The primary aim of this study is to compare traditional muscle function tests with computerized versions using body-worn motion sensors and video motion analysis of the same tests. The investigators selected the Timed Up and Go (TUG) test as the investigators primary variable for this aim with several other function tests (e.g., repeated chair rise, 6-meter walk, 2-minute walk, Romberg stance, semi-tandem / tandem stance) as secondary variables. The investigators primary hypothesis is that the computerized versions of the TUG test are highly correlated (>0.9) with the traditional method, but with comparable or better reproducibility. Secondary analyses will correlate other function tests with their computerized version, again with the hypothesis that they are highly correlated and that computerized versions are of similar or better reproducibility. This analysis will also compare traditional assessments of balance with a computerized balance method, computerized dynamic posturography.

Inclusion Criteria:

1. Ambulatory, community dwelling men and women age ≥ 70 years
2. Able and willing to sign informed consent
3. Able to stand without assistance

Exclusion Criteria:

1. History of myocardial infarction within the prior six months or ongoing angina
2. History of injury or surgery within the prior six months which limits the ability to ambulate
3. History of malignancy with metastasis to the musculoskeletal system
4. Neuromuscular disease or severe end organ disease impairing balance or muscle function to the degree that completion of all study tests is unlikely.

This study will evaluate community dwelling women and men ≥ 70 years recruited from the Madison, Wisconsin area.