Effect on training on myocardial oxygen supply/demand balance

Area of Science:

• Cardiology
• Sports Medicine
• Physiology

Background:

• Assessing myocardial oxygen supply and demand is crucial for understanding cardiac health.
• Endurance training is known to improve cardiovascular function, but its specific effects on myocardial oxygen balance require detailed investigation.

Purpose of the Study:

• To evaluate the impact of endurance conditioning on the balance between myocardial oxygen supply and demand.
• To compare these effects in well-trained individuals versus sedentary controls.

Main Methods:

• Utilized the diastolic pressure time index (DPTI) to estimate subendocardial blood supply.
• Employed the tension time index (TTI) to quantify myocardial oxygen demands.
• Measured DPTI and TTI during a progressive treadmill test in trained and sedentary subjects.
• Calculated the DPTI/TTI ratio to assess the myocardial oxygen supply/demand balance.

Main Results:

• Trained subjects exhibited a significantly higher DPTI/TTI ratio at rest and submaximal workloads compared to controls.
• At maximal workload for controls, trained subjects had lower TTI and higher DPTI, resulting in a significantly improved DPTI/TTI ratio.
• Both groups achieved similar supply/demand balance at near-maximal heart rates, but trained subjects were at higher workloads.

Conclusions:

• Endurance conditioning enhances myocardial oxygen supply and demand balance at submaximal workloads.
• Training increases exercise capacity and reduces myocardial oxygen demand, thereby lowering the risk of cardiac ischemia.
• Improved oxygen supply/demand balance in trained individuals supports greater work capacity and cardiac efficiency.