Chest expansion is a respiratory system assessment technique which is easy to use and gives an idea about the chest mobility and the capacity of lung to expand. There is a difference between the normal adult and paediatric respiratory system with respect to the anatomical and physiological development of lungs.

               The cross-sectional shape of infant thorax is cylindrical and not elliptical as in adolescents or adults. Cartilaginous and extremely compliant chest wall of new-born allows necessary distortion of the infant’s thorax to travel through the birth canal. The rib cage of an infant has more horizontal alignment of ribs compared to the oblique configuration of ribs seen in adults giving rise to a variation in the biomechanics.

               Normally, the process of inspiration is active and that of expiration is passive. This occurs as the pump handle movement is seen in upper thorax while the bucket handle movement seen in lower thorax. With inspiration there is pump handle movement which causes increase in the anteroposterior diameter of thorax, while in the bucket handle movement there is an increase in the transverse diameter of lower thorax. Movement of the ribs occur at the costotransverse and costovertebral joints. Orientation of these joints varies in the upper and lower joints. The transverse diameter is greater than the anteroposterior diameter giving it an ellipsoid shape with the ratio 7:5.

               The development of alveoli in lung continues and is completed by 10yrs of age, most of which occurs in first 6 months of life. The number of alveoli increases with increase in height.

Normal chest wall mobility is important for effective lung expansion and subsequent ventilation. Respiratory evaluation is an integral part of Chest Physiotherapy. Hence, normative values of chest expansion in paediatrics and adults are different. Therefore, there is a need to study paediatric respiratory system separately.

                 Normative values of chest expansion among healthy young individuals of the age group 5 – 12 years are known but there is no evidence of its intrarater reliability. Hence to check this intrarater reliability, the individuals from 5 – 12 years age group have been chosen.

                 Intrarater reliability is defined as the consistency of data recorded by one rater over several trials. It is a diagnostic tool used to check the test validity. The intrarater reliability studies will help to check the reliability of the normative values.

                As chest expansion is a non-invasive method of lung function and chest mobility, aim of the study is to check the reliability of the chest expansion in paediatric age group – in 5-12 years in Pune City.