Complete Reversion of Cardiac Functional Adaptation Induced by Exercise Training.
Purpose: Long-term exercise training is associated with characteristic cardiac adaptation, termed athlete's heart. Our research group previously characterized in vivo left ventricular (LV) function of exercise-induced cardiac hypertrophy in detail in a rat model, however the effect of detraining on LV function is still unclear. We aimed at evaluating the reversibility of functional alterations of athlete's heart after detraining.
Methods: Rats (n=16) were divided into detrained exercised (DEx) and detrained control (DCo) groups. Trained rats swam 200min/day for 12weeks, control rats were taken into water for 5min/day. After the training period both groups remained sedentary for 8weeks. We performed echocardiography at week 12 and 20 to investigate the development and regression of exercise-induced structural changes. LV pressure-volume analysis was performed to calculate cardiac functional parameters. LV samples were harvested for histological examination.
Results: Echocardiography showed robust LV hypertrophy after completing the training protocol (LVmass index: 2.61+/-0.08 DEx vs. 2.04+/-0.04g/kg DCo,p<0.05). This adaptation regressed after detraining (LVmass index: 2.01+/-0.03 vs. 1.97+/-0.05g/kg,n.s.), which was confirmed by post-mortem measured heart weight and histological morphometry. After the 8-week-long detraining period regression of the previously described exercise-induced cardiac functional alterations was observed (DEx vs. DCo): stroke volume (144.8+/-9.0 vs. 143.9+/-9.6[mu]l, p=0.949), active relaxation ([tau]: 11.5+/-0.3 vs. 11.3+/-0.4ms, p=0.760), contractility (preload recruitable stroke work: 69.5+/-2.7 vs. 70.9+/-2.4mmHg, p=0.709) and mechanoenergetic (mechanical efficiency: 68.7+/-1.2 vs. 69.4+/-1.8%, p=0.742) enhancement reverted completely to control values. Myocardial stiffness remained unchanged, moreover no fibrosis was observed after the detraining period.
Conclusion: Functional consequences of exercise-induced physiological LV hypertrophy completely regressed after 8weeks of deconditioning.
(C) 2016 American College of Sports Medicine
Autor / Fonte:Attila Oláh, Dalma Kellermayer, Csaba Mátyás, Balázs Tamás Németh, more. Medicine and Science in Sports and Exercise 2016 October 14