Multi-dimensional physical activity assessment recommended

By Helen Albert, Senior medwireNews Reporter

Research suggests that assessment of physical activity level should evaluate a person's overall level of moderate or vigorous activity as well as their amount of sedentary time to get an accurate estimate.

Dylan Thompson (University of Bath, UK) and Alan Batterham (Teesside University, Middlesbrough, UK) recruited 100 healthy men aged an average of 28 years to assess their physical activity levels.

The participants were asked to wear a device that allows synchronized accelerometry and heart rate monitoring for 7 days and nights, with the monitor only being removed to change the electrocardiogram electrodes.

Thompson and Batterham divided the activity of the participants into total Physical Activity Level (PAL; total energy expenditure/resting energy expenditure), moderate activity (above 3 metabolic equivalents [METs]), vigorous activity (at or above 6 METs), highly vigorous activity (at or above 10.2 METs) or sedentary time (activity below 1.5 METs).

As reported in PLoS ONE, the researchers measured how many thresholds for each of the types of activity were reached for the men. For example, achieving more than 60 minutes/day of moderate activity in 1 min bursts or more or 30 minutes/day in 10 minute bursts or more; completing 25 minutes of vigorous intensity exercise at least three times per week; or spending less than 60% or less than 6 hours of the waking day in sedentary activity.

Notably, although some of the outcomes for the thresholds correlated with one another, achieving one threshold did not automatically mean that the participants achieved another. For example, 41 of the men had a low PAL score but only 17% of this group had consistently low physical activity across the individual physical activity measures.

"The results showed that some people score highly in certain types of physical activity, such as moderate intensity physical activity, but relatively poorly in other ways, such as overall physical activity energy expenditure. In other cases, some people look enormously sedentary if judged by sedentary time alone but, at the same time, they can score very highly for time engaged in vigorous intensity physical activity," said Thompson in a press statement.

He added: "One of our concerns is that if we capture just one measure of physical activity this could be misleading for people and they might form the opinion that they are doing all the right things for their health when in fact there are other things that they could change to potentially get more benefit. Perhaps more importantly, for those people who are the least active, we should ensure that they understand that there are various options and ways to get some of the benefits from physical activity and there is more choice than ever before."

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