You’ve heard that you shouldn’t do cardio and strength training together (i.e., “concurrent training”) – supposedly, it hurts your gains ?
But what does “together” really mean?
Does it mean you cannot do them on the same day, or is there an acceptable period after which you’ve completed your cardio where you can proceed to strength train (and vice versa)?
There’s no need to wind yourself up into a knot with all these questions.
Below, find out everything you need to know about the “cardio and strength training interference effect” – including what it is, along with what you could do about it.
Spoiler alert: this article will also help answer the question: “Should I do cardio before or after I lift?” once and for all.
Does cardio ruin muscle gains?
First things first. Is the “interference effect” real? Or is it just a made-up phenomenon created to prevent gym-goers from spending too much time in the gym?
Well, unfortunately, the “interference effect” is an all-too-real phenomenon.
Studies have consistently found concurrent training – cardio and strength training performed together – leading to smaller strength and size adaptations than if an individual only engaged in lifting. Note: the opposite doesn’t occur.
So, in other words, cardio hurts strength gains, but lifting doesn’t appear to impact endurance adaptations.
How to avoid the interference effect
The key to avoiding the interference effect – so you maximize gains – is clear. You’ll have to keep cardio and strength training separated by at least 24 hours.
Or, at the very least, this was according to a 2018 meta-analysis published in the Journal of Sports Sciences, which found minimal to no interference effect when lifting and cardio was performed on separate days.
“Who has time to do cardio on separate days?”
Let’s be real. Once you get to a certain lifting experience level, it’s impossible to keep your cardio and strength training separate.
To illustrate: imagine if you had to do 16 sets for each muscle group to ensure optimal growth (applicable to a moderately-experienced to advance lifter). You'll have to split this up into 2 sessions for practicality and maximal hypertrophy reasons.
FYI, researchers suggest that going beyond 10 sets per muscle group in a single workout session will contribute to "junk volume".
Now … think about how many muscle groups you have – or you’d like to focus on:
Chances are, you’re going to need to train at least 4 – 5 times weekly just to hit that optimal volume for each muscle group.
So, where are you going to find the time to fit in your cardio needs – which is at least 150 to 300 minutes of moderate-intensity or 75 to 150 minutes a week of vigorous-intensity aerobic exercise?
Ans: you won’t be able to. And that leaves you with a single alternative. Concurrent training.
Ways to minimize interference effect
Yep – if you can’t avoid doing both cardio and strength training on the first day, well, you might as well embrace it. Only, of course, you’ll need to find ways to reduce the interference effect. Find details below.
1: Order: “Should I do cardio before or after I lift?”
The answer to the question, “Cardio before or after I lift?” is: “After”.
A 2003 study published in The Journal of Strength & Conditioning Research found that performing cardio before lifting can decrease volume performance by up to 10% for 8 hours.
Think this study is a little … well, old? Well, that’s a valid concern.
But you can rest assured that the finding is still very much relevant; a recent 2018 meta-analysis published in the Journal of Sports Sciences came to the same conclusion – that doing cardio before lifting was worse than the other way around for strength and hypertrophy, presumably due to “carry-over” fatigue.
No matter the mechanism through which cardio hurts your gains, though, one thing’s clear.
You should only head to the treadmill, elliptical, or rowing machine after you’ve completed your strength training.
2: Duration: “How long should my cardio sessions be?”
20 to 30 minutes is all you need.
Go beyond that, and you run the risk of your body adapting to aerobic needs – including promoting fiber interconversions toward type 1 (identified by slow contraction times and high fatigue resistance) and asynchronous motor unit recruitment (i.e., muscle fibers unable to fire simultaneously in a way that’s optimal for strength production).
The risk for this aerobic adaptation is exceptionally high when you go beyond 60 minutes.
3: Intensity: “How hard should I be going during my sessions?”
You should be doing high-intensity interval training (HIIT) whenever possible during your cardio sessions. Doing so minimizes the interference effect you’d typically see from engaging in concurrent training.
Why, though? Well, that’s because HIIT stresses your energy systems in a similar manner to resistance training and, as a result, causes similar adaptations (e.g., neuromuscular).
That said, a heavy emphasis is on the keywords, “whenever possible”.
You shouldn’t rely on HIIT as your primary form of cardio – if you do, you may run into recovery issues (simply because of how tough HIIT sessions are), which would hurt your strength and hypertrophy gains. So, do keep an eye on your recovery abilities.
Ease up on your HIIT sessions if you find that you’re getting increasingly sore from training.
Go beyond minimizing interference effect
Obviously, if you're looking for maximum strength and hypertrophy gains, you can't just work at minimizing the interference effect. You also need to be mindful of your exercise selection, workout programming, and choice of recovery techniques.
It’s a whole list of stuff that can quickly become overwhelming – especially when you don’t have access to help.
Well, lucky for you, there’s GymStreak. Offload all these nitty-gritty technical training details to this smart, AI-enabled personal trainer app, so you just need to do the work of showing up to the gym. How convenient is that?
Balabinis, C. P., Psarakis, C. H., Moukas, M., Vassiliou, M. P., & Behrakis, P. K. (2003). Early phase changes by concurrent endurance and strength training. Journal of Strength and Conditioning Research, 17(2), 393–401. https://doi.org/10.1519/1533-4287(2003)017<0393:epcbce>2.0.co;2
Hickson, R. C. (1980). Interference of strength development by simultaneously training for strength and endurance. European Journal of Applied Physiology and Occupational Physiology, 45(2–3), 255–263. https://doi.org/10.1007/BF00421333
Murlasits, Z., Kneffel, Z., & Thalib, L. (2018). The physiological effects of concurrent strength and endurance training sequence: A systematic review and meta-analysis. Journal of Sports Sciences, 36(11), 1212–1219. https://doi.org/10.1080/02640414.2017.1364405
Sabag, A., Najafi, A., Michael, S., Esgin, T., Halaki, M., & Hackett, D. (2018). The compatibility of concurrent high intensity interval training and resistance training for muscular strength and hypertrophy: A systematic review and meta-analysis. Journal of Sports Sciences, 36(21), 2472–2483. https://doi.org/10.1080/02640414.2018.1464636
Sporer, B. C., & Wenger, H. A. (2003). Effects of aerobic exercise on strength performance following various periods of recovery. Journal of Strength and Conditioning Research, 17(4), 638–644. https://doi.org/10.1519/1533-4287(2003)017<0638:eoaeos>2.0.co;2
Wilson, J. M., Marin, P. J., Rhea, M. R., Wilson, S. M. C., Loenneke, J. P., & Anderson, J. C. (2012). Concurrent training: A meta-analysis examining interference of aerobic and resistance exercises. Journal of Strength and Conditioning Research, 26(8), 2293–2307. https://doi.org/10.1519/JSC.0b013e31823a3e2d