Frequency of moderate-to-vigorous physical activity (MVPA) is a greater predictor of systemic inflammation than total weekly volume of MVPA: Implications for physical activity promotion.

Few studies have differentiated the effects of total physical activity volume vs. physical activity frequency on health. Therefore, the purpose of this study was to examine whether daily frequency of moderate-to-vigorous physical activity (MVPA) throughout the week or overall weekly accumulation of MVPA is a greater predictor of systemic inflammation. Data from the 2003-2006 NHANES were used, which included 2330 adults (≥ 20 years). Participants wore an accelerometer for 7 days to assess physical activity, with C-reactive protein (CRP) measured from a blood sample. Only participants with 7 valid (10+ hours/day of monitoring) days of monitoring were included. Two physical activity variables were created: 1) total weekly accumulation of MVPA, and 2) the number of days per week participants engaged in ≥ 30 min/day of MVPA. After adjusting for age, gender, race-ethnicity, poverty level, comorbid illness, body mass index, sedentary behavior, and smoking status, participants engaging in more days of ≥ 30 min/day of MVPA had lower log-transformed CRP levels (β=-0.01, P<.001), and in a separate multivariate model, total weekly MVPA volume (β=-0.005, P=.002) was also inversely associated with log-transformed CRP levels. However, when both MVPA frequency and total weekly volume were entered into the model at the same time, MVPA frequency remained significant (β=-0.01, P=.04), but total weekly MVPA volume was no longer significant (β=-0.001, P=.82). In conclusion, MVPA frequency, compared to total weekly MVPA accumulation, is a stronger predictor of CRP among the U.S. adults. Clinicians are encouraged to advise their patients to engage in consistent physical activity throughout the week.