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Cardio Interferes with Building Muscle?


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I think I read this in the New Rules of Lifting book.  Something about doing cardio interfering with the muscle building you get from lifting weights.  Anybody have any info on this that they can elaborate on?

I don't run at all, but I do enjoy long hikes/walks in the park and in the city.  But I don't want it to disrupt my weightlifting as I am actively trying to build muscle.

Thanks!

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It's down to AMPK regulating mTOR and depressing skeletal muscle protein resynthesis, and mostly this happens after cardio that's been strenuous enough to impact your glycogen reserves to a significant degree. Walking doesn't do that at all on the flats and only to a limited extent on the hills, while running, fast biking and other activities that cause your breathing to increase kinda do.

 You can still do a bit of strenuous cardio, the usual rule of thumb is that more than 90 minutes a week of the hard stuff makes it significantly harder to build muscle. Note: harder, not impossible.

 'Course, you can walk practically forever with little to no reaction from AMPK which is why it's almost body builder tradition to walk on the treadmill for an hour every morning.

Wow.  That article was a bit over my head.  But thanks for your explanation  I do bike, but nothing strenuous.  So I'm glad it won't affect my muscle building.

Thanks Melkor!  Always so helpful and knowledgeable.

@ Melkor - have you come across any literature that discusses whether this can be overcome? It is my understanding that AMPk inhibts muscle resynthesis in skeletal muscle because it "turns off" energetically costly processes. But if you are on a caloric surplus diet (in fact AMPk increases appetite in the brain), could you overcome the inhibitory effect on AMPk?

Can I eat enough that the excess calories (preferably "good" calories, i.e. from protein) counteract the inhibitory effect of AMPk in skeletal muscle?

 

I'd be interested to know if you have come across anything that tests this.

From what I've gathered activation is directly linked to muscular glycogen depletion so overfeeding wouldn't interact with AMPK sufficiently fast to prevent it, but rapid glycogen restoration would probably minimize the effect size.

 Body builders get sold on stuff like waxy maize and various complex carbs all the time based on data gathered from endurance athletes; while it doesn't actually do jack **** for a body builder who doesn't in fact deplete glycogen to the extent you endurance types do, well, there is a point to it for you guys.

I have gotten into running a lot lately, and have found out I am pretty good at it.  I still would like to build muscle though.  Right now I am running 4 miles 3 days a week and weight training the other 3 days with 1 day off for rest.  So I won't see major strength gains bc of my running? I can now do two pull ups where a few months ago I couldn't do any.  And I know I have gained a lot of muscle but that could just be from weight loss too.. And here I wanted to run longer distances too in the near future.  It stinks you can't get both! : (

Strength is a trainable skill. It's only about 2/3 correlated with muscle size, the rest is down to neuromuscular coordination and motor learning, so you can absolutely get significantly stronger without adding a single gram of muscle mass.

 And remember, I said it makes it harder, not impossible to add mass- if your goal was to become a body builder and add as much sheer muscle mass as humanly possible as fast as you physically can you'd have to cut down on the cardio. If you're not in fact chasing after that particular goal I see no special problem with trying to improve running distance and adding whatever muscle growth your body feels like doing.

 It's only if you're trying to optimize on a particular variable you kinda have to make the choice, but you don't have to give up on becoming stronger. You just won't gain as much muscle mass as you could with less endurance training, and the difference would only really be noteworthy considered over a period of months.

Also there is a difference between running 30+ miles a week and running <10 miles a week. I don't think you should worry.

Original Post by armandounc:

@ Melkor - have you come across any literature that discusses whether this can be overcome? It is my understanding that AMPk inhibts muscle resynthesis in skeletal muscle because it "turns off" energetically costly processes. But if you are on a caloric surplus diet (in fact AMPk increases appetite in the brain), could you overcome the inhibitory effect on AMPk?

Can I eat enough that the excess calories (preferably "good" calories, i.e. from protein) counteract the inhibitory effect of AMPk in skeletal muscle?

 

I'd be interested to know if you have come across anything that tests this.

I have some papers that addressed this issue specifically (how to minimize the effects of glycogen depletion during things like the multi-day tour de France). The conclusions were focussed on the protein sparing effect that carbs have in these situations. Like Melkor said, getting the glycogen back up as fast as you can (and of course trying to minimize its original level of depletion) was the thing of most benefit. Feeding the test subjects more protein did not help, compared with giving them things like the glucose polymers that are in good sports/recovery drinks (also in red potatoes FYI).

For this research, they actually did a nitrogen balance on these guys for a week long series of killer workouts (simulated a tour de France on stationary bikes). Protein contains nitrogen, and if you burn up the protein for energy, you end up excreting the nitrogen in your urine and sweat, where they can collect and measure it.

add: the book (Food and Fluid related aspects in highly trained athletes, by Fred Brouns) is a bound collection of articles like "The effect of diet manipulation and repeated sustained exercise on nitrogen balance" You might be able to find it (used) somewhere like Amazon.

OP: the things I've mentioned above don't really apply to hiking, unless there are long uphills that you push really hard on (like for hours). It takes some very intense effort of fairly long duration to deplete your glycogen.

Original Post by oldguysrule: (simulated a tour de France on stationary bikes).

Those guys must have had some seriously chafed backsides.

At least the tests only lasted 6 days. They don't look happy in the pics (they had to go to complete exhaustion on two of the days).

 The effects of AMPk would only be inhibitory to protein synthesis if it lasts a long time after your cardio workout (4-8hrs).  It seems like if you kept your glycogen stores up with a pre-workout carb shake and sipped the same during your workout, you could still do moderate-vigorous amounts of cardio to help burn fat.  Protein synthesis occurs during your rest days, so it depends upon how elevated your AMPk activity post-workout.  I think the author alludes to careful planning of when you do bulking and cardio activities to minimize this effect.

i have heard that you are supposed to lift first and then do cardio...  you have to keep the body moving, no matter what age. my dad just joined jillian michaels online fitness program thru a review site http://loseweight2weeks.co after he had a heart attack. apparently she is the fitness guru who says you are supposed to lift first... 

Jillian Michaels could say anything she wanted and millions of peoples would swear it's the best advice ever.

I wouldn't trust anything she said, personally. She's just in it for the money.

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