Background and aims: It is known that physical performance declines with age in general, however there remains much to be understood in terms of age-related differences amongst older adults across a variety of physical components (such as speed, strength and balance), and particularly in terms of the role played by multimorbidity of chronic diseases. We aimed to detect the age-related differences across four components of physical performance and to explore to what extent chronic diseases and multimorbidity may explain such differences.

Methods: We analyzed cross-sectional data from a population-based sample of 3323 people, aged 60 years and older from the SNAC-K study, Stockholm, Sweden. Physical performance was assessed by trained nurses using several tests (grip strength, walking speed, balance and chair stands). Clinical diagnoses were made by the examining physician based on clinical history and examination.

Results: Censored normal regression analyses showed that the 72- 90+ year-old persons had 17-40% worse grip strength, 44-86% worse balance, 30-86% worse chair stand score, and 21-59% worse walking speed, compared with the 60-66 year-old persons. Chronic diseases were strongly associated with physical impairment, and this association was particularly strong among the younger men. However, chronic diseases explained only some of the age-related differences in physical performance. When controlling for chronic diseases in the analyses, the age-related differences in physical performance changed 1-11 percent.

Conclusion: In spite of the strong association between multimorbidity and physical impairment, chronic morbidities explained only a small part of the age-related differences in physical performance.