Thursday June 30 2011
The study looked at daily activity levels, not fidgeting
“Fidgeting makes you fit,” according to the Daily Express. The news is based on a study that examined the association between a measure of heart and lung fitness (called cardiorespiratory fitness or CRF) and the amount of physical activity that obese, inactive people got through everyday activity, rather than exercise.
It is generally accepted that CRF predicts the risk of heart disease, stroke or death from any cause. Current guidelines suggest that certain levels of moderate physical activity, sufficient to cause mild breathlessness for example, are needed to maintain heart and lung fitness. Researchers sought to examine whether other types of lower level activity had an impact on CRF as well.
Researchers concluded that lower levels of activity, termed incidental physical activity, were associated with improvements in CRF, although the changes seen were relatively small. As the study involved a small group of inactive, obese individuals in Canada, it is unclear whether the results can be applied to other groups of people.
While physical activity is an important part of a healthy lifestyle, the results of this study are not sufficient to alter current guidelines on recommended activity levels and don’t support fidgeting as a way of getting fit.
Where did the story come from?
The study was carried out by researchers from Queen’s University in Canada. It was funded by the Canadian Institute of Health Research, and was published in the peer-reviewed journal Medicine & Science in Sports & Exercise.
The findings of this study were generally overstated by the media. While newspapers reported health benefits from fidgeting, the study concerned incidental physical activity (IPA), which includes actions such as walking or lifting objects that a person might do as part of their daily routine. Also, the association between IPA and cardiorespiratory (heart and lung) fitness was quite small, and was generally driven by IPA that involved moderate physical activity (such as walking at a comfortable pace). The commonly reported finding that 30 minutes of light exercise, such as jiggling one’s legs while sitting, can improve cardiovascular fitness misinterprets the study’s findings.
What kind of research was this?
This cross-sectional study examined the association between daily activity and cardiorespiratory fitness (CRF).
Researchers report that moderate and high levels of CRF are linked to a reduced risk of cardiovascular disease and death from all causes. They say previous studies have examined the impact of physical activity on CRF by getting individuals to fill out questionnaires about the amount and level of physical activity they do. These questionnaires, however, may not accurately reflect a person’s activity, as specific events may be difficult to remember or estimate and because people generally only report intentional exercise as opposed to incidental daily activities.
Researchers sought to examine the association between physical activity and CRF using more objective measures of activity. The researchers believed that engaging in incidental physical activity might be sufficient to improve CRF.
What did the research involve?
Canadian men and women aged 35–65 years old were recruited to participate in the study. They were abdominally obese non-smokers who considered themselves to be inactive. Abdominal obesity was defined as having a waist circumference greater than 102cm for men and 88cm for women. They were asked to wear a device called an accelerometer, which detected and recorded physical activity each minute. Participants had to wear these devices for at least 10 waking hours a day on at least four consecutive days. Participants also recorded the time that they went to bed at night and woke up in the morning. Researchers used these self-reports to verify the data recorded by the accelerometer.
Each participant completed a treadmill test in order to measure their CRF. In this test, the participants were asked to exercise to their maximum ability on a treadmill while oxygen consumption was recorded. This method is an accepted way of measuring a person’s overall fitness.
Different forms of activity were classified as incidental physical activity (IPA), low physical activity (LPA) or moderate physical activity (MPA). Researchers then analysed the accelerometer data and, for each day, determined the:
- average duration of each individual’s activity in each of these categories, measured as minutes of activity per day
- average intensity of each individual’s activity in each of these categories, measured as number of accelerometer counts of activity per day
- average minutes of sporadic moderate physical activity, defined as engaging in MPA for less than 10 minutes at a time
- average minutes of moderate physical activity per day, defined as engaging in MPA for bouts of more than 10 minutes at a time
Researchers then compared participants’ activity duration and intensity with their CRF.
What were the basic results?
Researchers found that:
- Women had lower levels of CRF and did fewer minutes of moderate physical activity than men.
- Both men and women engaged in approximately five hours a day of incidental or low physical activity.
- None of the participants’ activity levels were long or intense enough to meet current United States Department of Health physical activity guidelines.
- Participants achieved CRF values in the low-to-good range (26-35 millilitres/kilogram body weight/minute [ml/kg/min] for men and 20-31 ml/kg/min for women).
When the association between duration and intensity of activity and CRF was assessed, researchers found that:
- Each additional count of activity per minute (the study’s measure of activity intensity) of incidental physical activity per day was associated with an average increase of 0.01ml/kg/min in CRF.
- Neither duration nor intensity of low physical activity were associated with CRF.
- One additional minute of moderate physical activity a day was associated on average with an increase of 1.36ml/kg/min in CRF.
- Individuals with the highest levels of total moderate physical activity had significantly higher CRF values than those with lower levels of MPA.
- An average increase of 27 minutes of accumulated daily MPA was associated with an average increase in CRF value of 3.8ml/kg/min.
How did the researchers interpret the results?
Researchers concluded that the association between incidental physical activity and CRF has important clinical and public health implications, given the previously established link between CRF and cardiovascular disease. They concluded that routine, sporadic activity done throughout the day is beneficial to CRF. This is contrary to current thinking, including US physical activity guidelines, that a threshold of activity must be reached before beneficial changes can be seen.
However, researchers say that although they found an association between incidental physical activity and CRF, the average intensity in their study was low and most of the association was driven by sporadic moderate physical activity. They say the average accelerometer values were associated with walking at a slow, leisurely pace (less than 5.0km an hour), while sporadic MPA was equivalent to walking at a comfortable pace (5.8km an hour).
Researchers also point out that, despite the positive associations found in their study, most participants only had peak CRF values at the low end of the healthy range. They suggest that further research is needed to repeat these results in a broader sample of people, and to assess whether changes in CRF translate into changes in cardiovascular disease risk factors.
This small, cross-sectional study described associations between objectively measured activity levels and cardiorespiratory fitness (CRF) in inactive, obese people. While cross-sectional studies are appropriate for determining associations between different factors, they cannot determine a cause-and-effect relationship. In this particular study, there is no way of knowing whether increased activity levels caused increases in CRF, or whether individuals who had greater CRF were more likely to engage in more activity throughout the day.
While researchers found a statistically significant association between incidental physical activity (or fidgeting, as reported in newspapers) and CRF, the effect was quite small and CRF scores were on the low end of the range. Additionally, most of the association was driven by short periods of higher activity levels.
While any physical activity may be better than none at all, this research does not provide sufficient evidence to alter guidelines for recommended levels of activity. It is likely that some degree of exertion is required in order to improve fitness, and the idea that fidgeting alone makes you fit is a misinterpretation of this research.
Analysis by Bazian.