Cardiac basal autophagic activity and increased exercise capacity.

Area of Science:

• Exercise Physiology
• Cardiovascular Research
• Cellular Biology

Background:

• Exercise training modulates cardiac function and cellular processes.
• High-intensity interval training (HIIT) and continuous moderate-intensity training (CMT) are common exercise modalities.
• Autophagy plays a role in cellular adaptation to stress, including exercise.

Purpose of the Study:

• Compare the effects of HIIT and CMT on exercise performance and cardiac function in rats.
• Investigate the influence of HIIT and CMT on basal autophagy in cardiac muscle.
• Determine the relationship between exercise adaptations, autophagy, and mitochondrial function.

Main Methods:

• Rats underwent 10 weeks of either sedentary control (SC), CMT, or HIIT.
• Exercise performance was assessed via time to exhaustion and grip strength.
• Cardiac function, morphology, autophagy markers, and mitochondrial content were analyzed using echocardiography, Western blotting, and electron microscopy.

Main Results:

• HIIT significantly improved time to exhaustion and grip strength compared to SC and CMT groups.
• Both HIIT and CMT enhanced exercise tolerance and cardiac morphology but did not alter systolic function.
• HIIT-induced performance gains correlated with enhanced basal autophagy and mitochondrial function in cardiac muscle.

Conclusions:

• HIIT is more effective than CMT in improving exercise performance in rats.
• Enhanced exercise performance with HIIT is associated with improved cardiac mitochondrial function and basal autophagic adaptation.
• Autophagy and mitochondrial markers were positively correlated, suggesting a synergistic role in exercise adaptation.