The athlete's heart. A meta-analysis of cardiac structure and function.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational cross-sectional studies
PubMed 10645932 · doi:10.1161/01.cir.101.3.336
What was done
A random-effects meta-analysis evaluated published echocardiographic structural and functional data in male athletes compared with control subjects. Athletes were categorized into purely dynamic sports (running), purely static sports (weight lifting, power lifting, bodybuilding, throwing, wrestling), or combined dynamic and static sports (cycling, rowing). The analysis included 59 studies comprising 1451 athletes.
What was found
Mean relative left ventricular (LV) wall thickness was significantly higher across all athlete groups compared with controls (0.36): endurance-trained (0.39, P=0.001), combined (0.40, P=0.001), and strength-trained (0.44, P<0.001). Athletes and controls differed significantly in LV internal diameter, posterior wall thickness, and interventricular septum thickness (all P<0.001). Direct comparison between endurance and strength athletes showed significant differences in relative wall thickness (0.39 vs 0.44, P=0.006) and interventricular septum thickness (10.5 vs 11.8 mm, P=0.005), alongside trends toward larger LV internal diameter in endurance athletes (53.7 vs 52.1 mm, P=0.055) and thicker posterior walls in strength athletes (10.3 vs 11.0 mm, P=0.078). Measures of cardiac function (LV ejection fraction, fractional shortening, and E/A ratio) showed no significant differences between athletes and controls.
Why it matters
This study provides aggregate evidence supporting the Morganroth hypothesis of divergent cardiac remodeling in dynamic versus static sports while confirming that athletic hypertrophy is not accompanied by resting functional impairment.
Limits
The meta-analysis included only male athletes, precluding generalization to female athletes. The underlying primary studies were cross-sectional observational designs, which cannot definitively establish longitudinal adaptation or control for potential unmeasured confounders such as body size, training volume, or anabolic-androgenic substance use. The abstract does not specify the total number of control subjects.
Cited by
- supports Rowers and skate skiers exhibit the largest heart sizes among competitive athletes due to the combination of high static strength and dynamic endurance demands in their sports.