Some may not agree with me on this one…
but here is my two cents! Any athlete, who competes at a high level usually, performs a 1rep max on a core lift. While preparing for a 1rep max it is very important to understand blood pressure and its role during training. For example, a high-level powerlifter’s blood pressure goes up into the zones of myocardial infarction (“heart attack”) during the maximal attempt. Look at nearly any video of a powerlifter during squat or deadlift maximal attempt; they are usually purple. All the muscles are contracting maximally, putting pressure on the arteries and veins, and making it difficult for blood to flow through the body. This causes the heart to work harder and push blood harder.
If you’re a sports performance coach, the SAID (Specific Adaptation to Imposed Demand) principle is another example of it. Since the heart has to work harder to overcome resistive forces and push blood through the body, the left ventricle greatly increases in size and density. Essentially this prevents the left ventricle from bursting. The heart is a muscle like any other. When it has to work harder, it grows in size.
When the heart increases in size as a result of pumping blood through the body, it also increases in contractility, which helps push the blood through without much resistance. In powerlifting, the muscle has to push against great pressure, causing it to get stiffer. This effect needs to be balanced through some sort of cardiovascular work, not necessarily high-intensity cardio work, but something that makes the heart work. The heart needs to get its good work out in, too!