Hi Kjd! (may I call you Kjd for short? 
)
I am not very familiar with the Medtronic algorithms. But from what I have gathered from our Darling Nicky, nobody is really very familiar with them.
All runs have different fuel systems they use from various sources. I hope you have had a chance to familiarize yourself with the general ideas behind exercise fueling on some of the posts here, if you were not already familiar with them.
Let’s look at a certain type of run, just as an example. If you were doing a pace that was easy-to-moderate, your fuel source might be close to 50% muscle glycogen and 50% fat metabolism. Suppose you were running for 1.5 to 2 hours.
You could possibly get by with zero basal during that time. During exercise, your body is better able to use the remnants of basal that you have turned off. During exercise your body is much more insulin sensitive. And also during exercise, your body has a process called “contraction mediated pathway” that is able to convert glucose without much insulin.
(Adenylate kinase (ADK) converts 2 adenosine diphosphate (ADP) molecules into 1 adenosine triphosphate (ATP) molecule and 1 adenosine monophosphate (AMP) molecule. The ATP is hydrolyzed for energy, and the AMP attracts 5’-adenosine monophosphate-activated protein kinase (AMPK). AMPK acts in a way similar to how protein kinase B (Akt) recruits TBC1D1), which releases GLUT4 to the cell surface and allows glucose uptake. Additionally, calcium ions released from the sarcoplasmic reticulum during muscle contraction also promotes GLUT4. Other pathways include ROS signaling, and nitric oxide signaling.)
All of that is well and good while you are running. But what happens when you stop? Your exercise has ended, so your body is no longer using the contraction mediated pathway. Plus you have been without basal for a few hours. So a spike after this type of run with extended zero basal is very common.
I combat this with a replacement bolus. When you are finished, you have to replace a portion of what you missed. Just resuming basal is probably not enough.
After every run, take in 4 things:
- carbs
- insulin
- protein
- water
Regardless or what your BG is, you need those 4 things.
what-should-i-consume-after-exercise
Of course, the amount of insulin you need will depend on your BG and how long you have been on zero basal.
Anyway, this is just a starting point. If you would like to work through some specific examples, let’s do that.