Longitudinal association of sedentary time and physical activity with pain and quality of life in fibromyalgia.

Objective: To analyze changes over time and the predictive value of baseline and changes of sedentary time (ST) and physical activity (PA) on pain, disease impact, and health-related quality of life (HRQoL) at 2- and 5-year follow-up in women with fibromyalgia.

Methods: This is a longitudinal and exploratory study with three time points. A total of 427 women with fibromyalgia (51.4 ± 7.6 years) were followed after 2 (n = 172) and 5 years (n = 185). ST and PA (light and moderate-to-vigorous [MVPA]) were assessed using triaxial accelerometers. Pain, disease impact, and HRQoL were measured using: pressure pain threshold, the pain subscale of the revised fibromyalgia impact questionnaire (FIQR), the bodily pain subscale of the 36-item short-form health survey (SF-36), a visual analog scale (VAS), the FIQR, and the SF-36 physical and mental components.

Results: Over 5 years, pressure pain threshold, ST, light PA, and MVPA variables were worsened, while FIQR and SF-36 variables were improved (Cohen's d < 0.1-0.3). Baseline ST or light PA were not associated with future outcomes, whereas greater MVPA at baseline was associated with better SF-36 bodily pain at 5-year follow-up (β = 0.13). Reducing ST and increasing light PA were associated with better bodily pain (β = -0.16 and 0.17, respectively) and SF-36 physical component (β = -0.20 and 0.17, respectively) at 5-year follow-up. Increasing MVPA was associated with less pain (pressure pain threshold, VAS, and FIQR-pain) and better SF-36 physical component at 2- and 5-year follow-up (β's from -0.20 to 0.21).

Conclusions: Objectively measured variables slightly worsened over years, while for self-reported outcomes there was a trend for improvement. Reductions in ST and increases in light PA and MVPA were associated with better HRQoL at 5-year follow-up, and increases in MVPA were additionally associated with better pain and HRQoL at 2-year follow-up.