Physical Activity in Adults With Amputation

Inclusion Criteria (all participants): * Ages 18-60 years * Able to read and speak English * Saltin-Grimby Physical Activity Level of I or II Inclusion Criteria (individuals with unilateral, transtibial amputations): * Unilateral, transtibial (below-the-knee) amputation * Currently wearing a prosthesis with use of an assistive device no greater than a cane * Wearing prosthetic at least 8 hours per day and inside and outside the home: This criteria will help to ensure that adults are beyond the initial weaning into a prosthetic period and are prosthetic users rather than nonusers. Inclusion Criteria (controls): * Pain-free in the legs and low back regions * Able to walk without an assistive device Exclusion Criteria: * Current infections or illnesses that would affect safe participation in the study * Past medical history of significant cardiovascular disease (e.g. congestive heart failure or previous heart attacks), significant neurological disease (e.g. Parkinson's, Multiple Sclerosis) significant neurological event (e.g. stroke), or major lung condition (e.g. Chronic obstructive pulmonary disease, emphysema) * Uncontrolled high blood pressure * Uncontrolled Diabetes Mellitus