While age and fat mass were inversely associated with cardiorespiratory fitness (CRF), the physical activity index was positively associated with CRF.
Among a sample of patients with inflammatory joint disease (IJD), fat mass, and age were inversely associated with cardiorespiratory fitness (CRF), while physical activity level was positively associated with CRF. Further, patients that exhibited normal CRF reporting a more favorable health profile, according to a study published in BMC Sports Science, Medicine and Rehabilitation.1 Investigators emphasized the need for exercise interventions aimed at improving CRF in this patient population.
IJD, which includes conditions such as rheumatoid arthritis (RA), psoriatic arthritis (PsA), and spondyloarthritis (SpA), are often categorized by pain, fatigue, joint inflammation, and functional impairments. Patients with these conditions are historically at an increased risk of CVD, partially due to the prevalence of obesity, hypertension, and dyslipidemia, which are known CVD risk factors.2
“CRF is identified as a modifiable prognostic factor for cardiovascular disease (CVD)-morbidity, but common CVD risk algorithms do not include CRF in the risk stratification,” wrote lead investigator Kristine Røren Nordén, PhD candidate, Center for Treatment of Rheumatic and Musculoskeletal Diseases (REMEDY), Diakonhjemmet Hospital in Norway, and colleagues. “Routine measures of CRF as a clinical vital sign has been recommended, but seldom realized in patient clinical care.”
In the randomized control trial, investigators assessed the link between various CVD risk factors, CRF, and disease activity in adult patients with IJD, as well as explored the differences between those with normal levels of CRF compared with patients with low levels. Patients were recruited from the Preventive Cardio-Rheuma Clinic, Center for treatment of Rheumatic and Musculoskeletal Diseases, Diakonhjemmet Hospital, Norway.
Peak oxygen uptake (VO2peak) with a cardiopulmonary exercise test (CPET) measured CRF, with normal CRF defined as VO2peak ≥ 80% and low CRF defined as VO2peak < 80%, according to age- and gender-stratified reference data. In addition to this measurement, body composition, disease activity, resting heartrate, inflammatory markers, blood pressure, and blood lipids were also assessed. Patients were required to report use of cigarettes/snuff, medications, pain, fatigue, disease duration, any history of CVD, habitual physical activity, and exercise beliefs and self-efficacy via a questionnaire. Links between disease-related factors, CRF, and CVD risk factors were cross-sectionally analyzed via multiple linear regression.
A total of 60 Norwegian patients with IJD were included in the analysis, with 57% females, a mean age of 59 years, the mean VO2peak was 30.2 ml/kg/min, and the median self-reported physical activity was matched to the lowest value for the composite index (0, interquartile range [IQR] 0–15). Increased CVD risk was reported in most (n = 49, 82%) of patients.
While age and fat mass were inversely associated with CRF, the physical activity index was positively associated with CRF. No significant associations were observed between CRF, disease-related variables, and CVD risk factors.
Patients with normal CRF (n = 30) had higher peak oxygen uptake (+ 9.4 mL/kg/min, P <.001),exercise self-efficacy (+ 6.9, P <.01), and high-density lipoprotein cholesterol (+ 0.5 mmol L−1, P <.001) when compared with the low CRF cohort (n = 30). Further, these patients had lower resting heart rate (− 8.0 beats/min, P < .01), triglycerides (− 0.5 mmol L−1, P < .01), and fat mass (− 8.7%, P <.001).
Investigators reported that the using the criterion method to quantify CRF, as well as utilizing backward multiple regression with independent variables, strengthened the study. However, limitations included the absence of casual interference due to the cross-sectional nature of the study design. They also mention the potential of selection bias as patients with low exercise self-efficacy may have been less likely to participate in the trial.
“Our results support data headlining inferior CRF levels in patients with IJD, further illustrating a continued need for exercise interventions to improve CRF,” investigators concluded.