Endurance Training - Good Or Bad For Heart Health?

We all know that exercise is good for you – but is it possible to take it too far, to the point where you could damage your heart? Dr. Juliet McGrattan investigates, and also shares her expert advice

- Dr. Juliet McGrattan

It’s irrefutable that exercise is good for your heart. Regular exercise will lower your heart rate and blood pressure and can reduce your risk of heart disease by 20-35 percent. The benefits are widely known and the evidence is strong. But is there a tipping point at which too much exercise becomes harmful to the heart? Could multiple and back-to-back endurance events actually increase your risk of cardiac conditions? This is a complicated and at times controversial topic but important to explore.

BASIC ANATOMY

First, let’s consider basic cardiac anatomy. The heart is made up of four chambers, two atria, and two ventricles. After the blood has circulated around the body, it returns through the veins into the right atrium, travels on to the right ventricle which then pumps it to the lungs. Here, the blood receives oxygen and flows on to the left atrium where it briefly lingers before being forcefully ejected by the thick, muscular left ventricle, to the rest of the body. The muscle making up the heart is a special kind of muscle called cardiac muscle and its contractions are controlled by a network of nerve pathways called the cardiac conduction system.

CARDIAC CHANGES WITH IMPROVED FITNESS

Increasing your fitness improves the effectiveness of the heart to pump oxygenated blood around the body. Like any muscle, cardiac muscle responds to an increased training load by strengthening itself during recovery. The muscular walls of the chambers contract with greater force, meaning that less-frequent heartbeats are required and resting heart rate falls. Larger volumes of blood are pumped with less effort. While blood pressure increases slightly during exercise itself, it falls when exercise stops and remains below its normal value for several hours. Regular exercise will reduce your heart rate, lower your blood pressure and improve your cardiovascular health.