Subjects assigned to the intervention group will undergo clinical strength testing. An individualized program will be developed for each subject based on his or her AMP test results and clinical strength testing. Subjects will then attend rehabilitation sessions 3 times per week for 8 weeks. Each session will last approximately 45 minutes including any required rest periods. Subjects will perform endurance, balance and strengthening exercises at each session. Every 6th session, subjects in the intervention group will perform a six-minute walk test, AMPPro and complete the AAS questionnaire. The results of each AMPPro test will be reviewed and the therapeutic exercise program revised according.