Objectives: The present study aimed to investigate the effect of two different exercise training protocols on myocardial fibrosis and the expression of some growth factors in aged rats. Method: Twenty-four male Wistar rats were randomly assigned to high-intensity interval training (HIIT) group, continuous exercise training (CET) group, and the control group. After 6 weeks of experiment, mRNA levels of fibroblast growth factor-2 (FGF-2), vascular endothelial growth factor (VEGF), adropin proteins, and myocardial fibrosis were assessed. Results: HIIT and CET induced a significant increase in the FGF-2 and adropin and a decrease in the myocardial fibrosis in compared with the control group. HIIT induced a significant increase in the VEGF if compared with the control group. There was no significant difference between CET and control group. Conclusion: Six weeks of HIIT and CET attenuated age-related myocardial fibrosis thereby an increase in angiogenesis-related molecules in cardiac and endothelial tissues.

In the present study, the effects of resistance training on regional hypertrophy and maximum strength of the elbow flexor muscles were compared between elbow flexion exercises performed with different shoulder joint angles (∼50° of flexion vs. extension) while matched for resistance profiles. In a within‐subject design, 15 young men (25.6 ± 2.1 y; 77.3 ± 6.8 kg; 175.1 ± 5.7 cm) underwent a resistance training program twice a week for 10 weeks (3–5 sets, 8–12RM), and their arms were dominant‐side balanced, randomly assigned to one of the two conditions according to elbow flexion exercises: unilateral cable curl with shoulder flexed (Preacher curl; PREA) or unilateral cable curl with shoulder extended (Bayesian curl; BAYE). B‐mode ultrasound imaging was used to measure changes in muscle thickness of the biceps brachii and brachialis at proximal, mid, and distal arm regions, and one‐repetition maximum tests were completed in each respective trained exercise before and after training. Both conditions showed significant increases in muscle thickness (p < 0.05) with no significant differences between them (p > 0.05) across the biceps brachii proximal, mid, and distal regions (relative change [Hedges' g effect size]; PREA: 6%[0.51], 7%[0.49], 7%[0.53]; BAYE: 9%[0.73], 9%[0.62], 9%[0.62]) and brachialis (PREA: 10%[0.72]; BAYE: 8%[0.65]). Similarly, significant improvements in maximum strength were observed (p < 0.05), with equivalent results between conditions (PREA: 28%[0.85], BAYE: 37%[1.22]; equivalence testing, p‐values = 0.061, 0.637). In conclusion, the shoulder joint angle does not seem to affect muscle hypertrophy and maximum strength gains after different elbow flexion exercises matched for resistance profiles.

Exercise‐induced stem cell activation is implicated in cardiovascular regeneration. However, ageing limits the capacity of cellular and molecular remodelling of the heart. It has been shown that exercise improves structure regeneration and function in the process of ageing. Aged male Wistar rats (n = 24) were divided into three groups: Control (CO), High-intensity interval training (HIIT) (80–100% of the maximum speed), and continuous endurance training (CET) (60–70% of the maximum speed) groups. Training groups were trained for 6 weeks. The expression of the Nkx2.5 gene was determined by real-time (RT-PCRs) analysis. Immunohistochemical staining was performed to assess the C-kit positive cardiac progenitor and Ki67 positive cells. The mRNA level of Nkx2.5 was significantly increased in the CET and HIIT groups (P < 0.05). Also, cardiac progenitor cells positive for C-kit were increased in both the CET and HIIT groups (P < 0.05). Exercise training improved the ejection fraction and fractional shortening in both training groups (P < 0.05). This study indicated that training initiates the activation of cardiac progenitor cells, leading to the generation of new myocardial cells (R = 0.737, P = 0.001). It seems that C-kit positive cells in training groups showed an increase in the expression of some transcription factors (Nkx2.5 gene), representing an increased regenerative capacity of cardiomyocytes during the training period. These findings suggest that the endogenous regenerative capacity of the adult heart, mediated by cardiac stem cells, would be increased in response to exercise. Exercise‐induced stem cell activation is implicated in cardiovascular regeneration. However, ageing limits the capacity of cellular and molecular remodelling of the heart. It has been shown that exercise improves structure regeneration and function in the process of ageing. Aged male Wistar rats (n = 24) were divided into three groups: Control (CO), High-intensity interval training (HIIT) (80–100% of the maximum speed), and continuous endurance training (CET) (60–70% of the maximum speed) groups. Training groups were trained for 6 weeks. The expression of the Nkx2.5 gene was determined by real-time (RT-PCRs) analysis. Immunohistochemical staining was performed to assess the C-kit positive cardiac progenitor and Ki67 positive cells. The mRNA level of Nkx2.5 was significantly increased in the CET and HIIT groups (P < 0.05). Also, cardiac progenitor cells positive for C-kit were increased in both the CET and HIIT groups (P < 0.05). Exercise training improved the ejection fraction and fractional shortening in both training groups (P < 0.05). This study indicated that training initiates the activation of cardiac progenitor cells, leading to the generation of new myocardial cells (R = 0.737, P = 0.001). It seems that C-kit positive cells in training groups showed an increase in the expression of some transcription factors (Nkx2.5 gene), representing an increased regenerative capacity of cardiomyocytes during the training period. These findings suggest that the endogenous regenerative capacity of the adult heart, mediated by cardiac stem cells, would be increased in response to exercise.