Age-associated changes in the level of physical activity in elderly adults.

[Purpose] This study aimed to clarify how light-, moderate-, and vigorous-intensity physical activity in older adults changes with age, subdividing physical activity according to intensity levels, by using an accelerometer. [Subjects] Older adults living independently in the community were included (n = 106, age: 65-85 years). [Methods] A triaxial accelerometer was used to measure the amount of light-, moderate-, and vigorous-intensity physical activity (1-2.9, 3-5.9, and ≥6 metabolic equivalents, respectively) and inactive time over 7 days. Light- and moderate-intensity physical activity levels were further subdivided into 1-1.9, 2-2.9, 3-3.9, and 4-5.9 metabolic equivalents, respectively. [Results] The amount of moderate-intensity physical activity at both sub-levels showed significant inverse correlations with age (r = -0.34, -0.33, respectively), but this was not seen with other levels. Both levels of moderate-intensity physical activity were independently predicted by age using multiple regression analysis adjusted for gender and body mass index. [Conclusion] These results suggest that understanding the reduction in moderate-intensity physical activity with age in older adults, subdivided according to intensity level, could be a useful index to increase the amount of higher intensity physical activity in stages, considering individual health conditions.