Estimated Cardiorespiratory Fitness and Grip Strength: Independent and Combined Associations With Multimorbidity Risk and Patterns in a Large-Scale Prospective Cohort Study.

BACKGROUND: Little is known about the associations between cardiorespiratory fitness (CRF), grip strength (GS), and their combined effect on multimorbidity. This investigation aimed to identify diseases associated with estimated CRF and GS, evaluate the associations among estimated CRF, GS, and their combination with multimorbidity. METHODS: This analysis was based on data from 63 177 individuals who provided valid CRF and GS data in UK Biobank. Phenome-wide association studies identified diseases associated with both CRF and GS, defining multimorbidity. Cox proportional hazard models, logistic regression, and quasi-Poisson mixed effects models were used to investigate the effects of CRF and GS on multimorbidity. RESULTS: A total of 32 diseases were included to constitute the multimorbidity indicator. During a median follow-up of 11.58 years, at least 2 diseases developed in 21 275 participants. Compared with their lowest tertiles, the highest categories of estimated CRF and GS showed hazard ratios (HR) of 0.77 (95% CI, 0.74-0.80) and 0.78 (95% CI, 0.76-0.81) for multimorbidity, respectively. The HR for the combination of the highest estimated CRF and GS was 0.62 (95% CI, 0.59-0.66). Low estimated CRF and GS were associated with an increased risk of cardiovascular disease, leading to related complications. CONCLUSIONS: High estimated CRF and GS were associated with low multimorbidity risk. Maintaining both estimated CRF and GS may be more effective than targeting either alone. Proactive cardiovascular health management is crucial for individuals with low estimated CRF and GS to prevent multisystem multimorbidity.