Weight Gain in College Football Players Is Mechanism of Subclinical Cardiovascular Pathology
Key findings
- Over three years of participation in U.S. college football, athletes demonstrated significant increases in weight and systolic blood pressure
- In parallel, there was a significant decline in cardiovascular efficiency, manifested by significant reductions in diastolic function and increases in arterial stiffness
- The prevalence of concentric left hypertrophy also increased across the study period
- Weight gain and hypertension were independently associated with increased arterial stiffness and the risk of concentric left ventricular hypertrophy
- Football players with this maladaptive cardiovascular phenotype should have close clinical surveillance both during and after football participation
According to multiple studies, former professional U.S. football players who were linemen or were obese during their playing years are more likely than men in the general population to die of cardiovascular disease. The underlying pathology is not well understood because these studies have been of short duration and have focused only on single components of cardiovascular health.
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To address this knowledge gap, Aaron L. Baggish, MD, director of the Cardiovascular Performance Program at Massachusetts General Hospital, Jonathan H. Kim, MD, MSc of the Emory Clinical Cardiovascular Research Institute and colleagues performed serial, multimodality cardiovascular phenotyping during the first three years of college football players' careers. In JAMA Cardiology, they report that players who gained weight and developed increased systolic blood pressure were at risk of developing concentric left ventricular (LV) hypertrophy, arterial stiffening and reduced LV diastolic function.
Study Details
Between June 2014 and June 2017, the research team serially enrolled 186 male freshman football players at two Division I universities. They were examined at four timepoints:
- Point 1 — During their freshman preseason
- Point 2 — At the immediate beginning of their freshman postseason, approximately five to six months after point 1
- Point 3 — At the immediate beginning of their sophomore postseason
- Point 4 — At the immediate beginning of their junior postseason
The athletes were examined clinically and by transthoracic echocardiography and vascular applanation tonometry. The primary outcome measures were:
- Left ventricular mass index and geometry (measures of cardiac structure)
- Early diastolic myocardial relaxation velocity (E′, a measure of LV diastolic function)
- Pulse-wave velocity (PWV, the gold standard measure of arterial stiffness)
Players who left the team for any reason, or did not have all data available, were ineligible for analysis. The final study cohort was 126 players, including 55 who completed all four examinations. They were evenly distributed by race (50% black, 49% white) and 39% were linemen. At baseline their average weight was 101 kg and their average systolic blood pressure (SBP) was 129 mmHg.
Cardiac Changes
- After adjustment for height, race and player position, the athletes demonstrated significant, progressive increases in weight (cumulative average increase, 4.74 kg; P < .001) and SBP (cumulative average increase, 11.6 mm Hg; P < .001)
- In parallel, there was a significant decline in cardiovascular efficiency, manifested by significant reductions in E′ and significant increases in PWV
- The trends of change in each outcome measure were not significantly different between linemen and non-lineman
Explaining the Decline in Cardiovascular Efficiency
In a multivariate analysis, weight gain emerged as an independent factor associated with increasing PWV and was nonsignificantly associated with declining E′. Systolic blood pressure was independently associated with PWV but not with E′.
Weight Gain and Concentric LV Hypertrophy
Across the study period, the researchers noted an increase in LV mass. The most noteworthy contributor was a continual increase in the number of players with concentric LV hypertrophy (relative wall thickness >0.42 with an LV mass index >102 g/m2). The prevalence was 3% at point 1, 12% at point 2, 18% at point 3 and 25% at point 4 (P = .001).
According to a multivariate analysis, weight gain and increased SBP were independent factors associated with the risk of concentric LV hypertrophy (respectively OR, 1.09; P < .001 and OR, 1.04; P = .02).
Recommendations
Even at these players' relatively young age, a maladaptive cardiovascular phenotype could often be detected. Players with this phenotype should have close clinical surveillance both during and after football participation.
Clinicians and athletic trainers charged with caring for football players should consider serial anthropometric and blood pressure measurements and regular testing to evaluate cardiac structure and function. The metrics used in this study can identify athletes who may benefit from lifestyle counseling and, when indicated, pharmacologic therapy.
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