• about
• foundation
• contact

Accuracy
Programming
System Requirements

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 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.
Back

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.
Back

Programming and System Requirements

StepWatch™ Analysis Software

The StepWatch™ Analysis Software is a user-friendly, highly intuitive interface for the StepWatch™ System. The software is used to program a monitor prior to deployment and to download, view and analyze the data when the recording session is over. Several reports are available for printing and data can be exported to a spreadsheet. The software also offers database function, allowing comparison of collected data to self, groups, or all.

Programming

Using the software, the user programs a monitor's sensitivity and the length of time to record (up to 2 months using 1 minute intervals). One also has the option of setting a monitor to begin recording some time in the future. Programming the monitor requires only that the user knows the subject's height and can answer 4 questions about the subject's gait.
View

There is also an advanced programming mode is available for highly unusual monitoring situations, or to allow the use of different epochs in data collection (default is 1 minute but it can be set from 3 seconds to 255 seconds).
Back

Data Download and Analysis

The monitor is downloaded via the USB docking station. Depending on the amount of data, download typically takes 15 seconds to a minute. After download the summary data is displayed in a window on your screen. View. The typical display is a histogram chart with the vertical axis representing steps/ minute and the horizontal axis representing time a 24 hour day shown in this screenshot). View. This information is also available for use as a printed report. View. Users can filter the data so that only part of a day is analyzed. View.

Analyses include a breakdown of time and steps spent at low, moderate and high activities and an activity/time analysis which finds the most active 1, 5, 20, 30 and 60 minute periods during each day. View. It also reports the average step count therein. View. These analyses are available in report format which can be printed. View. They are also displayed in pie charts and bar graphs. The pie charts show the steps or time at the different activity levels for a chosen day compared to the average for the included time/steps in your data file. The bar graphs show time or steps for all of the days at any combination of the high medium or low activity levels.
Back

System Requirements

The software is compatible with Win98 through WinXP and NT4 operating systems as well as and Macintosh OS 9 and OS X. The minimum suggested computer system is a Macintosh G3 or a Pentium 3 with CD-ROM drive, 128 MB RAM and at least 5 MB free hard disk space. The computer must have a USB port.
Back

StepWatch™ Hardware

The StepWatch™ System consists of StepWatch™ Activity Monitor, the StepWatch™ USB Dock and the StepWatch™ Analysis Software.

The StepWatch™ Activity Monitor 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 SAM has an expected life of 7 years with constant use. It can then be refurbished by OrthoCare Innovations. The case, made of high impact plastic, 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 strap can be removed and the monitor worn in a soft cloth sleeve at the ankle. In our studies on over 250 subjects, most report that they quickly forgot that they were wearing the monitor and only one complained of discomfort. The StepWatch™ has been cleared by the FDA as a class II device.

The StepWatch™ USB Dock connects to your Windows (98, 2000, ME, XP, NT) or Mac (OSX) computer via the USB port. It is the interface for communicating with the SAM, allowing programming and download. Communications with the monitor are via infrared light. Only one dock is required to support multiple monitors. The dock is powered by the USB connection and requires no batteries.
Back

StepWatch™ 3.0 Monitor

Size – 75 x 50 x 20 mm
Weight – 38 grams
Battery – 750mAh Lithium
Battery Life – Depends on usage. 7 years with heavy use
Accuracy – >98% independently validated
Sensitivity – User adjustable via software
Sampling Rate – 128/sec.
Housing – Thick polycarbonate. Injection molded
Attachment – Highest accuracy at ankle. Elasticized strap or cotton Lycra cuff
Recording Time – Up to 60 days minimum at full resolution
Resolution – 1 minute is standard. User adjustable from 3-180 seconds
Memory – 32KB. Includes 64 character user notes field
Temperature – Operating 0º to 50ºC / Storage: -20º to 70ºC
Shock / Drop – Survives multiple drops to concrete
Tamperproof – Permanently sealed
Waterproof/Floats – Yes
Factory refurbishable – Yes

StepWatch™ 3.0 Dock

Size – 106 x 68 x 31 mm
Weight – 150 Grams
Communication – USB to computer. IR to SAM.
Batteries – Not required
Power Consumption – 100 mA max
LED status indicators – 3