Sammendrag
Abstract
Background
There is a lot of research highlighting the importance of physical activity. However, how to increase or maintain physical activity as people age is an unanswered question. High intensity exercise had previously been shown to induce greater health effects than moderate intensity exercise, while the long-term effect of different exercise intensity on physical activity level have not been examined before. The present study aimed to assess the effect of 5 years of supervised exercise training at high- and moderate intensity, compared to a non-supervised control group on change in objectively measured physical activity in older adults.
Method
The present study was a sub-study of a randomized controlled trial (RCT), the Generation 100 study where older adults (70-76 years) have been randomized into either a high -intensity interval training group (HIIT), a moderate-intensity continuous training group (MICT), and a control group in which they were asked to follow the national guidelines for physical activity. In the present study only participants who wore the actigraph at baseline were included (n=1284). Participants were asked to wear an Actigraph GT3X for 7 days to objectively assess their level of physical activity. Physical activity was objectively assessed at baseline, after 1-, 3-, and 5 years for the main outcome counts per minute (CPM), and for the secondary outcomes light physical activity (LPA), moderate physical activity (MPA), vigorous physical activity (VPA) and sedentary time.
Results
There were no significant differences in change in CPM, LPA, MPA, VPA and sedentary time between HIIT, MICT and the control group neither at 1-, 3- and 5 years follow-up. From baseline to year 5 there was an average 23% decrease in CPM in all the three groups. Further, all the 3 groups had an average 39% decrease in LPA after 5 years, while all the groups managed to maintain their MPA levels throughout the study. Interestingly, there was an average 28% increase in sedentary time in the intervention groups from baseline to year 5.
Conclusion
The present study found no significant differences in change in CPM, LPA, MPA, VPA and sedentary time between the HIIT, MICT and control group neither after 1-, 3- or 5 years of an aerobic exercise intervention. There was a significant decrease in CPM and LPA after 1-, 3-, and 5 years. All the three intervention groups managed to maintain their MPA levels throughout the study. Our data showed a significant increase in sedentary time in all three interventions groups after 1-, 3-, and 5 years. This study shows that supervised exercise over five years did not influence physical activity levels compared to control group. Further our data indicates that different exercise intensity does not influence physical activity levels differently over a five-year period when measured by accelerometer when using absolute intensity thresholds.