If you’ve started exercising to become fitter, stronger or healthier, you’ve probably wondered whether cardio and muscle building work against each other.
You may have heard people say that running will “kill your gains” or that you should avoid cardio completely if you want to build muscle. Others argue that cardio is essential if your goal is to lose body fat.
With so many opinions online, it’s understandable if you’re unsure what to believe.
The good news is that, for most teenagers and young adults, you don’t have to choose between building muscle and improving your cardiovascular fitness.
In fact, these goals often work very well together.
This article is part of our Fat Loss & Cardio for Beginners (Healthy & Sustainable) cluster, where we explain how different forms of exercise contribute to healthy body composition. Rather than encouraging you to focus on one type of training, we’ll show you how strength training and cardio can complement one another as part of a balanced fitness routine.
If you’re worried that cardio might affect your muscle-building progress, you may also find Does Too Much Cardio Burn Muscle? and Why Strength Training and Cardio Are Better Together helpful alongside this guide.
Can You Build Muscle and Do Cardio at the Same Time?
Yes.
For the vast majority of people, it’s entirely possible to build muscle while including regular cardio in your weekly routine.
Your body doesn’t view strength training and cardiovascular exercise as two activities that must compete with one another.
Strength training encourages your muscles to become stronger and adapt to increasing demands, while cardio improves the efficiency of your heart, lungs and circulatory system.
Because these forms of exercise produce different adaptations, they can both contribute to improving your overall fitness.
Many athletes demonstrate this every day.
Footballers, rugby players, swimmers, rowers and countless other sportspeople regularly combine resistance training with cardiovascular exercise because each supports different aspects of performance.
For most teenagers and young adults, the question isn’t whether you can do both.
It’s how to combine them in a way that supports your personal goals.
Why Do People Think Cardio Stops Muscle Growth?
This belief has been around for many years.
Part of the confusion comes from observing endurance athletes.
Elite marathon runners, for example, often have lean physiques and relatively little muscle mass compared with competitive bodybuilders.
Some people assume this means cardio itself prevents muscles from growing.
The reality is much more complicated.
Endurance athletes train specifically to improve long-distance performance. Their programmes often involve very high volumes of cardiovascular exercise, different nutritional strategies and training goals that aren’t focused on maximising muscle size.
Bodybuilders, on the other hand, structure their training, nutrition and recovery around stimulating muscle growth.
These are two very different approaches to fitness.
That doesn’t mean someone completing a few runs, cycling sessions or games of football each week is unable to build muscle.
In most cases, moderate amounts of cardio fit comfortably alongside a strength-training programme.
Your Body Can Adapt to More Than One Type of Exercise
One of the remarkable things about the human body is its ability to adapt.
When you challenge your muscles through resistance training, your body responds by repairing and strengthening them over time.
When you regularly perform cardio, your heart and lungs gradually become more efficient at delivering oxygen to your working muscles.
These adaptations happen alongside each other.
That’s why someone can become stronger while also improving their endurance.
Although there may be situations where highly specialised athletes focus more heavily on one type of training, most people don’t need to choose one at the expense of the other.
If your goal is simply to become fitter, healthier and more confident, combining both forms of exercise is often one of the most balanced approaches you can take.
What About Body Recomposition?
You may have come across the term body recomposition.
This describes improving your body composition by reducing body fat while maintaining or building muscle.
For beginners, people returning to exercise after a break and many teenagers who are still developing healthy fitness habits, body recomposition is often an achievable goal.
Rather than becoming obsessed with the number on the scales, the focus shifts towards becoming stronger, improving your fitness and supporting your long-term health.
Strength training provides the stimulus your muscles need to grow, while cardio helps improve your cardiovascular fitness and increases your overall activity levels.
Together, they create a balanced foundation for improving body composition.
Why Strength Training Is Still Essential
If your goal is to build muscle, strength training should remain the foundation of your exercise programme.
Your muscles grow because they receive a challenge that encourages them to adapt over time. This challenge comes from resistance training, whether you’re using free weights, resistance machines, resistance bands or simply your own body weight.
As your body adapts, you’ll gradually become stronger and, with consistent training, your muscles can increase in size.
Cardio doesn’t provide the same stimulus for muscle growth.
Instead, it offers different benefits that support your overall health and fitness.
That’s why most balanced fitness programmes include both forms of exercise rather than relying on just one.
If you’re unsure how to begin resistance training, our Why Strength Training and Cardio Are Better Together guide explains how the two complement each other as part of a beginner-friendly routine.
What Role Does Cardio Play?
Although cardio isn’t the primary driver of muscle growth, it still plays an important role in a well-rounded fitness programme.
Regular cardiovascular exercise strengthens your heart and lungs, improves endurance and can make everyday activities feel easier.
Many people also find that improving their cardiovascular fitness allows them to recover more comfortably between sets during strength workouts and feel less tired during longer training sessions.
Cardio also contributes to your overall energy expenditure, making it a useful part of a healthy body composition plan when combined with balanced nutrition.
Importantly, this doesn’t mean you need to spend hours running every day.
Walking, cycling, swimming, rowing, dancing and team sports all count as cardio and can provide meaningful health benefits.
If you’re unsure which activity to choose, our guide What Is the Best Type of Cardio for Beginners? compares several beginner-friendly options.
Nutrition Matters Just As Much As Training
Even the best exercise programme won’t produce the results you’re hoping for if your body isn’t receiving the nutrition it needs.
Building muscle requires your body to repair and strengthen muscle tissue after each workout.
To do that effectively, you’ll benefit from eating a balanced diet that includes enough energy, protein, carbohydrates, healthy fats, vitamins and minerals.
Protein often receives the most attention because it provides the building blocks your muscles use during recovery.
However, protein isn’t the only important nutrient.
Carbohydrates provide fuel for both strength training and cardio sessions, while healthy fats support many normal bodily functions, including hormone production.
Rather than searching for a “perfect” diet, focus on eating a varied, balanced range of foods and staying well hydrated.
For teenagers especially, restrictive diets designed for rapid fat loss can make it more difficult to support growth, recovery and long-term health.
Recovery Is Where Progress Happens
Exercise challenges your body.
Recovery is when your body adapts to that challenge.
Getting enough sleep, allowing muscles time to recover between demanding workouts and managing your overall training load all play an important role in building muscle and improving fitness.
This is one reason why doing excessive amounts of high-intensity cardio alongside heavy strength training isn’t always the best approach.
If your body never has enough time to recover, both your strength performance and your enjoyment of exercise may begin to suffer.
For most beginners, however, this isn’t something to worry about.
A few cardio sessions alongside two or three strength workouts each week can usually fit together very comfortably when combined with sensible recovery habits.
If you’ve heard that cardio automatically destroys muscle, our article Does Too Much Cardio Burn Muscle? explains why the reality is far more balanced than many social media posts suggest.
Can Cardio Ever Slow Muscle Growth?
It can—but usually only under specific circumstances.
Very high volumes of intense cardio, combined with inadequate nutrition or insufficient recovery, may make it more difficult to maximise muscle growth.
This is most relevant for elite endurance athletes or advanced bodybuilders who are training at exceptionally high levels.
For the average teenager or young adult who goes for a few runs each week, cycles to school, enjoys swimming or plays football with friends, this isn’t normally something to be concerned about.
In fact, avoiding cardio altogether may mean missing out on important health benefits that support your long-term wellbeing.
Instead of asking whether cardio is “good” or “bad” for muscle growth, it’s more helpful to think about finding the right balance between strength training, cardiovascular exercise, nutrition and recovery.
How to Combine Cardio and Strength Training Successfully
The good news is that you don’t need a complicated training programme to build muscle while improving your cardiovascular fitness.
For most beginners, the aim should be to include both forms of exercise consistently throughout the week without feeling overwhelmed.
A simple routine might include two or three strength-training sessions alongside two or three cardio sessions.
Your cardio doesn’t have to involve long-distance running unless you enjoy it.
Walking, cycling, swimming, rowing, dancing or playing sports with friends can all contribute to improving your cardiovascular fitness.
Similarly, your strength training doesn’t need to involve spending hours in the gym.
Full-body workouts using bodyweight exercises, resistance bands or free weights can all help build strength when performed consistently.
If you’re trying to decide whether to perform cardio before or after lifting weights during the same workout, our guide Should You Do Cardio Before or After Weights? explains how your goals can influence the best order.
An Example Weekly Routine
There’s no single programme that works for everyone, but here’s an example of how a balanced week could look.
Monday
Full-body strength workout.
Tuesday
30–45 minutes of walking, cycling or swimming.
Wednesday
Rest day or gentle mobility work.
Thursday
Full-body strength workout followed by a short period of easy cardio if you enjoy it.
Friday
Football, basketball, tennis or another activity that raises your heart rate.
Saturday
Optional strength workout or active recovery.
Sunday
Rest and recovery.
This is only one example.
Your routine should fit around school, college, work, hobbies and family commitments. A programme you can realistically stick to every week is far more valuable than an ambitious schedule that’s impossible to maintain.
Common Mistakes to Avoid
Trying to Do Too Much Too Soon
One of the biggest mistakes beginners make is believing that more exercise always leads to faster results.
Adding daily high-intensity cardio alongside demanding strength workouts can leave you feeling exhausted, particularly if you’re new to exercise.
It’s usually better to build your routine gradually.
Ignoring Recovery
Progress doesn’t happen only during your workouts.
Your muscles adapt while you’re recovering.
Prioritising sleep, eating enough nutritious food and taking rest days when needed all help support long-term progress.
Focusing Only on the Scales
If you’re building muscle while becoming more active, your weight may not change as quickly as you expect.
That doesn’t mean your programme isn’t working.
You might notice improvements in your strength, fitness, posture, confidence, energy levels or the way your clothes fit long before the number on the scales changes significantly.
Our article Does Cardio Help You Lose Body Fat? explains why body composition is often a more useful way to think about progress than body weight alone.
Comparing Yourself to Other People
Everyone starts from a different place.
Your genetics, previous activity levels, nutrition, age and lifestyle all influence how quickly your body adapts.
Comparing your progress with influencers or experienced athletes online can quickly become discouraging.
Instead, focus on becoming a little stronger, fitter or more confident than you were a few weeks ago.
The Bottom Line
Yes, you can build muscle and do cardio at the same time.
For most teenagers and young adults, combining both forms of exercise is one of the healthiest and most sustainable ways to improve fitness.
Strength training helps build stronger muscles and bones, while cardio supports your heart, lungs and overall endurance.
When you combine sensible training with balanced nutrition, good recovery and realistic expectations, these two forms of exercise work together rather than against each other.
Rather than worrying that cardio will ruin your muscle-building progress, focus on creating a balanced routine that you genuinely enjoy and can maintain over the long term.