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Presence of Metabolic Syndrome in Football Linemen

ackie L. Buell, PhD RD/LD LAT ATCa,, Doug Calland, MS LAT ATCa, Fiona Hanks, MS LAT ATCb, Bruce Johnston, MS LAT ATCb, Benjamin Pester, MS LAT ATCc, Robert Sweeney, MS LAT ATCa, and Robert Thorne, MEd LAT ATCc

Abstract

Context: Metabolic syndrome is a clustering of symptoms associated with abdominal obesity that demonstrates a high risk for cardiovascular disease and type II diabetes mellitus.

Objective: To evaluate football linemen in National Collegiate Athletic Association Divisions I, II, and III schools for the presence of metabolic syndrome according to the American Heart Association/National Heart, Lung, and Blood Institute criteria as well as to document other related biomarkers.

Design: Cross-sectional descriptive study.

Setting: Three university locations on the first full day of football camp in early morning.

Patients or Other Participants: Of 76 football linemen, 70 were able to provide blood samples.

Main Outcome Measure(s): Height, mass, blood pressure, upper-body skinfolds, and waist circumference were measured at various stations. Two small venous samples of blood were collected and analyzed in a hospital laboratory for fasting insulin, glucose, high-density lipoprotein, total cholesterol, triglycerides, C-reactive protein, and glycosylated hemoglobin. The last station was a verbal family history for cardiovascular disease and diabetes; also, athletes filled out a nutrition attitudes questionnaire.

Results: Of the 70 athletes, 34 were identified as having metabolic syndrome according to measures of blood pressure, waist circumference, fasting glucose, high-density lipoprotein, and triglycerides. The mean total cholesterol-to-high-density lipoprotein cholesterol ratio for the group was 4.95, with 32 participants displaying values higher than 5.0. Twelve volunteers had total cholesterol levels greater than 200 mmol/L, 15 had high levels of C-reactive protein, and 9 had slightly elevated levels of glycosylated hemoglobin.

Conclusions: Although athletes might be assumed to be protected from risks of cardiovascular disease, we found a high incidence of metabolic syndrome and other associated adverse biomarkers for heart disease in collegiate football linemen. Early screening, awareness, and intervention may have favorable effects on the overall health outcomes of football linemen.

Keywords: obesity, football players, dyslipidemia, hypertension, insulin, C-reactive protein

Key Points

Football linemen with abdominal adiposity exhibited the clustering of symptoms associated with higher risks of diabetes and cardiovascular disease (metabolic syndrome).

Athletes with a waist circumference equal to or greater than 40 in (101.60 cm) should be evaluated for other risk factors (fasting blood glucose, blood cholesterol, and triglyceride levels and prehypertensive blood pressure levels) to determine metabolic syndrome status and risks.

Athletes with metabolic syndrome should be counseled about the associated risks and educated about lifestyle choices that may reduce these risks.

Recent authors1–4 have demonstrated that football linemen are obese according to body mass index (BMI) measures. It may be tempting to discount these reports because of the inappropriate application of BMI in athletes, but football linemen may not be as healthy as we presume them to be, and closer evaluation of these large athletes for metabolic syndrome is needed. Metabolic syndrome (MetSyn) is typically defined as a clustering of clinical symptoms associated with increased abdominal adiposity and includes negative health correlates such as high blood pressure, dyslipidemia, insulin resistance, impaired glucose metabolism, and possibly elevated inflammatory and prothrombotic makers.5 Clustering of MetSyn abnormalities increases the risk of coronary heart disease and diabetes.6–8 The physique of football linemen can be consistent with increased body and abdominal fat stores,9 which may be associated with the presence of MetSyn.

Football linemen often seek advice for a weight gain routine (diet and weight training), with the goal of becoming larger than their opponents.10 Ideally, the increased body weight would be increased muscle mass, but often players increase their body size by accumulating more adipose tissue, specifically in the abdominal region. In our experience as athletic trainers and sports nutritionists, some athletes are indifferent to the composition of the weight gain; they just want to be immovable and more competitive with large opponents.

Numerous guidelines have been published by various professional groups for the identification of MetSyn. The purpose of our cross-sectional, descriptive study was to identify the incidence of MetSyn according to the American Heart Association and National Heart, Lung, and Blood Institute (AHA/NHLBI) criteria5 in football linemen at the National Collegiate Athletic Association (NCAA) Division I (DI), II (DII), and III (DIII) levels. The most common criteria for MetSyn include elevated waist circumference, blood pressure, fasting blood glucose (FBG), and triglycerides (TG) and depressed high-density lipoprotein (HDL) cholesterol. Markers of inflammation and insulin resistance may be secondary markers of MetSyn and may reflect increased risk. Therefore, a secondary aim of our study was to document fasting insulin, C-reactive protein (CRP), and glycosylated hemoglobin (HbA1c) levels in this cohort of collegiate football linemen.

Methods

Participants

Offensive and defensive linemen were recruited by the football athletic training staffs at NCAA DI, DII, and DIII schools. The protocol was approved by the human subjects committee at each institution, and written informed consent was obtained from each volunteer before participation. A total of 77 athletes consented to the study; 1 athlete withdrew before any data were collected. Six participants were not willing or able to provide a blood sample, leaving 70 who provided complete data. Data collection visits were completed in early August 2006. Participation in DII was excellent, with all linemen choosing to take part (n  =  30). Many linemen in DI and DIII chose not to participate: DI participation was 76% (26/34), and DIII participation was 48% (21/44). We wrote the protocol for 80 participants, so heavy recruitment at the last site (DIII) was limited to those athletes willing to give a blood sample. Roster data on all nonparticipants were available for comparison. Linemen totaled 108 in the 3 schools, and 76 of those (70%) participated in the study.

Protocol

Data were collected by a research team of 8 to 12 members at each institution on the first full day of preseason training camp in the early morning after an overnight fast (at least 6 to 8 hours) and before significant team training or testing took place. Once volunteers consented, they proceeded through stations organized to measure height, mass, blood pressure, upper-body skinfolds, and waist circumference. Trained phlebotomists obtained 2 small samples of venous blood, and the athletes completed a short verbal interview to document family history, estimated time spent running and lifting in the last week, and current injury status. The athletes then completed a self-report nutrition attitudes questionnaire.

Specific Station Methods. Height was measured to the nearest 0.1 cm using a wall-mounted SECA stadiometer (model 210; Hanover, MD). Mass was recorded to the nearest 0.1 kg with a digital system (model BWB-800A; Tanita Corp of America, Arlington Heights, IL). Systolic and diastolic blood pressures (SBP and DBP) were obtained with a single measurement, using an extra-large adult cuff with a standard sphygmomanometer and stethoscope. To enhance reliability, the same research team member measured blood pressure at all 3 institutions. The skinfold measurements were standardized in the same manner, with 1 trained research team member obtaining all measures of triceps, subscapular, and chest skinfolds in triplicate for all participants. These skinfolds were selected to simplify data collection because volunteers only needed to remove their shirts.11 The recorded skinfolds were later summed and entered into standard equations specific to the age and ethnicity of the participant to estimate body density and fatness.11 While the volunteer's shirt was off, waist circumference was also measured by the same researcher using the anterior superior iliac spine as the landmark to measure to the nearest 0.1 cm.5

Blood was obtained by trained phlebotomists using a Vacutainer system (Becton Dickinson, Franklin Lakes, NJ) to draw approximately 25 mL total in serum separator and heparinized sodium tubes with a single needle stick. The serum separator tube was immediately centrifuged at 1300 revolutions per minute for 5 minutes, and both tubes were stored over ice in a cooler until submitted to the hospital laboratory for processing 2 to 6 hours later. Blood measures included fasting insulin; FBG; cholesterol panel (including total [TChol], HDL, and calculated low-density lipoprotein [LDL]; TG; CRP; and HbA1c. The fasting insulin and CRP samples were run on an Immulite system (model 2000; Diagnostic Products Corp, Los Angeles, CA). The SYNCHRON LX System (Beckman Coulter, Fullerton, CA) was used to measure FBG, total and HDL cholesterol, and TGs and LDL. Finally, the HbA1c samples were run on the VARIANT II TURBO instrumentation (Bio-Rad Laboratories, Hercules, CA).

After the volunteer gave the blood sample and visited the anthropometric stations, he proceeded to an interview station, at which he was asked about demographics and occurrence of obesity, diabetes, heart