Woman doing burpees at the gym

Cardio workouts: the two types of HIIT you need to do every week, according to an exercise professor

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These are the best cardio workouts to do every week – and an expert doctor has broken down just how long to do them for. 

When we think of cardio training, we tend to think of 10K runs or 45-minute HIIT classes. No wonder, then, that heart rate-raising workouts have a reputation for being hard, tiresome or inaccessible.

But according to Dr Andy Galpin, professor of kinesiology at California State University and an expert in exercise, strength and conditioning, it doesn’t have to be that much of a slog.

Talking on the Huberman Lab podcast, he broke down two different types of cardio we should all be doing every week – and it’s probably less than you think.

Workout 1: touch your max

Dr Galpin begins by breaking down “the week of endurance” by explaining that “you need to do something once a week that gets you to a maximum heart rate, or as high as you can possibly get”.

To work out your max heart rate, he suggests starting with an equation of 220 minus your age. “If you’re 40 years old, your maximum heart rate is probably about 180 beats per minute. Now I can tell you flat out right now, my max heart rate is close to 210, which means I’m 10 years old, so take that number with a grain of salt. That calculation is not a good proxy for physical fitness but it’s a rough number,” he says.

“Another easy way to do it if you have a heart rate monitor is to do the hardest workout you can possibly do, see what the highest number you get is and assume that’s close to your max.” 

Don’t have a heart rate monitor? You can always work with something called RPE, which stands for ‘rating of perceived exertion’. This works on an effort scale of 1-10, with 10 being your all-out maximum effort – try to aim for that level of work during this session. 

In terms of exercise selection, you can do anything that’s cardiovascularly taxing. “Do something where you’re like, ‘This is death – this is really, really, really challenging.’ That could be a sprint around a track or uphill. It could be burpees to death,” he explains.

But here’s the most important part of the workout – you don’t need to sustain that high heart rate. “Do it for however long it takes you to hit the max. It will probably be 30 seconds at a minimum because it’s hard to get you to a true heart rate max in shorter than 30 seconds. But if you did as many burpees as you can in 90 seconds, that will probably also get you to your max,” Dr Galpin explains.

You can stop after just one round of maximum pushing – meaning the whole workout takes just 30 seconds (plus a non-negotiable warm-up and cooldown). “In an ideal world, you might go for four to eight rounds in a single session. If each round takes you 20 seconds or 90 seconds, it’s fine. If you want to do 30 on, 30 off, 20 on 40 off, 40 on 20 off… those numbers don’t matter. As long as you touch that max heart rate, I’m good,” he says. 

Women on the rowing machine at the gym
You can choose any exercise that makes you breathless to work to your max heart rate

Dr Galpin acknowledges that this workout requires a lot of mental focus, as well as physical energy. “If you can’t muster the mental energy every week, do it every other week – that’s still very good. I get it, I’m a working person too, and sometimes you’re just like, ‘I cannot!’ Those workouts feel incredible afterwards but man, they are daunting. So if you hate it, it’s not realistic to think you’re going to be able to knock this out every week and you’re going to end up doing it at 70-80% which is not going to give you the benefits. So just don’t do it.”

Those benefits stem from the fact that “stress is what causes adaptation”, says Dr Galpin. He explains that every cardiovascular function will be adapted when pushed to its maximum, including stroke volume (the amount of blood pushed out with each pump), decreased resting heart rate, lung expansion, and changes at a cellular level such as capillary and mitochondria health. 

Workout 2: interval training

As well as working out at your maximum, Dr Galpin also recommends interval training. “The other piece I want is this middle ground training, which is about sustaining hard work for four to 12 minutes. Your heart rate doesn’t have to be quite as high – you don’t have to get to your max but can you get somewhere in the 80% range? And can you hold that for four minutes?” asks Dr Galpin.

You can work out what 80% of your maximum heart rate is after you’ve reached it in the first session. For example, if your max is 180 then you should be trying to sustain around 144 for at least four minutes.

Again, that can be divided up into blocks, such as two to six minutes of hard work with an equivalent amount of rest in between. “Repeat once if you have to. If you can, do it six to eight times. You can make it as long or short of a training session as you want to,” he explains. 

“Exercise choice can be whatever you want. You can do sled pushes, a kettlebell circuit, or any combination of things where you’re working without a break.”

Dr Galpin says that “you might even argue this gives the most cardiovascular benefit because it is sustained work output. That’s very critical – the downside of a conversational pace is that it’s physical activity, it’s movement, it’s blood flow with lymphatic drainage, but it’s not very cardiovascularly challenging. You’re just not going to get optimal health by just walking actively.”

It might be tough, but the good news is that all your cardio can be over in less than 25 minutes a week if you want it to. We’ll race you to the rower. 

Images: Getty

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Chloe Gray

Chloe Gray is the senior writer for stylist.co.uk's fitness brand Strong Women. When she's not writing or lifting weights, she's most likely found practicing handstands, sipping a gin and tonic or eating peanut butter straight out of the jar (not all at the same time).