We hear the claim sometimes that “cardio is the enemy of strength”. Is there truth to this assertion? The simple answer is no, though there is a bit more context to be discussed. Most important in this regard is to start by asking a few questions. First on this list is: 1. What are your training goals? Next is a two-part question: 2a. What is your current level of fitness? 2b. How long have you been training?  Last is to ask: 3. Do you find it easy, somewhat hard, or very hard to gain strength?


The only people who should be genuinely concerned about aerobic conditioning hampering their strength improvements are those who answered these questions thusly: 1. I am an elite level strength athlete looking to edge out my competition. 2. I have been training at a high level for two decades and have sufficient aerobic capabilities for my sport. 3. I have had to dedicate myself entirely to my sport to get where I am and am at a point where every bit of training and recovery to that end counts, otherwise I will slip behind my competition. If your answers do not read similarly, then you are like 99.9% of people who should be complementing your strength training regime with aerobic conditioning (and yes, this includes many high/elite level strength athletes as well).


As this article by Greg Nuckols states in it’s opening paragraph, “[a]t this point, it should be indisputable that aerobic training can improve almost every major marker of health, however, I think that it might actually improve your strength and size gains (or, at the very least, not hurt them) as well.” He goes on to clarify that, “aerobic training does not hamper strength training in and of itself. The effect starts materializing when it begins causing additional stress to the muscles and soft tissues.” He goes on shortly after to conclude that, “If your choice of cardio is 1) low impact, and 2) not overboard on volume and intensity, you shouldn’t have to worry about it negatively affecting your training or your results.”


Lastly, Greg adds, “There’s also a strong vein of broscience suggesting that low intensity steady state cardio may actually aid in recovery from workouts by promoting blood flow to the muscles without causing further damage. It makes sense intuitively (and I’ve noticed it to be true in my own training), though there are no studies confirming it at this time.” And this all applies before even considering long term benefits.


Greg goes on to bring up a number of long term effects, including some scientific studies suggesting aerobic training can essentially enhance the testosterone (by converting it into a more powerful and long lasting version called DHT) that our bodies produce naturally. Greg states, “The linked study found that aerobic exercise can increase the activity of the enzyme that converts testosterone to this more potent androgen, without altering the levels of the sex hormones in the blood. Essentially, if this finding holds true in humans, it means you can get a lot more “bang for your buck” from the testosterone you produce naturally.”


Greg also cites the importance of aerobic training in it’s effects on general work capacity: “building up work capacity at the beginning of the training cycle is necessary for the volume and intensity of training that’s necessary to hit PRs at the end of the cycle. Aerobic work can be used to build up that base.” Lastly, he cites the impact of resistance and cardiovascular training on body composition and how this all ties into strength improvements: “the combination of aerobic and resistance training has been shown to improve body composition more so than either in isolation.  Resistance training increases metabolic rate, while aerobic training decreases hunger more so than resistance training, which is perhaps what makes the combination especially potent.


With improved body composition comes a host of improved hormonal and metabolic markers.  Improved insulin and leptin sensitivity, increased testosterone, lower estrogen (since adipose – i.e. fat – tissue contains the aromatase enzyme which converts testosterone to estrogen), and many more – all of which contribute to an improved biochemical environment for muscle and strength gains.”


So now the question becomes “what sorts of aerobic conditioning can/should I do to complement my training regimen?” The beauty of the answer to this question is that aerobic training is such a broad concept. It can encompass long, sustained training, down to short, intense intervals and single efforts lasting as few as 4-5 minutes. It can also encompass an essentially infinite number of movements and movement combinations. What is clear is that there is a known “interference phenomenon”, as some studies suggest, though said interference seems to hinge largely on overtraining/under recovery, as well as residual fatigue. Essentially, if one is doing more aerobic training than they can recover from prior to their next strength training session, their strength training, and thus strength improvements, will be compromised.


So to come back full circle and effectively answer the initial question: any and all forms of aerobic training are fair game as long as they 1. are not done in excess of an athlete’s ability to recover from them between sessions, and 2. are programmed intelligently so as to avoid residual fatigue, or at least allow the athlete adequate recovery from said fatigue prior to their next strength session. Greg also adds some important insight here in a follow up to the above mentioned article: “Low intensity cardio should be prioritized over interval training for the most part”. He contrasts this to interval training which “can improve aerobic capacity by itself, and yes, it’s much more time-effective than low-intensity cardio… [h]owever, while you get some of the benefits you’d get from low intensity cardio, you don’t get all of them.”


The missing benefits he refers to here are adaptations in the heart which allow a greater capacity of blood, and thus oxygen, to enter the heart and subsequently flow to the muscles and organs to allow for energy replenishment. He also adds that, “interval training is much more “costly” in terms of recovery”. So while it is okay for a strength athlete to “switch things up” from time to time, lower intensity aerobic work will likely take less away from your strength improvements and may actually be beneficial. Note, however, that this is not a recommendation to put in, say, 100 miles of roadwork per week, rather a suggestion to incorporate a small amount of low intensity aerobic training in your regimen. This could be, for example, 30 minutes of cycling at a tick above a conversational pace, twice to three times per week.


So instead of being that guy/girl who complains of walking up a long flight of stairs because it will interfere with your “gainz”, think about the beneficial impact that aerobic conditioning can have on your strength and put some cardio back into your training regimen!


Nuckols, Greg. 2014. “Cardio and Lifting – Cardio won’t hugely impact your gains in the short run, and may be beneficial for strength and size in the long run.” Strengtheory, March 3. http://www.strengtheory.com/cardio-and-lifting-cardio-wont-hugely-impact-your-gains-in-the-short-run-and-may-be-beneficial-for-strength-and-size-in-the-long-run/

Docherty, David, and Ben Sporer. 2000. “A Proposed Model for Examining the Interference Phenomenon between Concurrent Aerobic and Strength Training.” Journal of Sports Medicine Volume 30, Issue 6 , pp 385-394. Victoria BC: Springer International Publishing. http://link.springer.com/article/10.2165/00007256-200030060-00001
Nuckols, Greg. March 25, 2015. Avoiding Cardio Could Be Holding You Back. Strengtheory. http://www.strengtheory.com/avoiding-cardio-could-be-holding-you-back/


All quotes above from Greg Nuckols posted with permission from the author.