Cardio And Muscle Building - Mutually Exclusive Or Synergistic?

Cardio, a word dreaded by most bodybuilders and physique competitors alike. Naturally, like many other gym topics, cardio is tough to extricate from mainstream misinformation.

Like usual, there exists the dichotomy of something being wholly “good” or “bad” in terms of its application to your fitness regimen. While I am rarely a fan of such ultimatum viewpoints, it’s not surprising that gym enthusiasts migrate to the poles (e.g. High-intensity interval training or low-intensity-steady-state) on the topic of cardio.

So what is the verdict on cardio? We know that it can in fact be beneficial for weight/fat loss, but are any forms of cardio necessary for building a more muscular body? Should cardio always be included in your fitness/training regimen, irrespective of the goal and individual in question? Or does cardio only serve to hinder muscular hypertrophy? Or even worse, does cardio speed up/promote muscular atrophy?

These are all pertinent questions to consider if you’re serious about your training and goals, both in and out of the gym. This article will examine what the data has to say about the topic of cardio and it’s impact on muscle building, and will include examples of how to incorporate various forms of cardio into your training routine.

Also, remember that no amount of experiments can prove a scientific theory, but one experiment may be able to disprove it; thus, there tends to be idiosyncratic consensuses in many fields of research (especially exercise physiology) until something is falsified by empirical evidence. I ask that you ditch any bias you may have before proceeding with this article, just bear with me and keep an open mind before you jump on the “HIIT bandwagon” or whatever form of cardio you “believe” in.

Cardio Intensities

Recently there has been somewhat of a paradigm shift in what people believe is the most optimal intensity to perform cardiovascular exercise at—that being the shift from low intensity, steady-state cardio (e.g. walking) to high intensity interval training (e.g. running sprints). Rather than turn this into a heated debate over which form of cardio is superior, we will instead examine the pros and cons of both forms and their impact on the muscle-building process.

Most traditional fitness wisdom would suggest that LISS cardio is the better option since it burns more “fat for fuel” than HIIT which is predominantly glycolytic. However, this is a shortsighted theory and has little conclusive literature to support its position. In fact, HIIT cardio appears to not only burn more fat (in the long run) but also enhances muscle gain in active individuals. (1)

There are a myriad of physiological effects that HIIT stimulates that typical LISS cardio does not. Studies consistently find that the metabolic adaptations incurred by HIIT, such as excess post-exercise oxygen uptake (EPOC), endocrine activity, blood lipids, heart function, etc. are much more pronounced than those established from LISS cardio. (2,3)

What this means, essentially, is that while LISS cardio may burn more percentage of the calories from fat during the actual training session, its metabolic benefits are rather acute and don’t extend nearly as far as HIIT does. With LISS cardio, you’re basically playing the calories in vs. calories out game, whereas HIIT is more analogous to actually putting your body through a resistance training session. Intuitively then, you can see why HIIT would be preferable for someone looking to build muscle.

Now don’t get too ahead of yourself just yet and assume that HIIT should be the only form of cardio you do for the rest of your years on this giant blue ball we call Earth.

Is LISS cardio really the enemy?

Though it’s rapidly becoming vilified by many gym-goers, LISS cardio does still serve a purpose in certain fitness/training regimens. No, it may not be the optimal way to promote positive/favorable metabolic adaptations, but it does still provide benefits.

For starters, LISS cardio is a non-taxing form of exercise, both physically and mentally; it’s easy on the joints, doesn’t require much conscious effort or technique, and doesn’t need much psychological devotion. Honestly, who can’t muster up the energy to get off the couch and go for a walk around the neighborhood with their dogs? Oh wait, I think that’s one of the main reasons we are facing an obesity epidemic in the United States right now…but I digress.

Back on point here, LISS cardio doesn’t require intense physical effort like HIIT does and can be incorporated into most any trainee’s routine without much interference/impedance on muscle and/or nervous system recovery. In fact, LISS cardio may actually promote muscle recovery (when done in moderation) since it is conducive to blood flow—more blood flow to muscles leads way to enhancing the recovery process.

Moreover, LISS cardio does still offer general health/wellbeing benefits too. I think one thing that people pass right over when they consider LISS cardio is that it just makes some people feel good (thanks to endorphins and other neurotransmitter alterations). And one thing I can damn well assure you is that if someone is actually enjoying their workout, they will probably stick to it in the long run.

I’d rather have a trainee doing something they enjoy and will actually stick to then dreading every waking moment they’re in the gym and quitting after a week of training. More simply put, if something is suboptimal but actually carried out it will always prevail over an optimal plan that is left inert.

The key to remember here is moderating the amount of LISS cardio done so as not to adapt the body to doing superfluous amounts of LISS everyday; this can actually enact a sort of reverse adaptation whereby the body down-regulates it’s basal energy expenditure to compensate for all the calories you’re burning off from the cardio regimen you maintain. So no, doing hours on end of LISS cardio does not pay dividends towards muscle building/recovery, nor fat loss for that matter.

Naturally then, the question that arises is “What exactly is a moderate amount of cardio?” Well, moderate is a term that is inherently vague, so to put a more tangible value on the amount of LISS cardio necessary to derive the aforementioned positive benefits while limiting the negative physiological adaptations it’s going to depend on what your activity level is like outside the gym and what your goals are.

In this case, since this article is assuming you’re looking to build muscle, we can still provide some rough estimates of how much LISS cardio you may consider keeping in your program without hindering your muscle gain (and possibly even enhancing it via improved recovery). Furthermore, since muscle building still ultimately will boil down to eating sufficient nutrients/calories; make sure you’re accounting for the extra caloric burn from any cardio you perform.

How much cardio should I do while trying to build muscle?

As mentioned above, the type and duration of how much cardio you should incorporate into your training regimen when trying to build muscle will vary based on a variety of factors. If you tend to put on weight easily and are more endomorphic, you can get away with (and would probably benefit from) a few LISS cardio sessions (30-40 minutes should be plenty) and maybe 1 or 2 HIIT sessions every week.

Contrarily, if you’re someone who is more ectomorphic and has trouble gaining weight as is then you may have to limit your cardio if you hope to build any appreciable muscle size. You can still do a few LISS and/or HIIT sessions each week, but you will want to make sure you’re making up the difference with your food intake.

The key here is to make cardio act in synergy with your resistance training program, not detract from it. Obviously if your priority is building muscle, it doesn’t make much sense to emphasize cardio over weight training since the latter is imperative to muscle growth and the former is more of a helping hand.

This is why some LISS cardio can be useful for individuals, since it can be incorporated pretty much whenever without much effect on weight training performance. If you like getting a good sweat going before training, then by all means do a quick LISS cardio session before you train with weights. Moreover, if you feel better doing LISS cardio after weights or on days off from weight training then just do it then. The timing of when you do LISS is rather insignificant.

HIIT on the other hand needs to be incorporated a bit more strategically because it may interfere with weight training if you don’t recover well. This will take some trial and error on the trainee’s part to figure out when to perform HIIT. Believe it or not, HIIT can be a good adjunct to finish off your leg training workouts, and this is also one way to minimize the compounding delayed-onset muscle soreness from it since it’s essentially just like adding another leg exercise to your weight training routine.

The options are really limitless for how you want to incorporate your cardio sessions. As said before, just make sure you incorporate them in a fashion that is helping your goal of building muscle and not taking away from it.

HIIT vs. LISS cardio…for the umpteenth time ever.

Ok, yes, I realize some people reading this article may be the hardest core aspiring bodybuilders out there and their immediate reaction to the above is that only lazy pansies do LISS cardio. You know what, if you feel that way and want to stick strictly to the “sprint-until-you-puke--or-don’t-bother-doing-cardio-at-all” attitude, that’s great, go ahead tough guy. My only beef with that train of thought is that HIIT is not always a practical model of exercise for the trainee in question.

For example, while HIIT may be superior to LISS in terms physiological benefits, I’m not about to go recommend that a morbidly obese, 50 year old lady who can barely walk up the stairs go run wind-sprints until she passes out. Is that really necessary? If my elderly mom, whom God bless her soul she doesn’t read this, came up to me and asked what type of cardio she should do just to improve her overall health and wellbeing, it’s unlikely I’m going to advise her to go push a car up hills because it will probably send her into cardiac arrest before she ever completes one interval.

Now I know those are somewhat extreme examples (but hey, most of the country is obese now so maybe they’re not that unlikely), but it iterates the necessity of mending the gap between practical and optimal. In the aforementioned instances, I would much rather have these individuals incorporate LISS cardio until they were in good enough physical shape to perform a few HIIT sessions each week. 

Uh, what about medium-intensity, steady-state (MISS) cardio?

  I’m sure some readers are wondering why MISS cardio (e.g. running/jogging, moderate-effort cycling, stairmaster, elliptical, etc.) is absent from this article, which is a fair concern. Without making this more complex than it needs to be, MISS cardio presents the problem that it isn’t high intensity enough to elicit the physiological benefits of HIIT, yet it is still somewhat taxing physically and can actually hinder muscle gains. (4)

Essentially, MISS cardio doesn’t present much benefit over LISS cardio except for aerobic performance increases and it can actually cause deterioration in anaerobic performance. Unless your goal is to look like and perform like a marathon runner, I see little value in incorporating MISS cardio while trying to build muscle.

Final thoughts

As noted in the preamble, this article is meant to provide an impartial look at the various cardio intensities and how they can impact your muscle-building efforts. At the end of the day, it will vary based upon your own goals and body physiology how much and what type of cardio you should consider incorporating in your training regimen, but it is likely that some amount of cardio will benefit the majority of trainees.

As always, be smart when going about your overall fitness plan and if something isn’t working as you would expect then consider trying something else or changing what you’re doing. There is certainly no reason that you can’t still build muscle while adding in some cardio, especially if you’re diligent with your dietary intake.

References:

1. Davis, W. J., Wood, D. T., Andrews, R. G., Elkind, L. M., & Davis, W. B. (2008). Concurrent training enhances athletes' strength, muscle endurance, and other measures. The Journal of Strength & Conditioning Research, 22(5), 1487-1502.

2. Laursen, P. B., & Jenkins, D. G. (2002). The scientific basis for high-intensity interval training. Sports Medicine, 32(1), 53-73.

3. Wisløff, U., Støylen, A., Loennechen, J. P., Bruvold, M., Rognmo, Ø., Haram, P. M., ... & Skjærpe, T. (2007). Superior cardiovascular effect of aerobic interval training versus moderate continuous training in heart failure patients a randomized study. Circulation, 115(24), 3086-3094.

4. Shephard, R. J. (1968). Intensity, duration and frequency of exercise as determinants of the response to a training regime. Internationale Zeitschrift fuer Angewandte Physiologie Einschliesslich Arbeitsphysiologie, 26(3), 272-278.