Association between daily level of objective physical activity and C-Reactive protein in a representative national sample of adults with self-reported diagnosed arthritis or fibromyalgia

Examine the association between physical activity and sedentary time with high sensitivity C-Reactive protein levels in adults with arthritis and fibromyalgia. We also investigated the dose of physical activity that was associated with lower clinical levels of high sensitivity C-Reactive protein (< 3 mg/L).

Observational design was used to evaluate the variables of interest-based on the Canadian Health Measures Survey cycle 1–3 (2007–2012). Generalized adjusted additive models were used to explore the shape of the association between high sensitivity C-Reactive protein, daily physical activity, step count and sedentary time. High sensitivity C-Reactive protein was measured with blood samples. Physical activity, number of steps and sedentary time were objectively assessed using an Actical accelerometer.

Daily moderate to vigorous physical activity and step count were significantly associated with lower high sensitivity C-Reactive protein levels, but daily light physical activity and sedentary time were not associated with high sensitivity C-Reactive protein levels, even after controlling for age, sex, daily smoking, body mass index, household income, level of education levels, marital status, work year and accelerometer wear time and season of accelerometer. Non-linear dose–response patterns were observed between daily moderate to vigorous physical activity as well as step count with high sensitivity C-Reactive protein levels. Lower high sensitivity C-Reactive protein levels were associated with 1–150 min of daily moderate to vigorous physical activity and with daily step count starting at 4000 in people with arthritis. Adults with fibromyalgia had lower levels of high sensitivity C-Reactive protein when engaging in 10–35 min of daily moderate to vigorous physical activity and in 5000–9000 daily steps. Optimal and specific doses of daily moderate to vigorous physical activity and steps were independently related to lower high sensitivity C-Reactive protein levels in adults with arthritis and fibromyalgia.

Daily moderate to vigorous physical activity and step count were associated with high sensitivity C-Reactive protein levels that were below the clinical threshold. Given the positive outcomes of physical activity on health, adults with arthritis and fibromyalgia may benefit from these specific recommendations.