Clinical Utility of the 1-minute Sit to Stand Test as a Measure of Submaximal Exercise Tolerance in Patients With Cystic Fibrosis During Acute Pulmonary Exacerbation

Inclusion Criteria: * patients age 6-35 with cystic fibrosis who are admitted for a pulmonary exacerbation and receive ongoing physical therapy throughout their admission. Exclusion Criteria: * patients with cystic fibrosis who are under the age of 6, * patients with cystic fibrosis who are not admitted for a pulmonary exacerbation, * patients with cystic fibrosis who are not being followed regularly by physical therapy (\>5x/week) throughout their inpatient admission, * patients with cystic fibrosis who are unable to follow instructions for standardized testing, * patients with cystic fibrosis who are not medically stable to participate in submaximal exercise testing. * patients whose inpatient admission is anticipated to be \<1 week. * Patients who are readmitted to the hospital within the year will not be included in the study more than once.