Is higher intensity cardio on off days detrimental to strength training?

Question

I'm trying to build muscle and put on mass, and am currently doing a routine of the following activities:

• Sunday: Off
• Monday: Light cardio
• Tuesday: Lifting
• Wednesday: Light cardio
• Thursday: Lifing
• Friday: Light cardio
• Saturday: Lifting

If ~30 minutes of running counts as light cardio, will it be detrimental to my mass building and gains if I do more intense cardio (e.g. calorie burn goals rather than time) on my non-lifting days?

I imagine timing would be important like running at least a couple hours after eating so I'm not taking calories away from repairing my muscles but I can't quite phrase this question succinctly enough for a google query

Answer 1

Most forms of high intensity cardio can still be pretty damaging to the body. Especially running which I assume is what you're going to do based off the question. The constant pounding on the ground and the hard pushes take a lot out and require recovery.

So, yes, it is possible that high intensity cardio limits your ability to recover between lifting sessions. It is also possible that the additional cardio makes you too exhausted to fully complete the sets you need during your next lifting session.

That isn't to say you can't do it at all. You just need to be smart about it. High intensity cardio on the same day as lifting will allow for full recovery between sessions. It can be regarded as assistance work for the strength training (because it is). Make sure you do it after the lifting session, or a few hours before so you're not exhausted when you need to lift.

Answer 2

You already accepted the answer but I will still come in. If you perform a search in Google with the following keywords "competing signal strength aerobic" you should find interesting articles.

In summary, some research shows that aerobic and strength training sends the body competing signals. Practically, this means you apparently cannot optimally develop strength & aerobic at the same time. Focus on one, maintain the other. Then switch if you desire to increase the untrained skill.

After reading this, I came back to a more "classical" training periodization after trainig "the crossfit way" for 2 years. Time will tell if I am right :)