Cardiorespiratory fitness, physical activity level, and chronic pain: are men more affected than women?

OBJECTIVE: To evaluate the cardiorespiratory endurance (CRE) and physical activity level of patients with chronic pain compared with healthy subjects. DESIGN AND SUBJECTS: Cross-sectional study, with a consecutive sample of 55 patients with chronic pain (20 men, 35 women). Comparison of CRE and physical activity indices obtained in patients with data available in the literature for age-matched healthy subjects. SETTING: A multidisciplinary pain center in a city of more than 1,000,000 inhabitants. OUTCOME MEASURES: A physical working capacity index (PWC65%/kg) and physical activity level scores and subscores obtained with two questionnaires (the Baecke and the Five-City Project questionnaires). RESULTS: The physiological gender difference in CRE indices that characterizes healthy subjects was not observed in patients with chronic pain. When compared with values previously obtained in controls, male patients presented with a very significant 34% reduction in PWC65%/kg. The 17% reduction found in women hardly reached significance level. The Baecke total physical activity score was significantly higher in female than in male patients, a finding not observed in healthy controls. There was no significant difference between male and female patients in the Five-City Project total physical activity score expressed in kilocalories per day per kilogram (i.e., normalized for body weight), although data from the literature show that healthy men present with a significantly higher level of physical activity compared with healthy women. CONCLUSIONS: Data on CRE and the physical activity level of patients with chronic pain obtained in this study show that chronic pain may have a greater impact on male than female patients. Sociocultural factors are probably at the origin of this phenomenon.