This study aims to understand and compare the metabolic and mechanical demands placed on the body while walking normally and walking with the use of an apparatus that drives leg swing through the use of the arms. This information will help the investigators identify how arm swing mechanics helps minimize energy demands and to use this knowledge to design walking rehabilitation interventions in the future.

Inclusion Criteria:

• Apparently healthy and free from neurological disease and/or body related injury
• Community-dwelling young men and women 18-36 yrs
• Use and be contacted by telephone
• Speak, read, understand, and complete a questionnaire in English
• Body mass index < 30 kg/m2

Exclusion Criteria:

• not of the specified age range or Body Mass Index
• inadequate aerobic fitness training
• answering "no" to question #3 on Screening Form ("Is participant in good general health?")
• answering "yes" to:
• question #4 ("any difficulty with mobility?")
• question #5 ("problems with balance/dizziness?")
• question #6 ("lingering symptoms/pain from injury?")
• question #7 ("chest pain/shortness of breath?")
• question #8 ("high blood pressure/hypertension?"), or
• questions #9, 10, 11 ("first degree family history of heart attack?")
• question #12 ("smoke cigarettes?")
• question #13 ("diabetes?")
• question #14 ("high cholesterol?")
• question #15 ("Is participant pregnant?")