Physical activity and cardiorespiratory fitness are associated with improved cardiovascular health and reduced all-cause mortality. The relation between self-reported physical activity, objective physical fitness, and the association of each with cardiometabolic risk has not been fully described. We studied 2,800 healthy Brazilian subjects referred for an employer-sponsored health screening. Physical activity level was determined as “low,” “moderate,” or “high” with the International Physical Activity Questionnaire: Short Form (IPAQ-SF). Fitness was measured as METs achieved on a maximal, symptom-limited, treadmill stress test. Using multivariate linear regression analysis, we calculated age, gender, and smoking-adjusted correlation coefficients among IPAQ-SF, fitness, and cardiometabolic risk factors. Mean age of study participants was 43 ± 9 years; 81% were men, and 43% were highly active. Mean METs achieved was 12 ± 2. IPAQ-SF category and fitness were moderately correlated (r = 0.377). Compared with IPAQ-SF category, fitness was better correlated with cardiometabolic risk factors including anthropomorphic measurements, blood pressure, fasting blood glucose, dyslipidemia, high-sensitivity C-reactive protein, and hepatic steatosis (all p <0.01). Among these, anthropomorphic measurements, blood pressure, high-sensitivity C-reactive protein, and hepatic steatosis had the largest discrepancies in correlation, whereas lipid factors had the least discrepant correlation. When IPAQ-SF and fitness were discordant, poor fitness drove associations with elevated cardiometabolic risk. In conclusion, self-reported physical activity level and directly measured fitness are moderately correlated, and the latter is more strongly associated with a protective cardiovascular risk profile.
In this study, we analyzed a population of relatively healthy adult Brazilian men and women to describe (1) the correlation between self-reported physical activity and directly measured fitness, (2) the relative association of self-reported physical activity and measured fitness with modern cardiometabolic risk factors, (3) the characteristics of subjects with discordant self-reported physical activity and measured fitness, and (4) the implication of this discordance on cardiometabolic risk.
Methods
The study population consisted of 2,800 Brazilian men and women (age range 19 to 78 years) free of baseline cardiovascular disease who were evaluated as part of an employer-sponsored health examination at the Preventive Medicine Center of the Hospital Israelita Albert Einstein in São Paulo, Brazil, from November 2008 to July 2010. The clinical examination consisted of a medical history questionnaire and comprehensive physical examination by a physician including anthropomorphic measurements of obesity, fasting blood laboratory analysis, and hepatic ultrasound for determination of liver fat. Patients were screened for excessive alcohol consumption using the Alcohol Use Disorders Identification Test (AUDIT). The AUDIT test was developed and validated by the World Health Organization among men and women of different ages and nationalities. A total score of ≥8 is generally accepted as an indicator of hazardous and/or harmful alcohol use.
Blood specimens were collected after an overnight fast. Laboratory analysis included a standard lipid panel, fasting glucose, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, and creatinine, all of which were analyzed using a Vitros platform automated laboratory system (Johnson & Johnson Clinical Diagnostics, New Brunswick, New Jersey). High-sensitivity C-reactive protein (hs-CRP) was determined by immunonephelemetry (Dade-Behrin GmbH, Mannheim, Germany). Hepatic steatosis was assessed by ultrasonography after a minimum 6-hour fast using an Acuson XP-10 device (Mountain View, California). Images were read by 2 board-certified radiologists blinded to laboratory test results. The diagnosis of hepatic steatosis was identified as a bright liver with contrast between hepatic and renal parenchyma.
Metabolic syndrome was defined at the time of the baseline examination using the International Diabetes Foundation criteria. Dyslipidemia was defined as triglycerides (TGs) ≥150 mg/dl, high-density lipoprotein (HDL) <40 mg/dl for men, and HDL <50 mg/dl for women.
Physical activity level was assessed by a physician using the International Physical Activity Questionnaire: Short Form (IPAQ-SF), which was previously validated in a similar patient population. The IPAQ-SF traditionally categorizes subjects into 1 of 3 distinct qualitative categories of physical activity: high, moderate, and low. According to IPAQ-SF scoring guidelines, high physical activity is equivalent to >1 hour of moderate-intensity activity over and above basal activity or >30 minutes of vigorous-intensity activity above basal levels daily. Moderate activity is defined as 30 minutes of at least moderate-intensity activity on most days of the week, and low activity describes all subjects not meeting the aforementioned criteria. For purposes of continuity with the previous literature, participants were stratified into these 3 categories of physical activity (low, moderate, and high) for the primary analysis of our data.
Fitness was quantified by the total time achieved on a maximal, symptom-limited, exercise treadmill stress test using either an Ellestad or a standard Bruce protocol. Stress test duration was converted into METs using previously validated methods of conversion.
For an Ellestad protocol exercise stress test, the following conversion formula was used for men and women :
VO 2 max = ( 3.933 × total time on the treadmill + 4.46 )
For a standard Bruce protocol exercise stress test, the following gender-specific formulas were used to convert total treadmill time achieved to V o 2 max :
Males VO 2 max = ( 2 . 9 × total time on the treadmill ) + 8 . 33 Females VO 2 max = ( 2 . 74 × total time on the treadmill ) + 8 . 03
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
