I want to build muscle, but I enjoy cardio and don't want to gain weight. Will running and HIIT hinder my gains?

• It's a fitness myth that cardio causes your muscles to shrivel up or prevents them from growing.
• What's crucial, however, is that cardio doesn't limit your capacity to perform strength training.
• Equally, recovery is key for muscle growth, so make sure you aren't overtraining.
• Read more Working It Out here.

Dear Rachel,

After years of doing cardio and HIIT classes, I'm trying to incorporate more strength training into my fitness regime as I want to build some muscle (and have next to none). My question is: If I carry on doing my cardio, will it hinder my muscle-building? I used to run two or three times a week and do a couple of HIIT classes, but have now cut that down by half. I'm not sure if I should cut cardio out altogether though, because I do want to build muscle but am nervous that I'll gain weight if I stop running and doing HIIT. Help!

- Confused By Cardio

Dear Confused,

This is an excellent goal to have. Building more muscle not only brings about tons of health benefits but is incredibly empowering (and makes your body look amazing).

"Gym bro" culture says that cardio is to be avoided, lest it "kill your gains," but this isn't true.

Whether you want to lose fat, build muscle, or do both, strength training is a great way to start. But that's not the only thing to consider when it comes to exercise. Cardio is incredibly important for your overall health, but possibly the most important factor is what you enjoy and will stick to.

Cardio doesn't necessarily hinder muscle growth if you're training right

Every body responds differently to cardio and strength training. But most people probably don't need to worry about cardio harming muscle growth, Ngo Okafor, a celebrity personal trainer, told Insider.

"Doing cardio, HIIT classes, or running does not necessarily hinder muscle-building," he said.

The key is not to let the cardio interfere with your resistance workouts. And there are only so many hours in the day. Only you know if running and HIIT, or high-intensity interval training, classes leave you too fatigued to lift weights.

To build muscle (aka hypertrophy), you generally want to lift weights heavy enough that you can perform sets that put your muscles under tension for 60 to 90 seconds, Luke Worthington, a personal trainer, previously told Insider. This usually means sets of 12 to 15 reps, but it depends on your tempo.

"Training for hypertrophy requires causing 'metabolic damage' to muscle cells and then refueling them with a surplus of amino acids [through protein] and calories to lay down new muscle tissue," Worthington said.

Focus on compound movements like deadlifts, squats, and bench press too.

Ensuring your body can recover between strength workouts is key

When it comes to building muscle, the magic actually happens when you're recovering from your workouts, not in the gym, so you need to make sure your body has enough rest between workouts.

Many strength-training fans do what's known as "active recovery," which usually means some form of steady-state cardio like a leisurely cycle, a walk, or a gentle jog. This can help the muscles recover by increasing blood flow.

More-intense cardio, like sprints or HIIT classes, is likely to add more strain to the muscles, so you might need to be mindful of how the exercises make you feel.

However, some research suggests HIIT preserves muscle better than steady-state cardio does.

Personally, I do dancing, swimming, and netball alongside my weightlifting - they don't take away from my strength gains, and I enjoy them.

"Most people do not possess the work capacity required to do it all," Okafor said.

"Since we draw our energy from one source, we have to be mindful of our fitness goals. If our goal is building muscle, then the priority has to become strength training and increasing the nutrition necessary for optimum muscle-building."

You need to eat right for muscle growth, which ideally means being in a small calorie surplus (though as a weightlifting newbie you may still see growth at maintenance or even in a deficit).

"Incorporate good nutrition to provide protein for muscle growth and carbohydrates and fats to fuel and enhance recovery from your intense workouts," Okafor said.

You'll likely experience 'newbie gains' when you begin lifting weights

I, for one, am jealous that you're about to get into proper strength training, because you'll likely experience a wonderful thing called "newbie gains" - this is when you start lifting weights and your body responds so brilliantly to the new stimulus that you can build muscle and strength pretty quickly.

Luke Goulden, a personal trainer, told Insider that you'd done the right thing by cutting down on cardio already, mainly because it leaves you more time to work on those all-important gains.

"Factor in that you have never done any strength training before, it's likely you will respond very well and quite quickly," he said, adding that you'd have to do an "excessive" amount of cardio for HIIT to hinder muscle growth.

While you do generally burn more calories doing cardio than resistance training, the more muscle you have, the more calories you burn at rest, so it pays off in the long run. Don't worry too much about gaining fat - whether you do or not largely comes down to how much you're eating, so keep an eye on things and adjust accordingly.

Moving in ways you enjoy is most important

Some research suggests that cycling is better than running for preserving muscle - but ultimately there's no such thing as a perfect training regimen, because we're all different.

If you enjoy your cardio workouts and runs, you don't need to cut them out to build muscle. If you're doing HIIT only because you think you have to, I'd drop it. It's certainly not necessary, and life's too short to do workouts you hate.

Yes, you need to strength-train to build muscle, and cardio is important for health. But you'll stick to a fitness plan if you enjoy it.

"I am very confident to say there is a happy medium for you being able to keep on top of your cardiovascular fitness, lift weights, and build muscle at the same time," Goulden said.

"Keep on top of your rest and recovery, make sure you are eating enough and consuming a good amount of protein, and you should be."

Wishing you well,
Rachel

As a senior health reporter at Insider and a self-described fitness fanatic with an Association for Nutrition-certified nutrition course under her belt, Rachel Hosie is immersed in the wellness scene and here to answer all your burning questions. Whether you're struggling to find the motivation to go for a run, confused about light versus heavy weights, or unsure whether you should be worried about how much sugar is in a mango, Rachel is here to give you the no-nonsense answers and advice you need, with strictly no fad diets in sight.

Rachel has a wealth of experience covering fitness, nutrition, and wellness, and she has the hottest experts at her fingertips. She regularly speaks to some of the world's most knowledgeable and renowned personal trainers, dietitians, and coaches, ensuring she's always up to date with the latest science-backed facts you need to know to live your happiest and healthiest life.

Have a question? Ask Rachel at workingitout@insider.com or fill out this anonymous form. All questions will be published anonymously.

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