Accelerometer Analysis

Accelerometers provide the capability for quantitative and portable measurements, calculating the acceleration of an individual segment or whole body in both sleep and awake states.8,9,10 They are also utilized for tremor analysis, assessment of physical activity, and quantification of metabolic energy expenditure.7 Acceleration of the trunk reflects the cyclical movement of the trunk as it slows down and speeds up, rises and falls, and moves from side to side.9 Accelerometers generally offer greater accuracy with detecting movement in individuals with gait disorders.11 Accelerometer data provides quantitative measures of gait, identifying specific gait changes in patients predisposed to falls, and can be used to objectively quantify ambulatory activity levels.10
If an accelerometer is to be worn over an extended period of time, participant discomfort is important to consider, including its
raises the concern that there may be ambiguity regarding the cut-off time for those with a high risk of falls.15 They reported that a time greater than 15 seconds could indicate 74% greater risk of recurrent falls for healthy older adults.15 In regards to patients who have suffered stroke and have mild to moderate disability, Ng S et al. defined an average time to be 17.9 seconds (+/-1.2s) with the FTSS.4 Using tri-axial accelerometers may provide more information and a more accurate assessment of fall risk.15
A tri-axial accelerometer incorporates three accelerometer measurements into a single device for gathering information on three-dimensional movement.9 Doheny et al. analyzed community-dwelling older adults, performing four repetitions of the FTSS with a tri-axial accelerometer attached to the lateral thigh to record femoral acceleration.15 Another tri-axial accelerometer was attached to the sternum and captured acceleration of the torso.15 This study suggests that the smoothness of a sitting down motion is just as indicative of fall risk as it is of