Food that improves cardio performance

Published on 18 October 2021

What happens to your body when you’re doing cardio

If you’ve ever done a cardio workout, you’ll probably be familiar with that point where your body basically says NO!

Cardiovascular endurance is a measure of how well you can do exercise that involves your whole body at moderate to high intensity for an extended time.

Manning explains that endurance is “basically how long you can repeat a particular movement or exercise before failing”.

He reveals that when you’re smashing out a cardio session, your body taps into different energy reserves, but which energy reserves get the call-up depends on a few factors.

“What reserve of energy you tap into during a cardio workout will depend on a number of things, including exercise intensity and duration, your percentage of VO2max and how well fuelled you already are,” says the personal trainer.

VO2max for those who aren’t familiar is what’s known as your maximum oxygen uptake. Essentially, it’s the measurement of the maximum amount of oxygen a person can utilise during intense exercise.

Manning points out that when we’re resting, muscles prefer to use triglycerides as a source of fuel. But when we’re doing cardio, there’s a shift.

Triglycerides are a type of fat (lipid) found in your blood. When we eat, our bodies convert any calories it doesn’t need to use right away into triglycerides.

“Triglycerides will contribute less during cardio, while carbohydrates (in the form of blood glucose and muscle glycogen), will increase - so the higher the intensity and the longer the duration of the exercise, the more we break down glycogen in the muscle and liver for use,” Manning explains.

What to eat to fuel your cardio endurance

Firstly, don’t avoid carbs. Manning says foods such as grains are ‘carb-tastic’ for cardio exercise.

“Endurance exercise is going to be a very carbohydrate demanding exercise. So, if performance is what you are aiming for, then being adequately fuelled with foods like rice, potato, bananas and pasta is important,” he says.

The nutritionist adds that if your carbohydrate stores aren’t great pre-cardio, this could work against you. That’s because the more your carbohydrate stores deplete, your body starts relying on fat stores, which means the intensity of your workout is lowered, and so is your performance. Not really what you want when you’re aiming for endurance.

What food and drinks to avoid in order to boost endurance

When it comes to endurance exercising, drinking alcohol as a regular pattern can negatively affect your performance in the gym. Alcohol is a sedative that slows down functioning.

“Unfortunately, alcohol doesn’t do much for us in terms of performance or body composition, so I would definitely moderate that,” advises Manning.

Caffeine on the other hand, when taken in the appropriate amount, can boost one’s performance. Caffeine stimulates the body’s central nervous system, improves reaction time and can reduce fatigue.

“Caffeine is an interesting one as it has been shown as performance-enhancing in many scenarios and the guidelines for how much to have to achieve this effect is actually quite high when you compare it to an average coffee drinker’s intake,” explains Manning.

A study by the American National Library of Medicine found that around 4.5mg of caffeine increased endurance in athletes, with the athletes able to cover an extra 3.2km more when compared to others who were given a placebo.

If you don’t consider yourself an athlete but want to boost your gym performance, you may want to down a cup of joe roughly 45 minutes before a workout. Studies show that maximum caffeine concentration hits at about 45 minutes post consumption.

Find your middle-ground when it comes to caffeine

But before you go upping your caffeine levels, it’s probably best to chat with your trainer or sports dietitian first.

While consuming caffeine before a workout can be beneficial in enhancing performance, Manning warns consuming too much for those who are hypersensitive to caffeine can cause adverse reactions.

“Some people may be hyper responders or non-responders which can mean that caffeine isn’t the right option for them,” Manning advises.

Even at amounts less than 100mg, people who are hypersensitive to caffeine can experience symptoms such as insomnia, jitters, and an increased heartbeat.

Carbs and caffeine combo

It appears as though carbs and caffeine can work hand-in-hand when it comes to endurance too.

A study showing that when combining caffeine and carbohydrates, performance was boosted by 4.6 per cent compared with carbohydrates alone.

When to eat for endurance

If including carbs into your pre-workout, when you eat them and what type of carbs you eat are important factors, says Manning.

His advice is to have higher GI carbohydrates (i.e. white rice, breakfast cereals, potatoes) closer to your workout and low GI carbs (i.e. soy products, beans, fruit, pasta, oats) further out from exercise.

“Eating anything too close to exercise can give you some gastrointestinal upset, so experimenting with what works best for you both in terms of what you eat and when is always best.”

Byron Manning is a personal trainer at Aquanation and Aquahub and holds a Bachelor of Food and Nutrition Science and Masters of Dietetics from Deakin University.