How much exercise do you really need?

Boosting one's physical activity levels can have a dramatic and positive impact on heart health. But how much exercise do you need to reap health benefits?

Some experts say as little as eight minutes per day will lead to health benefits; others say you need to exercise at least 45 minutes four times per week. Some say you need to train at a high intensity: you should be finished by the time your session is over. Others say you should train at an easy pace.

So which is it?

According to the latest research data, you need to exercise moderately at least three times a week, 30 minutes per day (90 minutes per week) to experience health benefits, explain experts from the Sports Science Institute (SSISA). This should be a good starting point.

The more you exercise, the greater the health benefits. A recent study found that people who exercise between one and two hours a week have a 40 percent reduction in heart disease risk. Those who exercise for more than two hours weekly reduce their risk by 61 percent.

But if you stop exercising, the benefits are lost within a few weeks.

You should aim to exercise 2 – 3 hours per week. This could translate to five 30-minute sessions per week, or four 40-minute sessions per week. A maximum should be no more than five 45-minute sessions per week, at a moderate pace, say SSISA experts.

Which pace and intensity?
Although SSISA experts advise people to exercise at a moderate pace (60 – 80 % of your maximum heart rate), there are two schools of thought when considering intensity.

The first one maintains that exercising at lower intensities for a longer duration will allow for a greater utilisation of fat as an energy fuel source. This is therefore recommended to those who desire to lose weight. Another advantage is the lower risk for injury.

The second one maintains that short high-intensity bouts of exercise burns even more fat. While carbohydrates remain the primary fuel source, more fat is used when doing this type of exercise than in a long bout of low intensity exercise.

For more effective weight loss, shorter, high-intensity training bouts, rather than long and leisurely bouts are more effective. However, if you just want to maintain good fitness levels and attain better heart health, training at lower intensity (but not lower than 60% of your maximum heart rate) will be good enough.

Weight training or running?
You can only become fitter with cardiovascular exercise, such as brisk walking, cycling, running, swimming, rowing or any exercise that will get your heart rate up. Cardiovascular exercise should be the main focus of your programme, but ideally a good fitness programme should also include resistance training (such as training with weights or gym exercises), stretching after exercises and a balanced eating plan. Sports scientists recommend two to three 20-minute resistance training sessions per week. Resistance training should be progressive in nature, individualised and provide a stimulus to all the major muscle groups.

Take action
How and when to exercise

• Choose a moderate aerobic (rhythmic and repetitive) activity that you enjoy, like walking, swimming or cycling. Complement this with resistance training to strengthen the muscles of your stomach, back, shoulders, legs and arms.
• Exercise three to five days each week, 30 to 45 minutes per session.
• Warm up for five to ten minutes before aerobic activity.
• Stretch to cool down during the last five to ten minutes of the session.
• Do not overexert yourself. You should always be able to catch your breath and speak comfortably while exercising.
• Exercise at 60-80% of your maximum heart rate (see text box on this page). Note that you should monitor your heart rate.
• Exercise needn't be continuous – you could do five-minute walks six times a day, as long as it adds up to 30 minutes.
• You should put two or three days of the week aside for resting.
• Exercise with a friend. This will strengthen your commitment and make it more fun.
• Exercise first thing in the morning for better management of your weight, for sustained energy levels, and for better control of blood pressure.

When not to exercise
You shouldn't exercise if you:

• have a sore throat.
• have a raised temperature.
• have aching or sore muscles.
• feel unusually tired.
• have an injury that becomes painful when you start to exercise. Speak to your doctor or physiotherapist before continuing with your exercise regime.

Facts

• 61 %: Your risk for heart disease may drop by this margin if you exercise more than two hours weekly.
• 13 million: The number of extra beats an inactive person's heart has to give.
• Exercise improves blood cholesterol levels, and lowers blood pressure, body fat and blood-clotting factors. It also boosts insulin sensitivity and is a great stress reliever. Exercise is good for the heart, even after a heart attack.
• It's never too late to start exercising. In fact, the older you are, the more you need it. However, if you are older than 40, consult your doctor before embarking on an exercise regime.

What should your exercise heart rate range be?
During exercise, your heart rate will increase. But this should happen within certain limits. You should exercise with your heart beating between 60 – 80 % of its maximum. Here’s how to calculate it.

• Your maximum heart rate (MHR) = 220 minus your age. If you are 40 years old, your MHR = 220 – 40 = 180 beats per minute.
• Determine your lower-limit exercise heart rate (60 % of your MHR) as follows: (220 minus age) multiplied by 60%. For a 40-year-old this would be 180 x 60% = 108 beats per minute.
• Determine your upper-limit exercise heart rate (80% of your MHR) by multiplying your maximum heart rate by 80%. For a 40-year-old this would be 180 x 80% = 144 beats per minute).

(Health24)