You will lose your lean mass if you just do cardio

Did you actually read the study? If you did, you'd see how wrong that interpretation is.

Having read the study now, I don't see what you think is wrong about the site I quoted. The diet and endurance (cardio) group lost the most fat, 8% vs. 4.3% for the strength training group.

"Surprisingly, all dietary groups experienced similar reductions in body mass (−6.2, −6.8, and −7.0 kg for D, DE, and DES groups, respectively) and body composition (−5.8, −8.0, and −4.3% in D, DE, and DES groups, respectively),"

While the diet and endurance group gained lean body mass (+1.4 kg), the diet, exercise and strength training group lost fat-free mass (1.7kg or 3.7 lbs) just like the article I quoted said.

"whereas fat-free mass remained relatively constant (−0.1, +1.4, and −1.7 kg in D, DE, and DES groups, respectively) over the 12-wk period."

This study actually shows the opposite of what people citing it claim.

Read my previous post that I addressed to crissanderson of some of my comments on the study. Particularly note the fact about who the subjects were of the study. Also note that caloric intake/protein intake was not monitored. Also read my post shortly after that about how there are so many factors that can affect the results.

On top of that, the following conclusion is emphasized multiple times throughout the study by the authors:
"No significant changes were observed in fat-free mass over the 12 wk in any of the groups (Fig. 1 D). There were no differences in the magnitude of changes in body mass, percent body fat, fat mass, and fat-free mass among groups."
So why was this not mentioned in the website you linked?

Given all this information, do you think these small fluctuations are significant enough to support any of the conclusions of the analysis you linked (which even the AUTHORS of the study directly contradict multiple times in their conclusions)?

Read my previous post that I addressed to crissanderson of some of my comments on the study. Particularly note the fact about who the subjects were of the study. Also note that caloric intake/protein intake was not monitored. Also read my post shortly after that about how there are so many factors that can affect the results.

On top of that, the following conclusion is emphasized multiple times throughout the study by the authors:
"No significant changes were observed in fat-free mass over the 12 wk in any of the groups (Fig. 1 D). There were no differences in the magnitude of changes in body mass, percent body fat, fat mass, and fat-free mass among groups."
So why was this not mentioned in the website you linked?

Given all this information, do you think these small fluctuations are significant enough to support any of the conclusions of the analysis you linked (which even the AUTHORS of the study directly contradict multiple times in their conclusions)?

There was no difference in the MAGNITUDE of the changes. That doesn't mean there were no changes, or that the changes didn't favor cardio over lifting, just that the changes all in all weren't enormously different.

As far as other factors ... yeah, so? There is no study out there that's not going to be influenced by some variables.

Besides that, AUTHORS aren't necessarily free of bias. They even state that they were surprised at some of the results and don't understand what's going on entirely.

Which is still beside the point I was making, and discussion of the website I quoted is really a pointless distraction. This study has been pointed to on this forum and others to show that you have to lift to retain muscle mass. In-fact the study clearly does not show that. In my opinion it shows the opposite.

I would like to see some scientific proof that you'll lose lean mass or become "skinny fat" by just doing cardio. Honestly, I haven't lifted weights since my early 20's. I've run, done yoga, done martial arts for years... I had a DEXA scan done in 2004 at 29 years of age that showed I have 120 lbs of lean mass and I had one done a few weeks ago that showed the same 120 lbs of lean mass. I haven't lifted a single weight in that time and my diet has been all over the board, two pregnancies... not to mention 8 years have passed.

So... why is it that people are told not to do cardio only? If you already have a decent muscle base, why not just burn off the fat? I don't understand. It seems pretty hard to lose muscle... there was a time I wanted to.

You've just stated that you do yoga (static strength resistance training), martial arts (involves explosive strikes and kicks which is anaerobic and considered resistance training). So you JUST haven't been doing cardio only.
And lean mass doesn't ALWAYS mean muscle. You can get higher density in your bones, organs can gain mass etc.

But there have been studies done that show if protein balance is insufficient, muscle breakdown occurs.

Not much of a problem for the average runner of course - a jog around the block or even a 5k is not the same as a distance runner in training who does a half-marathon every day, and sprinters probably come under the strength training header since they're doing brief spurts of anaerobic activity.

Cyclists however can easily wind up with elevated protein breakdown - good thing you guys tend to drink lots of sugar water (sports drink). Insulin inhibits the breakdown of muscle protein...

And you do want to replace the glycogen stores pretty much immediately for optimal sports performance(Sports Med; 21(1), 7-17, 1996.) - it does make a difference for both us lifters and you endurance guys.

Plus, if glycogen stores remain remain low, muscle protein breakdown can result and lead to loss of muscle mass (Journal of Applied Physiology; 48, 624-629, 1980) - again not neccesarily a concern for the once-around-the-block amateur, but for the long distance/long duration crowd who spend hours on the elliptical, definitely.


A.C.E. Certified Personal Trainer/Group Fitness Instructor
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 28+ years and have studied kinesiology and nutrition

EXCELLENT ANSWER. THIS IS TOTALLY TRUE. I AM IN THE PROCESS OF STUDYING TO BECOME A PERSONAL TRAINER AND STUDIED THE IMPORTANCE OF RESISTANCE TRAINING JUST THE OTHER DAY. AWESOME ANSWER.

There was no difference in the MAGNITUDE of the changes. That doesn't mean there were no changes, or that the changes didn't favor cardio over lifting, just that the changes all in all weren't enormously different.

I never claimed there were no changes. Of course there's going to be changes when you are in a deficit. Also note that the strength training group had a lower RER (respiratory exchange ratio). Lower RER is an indicator of a higher rate of fat oxidation.

I should also add that the same folks (Kraemer et al) conducted an identical study with males a couple years later, and the results were that the diet-only group lost 3kg lean mass, the diet+endurance group lost 2kg lean mass, while the diet+endurance+strength training group lost 0.33kg lean mass. Also, the diet only group lost 6.68kg fat, diet+endurance lost 7kg fat, and diet+endurance+strength training lost 10kg fat.

Why the lack of consistency with the results between the two studies? To summarize Alan Aragon's analysis
1. lack of control in protein intake/calories. Dietary intake was also self-reported, which is a realistic limitation, but a limitation nonetheless.
2. gender differences
3. Another critical difference was that the lab used certified personal trainers for administrating the exercise programs of the men. Direct supervision of resistance training has been shown in studies to increase strength performance.

It would have been interesting to have both of the studies include a diet+solely strength training group.

As far as other factors ... yeah, so? There is no study out there that's not going to be influenced by some variables.

Yes, for the most part, there is a lack of adequate dietary control in the research so far when directly comparing strength vs endurance training effects on body composition.
But this still doesn't change the fact that what the grand majority of studies show, and what the real world shows - and what bodybuilders figured out a long time ago - is that strength training has a LBM-preserving effect in a deficit, while endurance training does not. This also makes logical sense when you consider the fact that hypertrophy (muscle gain) occurs to a much greater degree in fast-twitch muscle fibers that are stimulated by strength training rather than endurance training. Logically, you could argue that the same mechanism which causes hypertrophy in a surplus will optimally retain LBM in a deficit.

Which is not to say that you should do zero cardio.

Also, it's not as simple as "weights vs cardio" - even though people will put them into these categories for simplicity (understandably). The lines get blurred with circuit training, varying rest periods, etc. Read about the strength-endurance continuum if you're interested.

Lastly - genetics play a huge role in all this (calorie partitioning - how much muscle loss occurs in a deficit compared to fat loss and how much fat gain occurs in a surplus compared to muscle gain) - something called the P-ratio plays a huge role. Rather than explain it, I will just link you here. http://www.bodyrecomposition.com/muscle-gain/calorie-partitioning-part-1.html

I'll stop there since I already typed way too much.

ok you're dumb. sorry, but yoga and martial arts is strength training. running is strength training too if you run on hills. use your brain and think about what you're saying before you post something that isn't true. you are contributing to the ignorance.

martial arts is also strength training, it's more isometric but it's still strength training.

you can't tell me that doing something like au batido or queda de reins doesnt require an extreme amount of strength relative to your body weight. these are capoeira names but these are moves that are pretty much common in most forms of martial arts.

No one is saying these things won't build strength (or even a lot of strength over a long period of time...try telling Bruce Lee he wasn't 'strong'), just like running will build strength in your legs.

But no, martial arts are not 'strength training' perse.

martial arts is also strength training, it's more isometric but it's still strength training.

you can't tell me that doing something like au batido or queda de reins doesnt require an extreme amount of strength relative to your body weight. these are capoeira names but these are moves that are pretty much common in most forms of martial arts.

There is a difference between something that builds strength and actual 'strength training'. Stength training is training specifically to increase strength, its pretty obvious. Swimming would also (to a degree) build strength, but its obviously not strength training.

People just get too evangelical about their relative preferred exercises which in turn makes people defensive. It's not productive.

Amen! If the discussion gets a little too technical than I believe people will be more tuned out to what is being said. Keep it simple. Strength training is good for the body and has proven for myself to not only make me stronger but also make me a better and faster runner. I run, bike, use the Arc and I strength train; my body never knows what I'm going to throw at it from one day to the next

Personally, I don't want to be a big muscled body builder, but I greatly prefer my higher muscle mass (and higher body fat) look to that of a lower muscle mass that many runners seem to have.



I'm the one in yellow. I prefer my arms and legs over the arms and legs of the two girls ahead of me. I'd love to be as fast as they are, because they cream my *kitten* in races. :embarassed: We're all in the same age group (35-39). They're not skinny fat. They have low body fat, but also a lower muscle mass.

And I'm not all that muscular, as you can see when relaxed in normal clothes. But I'm not anywhere near a "runner's build."

I'd love to have a body like yours! Way better than those women in front of you

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