Shobhana, 38, a Chennai-based chartered accountant, vowed to make exercise a part of her lifestyle this year. She started by lifting weights under the supervision of a trainer and gradually worked her way into high-intensity interval training: exercises performed in short, powerful bursts of speed with a few seconds of recovery between each set.

However, at the end of three months, she had to abandon her training.

“Every bone in my body ached,” she says. “Instead of feeling refreshed or motivated after my exercise, I was exhausted all day. I couldn’t focus on work because I was so tired.”

A month later, Shobana switched to a fitness regimen that embraced low-intensity cardio—and felt much better. Today, she’s walking or cycling for an hour, three to four times a week, and her fitness has improved. She’s lost 4 kilos and, most importantly, feels refreshed and energetic.

While fast-paced exercises do offer excellent cardiac and health benefits, medical experts say they aren’t for everyone.

STEADY, BUT NOT TOO SLOW

Today, many health and fitness experts recommend a steady pace of exercise, especially if you are elderly, overweight, or recovering from illness. It can also be beneficial if you’re starting your exercise routine after a long sedentary period or are battling a medical condition such as heart disease, high blood pressure or severe asthma.

“Most people think that only vigorous exercise is good for them,” says. Dr VV. Muthusamy, cardiologist. “However, that’s not always the case.”

The president of the Indian Society of Hypertension and director of the World Hypertension League advises people to keep in mind their current fitness levels and medical history when planning workouts, especially if they have a family history of hypertension and heart disease.

“Exercising too vigorously can be very damaging for someone with high blood pressure, because it can make the condition worse, which in turn escalates a lot of other health problems,” he says.

EXERCISE TO AVOID INJURY

Some trainers now prescribe intensive workouts like magic pills, without looking into details such as lifestyle, nutrition levels, sleep quality, and daily stressors—all of which impact your fitness. This can leave people vulnerable to injury and burnout, as well as a weakened system, says Deepak Mudaliar, a Chennai physiotherapist and fitness trainer.

“Exercising at this (high) intensity is fine when you’re young or an athlete,” Mudaliar says. “But as you age, it’s difficult to sustain.”

This is because high-impact exercises, while revving the heart and burning fat, often add greater stress to the joints, particularly the knees and lower back. Painful inflammation of the tendons and muscles of the lower leg can cause frequent injuries, one reason why high-impact activity is often discouraged for beginners or people with a tendency toward arthritis.

“Earlier, high-intensity exercises often referred to those that used two or more muscle groups while still maintaining proper posture, technique and greater range of motion,” says Mudaliar. “However, today, most people want to see the best results from their fitness regimen in the shortest possible time. Such impatience and the craving for weight loss has started a new trend. High-intensity exercise now means taking exertion to its peak, even if your body isn’t conditioned for it. And even if you can cope with it now, it is definitely not good for you in the long run.”

PUT YOUR HEART INTO IT

What is good for you in the long run is steady-state cardio workouts, experts say. To be effective, you’ll need to maintain a sustained pace, but not necessarily an easy one. Most modern equipment in the gym (such as the latest treadmills and exercise bikes) come fitted with handlebar sensors that can measure heart rate through your palms and while you are exercising. Use these sensors to exercise at an intensity that helps you reach a range around your ‘target heart rate,’ which is the most opportune range for fat burning.

Finding your target heart rate involves some calculation. You’ll need to know two figures—your resting heart rate and your maximum heart rate. Your resting heart rate is the number of times your heart beats in one minute, when you’re completely relaxed and at rest.

“It’s best to check for this right after you wake up from a good night’s sleep,” says Mudaliar. “Place your fingers on your wrist and count your pulse (for one minute). Evaluate the average of three readings, taken on consecutive days. It’s usually between 60 and 80.”

Your maximum heart rate is obtained by subtracting your current age from 220, and finally, to find your target heart rate, subtract your resting rate from your maximum rate. So, if you’re 40 years old, with a resting heart rate of 70, your maximum heart rate would be 220 minus 40, which is 180. Your target heart rate would be 180 minus 70, or 110 beats per minute.

Most fitness trainers advise you to exercise at 60 to 80% of this target heart rate (66 to 88 in our example). However, some like Mudaliar, prefer that you start at only 40 to 60% in the beginning (i.e., 44 to 88).

“This rhythmic consistency conditions your heart better and builds endurance and stamina,” he says.

So find your target heart rate and get moving at a pace that works for you!