The most popular post I've ever made to this blog, without question, covered metabolic resistance training for fat loss. Since I first made that post, the whole "metabolic movement" has exploded onto the fitness scene. I still love metabolic circuits (although, I should point out, ANY type of training is "metabolic"), but, my thoughts on-and use of-this type of training has changed since I first made that post. Allow me to explain...
If you are trying to OPTIMIZE and not just IMPROVE strength and/or muscle gains, I think performing metabolic circuits, metabolic resistance training, HIIT, etc. on the days you do not strength train is a bad idea. Doing body weight circuits, band circuits, med ball circuits, HIIT training on an airdyne bike or rower, complexes, "tabata's", countdowns, kettlebell circuits, TRX circuits, sledge hammer work, sled/prowler work etc...or combing all of this stuff together into one big circuit...on the days you do not strength train (off days) will interfere with your recovery and slow progress.
If your primary goals are to optimize strength and/or lean muscle gains, I would limit the amount of metabolic work you do. Ideally, this stuff should be used at the end of your normal strength training workouts and should not exceed 10 minutes total. This is more than enough to improve and/or maintain your conditioning while focusing on strength and lean mass gains, and this is exactly what I do with my private clients who are interested in optimizing strength. Doing more of it as a stand alone "cardio" workout on the days you don't strength train is going to interfere with recovery. Some will say it won't because the loads you are using when performing metabolic circuits are typically only 25-50% of max strength (or often times just body weight), but I call bullshit. Sure, this isn't very heavy...but it's heavy enough to screw up your recovery and make your next workout a real grinder.
If you are trying to optimize strength and mass gains, I'd rather see you do foam rolling/mobility/activation/stretching circuits on your off days, and, in addition, maybe do a 30 minute walk or do some very light steady state cardio for 20-30 minutes. All I hear about is how low intensity cardio saps strength gains and causes you to lose muscle. Again, I call bullshit. Where is the research on this? I think this is more "fitness industry and gym myth" than anything else. If anything, it's the exact opposite: the overuse and improper application of "metabolic" work, HIIT etc. is what is TRULY slowing down peoples progress in terms of strength and mass gains.
Look, I'm not saying "don't do metabolic work" if you are trying to optimize (again, not just improve) strength and/or lean mass, but just apply it properly-at the end of your normal workouts (and don't go overboard). I think, even if you are trying to optimize strength and mass, you still should be in good condition and have good work capacity and power endurance. BUT, you can achieve these goals with a limited amount of "metabolic" training once or twice weekly for 5-10 minutes at the end of your normal workouts. Here is what a sample weekly scheduled might look like for someone who is primarily interested in optimizing strength and/or lean mass gains, wants to get the conditioning benefits of metabolic work (and enjoys it), but doesn't want it to interfere with recovery:
Monday: Upper Body Strength Work w/ a 5-10 minute metabolic circuit thrown in at the end (upper body focused metabolic work)
Tuesday: Lower Body Strength Work w/ a 5-10 minute metabolic circuit thrown in at the end (lower body focused metabolic work)
Wednesday: 30 minute walk OR 20 minutes of steady state cardio and/or a mobility/activation/foam rolling/stretching circuit (maybe 20 minutes total on this)
Thursday: Same as Monday
Friday: Same as Tuesday
Saturday: Same as Wednesday
Sunday: Total and complete rest
Santa Clarita, CA based trainer Alwyn Cosgrove has stated that, within the fitness industry, there is typically a cycle of both under and over reaction to any "trend". Well, right now, there is severe over reacation to "metabolic training". I think the popularity of CrossFit and "MMA style" training (although the top MMA strength coaches actually take a more traditional approach when dealing with these athletes) has fueled this fire. This is all fine and good, but, it's all goal dependent. I get emails from well intentioned guys who are trying to get substantially stronger and wonder why their progress has slowed since they added an "MMA conditioning class" or CrossFit Session on the days they don't strength train. The answer is this little thing called recovery and super compensation.
While I'm ranting a bit, let me also address the "anti steady state cardio" movement as well. Now no one is allowed to do steady state cardio. It's off limits. You are not "in the know" if you are still doing it. If it's not short and intense and not an interval it's a waste of time. You are "so 1990" if you are doing steady state, moderate intensity cardio. Well, the funny thing is, the same people who subscribe to this "movement" are also the ones who bitch about not being able to get stronger or larger. Sorry, but the most heavily muscled athletes on the planet (arguably)-competitive body builders-have been doing steady state cardio for years...I don't see them shrinking up. You won't find many body builders doing hybrid kettlebell/TRX/Prowler circuits. This isn't to say these athletes couldn't benefit from some of this type of stuff (again, properly scheduled and applied), but they know, intuitively, that steady state work is not as taxing on their recovery abilities.
Bottom line: I don't like absolute fitness rules, trends, movements, or cults. I think metabolic training is fun, productive and beneficial...but it is also goal dependent and has to be applied properly. In my next two posts, I'll continue with this topic, focusing on two other populations of fitness enthusiasts who have different goals than those trying to optimize strength and/or size gains: fat loss focused folks and the general fitness crowd. As you might guess, the application of "metabolic" work for these populations is different...but you'll have to wait until next week.
Yours in Strength, Fitness & Health,