A study just published in PLOS ONE has compared adherence to physical activity recommendation in older adults when using absolute versus relative intensity definition of physical activity.
“I was walking with my father in a beautiful forest in Norway at a pace that was easy for me but left him breathless. The traditional method used to assess physical activity in research would not differentiate between the level of intensity my father experienced compared to myself while walking. And that’s when I had the idea to do this study”, says Nils Petter Aspvik, co-author of the study and PhD candidate at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway.
Physical activity is good for health and well-being. This is true for both the old and the young. For that reason, the public health agencies around the world advocate regular physical activity to maintain or improve health and well-being, delay onset of diseases and prolong life.
Current physical activity recommendations for both younger and older adults advocate 150 minutes of absolute or relative moderate to vigorous intensity activity per week. Absolute intensity physical activity refers to an activity that has the same energetic cost for young and old, fit and unfit. Relative intensity, on the other hand, is often given in terms of individual abilities such as fitness and is less costly for the very fit compared to the unfit individuals.
In order to evaluate the current physical activity recommendations in large populations, investigate the relationship between physical activity and health and generalize the findings, we must be able to assess adherence. Adherence to current recommendations was assessed in multiple studies, and depending on the method used, the estimates ranged from 1 % to 52 %. Comparisons between studies, populations and countries were often not possible because of differences in data analysis and methodology of physical activity assessment.
While the public health agencies suggest that relative intensity physical activity can be used to meet the recommendations, only absolute intensity physical activity definition is applied when assessing adherence. This can be problematic, especially when it comes to older adults who are often unable to reach the absolute moderate to vigorous intensity due to declining health and fitness.
The NTNU study was part of a large randomized controlled clinical trial with the primary objective of investigating the effect of exercise training on disease and death in the older adult population. The team conducted a cross-sectional study of 1219 older adults from Norway aged 70-77 years. The scientists used accelerometers to measure adherence to recommendations while applying both the absolute and relative (adjusted for fitness and gender and derived specifically for older adults) intensity definition of physical activity.
“What we found was quite interesting. When using the absolute physical activity definition 29% of our older men and women met the recommendations, while a whopping 71% did so when relative physical activity method was applied. We do not know if this new method will help us identify people at risk of health problems better. That is something that we need to investigate in the future”, says Aspvik. Furthermore, researchers showed that fit older adults were more likely to meet the recommendations, regardless of the method used in assessment and women were more active than men at relative but not absolute intensities.
According to Aspvik the take-home message of the study is that ”physical activity recommendations are there for a reason and should in no way be negated, but how me measure the adherence to those recommendations, especially among older adults, should be considered and adjusted to the individual, because clearly one size does not fit all”.
Hallgeir Viken, researcher at CERG and Nils Petter Aspvik, researcher at Department of Sociology and Political Science