Plantar fasciitis is the most common cause of heel pain affecting 10 -15 percentage of the general population.In Indian population the Prevalence of patients with heel pain and calcaneal spur is to be 59 percentage. The aim of the study is to analyze gastrocnemius muscle thickness using ultrasonography and its influence on physical performance among subjects with sarcopenia and plantar fasciitis. Windlass test is done to test plantar fasciitis in patients coming to physiotherapy OPD.SARC-CalF questionnaire is filled by the therapist in order to find if the patient is sarcopenic or non-sarcopenic. Patients having greater than or equal to 4 score in this questionnaire with Calf Circumference less than 34 cm for men or less than 33 cm for women indicates low muscle mass. Then patients are taken for an ultrasonography imaging, through which the muscle thickness of the medial gastrocnemius is to be assessed. Those with medial gastrocnemius muscle thickness reduced more than 1.5cm are taken in the sarcopenic group, and patients having muscle thickness 1.5cm or more are taken in the non-sarcopenic group. After assessing the medial gastrocnemius thickness, the patient’s physical performance is assessed in both the groups. For assessing the physical performance, the patient is asked to walk a distance of 4 meters in a straight line. 0.8m per sec is the optimal time for the patient to walk. Patients should complete 4 meters in 3.2seconds.