Effect of a 5-Year Exercise Intervention on Objectively Measured Physical Activity and Sedentary Time in Older...

Interventions promoting increased physical activity (PA) and limited sedentary time in older adults are urgently required. This study examines how 5 years of supervised high-intensity interval training (HIIT), or moderate-intensity continuous training (MICT) affects PA and sedentary time measured objectively, during, and 5 years after the intervention, compared to an unsupervised control group.

In total, 1405 participants with a mean age of 72.8 years, consisting of 51% females, were randomized 1:1:2 to 5 years of 2 weekly sessions of HIIT (90% of peak heart rate), MICT (70% of peak heart rate), or as controls asked to follow national PA recommendations. Total PA, number of steps, sedentary time, light PA, moderate PA, and vigorous PA were measured with ActiGraph GT3X+ monitors at baseline, years 1, 3, 5, and 10.

There were no significant between-group differences throughout the study. However, HIIT, MICT, and control demonstrated significant changes after 1 year, including decreased total PA (-10%, -9%, and -9%, respectively), increased sedentary time (164, 163, and 163 min/d, respectively), and increased moderate PA (21, 21, and 19 min/d, respectively). Furthermore, after 10 years, pooled moderate to vigorous PA was maintained or increased in all groups (5.7, 1.9, and 1.5 min/d in HIIT, MICT, and control, respectively).

HIIT, MICT, and control exhibited a similar long-term effect on objective PA and sedentary time in a general population of older adults. Notably, both supervised and unsupervised exercise combined with regular follow-up hindered the expected age-related decline in moderate to vigorous PA over 10 years.