StepWatch Accuracy

The StepWatch was developed as a research instrument for looking at the real world activity of lower limb amputees. It was discovered that typical step counting devices, i.e. pedometers, were not especially accurate even for non-amputee subjects and were terrible for people with atypical gait.

The StepWatch system is the most accurate ambulatory activity monitor on the market. Independent researchers have consistently reported accuracies above 98% in a variety of peer reviewed publications. The monitor does not rely on impact to count a step, like most pedometer devices, and can detect steps even for a person with very gentle shuffling gait. It can also be set to accurately count the steps of a child running.

The StepWatch system is programmed at the beginning of a data collection session so that the sensitivity matches the user's gait. Programming is a simple process of entering the subject's height and answering 4 questions about the person's gait.. These questions help determine the subject's cadence and how dynamic their step is. After programming, the monitor's red LED will blink when it counts a step for up to 255 steps (the number of blinks is programmable). This allows the user to determine that the monitor is set appropriately.

Because the monitor is worn just above the ankle it is not susceptible to motion of soft tissue. Soft tissue motion can induce significant errors in belt worn devices. Also, because of directional sensitivity, the StepWatch is not affected by off-axis accelerations and will not pick up vehicle vibration and similar events that may be counted by other designs.


Last updated: Thursday, March 4, 2004