After telling people I am trying to do 90 minutes of cardio per day to boost my weight loss (5-6 days per week, 3-4 days of weights) they all told me that I would be losing muscle mass and something to do with glycogen.

This confuses me.

I go on hikes ALL the time, we start at 7am and sometimes don't get to camp until 5pm in the afternoon, that is prolonged cardio, would that mean I am losing muscle? HOWEVER, we are eating carb loaded snacks to keep us going.

SO.
If I continue with doing 90 minutes of cardio am I going to lose muscle instead of fat?
AND.
Yesterday I walked to and from work (total of 12km) it took me about 2 hours, is this bad? It was pretty low intensity.

I just don't understand WHY the body would use something like LEAN MUSCLE to power the body instead of a nutrient like FAT?

Dietary fat and body fat is not the same thing. The fat you eat, does not transfer to your body. It's more complicated than that. Your body chooses to burn muscle because it's harder to maintain..Muscle USES calories to be present, while fat virtually does very little. Your body will try and break down the muscle, because it's naturally low on it's priority list. Your body's natural response is to preserve fat for survival. A way to preserve muscle while dieting, is to eat adequate proteins and do some resistance training as well. Yes, all cardio and no resistance training while feeding primarity on carbs will cause maximal loss in muscle tissue. Try getting your calirioes from protein, carbs and good fats, while balancing your cardio with some resistence training. Anyway, pretty lamans terms, if u want details, chat with some of the disciples on the board =D.

night

Resistance Tranining I do
I eat adequate protein

So I should be right on my hikes then? I know that when you get to a lower weight losing muscle becomes an issue.

In order to understand why the body loses lean body mass while doing prolonged cardio it's important to first understand the different muscle types and energy systems. In short you have two types of muscle fibers (although there is a range between the two): Fast Twitch (FT) and Slow Twitch (ST). In addition your body rely's on a combination of four different energy systems. The one that applies here is the aerobic or oxidative system.

Fast twitch muscle fibers are used for strong powerful contractions of limited duration and have more potential to hypertrophy (grow in size). This is why sprinters are very defined. They rely on the other three energy systems (phosphagen, fast and slow glycolisis)

ST fibers are used for longer duration when strength and power is limited. They rely on the aerobic energy system in which oxygen is a key component.

Basically what happens by doing long distance cardio is that the ST fibers dominate in the body which happens at the expense of the bigger FT fibers. This is because in order to use the aerobic system efficiently your body wants the muscle to be as thin as possible to allow for the passage of oxygen in and out of each muscle cell for energy production.

If you are trying to lose weight and tone up sprinting is a better option assuming you can safely do it. Just start off slow in terms of reps and distances and find someone qualified to instruct you.

Hiking and walking to work are by no means bad for you. However, they should only be an addition to your exercise routine which should consist of weight training (free weights, no machines) and sprinting/interval routines.

Good luck,

Jon

Saying "no machines" is a bit extreme and I don't think you should discourage people from using one or another but rather encourage the use of Strength Training in general. Obviously, the most important aspect is the stabilizer muscles not being targeted with machines (bench press machines come to mind greatly for me).

EDITED: There are several articles like this on the internet, but here is one that is well written and broken down.

Free Weights vs. Strength-Training Equipment - Strength/Resistance Training - FitFacts - American Council On Exercise(ACE)

True, saying no machines at all is a bit extreme, but for the general population they are actually more dangerous than free weight training or training with cables.

The fact is machine training, for the most part (there are some very advanced machines), forces the lumbar vertebrae into flexion and puts extreme compression forces on the spine and other joints without the need to stabilize the joint. Machines also teache incorrect motor mechanics which in turn leads to a higher incidence of injury.

In addition for weight loss you will be burning more calories using the free weight exercises and stabilizing joints which in turn can help prevent/lower the incidence of back pain, knee pain, and shoulder pain.

This subject can get much more in depth, but I encourage you to do some research and find out for yourself. Try checking out Stuart McGill to get started.

I don't need to research this, sorry it seems that I've come off as ignorant to you on the subject. You agreed with me saying don't rule out machines completely... that was my only valid point, except...

I don't agree with the statement that there is a higher incidence of injury with machines than free weights. I've been a part of the football program at my high school for almost seven years now, I've seen some athletes do some VERY serious things to their bodies using the free weights... I can count on one hand injuries from the machines (usually due to a kid showing off with more weight than he should be using).

Again, for beginners... machines are ABSOLUTELY fine. Hell, even for some advanced lifters machines are fine, it is based on preference and goals.

Listen, I am sorry, I didn't want to come off as snotty and I am thread crapping here... but I did want to say I am very aware of the free weights vs. machines debate. I like to use both in my program (switching it up from bench press machines to dumbbell presses from time to time). I just didn't want someone reading this thread and thinking machines were evil or something, you seem to know things you are talking about (or like to come across like you do), so please don't take offense to my questioning your knowledge.

I don't do machines, I use dumbells for a lot of exercises. However I do use the assisted pull up and dip machines, and the lat pull down machine.

I find free weights more challenging, thats why I do it.

Hmmm, funny that I always thought that free weights increase risk of injury due to people frequently use more weight than they should, and since you use more muscles to maintain balance using freeweights, would in return also increase your risk of injury if used improperly..But what do I know?

So, I've ben wanting to lose some lbs. too and have notice that I dropped too fast and now my skin needs to catch up with the muscle shrinkage. My doctor said, "loose 30 lbs". Whaaattttt, no way I'm husky and have BIG bones. Well I lost 15 lbs. I'm not so husky now and can see the BMI chart is probally pretty close to what I ought to weigh. I've been taking a class in food and nutrition and have learned that when we diet we loose 25% lean tissue mass or muscle and 75% body fat. A crash diet can cause up to 50% muscle, if you drive your body into starvation mode. Of course exercising or pumping iron will slow down muscle loss. My guess is that loosing weight slowly, i.e. a couple of pounds a month with exercise and a healthy diet would probably keep our bodies happy. IMHO

So, I've ben wanting to lose some lbs. too and have notice that I dropped too fast and now my skin needs to catch up with the muscle shrinkage. My doctor said, "loose 30 lbs". Whaaattttt, no way I'm husky and have BIG bones. Well I lost 15 lbs. I'm not so husky now and can see the BMI chart is probally pretty close to what I ought to weigh. I've been taking a class in food and nutrition and have learned that when we diet we loose 25% lean tissue mass or muscle and 75% body fat. A crash diet can cause up to 50% muscle, if you drive your body into starvation mode. Of course exercising or pumping iron will slow down muscle loss. My guess is that loosing weight slowly, i.e. a couple of pounds a month with exercise and a healthy diet would probably keep our bodies happy. IMHO

Actually, to clarify the issue of losing muscle mass while doing cardio.

Your body uses a combination of energy sources during exercise such as ATP-CP, Carbohydrates, Fat and Protein.

basically if you do intervals meaning fast then slow then fast...
you will not use as much protein as an energy source, this will result in better maintenance of your lean body mass or muscle mass.

Huh?

Huh?

Not necessarily.

Stuart is the man.