Exercising hard for a healthy life? That's not always necessary

Many people think you only see results when you push yourself to the limit in the gym. High-Intensity Interval Training, or HIIT for short, certainly improves your fitness, but if you're aiming for a longer, healthier life, it might be better to moderate your workouts.

Zone training, for example, is ideal for this.

"Zone training means you exercise at different intensity levels based on your heart rate ," personal trainer Warren Whitely explains to The Times . "Your maximum heart rate is roughly calculated by 220 minus your age. For me, at 33, that's 187 beats per minute. It's not a perfect method, but it's a good starting point. Each zone is a percentage of that number."

• Zone 1 (50-60 percent effort): light exertion, such as yoga or gentle cycling.
• Zone 2 (60-70 percent effort): The ideal middle ground. You exercise hard, but your breathing remains steady. This involves steady movement such as brisk walking, relaxed cycling, or gentle swimming, for at least 30 minutes at a time without reaching complete exhaustion.
• Zone 5 (90-100 percent effort): maximum effort, can only be maintained for a short time.

Zone 2 is known as the fat-burning zone. At this intensity, your body primarily uses fat as fuel, because your muscles receive enough oxygen to efficiently convert fat into energy. At higher intensities, your body switches to carbohydrates more quickly, because fat takes longer to provide energy. So, during a long walk, you burn a higher percentage of fat than during a HIIT class.

Additionally, Zone 2 boosts your metabolism. Your body learns to use fat as its primary fuel, even at rest. It improves cardiovascular health, regulates blood sugar, and increases metabolic flexibility—the ability to switch between different fuel sources. These benefits are all linked to a longer and healthier life.

Zone 2 training can also improve the function of mitochondria. These are the small powerhouses in your cells that convert food and oxygen into usable energy. With age, their efficiency decreases, which can lead to fatigue, loss of strength, and an increased risk of metabolic problems like insulin resistance or high blood sugar.

Regular, consistent exercise stimulates mitochondria to function more efficiently and form new compounds, a process called mitochondrial biogenesis. More and healthier mitochondria mean your cells can produce energy more effectively and potentially slow the signs of aging.

Zone 2 is easy to maintain and puts less strain on your joints and nervous system. "You're less likely to get injured and can keep it up longer," says personal trainer Fiona Kavanagh. Of course, you can add a more challenging workout every now and then.

New research suggests that higher intensity exercise may have additional benefits for the heart, muscles and mitochondria.

But Whitely emphasizes: "You don't have to push yourself to the limit every time. Zone 2 is your base, with one or two short, more intense sessions per week. Sometimes the magic is in slowing down."