CHANGES IN LEFT VENTRICULAR FUNCTION AND MORPHOLOGY IN RESPONSE TO HIGH-INTENSITY, CROSS-TRAINING.

Abstract

It is a widely accepted concept that different exercise modalities produce different effects of myocardial hypertrophy in athletes; a sport-specific hypothesis proposed by Morganroth et al. (1977). The literature would also suggest that left ventricular function is altered by endurance and resistance type exercise and that there are distinct differences between the functioning of an endurance- and resistance trained heart (Mantziari et al. 2010 & Spence et al. 2011). However, there is a distinct lack of research examining the effects that high intensity cross-training has on left ventricular function and morphology. A group of CrossFit athletes (8 males, mean age 27 ± 4 years) who had been training using the CrossFit modality for over a year and a half were included in the study. Written informed consent was approved by the Cardiff Metropolitan University ethical committee. A group of sex-matched, healthy individuals who perform ≤ 2 hours of physical activity per week served as controls. All participants underwent a complete echocardiographic evaluation and completed a V ̇O2 maximum test on a cycle ergometer to determine aerobic fitness. The trained participants had significantly increased left ventricular cavity dimensions at end diastole (P < 0.05) in comparison to sedentary controls (5.3 ± 0.6 cm vs 4.5 ± 0.5 cm, respectively) this was also evident with left ventricular cavity dimensions at end systole (3.5 ± 0.6 cm vs 2.9 ± 0.5 cm (P < 0.05)). Left ventricular posterior wall thickness at end diastole also proved to be significantly increased (P < 0.05) in comparison to controls (1.7 ± 0.4 cm vs 1.1 ± 0.3 cm, respectively). Left ventricular posterior wall thickness at end systole in trained individuals was significantly greater (P < 0.05) than in controls (2.1 ± 0.3 cm vs1.6 ± 0.2 cm). Stroke volume was significantly increased in the trained participants (P < 0.05) when compared with controls (105 ± 16 ml vs 71 ± 15 ml). Ejection fraction was also significantly increased in trained participants (P < 0.05) in comparison to controls (54 ± 8 % vs 43 ± 4 %). In conclusion, these findings demonstrate that high intensity, mixed modality cross-training produce significant adaptations to the morphology and function of the left ventricle when compared to sex-matched controls. The findings from this study provide some support for the Morganroth hypothesis.