StepWatch System Overview


The StepWatch Activity Monitor (SAM) is a highly accurate, unobtrusive instrument worn on the ankle. Consisting of a sensor, electronics and battery inside a polycarbonate case, the StepWatch is completely sealed and very durable. It allows no adjustment by the wearer and requires no maintenance by the owner. The instrument measures 75 x 50 x 20 mm and weighs approximately 38 grams (1.3 oz). The case is contoured to fit comfortably against the leg. An elastic attachment strap ensures that the monitor remains securely attached to the ankle without irritating the skin. Alternatively, the straps can be removed and the monitor worn in a soft cloth sleeve at the ankle.

The StepWatch monitor continuously records the number of steps per time interval over extended monitoring periods. The time interval is adjustable, but one minute is encouraged for standardization. Subjects are typically monitored for 1 - 2 weeks, but the StepWatch monitor can record for up to 2 months at one-minute intervals before needing to be downloaded. The time-sequenced data allow patterns of activity and rest to be visualized in great detail.

StepWatch Operation

The SAM is programmed and downloaded to a host computer via its USB docking station. Programming and downloading are controlled with the StepWatch Analysis Software (Win/Mac compatible). The monitor's sensitivity is optimized for a subject's gait characteristics by the standard programming mode, shown below, or explicitly using the advanced programming option. The standard mode permits users to confidently program the StepWatch by entering the subject's height and answering simple questions that describe the subject's gait. This method is highly accurate for most applications. If desired, the effectiveness of the settings may be verified with a short test trial.

Last updated: Thursday, March 4, 2004