Left ventricular performance characteristics in trained and sedentary dogs

Area of Science:

• Cardiovascular Physiology
• Exercise Science
• Sports Medicine

Background:

• Understanding the impact of exercise on cardiac function is crucial for sports science and clinical cardiology.
• Previous research has explored training adaptations, but specific effects on left ventricular (LV) performance require detailed investigation.

Purpose of the Study:

• To investigate the effects of chronic endurance training on left ventricular (LV) performance in a canine model.
• To assess changes in LV dimensions, pump function, and contractility following a 10-week training program.

Main Methods:

• 14 dogs were studied, with 9 undergoing chronic implantation of LV pressure transducers.
• An exercise group (n=5) underwent 10 weeks of progressively rigorous treadmill training.
• A sedentary group (n=4) and sham-operated dogs served as controls, with ventricular function assessed via ventriculography.

Main Results:

• Trained dogs exhibited a decreased heart rate response to graded exercise.
• LV end-diastolic volume significantly increased post-training (P < 0.05), while ejection fraction remained unchanged.
• Stroke work (P < 0.05) and indicators of contractility (peak dP/dt, peak contractile element shortening velocity) increased in trained dogs.

Conclusions:

• Chronic endurance training significantly alters left ventricular (LV) size, specifically increasing end-diastolic volume.
• Training improves LV pump performance and contractility, as evidenced by increased stroke work and velocity indices.
• These adaptations suggest a beneficial effect of endurance training on cardiac function.