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Low and High-Intensity Swimming Exercises induce Distinct Adaptations of Left Ventricle in Rats

Saifu ,, Asmuddin ,, La Sawali, Hasanuddin Jumareng, Abdul Saman, Wolter Mongsidi, M. Zainal Arwih, La Anse, M. Rusli, Muhtar Asegaf

Abstract


Aim. This study presents the influence of exercise on the development of a non-pathological cardiac hypertrophy.

Materials and methods. Thirty male Wistar rats were assigned into three groups: (1) high-intensity training (HI, n=10), (2) low-intensity training (LI, n=10), and (3) sedentary as control (C, n=10). The rats in the LI and HI groups were submitted to perform a continuous and intermittent swimming, respectively, for 13 min, 3 times/week/ 8 weeks. The exercise was divided into an acclimation and a maintenance phase with different workloads for each group. Here, we observed three variables of cardiac hypertrophy which included heart weight (HW), left ventricular thickness (LVT) and area of the left ventricular chamber (LVA).

Results. Swimming has increased the ratio of HW to body weight (BW) significantly, 31 and 21% in the LI and HI group (p<0.01), respectively. Histological analysis showed that the LVT was greater in HI (9%) than in LI group (4%), p<0.01. In contrast, the LVA was found to be greater in the LI (16%) than in HI group (11%), p<0.01. Microscopic analysis of the cross-sectional area of LV revealed that LI training increased the length of sarcomeres resulting in reducing the density of cardiomyocytes. In contrast, HI training increased the density of cardiomyocytes by thickening of the sarcomeres.

Conclusion. Our findings demonstrate that the swimming exercise induces the non-pathological cardiac hypertrophy. In addition, training with low and high-intensity particularly promotes distinct adaptations in left ventricle leading to the development of an eccentric and a concentric cardiac hypertrophy, respectively.


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