I know quite a few people who wear who wear wrist pedometers and you have probably seen them as well. I think it is a great way to generally keep track of daily activity and keeps people working toward fitness goals. You can quickly check how many steps you have in for the day, add up any distance hike or walk, add to existing totals or, try to increase your total amount of steps for the day/week. They are a great monitoring device. However, I have often wondered how accurate they are.
In a recent study published in the American College of Sports Medicine researchers put them to test under laboratory conditions. The purpose of this study is to compare step outputs obtained from waist and wrist accelerometer attachment sites under laboratory and free-living conditions. Under the laboratory condition, participants wore both a wrist pedometers and one at their waist while walking/running at treadmill at varying speeds. The researchers visually counted steps while the subjects were on the treadmill. Participants then wore both devices for 7 days. All pedometers step data were processed applying both the manufacturer’s default and low-frequency extension filters. The data were analyzed and paired sample t-tests were used to evaluate mean differences in steps per minute and the four estimates produced from the waist- and wrist-worn accelerometers in the laboratory study. Free-living differences in mean steps per day detected between the waist and wrist were computed.
The results indicated that relative to visually counted steps, the waist attachment site generally outperformed the wrist attachment site at most speeds, regardless of the applied filtering process. Under free-living conditions, the waist-worn device detected 6743 ± 2398 (default filter) and 13,029 ± 3734 (low-frequency extension) steps per day. The concurrently worn wrist accelerometer detected 9301 ± 2887 (default filter) and 15,493 ± 3958 (low-frequency extension) steps per day.
According to the study, “The wrist attachment site detected consistently fewer visually counted steps than the waist attachment site at most treadmill speeds during laboratory testing. In contrast, the wrist attachment site produced a higher average step count (ranging from approximately 2500 to 8700 more steps per day under free-living conditions, dependent on the filtering process applied) than the waist attachment site under free-living conditions. In conclusion, step outputs obtained from waist- and wrist-worn accelerometer attachment sites are generally not comparable under either laboratory or free-living conditions.”
What this means to me is that they pedometers are exactly accurate but more importantly can be a reasonable way to measure activity so you may want to give one a try!