Up your cardio game: How to improve cardio fitness

Cardio, also known as endurance exercise, is an important part of every workout routine. It can help you reach your fitness goals, manage your weight and improve the function of your heart and lungs.

While you're probably familiar with the basics of cardio, there's plenty more to know if you want to seriously increase your fitness level.

Whether you're aiming to run a marathon this year or just looking to enjoy your weekly run a bit more, here's our deep dive on all things cardiovascular fitness.

Explaining cardio exercise

Cardiovascular exercise, or cardio for short, is any activity that increases your heart rate, gets you sweating and increases blood flow [1]. Common examples include running, walking, cycling, swimming and rowing [3].

The main goal of cardio is to improve your heart and lung function. This allows your body to pump blood and use oxygen more efficiently [3].

There are 2 different types of cardio exercise:

• Aerobic: moderate intensity exercise done for a long time, such as running or swimming
• Anaerobic: short bursts of intense activity, such as sprinting or HIIT training

Aerobic exercise helps build up your cardiovascular endurance, while anaerobic exercise is good for strength and power. Cardio is one of 4 types of exercise to include in your weekly routine, with the others being strength, balance and flexibility [2].

What are the benefits of cardio training?

Regular exercise is about more than maximising your appearance, it’s about improving your overall health too. Here are 5 benefits to cardio training that can motivate you to get moving this week.

Helps with weight loss

Cardio exercise is a proven strategy for maintaining a healthy weight [3]. When combined with a balanced diet, cardio puts you into a calorie deficit, which is the first step to losing weight and keeping it off.

More specifically, it helps you burn calories from both fat and carbohydrates. It can also help regulate blood sugars, lower cholesterol and blood pressure levels.

There are lots of ways to get started with weight loss through cardio; from talking to your doctor to working with a personal trainer or joining a programme, like Compound.

Compound combines medical treatments, diagnostics, prescriber support, and personalised nutrition and exercise plans for an effective programme that helps men unlock body recomposition.

• Up to 15% weight loss with clinically backed treatments
• Lose fat and gain muscle with customised diet and movement plans
• Track metrics and progress within the Compound app

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Improves your endurance

The more endurance you have, the less tired you feel during the day [3]. Cardio exercise is well-known for its ability to improve your stamina and endurance.

People with higher endurance tend to find everyday tasks easier, from taking the stairs to carrying groceries or walking long distances. Having a high level of endurance can also enhance your other workouts, helping you train for longer without getting tired.

Good for your heart

As we mentioned earlier, one of the main goals of cardio is to improve your heart function [3]. It strengthens the heart muscles, which allows them to pump blood more efficiently throughout your body. This, in turn, helps transport oxygen to where it’s needed. 

Along with your heart, cardio is also good for strengthening your bones, muscles and joints [1].

Better mental health

Feel happier after a run? There’s a good reason for that. Cardio exercise releases endorphins, which are known as the ‘feel-good’ hormones [3]. 

Research has also found that cardio can help reduce stress and improve sleep quality [1][3]. 

Lower risk of disease

Everyone knows that getting active is good for you, but what exactly are you protecting against? According to research, cardio exercise can help reduce the risk of multiple serious diseases [1].

What are the best ways to increase cardio fitness?

In a review of multiple studies, researchers found that adjusting the intensity, frequency or duration of your exercise is the best way to improve cardio fitness [5].

Intensity

The greatest improvements to people’s fitness were found through increasing the intensity of their exercise. This means reaching 90-100% of your maximum power [5]. How do you know when you’ve hit the sweet spot? This comes down to your heart rate and breathing. 

Vigorous or intense exercise is the kind that has you huffing and puffing, which means your heart rate has gone up significantly [1]. In comparison, moderate intensity exercise still gets your heart rate up without leaving you breathless.

If you’re new to exercise or have a pre-existing health condition, it’s important to speak with your doctor for recommendations on a safe and effective exercise routine. 

If at any time you feel pain or tightness in the chest, shortness of breath or dizziness, stop exercise and take a rest.

Frequency

When you’re new to cardio training, you can get away with a pretty relaxed schedule, experiencing fitness gains from only 2 sessions per week.

However, as your fitness levels increase, you need to increase the frequency of training. Once you’ve built a base level of fitness, further gains require a minimum of 3 sessions per week [5].

Duration

The length of your workout also has a role to play. You need to match up the duration of your exercise to the intensity [5]. For example, low-intensity exercise like a light jog works best for a longer duration — 35 minutes or more.

On the flip side, high-intensity exercise allows you to exercise for less time, under 35 minutes.

Build up over time

No matter how you decide to mix up your cardio workouts, be sure to build new habits slowly [2].

If you’re new to cardio, then start small with 10-15 minutes of exercise per session. Your first goal could be simple, such as improving your aerobic capacity by doing 30 minutes of cardio on 5 days per week.

When you’ve achieved this goal consistently, you’re ready to ramp up the workout. This is when you can gradually increase the intensity, duration or difficulty. For example, add 10 minutes to your run or swap from running on flat ground to a hilly trail.

Always make time for a warm-up and cool down as well, which preps your muscles for movement and helps prevent injury. It's as easy as adding 5 minutes of slow movement to the start and end of your cardio workouts [1].

How long does it take to improve cardio fitness?

There’s no magic number to give you, as every person's body responds differently to exercise. What we can tell you is that various studies have found positive results on cardio fitness in as little as 2 weeks [7].

But that doesn’t mean it’s your peak fitness. It takes around 3-4 months of consistent exercise to form a habit and see the best results [1].

What happens if you stop exercising?

It’s normal for life to get busy, and a lot of people take a break from exercise when this happens. In quite frustrating news, cardio fitness is the first to drop, losing endurance in as little as 2 weeks, whereas strength takes up to 8 weeks to fade [8].

But even after a long break, muscle memory can help you rebuild fitness just as quickly. Research suggests you can regain up to half of your fitness level in 10-14 days.

If you've had an extended break (12 weeks or more), then getting back to your full fitness level can take up to 8 weeks.

How can I improve my cardio fitness score?

The most common measure for a cardio fitness score is your VO2 max. The V stands for volume and O2 for oxygen [4]. VO2 max represents your maximal oxygen uptake. In other words, how much oxygen your body uses while exercising.

Your muscles need oxygen to create adenosine triphosphate (ATP), which is their main energy source. The more oxygen your body takes in, the more ATP it can generate. The more ATP, the more power you have for your workout.

A high VO2 max score means your body is good at transporting and using oxygen. There are lots of ways to improve your cardio fitness score. Here are 4 proven methods.

Interval training

Interval training is a good way for everyone to improve their cardio fitness, especially people who are already quite active [4]. 

Interval training is a short exercise session that alternates between high intensity (90% of your VO2 max) and brief rest periods, also known as active recovery [7]. Common examples include high-intensity interval training (HIIT), sprint interval training (SIT) and repeated-sprint training (RST).

Mix up your usual exercise routine

The more you do the same routine, the more your body adapts to it. Mixing up your usual exercise can be a good way to get your body working harder.

For example, you could swap from running to swimming, increase your running pace or add 10 minutes to your usual workout length [4].

Lose weight

Everyone’s VO2 max is relative to their weight, which means losing weight by itself is an effective way to increase your cardio fitness score [4].

Adjust your lifestyle

Lifestyle habits play a big role in your overall health and fitness. For example, multiple studies have found that smokers have lower cardio fitness scores than non-smokers [6]. 

Physical activity is another important factor. It’s different from exercise in that it’s not about pushing your body harder, but about gentle movement throughout the day.

Research shows that people who are physically active during their free time have higher cardio fitness scores.

Can 30 minutes every day increase cardiovascular fitness?

Any aerobic activity, for any amount of time, has the potential to increase your cardio fitness. But, as we highlighted earlier, intensity makes a difference [5]. 

If you’re exercising at a lower intensity, such as walking, then you probably need more than 30 minutes to reap the full benefits. Higher intensity exercise is more effective for short durations, such as 30 minutes or less.

That’s one reason that interval training has been trending lately. It helps you improve fitness in a short amount of time, which is key for time-poor modern living [7].