In the process of arguing with a friend on the topic of glycogen depletion, I realized that I understood the point I was trying to get across but not how to say it exactly. I'm not sure that I was right, of course..that's why I'm here. She randomly spouted out a few words in conversation that I simply couldn't let go. "Within 30 minutes of weight lifting, your glycogen stores are depleted." I stopped her right there, and told her she was wrong that it takes much longer than this. My understanding is as follows:
Aerobic ATP production --> fatty acids, glucose, glycogen --> limiting factor for ATP = inadequate oxygen extraction, or in an endurance athlete's case, glycogen depletion.
Anaerobic ATP production --> glucose, glycogen --> limiting factor for ATP = lactic acid buildup followed by muscle inhibition.
Phosphagen system --> Creatine phosphate, stored ATP --> limiting factor for ATP = well, not much of either is stored in the muscle, maybe enough for ~10 second max effort.
Glycogen depletion generally takes between 60-180 minutes. With that being said, I understand glycogen depletion in a marathon runner's case, but is it possible in other forms of exercise? Hypothetically speaking, if someone were to hold a 10lb bar and curl slowly (maybe 40-50% effort, low intensity, below region of anaerobic threshold) and consistently produced ATP aerobically, would glycogen depletion occur after 60-180 minutes? It seems to me that regardless to weight, whether it be 5, 10, or 20 lbs the muscle would begin to 'burn' after X amount of time, signaling lactic acid buildup. BUT lactic acid is a byproduct of ANAEROBIC ATP production and if one were to remain aerobic why would it be present?
Also, given that weight lifting is generally an intense activity and lactic acid inhibits muscle contraction past a certain point, forcing a break, wouldn't it take hours to deplete glycogen?
I think at this point I'm just confusing myself
Thread: Glycogen Depletion.