The chances are you’ve heard of HIIT—the work-rest-repeat form of cardio workout that had everyone doing burpees in their bedrooms during the pandemic. But you might not be so familiar with its heavyweight cousin, HIRT.
HIRT stands for high-intensity resistance training, which takes the format of HIIT workouts and adds muscle-building moves. This results in sessions that are capable of boosting your aerobic capacity, improving your strength, building muscular endurance and packing on mass, usually in the space of 30 minutes or less.
It’s a type of training Thor actor Chris Hemsworth promotes on social media (for instance, in this series of eight workouts) and includes in his workout app, Centr. So to find out more about HIRT, we spoke to Centr’s HIRT expert Ingrid Clay.
What is high-intensity resistance training (HIRT)?
High-intensity resistance training is an example of concurrent training, which combines resistance training with conditioning.
“There are both conditioning moves and bodybuilding ones,” says Clay. “I have a bodybuilding background—I competed for 10 years—so I tend to pull from that in my Centr HIRT classes.
“Especially in the Centr Sculpted program, I’ve drawn on the repetitive element of bodybuilding, while also taking the weight up each round to shape the body.
“Then, deviating from bodybuilding and taking a page from HIIT, I’m also putting in moves like the clean and press, and thrusters to get the heart rate up, but I’m still incorporating weight to build strength as well.”
Clay also says she uses work periods of about 45 seconds for each exercise, rather than the 30-second efforts you frequently see in HIIT.
What are the benefits of high-intensity resistance training?
“HIRT will make you stronger,” Clay says. “You’ll also see increased muscular endurance, and increased cardiovascular fitness.”
Just like HIIT, one of the attractions of HIRT is that you can have your workout wrapped up within half an hour or so. And many HIRT sessions require only one type of free weight, such as dumbbells or a kettlebell, so it’s an ideal training style for home workouts.
What is the difference between HIIT and HIRT?
“HIIT is a bit more high-intensity and cardio-focused. With HIRT, you pull back on the amount of cardio and focus a bit more on strength,” says Clay.
In a HIRT workout, you take the hypertrophy-focused moves a little slower than the speedy conditioning exercises in HIIT sessions. This allows you to increase the targeted muscle’s time under tension, but because of the short rest periods, you’ll raise your heart rate and keep it high.
Is HIRT good for building muscle?
HIRT is better than HIIT for building muscle, but it won’t be as effective at packing on mass as a dedicated bodybuilding program, where this is the sole goal.
If you find your bodybuilding progress has slowed, you may benefit from a different style of resistance training. “If you’re doing the same thing over and over again in your training, you plateau, and you won’t see any change,” says Clay. “It’s good to throw something else in there to give your body a different kind of challenge.”
Is HIRT good for burning fat?
“Absolutely,” says Clay. “You still have the same benefits from HIIT, but you’re also lifting weights, and that burns fat a little faster.”
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