Physical activity is an important aspect of healthy aging. It encourages overall well-being and mental health, and helps reduce the risk of falls and of functional impairment. Research on physical activity has made important contributions to our understanding of aging, and continued research will be crucial for informing individuals and developing programs to encourage physical activity.
Physical activity is most often assessed by self-report questionnaire, but it is becoming increasingly apparent that individuals tend to do a poor job of accurately recording and reporting the amount of physical activity they perform. For this reason, it is important to develop objective measures of activity that can be used in research involving older adults. A recent review of active aging literature summarizes the findings on accelerometer-based research involving older adults.
An accelerometer is a device that measures force resulting from movement. In research, these can be placed fairly unobtrusively on research participants to record the duration, frequency, and intensity of their motion. Accelerometer-based measures seem potentially more useful than other measures such as pedometers that can only count steps, or other devices like video cameras or motion sensors that can only record motion in a specific area.
For this review, researchers sought out all peer-reviewed, English-language papers that used accelerometer-based activity monitoring with samples of older adults. The researchers excluded papers that had a sample size of less than ten participants, or were exclusively laboratory-based or sleep monitoring studies. In all, the researchers identified 134 studies for their review.
The earliest study took place in 1992, while most of them were published between 2008 and 2011. The most common length of time during which movement was monitored was one week, though studies ranged in duration from two days to 450 days. About half of the study samples were with healthy community-dwelling adults, while the other half involved adults who were receiving institutional or clinical care.
Overall, there was a wide variety in the methods used to collect data as well as the kind of data found. The researchers were able to compare three variables across the studies: energy expenditure per day; time spent walking; and time spent in physical activity. Because the studies used different brands of accelerometers and had different objectives, it is difficult to definitively summarize the findings, however, comparing the different studies did provide useful insights.
For example, healthy older adults not involved in sports actually appeared to have a higher amount of total physical activity than older adults involved in sports, but those involved in sports expend more overall energy than healthy “non-sports” people. Further, “activity pattern” seems to be an important emerging variable, given findings that taking periodic breaks from physical activity may help prevent sedentary behavior over the long term.
Overall, activity monitoring is a rapidlygrowing area of research. This review points to some important emerging research topics, such as the benefits of different patterns of activity, and the need for researchers to collaboratively develop shared standards to facilitate the comparison of different accelerometer studies.
Taraldsen K, Chastin SFM, Riphagen II, et al. (2011). Physical activity monitoring by use of accelerometer-based body-worn sensors in older adults: A systematic literature review of current knowledge and applications. Maturitas, epub ahead of print.