Ask the Experts

Q I am a 57-year-old man with high cholesterol. I am not on any medication as my doctor has advised me to exercise and change my diet to reduce my cholesterol level.

More than six months ago, I started exercising at least three times a week. My usual routine is to brisk walk for 15 minutes then jog for 20 minutes on the treadmill at 8kmh. Then I spend about 30 minutes at a few stations in the gym toning various muscles. I feel perfectly fine after each workout.

Recently, I started monitoring my heartbeat during my treadmill run. My heart rate was averaging 175 beats per minute. I understand that this exceeds my maximum heart rate and could be dangerous.

As a precaution, I switched to brisk walking at 5.6kmh and my heart rate dropped to 135 beats per minute. However, I find that this regimen is not strenuous enough as I hardly perspire. I would like to resume my previous level of activity.

My average daily blood pressure reading is about 135/80mmHg and my resting pulse rate is about 65 beats per minute.

Do I need to go for some medical tests before I return to my previous exercise regimen?

A Regular exercise has been shown to be beneficial. It not only reduces your risk of heart attack, but can also lower blood cholesterol levels and improve blood pressure control.

The recommended maximum heart rate is only a rough guide, generally derived from subtracting your age from 220. However, there is a wide variation in how we respond to physical stress.

Many people can tolerate much higher heart rates during exercise, while some may not attain the formula-derived number.

Therefore, heart-rate tolerance is specific to the individual and better determined by experience. The main role of the maximum heart rate in exercise is to provide a guide for training.

In a clinical test, your doctor's goal may be to push the exercise load until it is limited by symptoms such as chest discomfort, shortness of breath or fatigue. During this process, the heart rate may well rise above the maximum heart rate.

It is reasonable for you to increase the intensity of your exercise regimen as long as you feel comfortable. However, if you find that your heart rate starts to climb while performing the exercise workload, or if your effort tolerance becomes poorer, you should consult your physician.

Similarly, seek medical advice if you experience chest discomfort, shortness of breath, dizziness or palpitations (irregular heart beat) during exercise.

As you are in your 50s and have high cholesterol, I recommend consulting your physician about maintaining a regular blood pressure, doing blood glucose checks as well as screening for heart disease based on your cardiac risk profile.

Other factors that can increase a person's risk for coronary artery disease include smoking and diabetes.

Although most patients with severe heart disease experience symptoms of chest pain or breathlessness, some have "silent heart disease" that is only detected through medical imaging tests such as electrocardiograms, echocardiograms or computed tomography scans.

If you are concerned about your heart health or experience any worrying symptoms, you should undergo some medical investigations before embarking on a more strenuous exercise regimen.

This article was first published on June 18, 2015.
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