The effect of cardiorespiratory fitness assessment in preventive health checks: a randomised controlled trial.

Background: Poor cardiorespiratory fitness (CRF) increases morbidity and mortality risks. Routine CRF assessment in clinical practice has thus been advocated, but little is known about the effect. In this study, we investigated the effect of CRF assessment on CRF in a preventive health check programme.

Methods: We used a randomised design, in which we invited 4153 middle-aged adults and included 2201 participants who received a preventive health check with CRF assessment (intervention) or without CRF assessment (control). After 1 year, participants were examined. The primary outcomes were adjusted absolute (l/min), relative (ml/kg/min), and poor (%) CRF assessed by the Astrand-Ryhming test. We adjusted for baseline physical activity and intra-cluster correlation within general practices.

Results: A total of 901 attended the 1-year follow-up. In the intervention group, absolute CRF, relative CRF, and poor CRF were 2.7 l/min (95% confidence interval [CI]: 2.6; 2.8), 34.5 ml/kg/min (95% CI: 33.5; 35.4), and 31.0% (95% CI: 26.8; 35.2). In the control group, the corresponding figures were 2.8 l/min (95% CI: 2.7; 2.9), 35.2 ml/kg/min (95% CI: 34.2; 36.1), and 25.9% (95% CI: 21.8; 30.0). Adjusted absolute CRF was lower in the intervention group (-0.1 l/min [95% CI: -0.2; -0.01]). Adjusted relative CRF (-0.7 ml/kg/min [95% CI: -2.0; 0.6]) and poor CRF (5.0% [95% CI: -0.002; 10.1]) did not differ between groups. No differences were found when adjusting for potential confounding factors.

Conclusion: Preventive health checks with CRF assessment did not provide higher CRF levels at 1-year follow-up than preventive health checks without CRF assessment.