Purpose: American-style football (ASF) participation rates in the United States are highest among high school (HS) athletes. This study sought to compare the cardiovascular response to HS versus collegiate ASF participation.
Methods: The ASF participants (HS, n = 61; collegiate, n = 87) were studied at preseason and postseason time points with echocardiography and applanation tonometry. Primary outcome variables included: left ventricular (LV) mass index, LV diastolic function (early relaxation velocity [E']), and arterial stiffness (pulse wave velocity [PWV]).
Results: High school (17.1 ± 0.4 yr) and collegiate ASF participants (18 ± 0.4 yr) experienced similar LV hypertrophy (ΔLV mass HS = 10.5 ± 10 vs collegiate = 11.2 ± 13.6 g·m, P = 0.97). Among HS participants, increases in LV mass were associated with stable diastolic tissue velocities (ΔE' = -0.3 ± 2.9 cm·s, P = 0.40) and vascular function (ΔPWV = -0.1 ± 0.6 m·s, P = 0.13). In contrast, collegiate participants demonstrated a higher burden of concentric LV hypertrophy (21/87, 24% vs 7/61, 11%, P = 0.026) with concomitant reductions in diastolic tissue velocities (ΔE': -2.0 ± 2.7 cm·s, P < 0.001) and increased arterial stiffness (ΔPWV: Δ0.2 ± 0.6 m·s, P = 0.003), changes that were influenced by linemen who had the highest post-season weight (124 ± 10 kg) and systolic blood pressure ([SBP], 138.8 ± 11 mm Hg). In multivariable analyses adjusting for age and ethnicity, body mass was an independent predictor of post-season PWV (β estimate = 0.01, P = 0.04) and E' (β estimate = -0.04, P = 0.05), whereas SBP was an independent predictor of postseason LV mass index (β estimate = 0.18, P = 0.01) and PWV (β estimate = 0.01, P = 0.007).
Conclusions: The transition from HS to college represents an important physiologic temporal data point after which differential ASF cardiovascular phenotypes manifest. Future work aimed to clarify underlying mechanisms, and the long-term clinical implications of these findings is warranted.