Athlete's Heart

Continued...

Up to 69 percent of aerobically trained athletes demonstrate phasic sinus arrhythmia. This benign rhythm discrepancy becomes more common as you become more fit; it temporarily disappears when you increase your heart rate with exercise.

Physicians have noted several other changes that reflect the heart's normal adaptation to training. Besides lowering the resting pulse rate, training makes the pulse more forceful, producing a harmless murmur as blood flows through the heart and blood vessels.

The athlete's heart may also appear slightly enlarged on a chest X-ray and an electrocardiogram (EKG) may chart patterns that would not show on the EKG of an untrained heart. However, these do not indicate disease.

Aerobics vs. Anaerobic Training

Like other muscles, your heart responds in a healthy way to specific training. if your training is principally aerobic, your heart must handle a large volume of blood. Its internal chambers will enlarge slightly and its overall size will increase.

The stroke volume - the amount of blood ejected from the chambers with each beat-will also increase, as your pulse rate decreases. These adaptations allow your heart to pump blood with maximum efficiency.

On the other hand, weight-lifting or resistance training will cause your heart muscle to thicken without enlargement of its cavity. This adaptation enables it to generate the increased blood pressure necessary for anaerobic exercise but doesn't contribute to a more efficient stroke volume or a lower pulse rate. If you combine aerobic and resistance training, your heart will of course show the benefits of both types of exercise.

Whatever type of training you do, changes in your heart muscle occur gradually over the first four to six weeks of consistent training. Aerobically trained athletes will notice this adaptation through their lower resting heart rates.

Some researchers have noted increased resting heart rates with overtraining. If your resting heart rate suddenly increases from 60 to 70 beats per minute and you are working harder than usual, watch out! You may be overtraining and need to slow down. When you stop training completely your heart will return to your untrained heart rate within three to four weeks.

While there are many benefits to aerobic conditioning of the heart muscle, a trained heart does not make you immune from heart problems.

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Foreword: Billie Jean King

Comments by Barb Harris
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