It’s a question that comes up in gyms all the time. Many people worry that adding cardio into their program will undo the hard work they’re putting into lifting. The truth is more nuanced. Cardio doesn’t have to be the enemy of muscle growth. It all depends on how you approach it, the type you choose, and how you balance it with strength training.
The science behind cardio and muscle gain
At a cellular level, strength training activates pathways like mTOR, which promote muscle growth. Cardio, particularly endurance training, can trigger AMPK, which focuses on energy efficiency. When AMPK dominates, it can interfere with mTOR and blunt hypertrophy. However, studies show that the interference effect is less significant when cardio volume is controlled, intensity is managed, and nutrition is adequate. The science suggests cardio can coexist with muscle growth if planned properly.
How cardio affects muscle recovery and growth
Cardio influences recovery in different ways. High volumes of intense cardio can increase fatigue and reduce your ability to recover from strength sessions. It can also increase energy demands, leaving fewer resources for muscle protein synthesis. On the flip side, low to moderate intensity cardio can improve blood flow, enhance nutrient delivery, and even support active recovery. It’s all about the type and timing of cardio in your training week.
Is there a balance between cardio and strength training?
Yes, and balance is the key. Prioritisation should always reflect your main goal. If muscle gain is the priority, strength training should come first, with cardio structured around it. A good approach is to separate sessions by at least six hours, or even place them on different days. This ensures both types of training get the energy and focus they need. Planning your schedule carefully helps avoid the pitfalls of doing too much at once.
Types of cardio: which ones are best for muscle gain?
Not all cardio is equal when your goal is muscle growth. Low intensity steady state (LISS) cardio, like walking or cycling at a gentle pace, is less likely to interfere with hypertrophy and can aid recovery. Non-impact options such as rowing or cycling are often better than high-impact running, which can stress joints and muscles already taxed by lifting. High intensity interval training (HIIT) can be useful, but should be applied sparingly, as it creates significant fatigue.
How much cardio is too much when trying to build muscle?
Too much cardio is relative to your training background and recovery ability. As a general rule, 2–3 moderate sessions per week won’t hold back muscle growth for most people, provided strength training and nutrition are prioritised. When cardio starts to dominate your weekly workload or leaves you sore and drained before lifting sessions, that’s when it becomes counterproductive. Monitoring progress and adjusting volume is essential.
The role of nutrition in combining cardio and muscle gain
Nutrition underpins the balance between cardio and muscle building. Adequate calories ensure your body has fuel for both strength and endurance demands. Protein intake should be consistent and sufficient to support muscle repair and growth. Carbohydrates are especially important for fuelling cardio sessions, while fats play a role in overall recovery and hormone health. Hydration and micronutrients also help maintain performance across both types of training.
The bottom line
Cardio isn’t bad for muscle gain—it just needs to be programmed intelligently. Choosing the right type, keeping the volume under control, and aligning nutrition with your workload makes it possible to build muscle and improve fitness at the same time. If you want expert help creating a plan that fits your goals, get in touch with us and we’ll guide you in the right direction.
