Maximize Your Gains: The Truth About Cardio and Muscle Growth
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Chapter 1: The Relationship Between Cardio and Muscle Growth
Is cardio detrimental to your muscle-building efforts?
Many fitness enthusiasts may shy away from cardiovascular workouts—such as running, swimming, or cycling—when trying to increase muscle mass. This notion stems from the "interference effect," which suggests that engaging in different types of fitness training (like strength and endurance) could potentially hinder improvements in one or both areas compared to focusing solely on one.
But is this really the case? Do you have to sacrifice muscle gains for better cardiovascular fitness?
The answer is both yes and no.
If your aim is to excel in one discipline, you’ll need to focus your training accordingly. Bodybuilders, for instance, should dedicate more time to muscle-building exercises, while those preparing for triathlons will require extensive endurance training. However, it doesn’t mean you must completely abandon the other form of training.
It's important to note that the following insights are derived from recent research and should not replace professional medical advice. Always consult with a physical therapist to tailor an approach that suits your individual goals and requirements.
Recovery Capacity Matters
A recent comprehensive study reviewing 43 research articles offers reassurance regarding the concern of losing muscle gains. The findings indicated that engaging in both cardiovascular and strength training did not lead to any significant differences in muscle growth or strength compared to strength training alone. However, it did show a reduction in explosive strength or power, particularly when both types of training were performed in the same session with less than a three-hour interval. While a three-hour separation lessened the interference effects, they were still present.
Two crucial points emerge from this study:
- The total volume of strength training remained consistent (e.g., 40 minutes of strength training versus 40 minutes of strength training plus 20 minutes of cardio). Volume is paramount for muscle growth, while intensity is crucial for strength.
- To effectively build muscle, training should be taken close to failure, but this can be achieved at various intensities (approximately 30–80% of your one-rep max). Aim for a minimum of 10 sets per muscle group each week. For strength training, efforts should be around 80% or more of your one-rep max, with a focus on speed.
These are optimal guidelines for individuals who are already trained. Beginners will still see muscle and strength gains at lighter intensities and lower volumes; however, to avoid stagnation, progression is essential.
The second key takeaway is that while maximal neural activation remains intact, the rate of motor unit recruitment may be affected.
Strength relies on the total force produced by recruiting more muscle, which includes both adding muscle and enhancing motor unit recruitment (the connections between nerves and muscle). Increasing the number and synchronization of motor units leads to greater force production.
For power (the speed of force production, as in jumping), rapid recruitment of motor units is necessary. However, cardio may temporarily hinder this power output, though the precise mechanism behind this remains unclear.
As a physical therapist, I adjust exercise programming based on these findings. The decline in power output may negatively affect the quality of strength training, leading to a diminished training response over time. If a client aims to develop power (like in sports involving sprinting and jumping), I tend to limit aerobic training during the final stages of their program.
During earlier rehabilitation phases, when the focus is on building capacity, I integrate both resistance and cardiovascular training, ensuring adequate recovery strategies are in place.
The Interference Effect: Key Considerations
This brings us to the heart of the interference effect: recovery.
The authors of the research suggest that reduced power output may stem from fatigue caused by aerobic training. Could additional exercise lead to overtraining?
If you replace strength training with cardio (30 minutes of each instead of a full hour of strength training), you will indeed see diminished muscle growth compared to exclusive resistance training. But this doesn’t imply that cardio has obliterated your gains; rather, you’ve opted to decrease your overall training volume.
If you add 20 minutes of cardio to a 60-minute strength session, however, you need to factor in the extra demands on your body and adjust your recovery accordingly.
The extent of the interference effect can fluctuate based on exercise type, intensity, and individual goals. Some studies suggest that proper scheduling and sufficient recovery time can mitigate these effects. For instance, it’s advisable to avoid intense cardio on leg days.
The Importance of Cardiovascular Exercise
Keep in mind that cardiovascular training is essential for overall health and longevity. It serves as a defense against numerous chronic diseases. Even low-intensity cardio can be advantageous.
A study investigated the effects of adding 3,000 extra steps per day to an exercise regimen, with participants initially averaging 4,000 to 5,000 steps. While increasing overall physical activity is generally beneficial, the addition of just 3,000 steps led to significant improvements in fitness and body composition among participants.
Though this study doesn’t assert that 3,000 steps is the magic figure for all exercise routines, it highlights the importance of considering total physical activity alongside structured workouts.
I strongly encourage finding ways to incorporate cardiovascular exercise into your training regimen.
Your muscle gains are secure.
If you enjoy podcasts, I delve deeper into this subject and more on The Clinical Gap Podcast.
Chapter 2: Debunking Cardio Myths
The first video, "How To STOP Cardio From Killing Your Gains," discusses the common pitfalls that can occur when trying to balance cardio and strength training, helping you optimize your workouts.
Chapter 3: The Impact of Cardio on Muscle Growth
The second video, "Does Cardio Inhibit Muscle Growth?" explores whether incorporating cardio into your routine affects your muscle-building goals, providing insights into effective training strategies.