Table 2 Description of physical activity measurements in each study

Scarmeas et al. [13]

Metabolic equivalents were assigned to 3 different categories of activities: vigorous, moderate or light. Low physical activity defined as: 0 hours per week. High physical activity defined as: 1.3 hours of vigorous, 2.4 hours of moderate, 4 hours of light physical activity. Participants self- reported their activity levels.

Buchman et al. [8]

Daily physical activity assessed with Actigraphy for up to ten days. Total daily physical activity was the daily sum of all activities recorded.

Scarmeas et al. [14]

Metabolic equivalents were assigned to 3 different categories of activities: vigorous, moderate or light. Low physical activity was defined as: 0 hours per week. High physical activity was defined as: 1.3 hours of vigorous, 2.4 hours of moderate, 4 hours of light physical activity per week. Participants self- reported their activity levels.

Larson et al. [15]

Participants reported the number of days per week engaged in the following activities for at least 15 minutes: walking, hiking, bicycling, aerobics, swimming, weight training or stretching. Study was divided between those who do 3+ activities per week versus those who did fewer than 3 activities per week.

Lindsay et al. [12]

Participants asked if they engaged in regular physical activity (yes/no). Physical activity was not explicitly defined.

Podewils et al. [7]

Participants listed frequency and duration of 15 activities over the previous 2 weeks. Activities were assigned metabolic equivalents in accordance with intensity level.

Abbott et al. [16]

Participants were asked about the average distance they walked per day. The most active group walked more than 2 miles per day while the least active walked less than 0.25 miles per day.

Yoshitake et al. [17]

4 categories of physical activity for leisure and for work. The physically active group was defined as reporting exercise daily during the leisure period or participating in daily moderate to severe activity at work.

Ravaglia et al. [18]

Participants asked about city blocks walked, flights of stairs climbed and frequency/duration in various sports activities per week in the past year. Each activity was assigned a metabolic equivalent.