Cardio exercise explained - with examples of the best workouts

Cardio exercise is often seen as something that makes you hot, sweaty and out of breath – but that’s not necessarily the case.

From improving the function of your heart and lungs to helping you lose weight, cardio has many benefits – not least that it can be a lot of fun!

In this article, we’ve got the lowdown on everything you need to know about cardio exercise – what it is, why you should do it, and how to get started.

What is cardio?

The term 'cardio' is short for cardiovascular exercise. It can also be referred to as aerobic exercise, and it’s often what a lot of people think of when talking about exercise.

It’s a form of activity that raises the heart rate, and it got its name because it primarily works the cardiovascular system – the heart and lungs. Some good examples include jogging, cycling, HIIT, or taking part in an aerobics or dance fitness class.

On the flip side of cardio is strength training. This primarily refers to using weights in your workout to get stronger. Examples include lifting weights in the gym or using resistance bands.

Certain types of cardio can also help you to build muscle and increase strength, but you ideally need to include both forms of exercise in your fitness regime for the best results.

Sitting in the middle, we have functional fitness. This form of exercise uses both cardio and strength training combined. Your heart rate will rise, but you’ll also use weights or some form of resistance to get stronger.

You’ll often find functional fitness classes, such as kettlebells or circuit training, on offer in a gym.

Why do cardio exercise?

Collectively, we are more sedentary than ever. In England, one in three men and nearly one in two women are classed as not being active enough for good health. This means they’re not achieving the Government’s recommendation of either at least 150 minutes (about two and a half hours) moderate physical activity per week, or 75 minutes of vigorous activity, like running.

In part, this shift can be attributed to changes in lifestyle: fewer people have manual jobs now, more people drive instead of walk, and advancements in technology mean we barely have to move from our armchair to get food.

But this inactivity is taking its toll, with the World Health Organization (WHO) warning that almost 500 million people globally will develop heart disease, obesity, diabetes or other noncommunicable diseases (NCDs) due to physical inactivity between 2020 and 2030, unless governments take urgent action.

The British Heart Foundation (BHF) recommends aerobic exercise to help lower blood pressure, reduce cholesterol, and lose weight. Cardio makes your heart work harder to pump all the blood to your muscles during exercise, and your lungs get a workout as you’re breathing harder.

Over time, this makes the heart and lungs work more efficiently, lowering your resting heart rate. This in turn lowers the risk of many preventable diseases, such as heart disease or type 2 diabetes. If conditions such as high blood pressure or heart issues run in your family, regular cardio exercise could possibly keep these at bay.

Speaking to Saga, personal trainer, dance instructor and BioSure ambassador Francesca Bradford also stresses the mental health benefits of cardio. She says that the way exercise makes us feel is important, as it’s often what keeps us coming back for more.

“The release of endorphins and serotonin improves mental wellbeing, increases self-esteem and helps relieve stress," she says.

"There’s also physical benefits such as improved heart health, enhanced brain health and better immune system function. What’s not to like?”

Is cardio good for weight loss?

Any form of exercise – whether it’s cardio, strength, or a mixture of the two – will burn calories. So in that regard we can say yes, cardio is good for weight loss.

“Ultimately, cardio leads to weight loss, as you are moving more than you were previously and therefore burning more calories,” Bradford says.

However, it shouldn’t be solely relied on to lose weight. Instead, take a holistic approach and combine exercise with a healthy diet for the best results.

“The only way to lose weight is to consume fewer calories than you are burning,” says Bradford.

This is known as a calorie deficit. Consuming 500kcal less than you burn in a day is about right for steady and sustainable weight loss (meaning you won’t pile it back on when you stop), but how much you burn will depend on factors such as age and weight.

For example, a person weighing 70kg (11st), running for 30 minutes at a pace of 12 minutes per mile, would burn around 300kcal. So, you’d need to run nearly an hour a day every day to create that deficit and lose approximately 0.5kg (1lb) a week.

Another way to do this is just to eat less. If you burn around 2,500kcal a day, but you eat 2,000kcal, you’ve created your 500kcal-a-day deficit. Of course, as you lose weight, you need to eat fewer calories, and there comes a point when you can’t cut them any further just from food.

Therefore, the best option is to combine exercise and a calorie deficit so that as your fitness and weight loss increases, you don’t need to keep lowering the amount you eat.

A note on afterburn

Cardio exercise will burn calories while you’re doing it and for a while after. This is known as afterburn, or – to give it its technical name – excess post-exercise oxygen consumption (EPOC). It refers to how much extra oxygen your body consumes after exercise. In fact, afterburn can contribute between 6% and 15% of your total energy expenditure in a workout. This adds up over time and could result in as much as 2.7kg (6lb) of weight loss a year.

Afterburn varies according to the amount and level of exercise you do. The best results come from short, intense workouts, such as high intensity interval training (HIIT), or strength training.

Strength training will also permanently boost your calorie burning ability by building more lean muscle. The more muscle you have on your body, the better it is at burning fat. For this reason (and many others), we’d recommend building a combination of exercise types into your regime.

Getting started with cardio

“So many people dread the thought of getting started,” Bradford tells us.

“I always advise that the best way to start your cardio journey is to incorporate it into your current lifestyle, so that it doesn’t feel like a monumental task and is easier to cope with mentally.

“Things like parking further away at the supermarket, getting off the bus a stop earlier, or walking for just 20 minutes per day can have a real, tangible impact. It doesn’t have to be strenuous. Once this is part of your daily routine it is far easier to increase the intensity (walking faster and further) as both your mind and body are ready for it.”

There are so many different options for cardio exercise (as we outline below) that it should be easy to pick something you like. You don’t need to be an expert, and you don’t need to exhaust yourself every time you exercise, either.

A positive mental attitude helps. You’re doing something that your body will thank you for, both now and in the future. If you’re brand new to exercise, be prepared to be a bit sore at first, particularly if you start an exercise class that uses muscles you don’t normally work (for example, a kettlebell class).

Don’t worry – DOMS (delayed onset muscle soreness) is perfectly natural, and it will ease as you become fitter and more accomplished.

How much cardio should I do?

The general guideline for exercise is 150 minutes per week, but you can do more than that if you wish to. This can be broken up into segments across the week and even across days.

For example, you might take a 10-minute walk in the morning and then go swimming for 30 minutes later in the day. You might rest the next day but the day after you might go to an hour-long spin class.

There’s no hard and fast rule, and remember, you’re more likely to stick to something if it’s enjoyable and fits in with your lifestyle.

What intensity should I be aiming for?

When doing cardio, your heart rate should be elevated but not dangerously so. It may rise and fall during a session according to your level of exertion.

It can be a good idea to wear a smartwatch or fitness tracker to check your heart rate while exercising. Heart rate can be divided up into zones, with zone one being very light – think walking along chatting to friends – up to zone five; an all-out sprint at maximum intensity, for example.

Broadly speaking, most of us should work in zones two and three for cardio, as this will bring the most benefits.  

Another way to measure how hard you’re working is using rate of perceived exertion (RPE) - how hard you feel you are working during exercise.

If an RPE of one is lying in bed, then 10 might be the hardest sprint you’ve ever done. When it comes to cardiovascular exercise, you want to be aiming between three and seven for noticeable benefits that won’t leave you struggling to recover.

The best cardio workouts

Yes, it really is that simple. If there’s an activity you enjoy that raises your heart rate, then that’s always going to be the best cardio choice for you. It doesn’t matter what your neighbour enjoys. If swimming three times a week is your favourite thing, then do that.

“Cardio doesn’t have to mean running for hours,” Bradford says.

“Enjoying team sports and group activities can encourage participation. If you enjoy dancing, then Zumba and barre deliver huge physical, mental and emotional benefits, and are classes that a lot of people really look forward to.”

Below we've outlined some examples of cardio exercises – find the one that appeals most to you and give that a go.

Outdoor cardio workouts

Walking is a great form of cardio and a good choice to get you started if you’re currently inactive. It offers lots of variation too; you can walk on a flat, hard surface if mobility is an issue, or venture out into the countryside or woodland to add in more challenging terrain (and you’ll build those leg muscles too).

If you’d like to progress to running, Couch to 5K is a fantastic app to help you get there, and we have a handy guide with all you need to know.

Indoor cardio workouts

Alternatively, you might love to do an aerobic workout. Most gyms and leisure centres have a wide range of classes on offer, from Boxercise to HIIT, and everything in between.

Spin is a hugely popular indoor cycling workout that is suitable for all levels of fitness and is gentle on your joints. Cycling to music, the instructor encourages you to increase or decrease the level of resistance on your bike as you sit or stand to cycle.

Of course, you might prefer to exercise in the privacy of your own home. YouTube has a wealth of cardio workouts to choose from, and the NHS even has its own platform for free exercise videos too.  

Cardio workouts that combine strength training

If you want to get stronger at the same time, you could choose an activity that uses weights too. Kettlebells is a great aerobic choice where you’ll also build muscle.

Pump-style classes use weights and basic movement patterns such as squats or lunges to get the heart rate up.

This is by no means an exhaustive list – and remember, any activity that gets the heart rate up can be classed as cardio. This includes gardening or housework, so you could even get fit while doing the spring cleaning.