Interactive effects of obesity and physical fitness on risk of ischemic heart disease

• Published in: International Journal of Obesity Vol. 41; no. 2; pp. 255 - 261
• Main Authors: Crump, C, Sundquist, J, Winkleby, M A, Sundquist, K
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-02-2017; Nature Publishing Group
• Subjects: 692/308/174; 692/499; Adolescent; Adult; Adults; Body Mass Index; Body size; Body weight; Cardiac and Cardiovascular Systems; Cardiovascular disease; Cardiovascular diseases; Child development; Clinical Medicine; Cohort analysis; Complications and side effects; Confidence intervals; Coronary artery disease; Disease prevention; Disease Susceptibility; Epidemiology; Exercise; Folkhälsovetenskap, global hälsa, socialmedicin och epidemiologi; Follow-Up Studies; Genetics; Health aspects; Health Promotion and Disease Prevention; Health Sciences; Heart; Heart diseases; Hospitals; Humans; Hälsovetenskap; Internal Medicine; Ischemia; Kardiologi; Klinisk medicin; Male; Medical and Health Sciences; Medicin och hälsovetenskap; Medicine; Medicine & Public Health; Metabolic Diseases; Middle Aged; Military Personnel; Muscle strength; Muscle Strength - physiology; Myocardial ischemia; Myocardial Ischemia - epidemiology; Myocardial Ischemia - physiopathology; Obesity; Obesity - epidemiology; Obesity - physiopathology; original-article; Overweight; Physical fitness; Physical Fitness - physiology; Public Health; Public Health, Global Health, Social Medicine and Epidemiology; Risk analysis; Risk Assessment; Risk Factors; Social factors; Socioeconomic Factors; Socioeconomics; Statistics; Sweden - epidemiology; Time Factors; Weight control; Workloads; Young Adult; Sweden; New York; United States > US; ANE, Sweden
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/ijo.2016.209

Background/Objectives:
Obesity and low physical fitness are known risk factors for ischemic heart disease (IHD), but their interactive effects are unclear. Elucidation of interactions between these common, modifiable risk factors may help inform more effective preventive strategies. We examined interactive effects of obesity, aerobic fitness and muscular strength in late adolescence on risk of IHD in adulthood in a large national cohort.
Subjects/Methods:
We conducted a national cohort study of all 1 547 407 military conscripts in Sweden during 1969–1997 (97–98% of all 18-year-old males each year). Aerobic fitness, muscular strength and body mass index (BMI) measurements were examined in relation to IHD identified from outpatient and inpatient diagnoses through 2012 (maximum age 62 years).
Results:
There were 38 142 men diagnosed with IHD in 39.7 million person years of follow-up. High BMI or low aerobic fitness (but not muscular strength) was associated with higher risk of IHD, adjusting for family history and socioeconomic factors. The combination of high BMI (overweight/obese vs normal) and low aerobic fitness (lowest vs highest tertile) was associated with highest IHD risk (incidence rate ratio, 3.11; 95% confidence interval (CI), 2.91–3.31;
P
<0.001). These exposures had no additive and a negative multiplicative interaction (that is, their combined effect was less than the product of their separate effects). Low aerobic fitness was a strong risk factor even among those with normal BMI.
Conclusions:
In this large cohort study, low aerobic fitness or high BMI at age 18 was associated with higher risk of IHD in adulthood, with a negative multiplicative interaction. Low aerobic fitness appeared to account for a similar number of IHD cases among those with normal vs high BMI (that is, no additive interaction). These findings suggest that interventions to prevent IHD should begin early in life and include not only weight control but aerobic fitness, even among persons of normal weight.