Maximum Fit Magazine

I want to check my understanding about fat-burning exercise: After exercising for awhile, the body depletes its stores of glycogen and shifts to burning fat for energy.  So the exercise done after this point counts for a lot more. 1) Is the above correct? 2) How can one tell when the body shifts to fat-burning?  A feeling of fatigue? 3) How long does it take for the body to produce more glycogen and shift back out of fat-burning mode?  Can one stay in the fat-burning mode even with extended rest breaks between exercises? (I'm thinking primarily of running.) Thanks in advance.

Can one stay in the fat-burning mode even with extended rest breaks between exercises? (I'm thinking primarily of running.) Interesting question.  Unfortunately I don't know an interesting answer (at least not one that is true.  My feeling is that once you stop the fat oxidation cycle it won't come back up very easily.  The reason I suggest this is because the fat oxidation cycle is very efficient when it is running but it is very inefficient to start up.  Therefore, I would suggest that once you take a significant break (maybe more than 30 secs-1 min???) that you have lost that fat oxidation efficiency and it then becomes that much harder to get back because you are already depleted of energy. BTW, lots of this type of discussion in misc.fitness. Dan Kelaher NCSU Ergonomics Lab

Thanks in advance. Michael K

I want to check my understanding about fat-burning exercise... ... When you increase your workload (start exercising), your muscles use glycogen because the energy is readily available. At the same time (if the exercise proceeds long enough), the body sends hormonal signals to release stored fat in adipose tissue.  This takes a little time, the hormones have to be released, travel to the fat cells, the triglyceride has to be broken down to free fatty acids, exported into the blood, and taken up by muscle cells. All this time glycogen is being used for energy. As fat burning increases due to mobilization of the adipose stores, the % of energy derived from carb burning decreases and fat burning increases (to perhaps a maximum of 50%).  ... ... Thanks for all the info.  It raises some more questions: What triggers the body to release the hormonal signals which release the stored fat?  Are the hormones released throughout the exercising?  Once the fat cells begin to release the stored fat, when do they stop releasing the fat?  What becomes of the fat which is released at or around the end of the exercising period? I managed to drop 20 lbs in about as many weeks over the summer, and I attribute this mainly to running 5 miles 3 times per week. I'd like to have a better understanding of the process.  From the info I've pieced together, it appears that running slow and steady (i.e., finding a pace which doesn't cause hard breathing) for a long time is the key, and that the first few miles are not the ones which burn much fat. By the way, how does one give the secret Caltech handshake over the internet?

Re: fat burning... Chinese qigong exercises, if done properly burn fat better than any aerobic exercise.

By the way, how does one give the secret Caltech handshake over the internet? I never learned the Caltech secret handshake.  I was shown the Gnome handshake, but since I haven't met another Gnome since leaving Caltech, I have forgotten it. Michael K