Seattleite said:
If someone is carrying around 20% BF (such as myself), will cardio sessions of 30-45 minutes burn away any muscle before it strips away most of the fat? I'm really hoping that it attacks the fat first and foremost and saves muscle for last, but wanted to get some expert advice.
I know that bodybuilders typically prefer HIIT over steady-state cardio since HIIT is more of an anabolic version, but will your body ever try to burn muscle if you have excess body fat that you need to get rid of? Does it burn some fat and then after a while switch to muscle? What is the actual science behind it all?
They say knowledge is power so knowing about how the body uses fuel may a vital key to weight loss and most importantly fat loss with lean body muscle retention. So what are the major sources for fuel in the body? Well to put it simply- fat and sugar, lipids and carbs-whatever terms you want to use there is the 4 calorie/gram carb and the 9 calorie/gram fat, incidentally protein is also 4 calorie/gram same as carbs.
It's important to understand that these two energy sources have for our purposes two locations-two components, one within skeletal muscles and one in the blood. Thus, four primary energy substrates fuel muscle contraction and physical activity.
In muscle: glycogen and triglicerides are the fuels and within blood: glucose fatty acids and tryglicerides. Amino acids from protein breakdown can undergo oxidative metabolism to be used to fuel muscle contraction. Although not primary energy substrates, amino acids are used as auxiliary fuels during muscular work. Exercise duration, carbohydrate content of the diet, and muscle glycogen levels affect protein use for fuel. Oxidation of branched-chain amino acids (leucine, isoleucine, and valine) within skeletal muscles is increased during prolonged exercise and when muscle glycogen stores are low. Protein may contribute up to 10-15% of the energy needs in endurance exercise, particularly when the athlete is carbohydrate depleted.
So whatever sport or activity you are doing these 4 sources of the two primary fuels are the source of energy for whatever is being done. Whether running a flat out sprint, jogging on the treadmill, pumping iron in the gym, or watching the boob tube that's all we have to feed the beast. Now many strength trained athletes have the idea that protein provides the energy to get er done. Well protein feeds and rebuilds muscle but think of it this way, you're laying flat on your back ready to do a set of 230lb bench presses- what's going to get er done- the muscle for sure muscle that you've built up over countless sets, but the fuel for this madness comes from carbs- and those carbs in good supply within muscle glycogen and blood/glucose are the only thing's that can move that quickly from potential to actual.
The body uses fat at rest and low intensity activity moving to an intersection point where both carbs and fat are used at mid-intensity(65% of VO2), and moving towards the upper intensity level (85% vo2)where mainly carbs are used. 65% of VO2 is the point where fat oxidation is greatist. Move that up a notch to 85% of VO2 and total carbs are used for fuel. Remember the four major fuels for exercise: muscle glycogen, plasma glucose, muscle triglyceride, and plasma fatty acids. Now the liver does store a small amount of glycogen that however is in general terms not that significant and is saved to fuel the brain-as the brain only does glucose. So let's get the liver out of the equation-although it too can be trained to store more glycogen.
So to answer your question Yes and no. The catabolic state is the question to which your question refers. What are some examples of catabolic states where the body scavenges protein for fuel? Go to any burn unit- those burn patients are Uber-catabolic they are wasting away. The anorexic eating disorder thing is another example. Tissue trauma even a surgical procedure. Think of HIV or really any chronic infection-these are all states where the body just can't keep up with the task of renewing itself.
Oxandrolone has been used with burn patients in this catabolic state to encourage the body through hormonal means to stay in a anabolic + nitrogen balance. It's also used by Aids patients for the similar purpose. Now another name for this compound is anavar. So really full circle. Are there any compounds likely to increase the anabolic state?
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