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Type 1 - Insulin sensitivity and different muscle groups

tim2000s

tim2000s

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Type of diabetes
Type 1
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After a number of months, I've recently switched to a punishing strength phase in the gym, which consists of three different sessions. Legs, chest and back and arms, on different days.

What I've noticed from my Libre profiling is that the arms and legs sessions make me significantly more sensitive to the Basal Insulin than the chest and back session does, everything else (timing, meals, etc) being the same.

I wondered whether anyone else had noticed the same?
 
My speculation would be Probably a greater muscle mass involved, therefore greater local glycogen depletion, hence need to replenish, therefore leading to the greater sensitivity post exercise
 
ElyDave said:
My speculation would be Probably a greater muscle mass involved, therefore greater local glycogen depletion, hence need to replenish, therefore leading to the greater sensitivity post exercise
Click to expand...

I'd certainly agree with that for the legs, but I'm not so sure about chest/back being smaller than arms. I also wonder whether "lever" type muscles have different glycogen stores and glucose receptors as the purpose of them is slightly different.
 
I do a little gym work out. My BG levels tend to drop a little only if I exercise to sweat levels. If I only exercise without feeling warm and sweaty then I have seen my BG levels rise..... I don't / can't test enough to fully confirm this trend (limited test strips and I don't have a libre). I also believe that if I push myself to far during exercise my BG levels rise... So I now stop exercising, or slow down / have a break, soon after I start sweating..... I would love to see my levels on a libre.... But can't justify the expense with the unreliability (at the moment.... Not being on insulin yet).
 
I don't know much about muscles but I wondered if it had anything to do with the type of muscle fibres that you predominantly using , The cells in the different types of fibre use fuel differently.
Fast twitch fibres have more glycogen but run out of it quickly (you use them for heavy weight lifting and for sprinting). You can't refuel fast so you reach exhaustion quickly.
Slow twitch ones are relatively low in glycogen, the cells have large triglyceride stores which they can also use.

During exercise, glucose can get into the cells in muscles via GLUT 4 transporters .These transporters come to the cell surface when either insulin 'arrives' on receptors or when muscles are contracted You need less insulin or even no insulin during aerobic exercise because of this. If you have a lot of these transporters getting glucose out of the blood without insulin then you will need less insulin
.
I wondered if there were more GLUT 4s on slow twitch fibres than fast ones and this seems to be the case. People with insulin resistance have also been found to have fewer glut 4 transporters than non diabetics http://diabetes.diabetesjournals.org/content/50/6/1324.full
(took me a while to find and I can now tell you that forestomach herbivores are less insulin sensitive than other mammals and that camels have high blood glucose levels and few GLUT 4 transporters)


Individuals differ in they proportions of the various fibres .I think that comes down to what you are born with (training?) Some parts of the body have more of one type than another. Legs tend to have more slow twitch fibres but the chest has more fast twitch ones. ( arms though also have slow twitch so that could throw my theory out of the window It may depend on what you are doing with your arms)
 
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