Effects of aerobic training, resistance training, or combined resistance-aerobic training on the left ventricular myocardium in a rat model

Abstract

This study follows the left ventricular (LV) hypertrophy in rats undergoing aerobic training alone (A), resistance training alone (R), or combined resistance and aerobic training (RA) (usually referred as concurrent training) program. A sedentary control group (C) was included. LV remodeling was evaluated using electron and light microscopy. The LV weight to body weight (LVW: BW) increased 11.4% in A group, 35% in the R group, and 18% in the RA group compared to the C group. The LV thickness increased 6% in the A group, 17% in the R group, and 10% in the RA group. The LV internal diameter increased 19% in the A group, 3% in the R group, and 8% in the RA group compared with the C group. The cross-sectional area of cardiomyocyte increased by 1% with the A group, 27% with R group, and 12% with RA training. The capillary density increased by 5.4% with A training, 11.0% with R training, and 7.7% with RA training compared with the C group. The volume fraction of interstitial collagen increased by 0.4% with training A, increased by 2.8% with R training, and 0.9% with RA training. In conclusion, except for the LV internal diameter, which increased more in the A group, the cardiac parameters increased more in the R group than in the other groups and in RA group than in A group. Collagen density increased from 5.4 6 0.8% in the C group to 5.8 6 0.6% in the A group (n. s.) (P > 0.05), to 8.2 6 0.7% in the R group (P < 0.05), and to 6.3 6 0.4% in the RA group (P < 0.05). These results demonstrate a significant increase for collagen content in the LV with R and RA exercise, but the increase was higher with R training alone than with RA training. Microsc.

Effects of Growth Hormone on Cardiac Remodeling During Resistance Training in Rats

“…In our study, that increased from 2.55% to 5.74%. Our collagen fraction values are not in accordance with those of the study by De Souza et al., 5 because the age and weight of the animals were different. However, other studies by our team with male Wistar rats of similar weights corroborate our findings, in which the collagen fraction varied from 2.5% to 3% in the control group.…”

“… 12 , 13 That hypothesis is supported by a study showing an increase in interstitial collagen formation induced by aerobic training or RT. 4 The study by De Souza et al 5 has shown a 2.8% increase in the interstitial collagen fraction in the group submitted to RT (control group = 5.5% and trained group = 9%). In our study, that increased from 2.55% to 5.74%.…”

“…Growth hormone has been often used to increase muscle mass and strength, and to enhance cardiac function during programs of resistance training (RT). Although the beneficial effects of RT on the cardiovascular system, such as increased capillary density, left ventricular (LV) hypertrophy, changes in connective tissue and benefits to the cardiac function, have been well established, 5 , 6 few studies have investigated the effects of chronic GH administration on cardiac remodeling during RT programs.…”

Evidence for distinct effects of exercise in different cardiac hypertrophic disorders

“…Indeed, it is important to clarify that resistance strength training actually result in concentric cardiac hypertrophy, and a reduction in internal ventricular chamber dimensions (Barauna et al 2007, De Souza et al 2014). The resistance-trained heart is therefore morphologically similar to a heart with pressure overload-induced pathological hypertrophy, although the important distinction is that resistance training-induced hypertrophy does not result in cardiac dysfunction in healthy human subjects (Hurley et al 1984, Hagerman et al 2000).…”

Exercise-Induced Regulation of Redox Status in Cardiovascular Diseases: The Role of Exercise Training and Detraining

“…Although these two types of exercise training have been studied extensively and their combination has been recently documented to promote health-related benefits in a wide range of populations [236], the effect of combined CVE and RE training on oxidative stress has been minimally studied.…”