Does Cardio Kill Gains By Burning Muscle?

For years there has been this idea floating around that cardio kills gains - that cardio and muscle growth are fundamentally incompatible and that including cardio training in your routine will kill the progress you’re trying to make with your strength training or that your body will start burning muscle tissue for energy.

While a cardio-heavy workout routine can result in reduced hypertrophy (aka muscle gains), it’s generally not a case of cardio simply “cancelling out” your strength progress - it’s all about how you’re training, how you’re fuelling your body, and how much rest you’re getting. Cardio has so many incredible health benefits and we will always recommend including it in your workout mix, but if you have specific training goals it’s important to get the balance right. 

What can we learn from the data and the experts 

As Lionel University explains, most data suggests that general cardio training does not burn muscle. If you’re following a strength training program and also adding a few cardio sessions into your weekly routine, it’s unlikely you need to worry about  muscle loss. 

One 2021 research review, in which 43 studies were included, found that concurrent aerobic and strength training does not compromise hypertrophy and strength development. If you’re combining cardio and strength training into a single session and the cardio element is leaving your muscles fatigued, you may find your explosive strength isn’t as high, so it’s important to think about your goals, listen to your body and take note of when you’re performing at your best.

When it comes to building cardio fitness and strength, the Sweat trainers know you don’t have to pick one over the other. They all include cardio (such as walking or running) in their training routines and continue to build strength and muscle through lifting weights. Unless you’re doing an extensive amount of cardio (such as training for a marathon), one cancelling the other out should not be a concern. 

But what if you AREN’T gaining muscle? 

If you’re doing a lot of aerobic exercise and are noticing muscle loss or a lack of muscle growth when strength gains are your goal, you need to look at your routine and lifestyle overall. Chances are, your cardio activities aren’t the only factor at play. 

To gain muscle, you need to consistently follow a strength training program and follow the principles of progressive overload to challenge yourself - even better if it’s a program specifically designed for hypertrophy such as Kelsey Wells’ PWR Strength or Katie Martin’s Strength & Sculpt. You’ll also want to prioritise rest to recover and rebuild, as well as include plenty of protein in your diet each day.

In each strength training workout, you want to feel fresh and capable of lifting close to failure. Intense or lengthy cardio sessions can leave you feeling fatigued and unable to lift heavy, so try to find a balance that allows you to show up feeling your best for your weights sessions if that’s where you want to see results.

If you’re neglecting your strength training, are eating in a significant calorie deficit, fatiguing yourself to the point you don’t have the energy to lift heavy, skipping your rest days, or opting for lengthy cardio sessions, those strength gains definitely aren’t going to come so easily.

Don’t skip your cardio

While it’s true that you don’t need to include cardio in your routine to see results when you’re following a strength training program, there are still a multitude of amazing reasons to make time for it. 

As the name suggests, cardio boosts your cardiorespiratory fitness and cardiometabolic function, reducing your risk of diseases such as heart disease and type 2 diabetes, strengthening your bones and joints, improving your mental health and extending your lifespan. 

Yes, we love strength gains, but we also want to train for longevity and cardio plays such an important role in that. That’s why in the Sweat app, you’ll find most programs include 1-3 cardio sessions per week, which you can even tick off with something as simple as a walk. 

Find a feel-good balance

It’s definitely possible to reap the benefits of both strength training and cardio - you just need to find a balance that works for you and make sure your training focus aligns with the goals you want to achieve. 

Not sure where to start? Whether you’re a beginner or advanced, training at home or in the gym, there are plenty of strength training programs in the Sweat app that take the guesswork out of your routine.