A lot of people who are interested in gaining muscle steer clear of any form of cardio. I think this is partly because they think cardio instantly shrinks your gains, but I also think this avoidance is evident more so because they simply just don’t like doing cardio (and really, who can blame them).
While it’s pretty blatantly obvious that excessive cardio will result in muscle loss (in the absence of pharmaceuticals that is), what about low to moderate amounts of cardio? Do these low amounts hurt you in your journey to gaining muscle, or potentially help you?
Like all things in the fitness industry, it depends on who you are and depends on many more factors than just what cardio workout you do at the gym. But for simplicity’s sake, let’s talk about the good and then the bad, and then finish with some practical application.
CARDIO AND MUSCLE BUILDING: THE GOOD
1. Enhanced recovery– Weight training for muscle growth causes significant damage to muscle tissue, which is then repaired by the body by delivering the raw materials required for repair/structure rebuild (proteins, glycogen, hydration, etc), and, the speed at which the damage waste products are removed. Cardio improves both of these repair markers as it brings excess blood flow to damaged areas resulting in a “flushing” effect. Removing waste products, and delivering more repair materials.
2. Improved nutrient utilization– Being insulin sensitive is highly beneficial when you are trying to take in large amounts of calories to support muscle growth. Cardio training improves insulin sensitivity and helps keep you leaner, two major factors for ensuring the nutrients you are eating are being absorbed within the lean tissue as opposed to the fatty tissue.
CARDIO AND MUSCLE BUILDING: THE BAD
1. Reducing caloric surplus– If you track your calories, this issue isn’t too big of a deal since you will understand and be able to measure where you need to be to allow yourself to do cardio and still remain in a 10-20% surplus. Low to moderate cardio sessions don’t actually burn that many calories, but longer intense sessions definitely can. This issue is more centred at the “hard gainer” who has issues eating lots of food in the first place. If you already feel stuffed all the time and aren’t gaining weight, don’t do cardio to make your problem even worse. If you do, you will have to consume even more food than you’re already uncomfortable with.
2. Interference signalling– Simply put, the longer and more intense your cardio sessions are, the more your strength and growth will be negatively effected as you will be sending mixed signals to your body. Your body will say…
“So, do you want me to grow? Or do you want me to be a better runner?”
There is a very large set of complicated nuances behind mixed signalling involving AMPk and mTOR pathways, but this is basically the jist of it. Excessive cardio results in your body not knowing what you want it to adapt to and therefore making you good at two things, but great at neither.
At the end of the day, if you keep things in the low to moderate zone you can absolutely perform cardio and have it even benefit your muscle gaining results (and I didn’t even touch on the cardiovascular health benefits). The point at which cardio effects your strength and muscle gain revolve largely around your calories, macros, genetics, and current conditioning– but I can fearlessly recommend 2-3 low-intensity sessions for 20-30mins every week. This will keep you in the right zone for signalling processes, and keep you recovering and growing as you should be.
Now that you understand the positives and negatives associated with your cardiovascular training, the question now is:
“Should I do cardio before I lift? Or after?”
A lot of clients who come to me do this long elaborate warm up on the treadmill before they lift weights, sometimes 20-45mins or so. I think in most cases this is a mistake. A few mins of warm-up is fine to raise core temperature and loosen up, but excessive amounts can be detrimental to your weight training in a few ways.
Research at the RMIT University working with well-trained athletes found that combining resistance training and cardio within the same session may disrupt genes for anabolism (Hawley, JA. 2009). Cardio before lifting reduced IGF-1 and MGF (which are two powerful muscle building growth factors), whereas cardio after lifting increased muscle protein breakdown. Hence, my comments on the interference effect above.
Beyond this, much more research exists in the field to support these findings that training for both strength and endurance impairs your gains in both categories (Nader, GA 2006…. Leveritt M. 1999…. Hakkinen K. 2003). Essentially, you become good at both, but excellent at neither. This can be ok if it matches your goals, but if you want to be super jacked and lean this is likely not the best route to take.
Beyond the disrupted chemical signalling effect we see here, it’s pretty common sense to think that if we do a cardio session before we lift that it is going to take away from our ability to present an overload to our muscles during training.
More cardio pre-training = Less energy for training.
Pretty hard to present a legitimate overload to your muscles via resistance training after a 30mins jog.
Looking at some of the above data, we can see that cardio is likely not ideal either before OR after training for those who have a primary goal of strength and muscle gain.
There is a solution though, because this research involves training for both within the SAME session. If you want to gain benefits from both avenues of fitness development in a more intelligent way, it’s going to be best for you to train them in different sessions separated 4-6hrs a part. Or, train them on their own days entirely so you allow enough time for the anabolic genes to instill their effect on the body (this is my preferred method).
I stand firm with my recommendation to incorporate 2-3 low intensity cardio sessions per week at 20-30mins per session as this can actually help with your muscle gaining efforts, but, I recommend you do these separate from your weight training workouts by 4-6hrs if you must train twice a day, but preferably, train them on their own days entirely.