Objective Low physical fitness and obesity have been associated with higher risk of developing heart failure (HF), but their interactive effects are unknown. Elucidation of interactions among these common modifiable factors may help facilitate more effective primary prevention.
Methods We conducted a national cohort study to examine the interactive effects of aerobic fitness, muscular strength and body mass index (BMI) among 1 330 610 military conscripts in Sweden during 1969–1997 (97%–98% of all 18-year-old men) on risk of HF identified from inpatient and outpatient diagnoses through 2012 (maximum age 62 years).
Results There were 11 711 men diagnosed with HF in 37.8 million person-years of follow-up. Low aerobic fitness, low muscular strength and obesity were independently associated with higher risk of HF, after adjusting for each other, socioeconomic factors, other chronic diseases and family history of HF. The combination of low aerobic fitness and low muscular strength (lowest vs highest tertiles) was associated with a 1.7-fold risk of HF (95% CI 1.6 to 1.9; p<0.001; incidence rates per 100 000 person-years, 43.2 vs 10.8). These factors had positive additive and multiplicative interactions (p<0.001) and were associated with increased risk of HF even among men with normal BMI.
Conclusions Low aerobic fitness, low muscular strength and obesity at the age of 18 years were independently associated with higher risk of HF in adulthood, with interactive effects between aerobic fitness and muscular strength. These findings suggest that early-life interventions may help reduce the long-term risk of HF and should include both aerobic fitness and muscular strength, even among persons with normal BMI.
- body mass index
- heart failure
- muscle strength
- physical fitness
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Contributor JS had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: CC, JS, MAW, KS.
Acquisition of data: JS, KS.
Analysis and interpretation of data: CC, JS, MAW, KS.
Drafting of the manuscript: CC.
Critical revision of the manuscript for important intellectual content: CC, JS, MAW, KS.
Statistical analysis: CC, JS.
Obtained funding: JS, KS.
Competing interests None declared.
Patient consent Participant consent was not required as this study used only registry-based secondary data. To ensure confidentiality, all names and national identification numbers were replaced by anonymous serial numbers in adherence to the Personal Data Act (1998:204) and the Act (1995:606) and Ordinance (1995:1060) on certain personal registers.
Ethics approval Regional Ethics Committee of Lund University in Sweden (No. 2010/476).
Provenance and peer review Not commissioned; externally peer reviewed.
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