PURPOSE: The purpose of this study is to determine if there is an increase in energy cost with lower leg casting of the dominant leg in healthy individuals using the Physiological Cost Index (PCI). METHODS: Eighteen subjects mean age of 25 years (23-32) performed the ¼ mile walk test without lower leg casting five to nine days prior to performing the ¼ mile walk test with lower leg casting. Subjects were given a 5 minute rest period prior to starting the test. Resting heart rate was taken following the rest period using a standard pulse oximeter. Subjects performed the walk test at their comfortable walking speed (CWS). At the completion of the ¼ mile walk test time was recorded using a standard stopwatch and the walking heart rate was taken using the pulse oximeter. PCI was calculated using the formula: PCI (beats/meter) = Walking heart rate - Resting heart rate (beats/min) Walking speed (meters/min) RESULTS: Preliminary results show a slight increase in energy cost. The value of the PCI without the cast was (.2644±.2076) and the value of PCI with the cast was (.2713±.1965) without outliers. Final results will be calculated at the termination of the study within one week. CONCLUSION: Initial data shows that there is not a significant difference in energy costs specifically in the PCI values in healthy individuals walking with lower leg cast when compared with those walking without a lower leg cast.