Most popular HIIT classes aren't actually high intensity, according to a personal trainer -- here's what a HIIT workout really is

Be:FIT LondonAlice Liveing.
  • There’s plenty of research to support the idea that high-intensity interval training, or HIIT, is just as beneficial as – if not more than – a longer, more traditional workout.
  • However, Alice Liveing, a personal trainer and Instagram star, said most HIIT workouts are actually moderately intense.
  • Real HIIT involves working to 90% capacity and can’t be maintained for a long period, she said.

There’s a growing body of research supporting the idea that high-intensity interval training, or HIIT, is just as beneficial as – if not more than – a longer, moderately intense workout.

HIIT involves short bursts of exercise with brief (30 to 45 seconds) intervals of rest in between. You should be working at maximum capacity and out of breath by the end of the workout, even though it can be as short as seven minutes.

In a study published in the June issue of the journal Certified, scientists compared a group of people on a HIIT plan for six weeks with a group doing traditional workouts for the same period. The interval trainers saw the same improvements in heart health and muscle tone as exercisers in the other group – and they saw most of the benefits in less than half the time.

However, according to a personal trainer, most boutique-gym HIIT workouts, which tend to last about 30 to 60 minutes, aren’t actually high-intensity workouts.

Alice Liveing, who shares photos of her workouts and lifestyle with her nearly 640,000 Instagram followers, is a trainer at Third Space and works with clients of all kinds, including the actress Suranne Jones (“Doctor Foster”) and the British television and radio presenter Maya Jama.

Speaking to Business Insider at Be:FIT London last month, Liveing said she started posting her “health and well-being journey” on Instagram a few years ago while touring as part of the musical “Annie” – she was previously a professional dancer, singer, and actress.

“I was really getting into training and wanted to understand more about my training, so I decided to qualify as a PT,” she said.

When the tour ended, Liveing needed a break from performing, she said.

“My body was just wrecked, and I was exhausted,” she said. “I decided that I would start PT-ing a bit on the side, and I just fell in love with it and enjoyed my time so much that I increased my hours, took on more clients, then was offered a job at Third Space.”

Liveing has written three best-selling books, is a monthly columnist for Women’s Health magazine, and just released a training app.

She works out four or five times a week – but you won’t see HIIT training as part of her regimen.

“It’s all weight training, resistance training, and a little bit of Olympic lifting,” she said.

She added that while HIIT is certainly very popular at the moment, “true HIIT isn’t what most people are doing.”

Most ‘HIIT’ workouts are actually moderate intensity

“Most people are doing moderate-intensity-level exercise rather than it being high intensity,” Liveing said. “For it to be high intensity, you have to be working at 90% capacity, so you’re literally going into that anaerobic threshold where you’re tapping into that energy system.”

Anaerobic threshold refers to the point during a workout when lactic acid starts to build up in the muscles – something that, during a HIIT workout, doesn’t occur until you’re working at close to 90% capacity, according to Liveing.

She added that most 45-minute “HIIT” workouts offered by boutique gyms aren’t HIIT at all, as it’s not possible to maintain that level of work for up to an hour.

“It’s MIIT – moderate-intensity interval training – and it’s basically cardio,” Liveing said.

Instead, she suggests: “Reduce the time of your HIIT. You shouldn’t be able to sustain that level of energy for a long period of time; it should be short, more intense, and not a long cardiovascular workout.”

Alice liveingBe:FIT London

One big workout won’t make a difference

Ultimately, Liveing said, it’s important to note that one effective workout won’t make an impact.

“The biggest piece of advice that I give people is that consistency is key,” she said.

“It’s not about coming to the gym with me and smashing out one session a week and thinking that’s OK,” she added. “That is great, but I also want you to be doing that consistently for the next 12 weeks to actually see results.

“One salad doesn’t make you healthy. One pizza doesn’t make you gain weight. It’s the same with training – one workout is great, but you need to have a consistency with that that allows you to have physical change rather than just pinning your hopes on one gym session a week.”

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