Quote Originally Posted by charger69 View Post
A little off topic, but can you explain the part about LISS and HIIT and the use of glycogen. Now I can see where some studies may be misleading.
Sure. if you follow any pro bodybuilders you'll see some of them doing a depletion phase a week or so out from a show followed by a carb back load day before and of the show. The depletion workouts are for glycogen depletion. a lot of this is done in their weight training as thats glycogen dependent , but for cardio you'll see some of them switching over from steady walking on a treadmill cardio to doing a spin bike with high intensity or the step mill or super incline treadmill with higher intensity. Reason is for more glycogen depletion.

think of the difference between a brisk walk or riding a bike up a steep hill . they can both be considered cardio, but the steady walk does not use glycogen , where as the bike uses a ton of glycogen. the bike requires contraction of muscles to power the bicycle, thats one reason why it uses glycogen as its fuel source. the walk does not.

so LISS cardio or MISS cardio on a treadmill will burn up blood sugars and oxidize fat for fuel.. the HIIT training will use these as well but with the resistance and intensity amped up it taps into glycogen.

a lot of the studies comparing HIIT to LISS can be skewed because of this . and they are really only accounting for calories burned. Sure a high intensity session of HIIT for 20 mins will keep your body systems revved up for an hour or two after the session is over and thus burn more calories. But a MISS cardio session done for a steady hour may end up oxidizing more actual fat (more of the calories burnt and from fat and not some fat plus a bunch of glycogen).

of course none of these studies are generally done on bodybuilders using a bunch of gear, drugs , and fat burners .. and this would skew the results to an entirely different level.