Aerobic Exercise Part 1
Spring is right around the corner, summer is on the way and weight rooms everywhere are filled with exercisers trying to hone their beach muscles for flaunting under the sun. This means that bench presses, curls and crunches must surely occupy top spots on the popular-exercise-of-the-month list this time out. But before you devote all of your exercise efforts to these important muscle-building maneuvers, keep in mind that the most important muscle of them all is one that you’ll never see displayed, no matter how scantily clothed those beach goers are. Without a strong myocardium, any other muscles you sport will have limited shelf life at best.
Myocardium is the technical term for the muscular tissue of the heart. Yes, you heard me right: The heart is actually a muscle. But there are some significant differences between cardiac muscle and those 650 skeletal muscles that we all know and love. One major distinction is that the heart is always up and running. In fact, it is responsible for pumping life-sustaining blood and that means 24 hour-per-day shifts with no time off for good behavior. The heart fulfills this requirement by contracting to eject blood that has accumulated in its chambers and, on average, it does this 60-100 times each minute simply to satisfy the requirements of rest. During exercise, circulatory demands increase and the heart must contract far more frequently to keep pace.
Another major difference between cardiac muscle and skeletal muscle is the means by which they use energy to power their contractions. Skeletal muscles have significant anaerobic capacity and can, therefore, operate pretty effectively both with and without a continuous supply of sufficient oxygen. That is why our skeletal muscles can generate the force required to allow us to sprint, despite the fact that the powerful contractions necessary to do so mandate more oxygen than the contracting muscles can consume. Sure, you can’t provide energy this way for long, but you can sprint for short bursts and that has important implications with respect to our survival. The heart has no such option.
The myocardium has an extremely modest anaerobic capacity. This means that the heart must continuously receive an adequate amount of oxygen to support its level of work. That is why the first place oxygenated blood goes when it leaves the heart is to the blood vessels that feed the heart muscle itself. This ensures that the oxygen demands of cardiac tissue are met first before all other areas get their supply. However, the vascular network that supplies heart tissue can become blocked and/or heart tissue can become excessively thickened so that existing vessels cannot reach the distanced areas. When this happens and portions of the myocardium don’t receive sufficient oxygen, muscle cells bite the dust and we call their demise a heart attack. If too much of the heart muscle dies . . . well, I’ll leave it up to you to guess the ending to that tale.
How hard the heart must work to meet its circulatory challenge is related to how many times it must contract and also how much systemic pressure it must overcome to expel blood each time it does. When high blood pressure is present, the heart is challenged much more than it should be and its tissue becomes thickened as a result. As the series of events detailed above suggests, the end result is far different than when you challenge your biceps with curls to make their circumference increase.
Unfortunately, in the majority of cases, the cause of high blood pressure is unknown. It can also be present without definitive signs and symptoms, which is why is has been labeled “the silent killer.” And to make matters worse, exercise isn’t a cure because despite the fact that there are myriad benefits associated with regular cardiovascular conditioning workouts, dramatic reductions in blood pressure are not one of them. So, the bottom line is you should have your blood pressure checked regularly and if it’s high, listen to your doctor and do exactly what he tells you!
If your heart is working against an ideal pressure, the next thing to ensure is that it has to beat a minimal amount of times to get its job done. If more blood can be pumped each time it contracts, this objective will be met. Regular aerobic exercise (continuous rhythmic contractions of many skeletal muscles for an extended period of time, as would be the case, for example, when jogging) results in the chambers of the heart becoming bigger and more capable of accommodating blood. The heart also becomes more efficient at expelling blood so that less is left in its chambers once contractions are complete. The end result is an ability to send more blood out with each beat and that’s good news because all submaximal requirements including those associated with the resting state can be met with fewer cardiac contractions. And rest assured your heart will appreciate the added time off! Aerobic exercise also helps keep your blood free from contaminants like cholesterol that can injure the lining of cardiovascular vessels. This prevents inflammation and plaque build-up that can eventually restrict flow.
This article was originally published in New Living Magazine, which can be accessed on-line at www.newliving.com.
