# "Does aerobic exercise really slow down muscle growth?"



## KryptoAllez (Jul 8, 2002)

*"Does aerobic exercise really slow down muscle growth?"* 

Many people are concerned that adding aerobic exercise to their
weight-training program will slow down muscle growth.

However, new research shows that strength training and aerobic
exercise performed concurrently for 10 weeks won't interfere
with gains in muscle size and strength.

To examine the effect of aerobic exercise and strength training
performed concurrently on the rate of muscle growth, researchers
assigned a group of 30 healthy (but untrained) male subjects to
one of three groups.

* Group one performed high-intensity strength training for three
  days each week. The program involved eight exercises, with
  four sets of 5-7 repetitions being completed for each exercise.
  The first set served as a warm-up. Subsequent sets were taken
  to the point of muscular failure. Subjects rested for 60-90
  seconds between sets.

* Group two completed three sessions of moderate-intensity
  aerobic exercise each week. Each workout lasted 50 minutes.

* Subjects in group three combined aerobic exercise and strength
  training. Both workouts were performed on the same day, with
  the order of strength and aerobic exercise rotated each
  training day. Subjects rested for 10-20 minutes between
  workouts.

Muscle strength and size were measured before and after the
program. The researchers also measured the size of individual
muscle fibers in the thighs. As you can see in the table below,
combining aerobic exercise and high-intensity strength training
didn't impair muscle growth.

Strength Group
- Quadriceps size + 12%
- Type II Fiber Size + 24%

Endurance Group
- Quadriceps size + 3%
- Type II Fiber Size + 4.5%

Combined Group
- Quadriceps size + 14%
- Type II Fiber Size + 28%

Gains in muscle strength, however, were slightly lower in the
combined group compared to the strength training group (7% and
12%, respectively).

These findings do suggest that aerobic exercise and strength
training performed concurrently for 10 weeks won't interfere
with muscle growth. However, there are several important points
about this study that you need to consider.

Firstly, although the test subjects were healthy, they were
untrained. Beginners usually show some kind of gain in muscle
size and/or strength no matter what type of program they follow.

If you have several years of training under your belt, and you're
following a split routine that involves training with weights
5-6 days each week, there's a good chance that aerobic exercise
will impair gains in strength and size.

Moreover, although aerobic exercise is usually added to a
program in order to speed up fat loss, the majority of research
shows that aerobic exercise as it's traditionally performed has
very little effect on the rate at which you lose fat.

A properly designed weight training program, combined with
interval exercise, is far more effective at promoting fat loss,
while also preventing the loss of lean muscle tissue that often
occurs during a low-calorie diet.

Reference

McCarthy, J.P., Pozniak, M.A., & Agre, J.C. (2002).
Neuromuscular adaptations to concurrent strength and endurance
training. Medicine and Science in Sports and Exercise, 16,
152-156

To view this update on-line, visit:

<http://thefactsaboutfitness.com/research/conc.htm>


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## I Are Baboon (Jul 8, 2002)

Interesting article.  Personally, I have a _very_ hard time adding muscle.  I blame it on the 8-10 hours per week of cardio exercise I get (combined with a three day upper-body weight training split).  I don't know _any_ really jacked cross-country mountain bike riders.  

Frustrates the hell out of me when all the weight training does not seem to do anything.


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## KryptoAllez (Jul 8, 2002)

Yeah, I hear ya.  I certainly wouldn't advocate any aerobic training for ectomorphs trying to add muscle mass.  I would be more apt to base a person's training on their genetics/body type and how they respond as an individual to different training methods.  But I do like keeping up on the studies they do on these subjects anyway.


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## I Are Baboon (Jul 8, 2002)

My only "saving grace" is that, although the muscle gains are slow and minimal, the strength is definitely increasing.  Plus, I am getting much stronger as a rider (which is obvious to anyone who rides with me).


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## Dr. Pain (Jul 8, 2002)

Quads...what a bunch of BS...measure arms or something else!


DP


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## KryptoAllez (Jul 8, 2002)

I was wondering how they measure individual muscle fibers.


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## I Are Baboon (Jul 8, 2002)

> _*Originally posted by KryptoAllez *_
> I was wondering how they measure individual muscle fibers.



Microscopes?


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## Sub-Zero (Jul 8, 2002)

> _*Originally posted by Dr. Pain *_
> Quads...what a bunch of BS...measure arms or something else!
> 
> 
> DP



What's wrong with measuring quads ??


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## KryptoAllez (Jul 8, 2002)

> _*Originally posted by I Are Baboon *_
> 
> 
> Microscopes?



I wonder how much tissue they'd have to cut out of the person...
eew, ouch!


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## raider6969 (Jul 8, 2002)

i do cardio every morning on empty stomach, i  have no problem gaining muscle


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## Snake_Eyes (Jul 8, 2002)

> _*Originally posted by KryptoAllez *_
> I was wondering how they measure individual muscle fibers.



Muscle biopsy.

As to the article, it was noted that the subjects were untrained, which means a different ballgame to those of us with some experience.

However, even so, *limited* endurance work can have a place in anyone's schedule, due to a variety of positive effects.


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