The purpose of this study was to evaluate subclinical atherosclerosis in retired professional football players. Two hundred one healthy former professional football players (mean age 50.8 years; mean body mass index 31.5 kg/m 2 ) were screened for the prevalence of cardiovascular risk factors, metabolic syndrome, and subclinical atherosclerosis by carotid artery ultrasound and compared with a cohort of men of similar body mass index referred for the assessment of subclinical atherosclerosis by carotid ultrasound. The prevalence of carotid artery plaque in the players was not significantly different from that of the body mass index–matched patients (33.3% vs 29.3%, p = 0.45). For the 2 groups, the prevalence of carotid artery plaque was >3 times higher than that reported in general population studies of patients with the same age range, gender, and exclusions. Metabolic syndrome prevalence was higher in linemen than in nonlinemen (45.8% vs 22.5%, p = 0.001), but there was no statistical difference in plaque presence between linemen and nonlinemen (27.1% vs 35.9%, p = 0.23). In conclusion, despite their elite athletic histories, former professional football players have a similar prevalence of advanced subclinical atherosclerosis as a clinically referred population of overweight and obese men.
Professional athletes are perceived by some to represent the pinnacle of health in our society. However, limited data suggest that professional football players in the National Football League, specifically linemen, may be at increased risk for adverse cardiovascular events and death after retirement. The increased body size that is typical in these men may be of concern. Body size is a strong predictor of shortened life span and earlier onset of cardiovascular disease, and a high prevalence of obesity-related conditions such as metabolic syndrome and obstructive sleep apnea have been reported in professional football players, although physical activity is known to reduce the risk for cardiovascular disease. It remains unclear whether the presence of high body mass index diminishes the benefits gained from an individual’s history as an elite athlete. As a measure of subclinical atherosclerosis, carotid artery plaque is strongly and independently associated with adverse cardiovascular events. To assess cardiovascular risk in professional football players, we evaluated carotid artery ultrasound and demographic and laboratory data in retired players without clinically apparent cardiovascular disease.
Methods
Invitations to participate in health-screening events conducted by the Living Heart Foundation were sent by the National Football League Players Association and the National Football League Alumni organization to retired players who live in and around the screening cities. The Living Heart Foundation has been conducting free health-screening events for retired National Football League players since 2004; our data are limited to 6 screening events done in conjunction with Mayo Clinic in 2006 and 2007. The study was approved by Pennsylvania State University Institutional Review Board and the Mayo Clinic Institutional Review Board. All players agreed to participate in this study and signed consent forms. Exclusion criteria for our analysis were age <35 or >65 years; diabetes mellitus as defined by history, medication use, or fasting blood glucose level ≥126 mg/dl; or the presence of clinical cerebrovascular, cardiovascular, or peripheral vascular disease.
The comparison cohort was obtained from the database of Mayo Clinic (Scottsdale, Arizona) from September 2006 through March 2008. This database consisted of all patients who underwent carotid ultrasound examinations for further clarification of cardiovascular risk as ordered by a referring physician. These individuals were subject to the same age, gender, and disease exclusion criteria.
To approximate the body mass indexes of the retired athletes, comparison subjects were limited to those with body mass indexes >28 kg/m 2 . Medical records were abstracted for pertinent demographic and anthropometric information. Metabolic syndrome was defined according to American Heart Association and National Heart, Lung, and Blood Institute guidelines.
Data included age, race, position played, and any history of diabetes, hypertension, smoking, and vascular disease. Smoking status was categorized as nonsmoker or former or current smoker. Hypertension was defined by previous diagnosis, medication use, or measured blood pressure ≥140/90 mm Hg. Hyperlipidemia was defined by previous diagnosis, medication use, or fasting calculated low-density lipoprotein (LDL) cholesterol level ≥130 mg/dl. Players were also categorized by race and position.
Each player was measured for height (meters) and weight (kilograms). Blood pressure and pulse were recorded 3 times and averaged. Body mass index was calculated as weight divided by height squared. Body surface area was calculated as the square root of ([height × weight × 100]/3,600). Laboratory analysis for each participant included fasting lipid profile and fasting glucose determination. Standard venipuncture was performed, and the samples were analyzed by Quest Diagnostics Inc. (Baltimore, Maryland). All laboratory values for the Mayo Clinic cohort were performed by Mayo Medical Laboratories and were extracted from the patient records. The fasting lipid profile reported total cholesterol, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, and triglycerides. Total cholesterol, HDL cholesterol, and triglycerides were measured using enzymatic techniques. The LDL cholesterol level was calculated using the Friedewald equation.
The Mayo patient cohort was obtained from all referring physician–ordered, clinically performed carotid ultrasound examinations for cardiovascular risk determination at Mayo Clinic from September 2006 to March 2008. Exclusion criteria were female gender; age >65 or <35 years; clinically apparent cardiovascular disease; diagnosis of diabetes mellitus, taking diabetic medication, or fasting blood glucose level ≥126 mg/dl; or body mass index ≤28 kg/m 2 . Data extracted were age, gender, medications, blood pressure, fasting glucose level, lipid profile, height, weight, blood pressure, and the presence or absence of plaque in the carotid arteries.
Carotid arterial plaque screening of both carotid arteries was performed at all 6 study sites and in the Mayo Clinic patient population using a standardized protocol, with imaging on a Siemens Sequoia or CV70 system with an 8-MHz linear-array transducer (Siemens Medical Solutions, Inc., Mountain View, California). Plaque screening was performed in the longitudinal and transverse planes, visualizing the common carotid arteries, carotid bulb, and proximal internal carotid arteries bilaterally. Sonographers were instructed to obtain 3-beat cine images of any suspect plaque. Studies were recorded to either DVD or magneto-optical disc in Digital Imaging and Communications in Medicine format for off-line analysis. Measurements were performed off-line by a single reader (RFB), who was blinded to all demographic criteria. Carotid artery plaque was defined as the presence of focal thickening ≥50% greater than that of the surrounding vessel wall, with a minimal thickness of 1.2 mm.
Unless otherwise specified, data are presented as mean ± SD or number (percentage). For continuous variables, comparisons between groups were performed using Student’s t test; for categorical variables, chi-square tests were applied. All p values were calculated using Student’s t tests or chi-square tests (or Fisher’s exact test if the number in any cell was <5). A p value <0.05 was considered statistically significant. Data analyses were performed using SAS version 9.0 (SAS Institute Inc., Cary, North Carolina).
Results
Three hundred thirty retired professional football players were evaluated; 245 were aged 35 to 65 years. Of these, 231 had interpretable carotid examinations; 6 had previously diagnosed vascular disease, and 24 had histories of diabetes mellitus or fasting blood glucose levels ≥126 mg/dl. Demographic, laboratory, and anthropometric data were analyzed in our final pool of former athletes of 201 men aged 35 to 65 years.
Demographic features and risk factor profiles of the players and Mayo Clinic controls are listed in Table 1 . The comparison group was statistically similar to the retired football players in age, body mass index, smoking prevalence, diastolic blood pressure, and total cholesterol, HDL cholesterol, and LDL cholesterol levels ( Table 1 ). The 2 groups differed in race, height, and weight. Systolic blood pressure was higher in the players, and triglyceride and fasting glucose levels were higher in the Mayo Clinic cohort.
| Characteristic | Retired Professional Football Players | Mayo Clinic Cohort | p Value ⁎ | ||
|---|---|---|---|---|---|
| n | Value | n | Value | ||
| Age (years) | 201 | 50.8 ± 9 | 123 | 49.6 ± 7 | 0.18 |
| Weight (kg) | 200 | 111.0 ± 18.9 | 123 | 99.4 ± 10.9 | <0.001 |
| Height (cm) | 200 | 1.9 ± 0.01 | 123 | 1.8 ± 0.1 | <0.001 |
| Body mass index (kg/m 2 ) | 200 | 31.5 ± 4.5 | 123 | 31.0 ± 2.7 | 0.18 |
| Body surface area (m 2 ) | 200 | 2.4 ± 0.2 | 123 | 2.2 ± 0.2 | <0.001 |
| African American | 201 | 113 (56%) | 107 | 2 (2%) | <0.001 |
| Smokers | 201 | 22 (11%) | 121 | 16 (13%) | 0.45 |
| Hypertension † | 201 | 38 (19%) | 86 | 6 (7%) | 0.50 |
| Systolic blood pressure (mm Hg) | 201 | 128.7 ± 16.4 | 122 | 123.7 ± 13.8 | 0.004 |
| Diastolic blood pressure (mm Hg) | 201 | 78.7 ± 10.9 | 122 | 78.4 ± 8.2 | 0.73 |
| Hyperlipidemia ‡ | 176 | 84 (48%) | 116 | 47 (41%) | 0.23 |
| Total cholesterol (mg/dl) | 201 | 198.8 ± 40.8 | 122 | 207.2 ± 40.1 | 0.07 |
| Low-density lipoprotein cholesterol (mg/dl) | 176 | 131.3 ± 25.6 | 116 | 126.4 ± 35.5 | 0.25 |
| High-density lipoprotein cholesterol (mg/dl) | 201 | 40.9 ± 16.5 | 122 | 50.1 ± 13.5 | 0.51 |
| Triglycerides (mg/dl) | 200 | 102.6 ± 64.6 | 122 | 162.2 ± 128.3 | <0.001 |
| Total cholesterol/high-density lipoprotein cholesterol ratio | 201 | 4.5 ± 1.7 | 122 | 4.4 ± 1.4 | 0.79 |
| Glucose (mg/dl) | 201 | 97.8 ± 10.5 | 118 | 102.1 ± 7.8 | <0.001 |
| Plaque | 201 | 67 (33%) | 123 | 36 (29%) | 0.45 |
⁎ Calculated using Student’s t test or the chi-square test (or Fisher’s exact test if the number in any cell was <5).
† Previous diagnosis, medication use, or measured blood pressure ≥140/90 mm Hg.
‡ Previous diagnosis, medication use, or fasting calculated LDL cholesterol level ≥130 mg/dl.
The comparative measures for African American and white players are listed in Table 2 . Table 3 lists the comparative data between linemen and nonlinemen. Linemen were larger than nonlinemen and had a higher prevalence of metabolic syndrome and hypertension, higher triglycerides, and lower HDL cholesterol.
| Characteristic | White | African American | p Value ⁎ | ||
|---|---|---|---|---|---|
| n | Value | n | Value | ||
| Age (years) | 88 | 52.6 ± 8.9 | 113 | 49.4 ± 8.6 | 0.01 |
| Weight (kg) | 88 | 244.7 ± 39.7 | 112 | 243.8 ± 43.0 | 0.88 |
| Height (cm) | 88 | 74.3 ± 2.4 | 112 | 73.2 ± 2.5 | 0.001 |
| Body mass index (kg/m 2 ) | 88 | 31.0 ± 4.2 | 112 | 31.9 ± 4.7 | 0.16 |
| Body surface area (m 2 ) | 88 | 2.4 ± 0.2 | 112 | 2.4 ± 0.2 | 0.40 |
| Lineman | 88 | 36 (41%) | 113 | 23 (20%) | 0.002 |
| Metabolic syndrome | 88 | 31 (35%) | 113 | 22 (20%) | 0.11 |
| Smokers | 88 | 13 (15%) | 113 | 8 (7%) | 0.08 |
| Hypertension † | 88 | 10 (11%) | 113 | 10 (9%) | 0.41 |
| Systolic blood pressure (mm Hg) | 88 | 128.8 ± 15.6 | 113 | 128.6 ± 17.0 | 0.93 |
| Diastolic blood pressure (mm Hg) | 88 | 79.2 ± 11.3 | 113 | 78.5 ± 10.7 | 0.66 |
| Hyperlipidemia ‡ | 78 | 35 (45%) | 98 | 39 (40%) | 0.50 |
| Total cholesterol (mg/dl) | 88 | 193.1 ± 38.7 | 113 | 203.2 ± 42.1 | 0.08 |
| Low-density lipoprotein cholesterol | 78 | 126.4 ± 34.7 | 98 | 135.1 ± 36.0 | 0.10 |
| High-density lipoprotein cholesterol (mg/dl) | 88 | 45.6 ± 14.8 | 113 | 51.6 ± 17.4 | 0.01 |
| Triglycerides (mg/dl) | 87 | 115.1 ± 78.2 | 113 | 92.9 ± 50.0 | 0.02 |
| Total cholesterol/high-density lipoprotein cholesterol ratio | 88 | 4.6 ± 1.7 | 113 | 4.3 ± 1.7 | 0.23 |
| Glucose (mg/dl) | 88 | 98.4 ± 11.0 | 113 | 97.3 ± 10.0 | 0.43 |
| Plaque | 88 | 28 (32%) | 113 | 39 (35%) | 0.69 |
⁎ Calculated using Student’s t test or the chi-square test (or Fisher’s exact test if the number in any cell was <5).
† Previous diagnosis, medication use, or measured blood pressure ≥140/90 mm Hg.
‡ Previous diagnosis, medication use, or fasting calculated LDL cholesterol level ≥130 mg/dl.
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