVC 63.06 (SD±15.24), and ISD 5.16(SD±0.66). Karl Pearson's correlation coefficient technique was used to correlate the effect of ISD on FVC in non smoking subjects. Where r = -0.77(t=4.51) and (p<0.01), there was a negative correlation of ISD on FVC. Correlation of Plumb line with FVC was done by spearman's rank correlation coefficient technique. There was a significant correlation of plumbline on FVC where p=0.0056(p<0.05).

The present study concludes that, in patients with FSP there is increase in the ISD and plumb line measurements and both these variables have an effect on FVC. As the ISD and plumb line measurement increases, there is decrease in the FVC.