In the past decade, the emergence of HIIT (high-intensity interval training) has completely changed the playing field when it comes to exercise. The message? That you can boost your health more in less time by engaging in short, sharp workouts that make you breathless.

Yet is HIIT superior to a far gentler fitness option such as yoga? Or are there different but nonetheless impressive benefits to exercises that engage your core muscles while you stretch, flex, balance and hold a posture? Here’s how HIIT and hatha yoga compare.

The backstory

HIIT

High-intensity interval training is a form of anaerobic exercise that helps you quickly use up your glycogen stores so that your body starts to burn fat for fuel. It involves exercises — like sprinting, jumping, lifting weights and doing push-ups — which allow you to expend a large amount of kilojoules in a short space of time. The aim is to get breathless while pushing yourself to the max for short intervals.

Yoga

The word “yoga” means unity, of mind, body and breath. This gentle form of exercise is not simply a workout; it is a moving meditation. It involves a series of movements and postures designed to unblock energy channels and bring your body into balance. The aim is that you leave the class filled with energy rather than feeling depleted. Hatha yoga, which is the most popular in Western countries, is an umbrella term for any type of yoga involving postures.

The workout

HIIT

This involves short bursts of high-intensity exercise followed by a short period of rest and recovery. It can be configured in different ways, including:

• A four-minute HIIT routine repeated for two, four or six cycles. This would involve eight activities carried out with maximum effort continuously for 20 seconds with 10-second rests between each activity burst. As you become fitter, you can increase the number of repetitions for each exercise within the time frame.
• Ten-minute workouts that involve 30 seconds of HIIT followed by a slower 30-second period of recovery between each burst.
• HIIT on a stationary bike. Research by Stephen Boutcher at Sydney University has shown that doing a series of eight-second sprints followed by 12 seconds of cycling for a period of 20 minutes helps produce catecholamines, chemicals that turn on the body’s fat-burning process. Doing this training three times a week is so effective its benefit equal cycling for one hour, seven days a week. The end result? Greater fat loss from the legs and trunk area. You could also use the same timeframe of eight seconds on and 12 seconds’ rest using any series of HIIT exercises.

Yoga

Most yoga sessions last an hour to an hour and a half. They usually involve:

• A brief relaxation at the beginning to make sure muscles are relaxed and stretch more easily and a brief relaxation at the end to unwind and centre yourself after the session.
• Mindful breathing. Known as pranayama, a Sanskrit word meaning “vital breath”, the breathing exercises used in yoga have aims such as cleansing the body, reducing pain and banishing anxiety.
• Poses, or asanas, fall into four categories:

1. Supine poses, performed at the beginning and end of the session, designed to make sure the body is relaxed.
2. Standing poses, to help strengthen the legs and develop balance.
3. Sitting poses, which include forward bends and twists.
4. Inversions, which involve poses such as head and shoulder stands that work on the lymphatic system. When your body is upside-down, it is beneficial for your organs because your blood circulates to parts of your body which wouldn’t normally get good blood supply.

Muscle strength and flexibility

HIIT

As your muscle strength improves through anaerobic fitness, you increase the density of your muscle fibres, becoming more toned, stronger and more able. As muscle is more metabolically active, this means you burn more kilojoules even when at rest. Meanwhile, movements like sprinting and jumping make your bones stronger, too.

Yoga

A popular misconception is that because yoga is slow-moving it does not develop fitness. In fact, if you regularly practise yoga you gain great strength from aligning and holding a pose. Yoga improves the body’s range of motion, upper-body strength and core strength and works individual areas of the body such as shoulders, calves and thighs. The stretches elongate the fascia, strengthening this protective sheath of connective tissue that covers all muscles and muscle cells. In addition, the stretching in yoga improves balance, posture and flexibility and maximises blood flow to muscles.

Oxygen intake and circulation

HIIT

Anaerobic activity trains the heart, lungs and cardiovascular system to process and deliver oxygen more quickly and efficiently to every part of the body. The stronger and more efficient your heart muscle, the more blood can be pumped with each heartbeat and the fewer strokes you need to rapidly taxi oxygen throughout your body. This is good news for overall health. Oxygen helps the body repair cells, convert carbohydrates into energy, break down waste products and toxins and fight free radicals, which cause diseases such as cancer.

Yoga

The less exercise you do, the more you deprive vital organs of blood and important nutrients. Yoga counters our often sedentary lifestyles and jobs by limbering up the spine (promoting movements that improve elasticity in the blood vessels) while its inverted poses use compression to pump more oxygen throughout the body. During yoga, major muscle groups are systematically stretched and relaxed, pushing fresh blood and oxygen through the tissues, which releases the tension there and allows muscles to relax and cool as well as ensuring they receive greater nourishment through the blood supply.

Weight loss

HIIT

If you’re keen to kickstart fat burning or maintain a healthy weight, HIIT is a far better choice than lengthier aerobic workout sessions. Interval training burns fat and improves fitness more quickly than constant but moderately intensive physical activity, according to research by the University of Guelph in Canada. Studies show that HIIT workouts trigger substantial beneficial health impacts, including a reduction in waist circumference, particularly around the trunk and abdomen, a change to a healthier hormonal profile and greater insulin sensitivity, reducing risk of weight gain and diabetes. Moreover, HIIT workouts provide these health dividends in shorter time.

If you incorporate weights into your HIIT, you will build even more muscle, which is a metabolically active tissue in the body. The more lean tissue you have, the higher your resting metabolic rate, so you burn more kilojoules even when at rest.

Yoga

Though yoga does not increase your heart rate as much as HIIT, holding a posture does require the engagement of many muscle groups and increases your heartbeat and speeds up your metabolism. It can also help weight management in more subtle ways. First, some yoga poses stimulate sluggish glands to increase their hormonal secretions. The thyroid gland, especially, has a big effect on your weight because it affects body metabolism. Poses such as shoulder stand and fish posture are specific for the thyroid gland and stimulate metabolism, helping convert fat to muscle and energy. This means that as well as losing fat you will have better muscle tone and improved vitality. In addition, deep yogic breathing increases the oxygen intake to the body cells, including the fat cells. This increases the burning of kilojoules.

Mind and brain

HIIT

Exercise that gets you breathless can keep your brain in good shape as well as your body and reduce the risk of dementia as you age. People also report a great sense of achievement after finishing a HIIT workout where they have pushed themselves to maximum capacity. Research at the University of Montreal has found that, after four months of HIIT, middle-aged people enjoyed greatly improved cognition and memory and also better oxygenation to the brain (which was visible on MRI brain scans). Exercise that stimulates circulation has also been shown to increase the release of brain chemicals like serotonin, the happiness hormone.

Yoga

Yoga triggers an obvious reduction in beta and alpha activity (the brainwaves we experience most often during day-to-day life) and an obvious increase in theta activity, which induces a state of calmness with reduced consciousness. Studies also show that, for hours or even days after practicing yoga, people enjoy a significant increase in levels of certain brain chemicals such as dopamine, which helps improve mental clarity and enhances calm. During yoga, followers learn to switch off stressful thoughts. This meditative state slows the entire body down while assisting the nervous system to completely relax. That brings enormous feelings of wellbeing, security and comfort.

After yoga meditation, people often report feeling more centred, calmer, clearer, more energised and reconnected to themselves. Research by Boston University has concluded that yoga may be superior to other forms of exercise in reducing anxiety and improving mood. They conducted brain scans on people before and after one hour of yoga and found that there was a 27 per cent increase in levels of GABA (gamma-aminobutyric acid), a neurotransmitter brain chemical that helps promote relaxation and counters feelings of tension and anxiety.

Injuries

HIIT

As high-intensity exercises can place great load on the joints, this kind of workout can sometimes strain joints such as the knees, wrists or areas like your back. This can make it a trickier exercise option for people as they get older — however, doing the training on a stationary bike can circumvent some of these problems.

Yoga

Repetitive strain and overstretching are to blame for most yoga injuries, which tend to occur in the wrists, shoulders, neck, spine, hamstrings and knees. These kinds of issues most often occur because beginners or people who don’t engage in regular practice push themselves too far too fast when they’re not yet strong or flexible enough to do a certain pose or are not holding the posture correctly.

General health

HIIT

This kind of exercise reduces the risk of heart disease, stroke and diabetes while also lowering blood pressure and unhealthy cholesterol levels. It improves the function and structure of blood vessels with particular benefits to arteries that deliver blood to our muscles and heart, shows research from McMaster University, which also found that just six minutes of HIIT involving sprint intervals is as effective as an hour a day of moderate exercise. As HIIT helps increase fat burning, it also reduces inflammation, which has been linked to conditions like allergy, cancer and autoimmune disease. However, if HIIT is your favoured way to work out, make sure you balance all the high-intensity moves with at least one session of yoga stretches a week — otherwise your muscles may become tight and more prone to injury and pain.

Yoga

Enhances circulation of the blood and lymphatic systems, improves muscular elasticity and strength, makes the spine more supple and releases muscular tension. Studies show that it can also help relieve the symptoms of asthma, arthritis, fluid retention, digestive issues, headaches and stress and can help reduce risk of atherosclerosis (blocked arteries), diabetes and obesity. In cases of chronic back pain, yogic poses can enhance strength and mobility and reduce discomfort. As yoga enhances balance and body strength, it can also help lower the risk of falls and fractures that commonly occur as people age. To balance your workout each week, make sure you also take some time to do exercise that gets you breathless — even if you do only a short session of 10 minutes.

Time crunch

HIIT

If you struggle to get to the gym or to fit in exercise because of a busy work schedule or the family/career juggle, HIIT might be your best workout option. It can allow you to schedule short exercise bursts of 10 minutes or less in the morning or afternoon or both. Or you could squeeze a session into your lunch break every day and still be maintaining fitness.

Just four minutes of vigorous activity three times per week is enough to make previously inactive men fitter and more healthy, shows research from the Norwegian University of Science and Technology. In one study reported in the American Journal of Human Biology, one group of people who engaged in HIIT training for 63 minutes weekly were compared with a group of people engaged in 420 minutes of aerobic style exercise weekly. Though both groups showed improvements to their cardiovascular health, the HIITers enjoyed those benefits in only 15 per cent of the exercise time.

Yoga

There’s no doubt that yoga workouts require commitment to surrendering a block of time but, as that time is spent promoting a calm, almost meditative state, many people willingly embrace the session. Some even regard their yoga session as quality “me” time for self-nurture, empowerment and stillness.

However, if you really enjoy the benefits of yoga and you’re pushed for time, you can still incorporate yoga practice into your day by setting aside smaller windows of time to engage in asanas, such as a series of standing postures or the sun salute sequence. Break this up into 10 minutes in the morning and at lunch time or the end of the end of the day and you will still enjoy many health benefits. Though a longer yoga session may sometimes seem like a difficult time commitment to fit in, you will often save time in other ways such as needing less time to unwind before bed and enjoying better-quality sleep, so it’s well worth ensuring you make time for longer yoga sessions.