for the last 7-8 years or so I have been bugged by occasionally getting hypoglycaemic episodes while riding. This would often happen while commuting home from work which was a 30 minute (no hills) ride. I would usually be riding at a zone 2 effort (based on RPE more than anything). The episodes could be pretty severe and I would end up shaking, sweating and generally feeling horrendous. I spoke to a GP about it, and after a couple of blood tests the advice was to put a bag of jelly beans in my bike bag. hmm thanks…
This was really brought home to me today. I had lunch (eggs, toast, avo, tomatoes), and then an hour or so later jumped on to do 1.5 hr Endurance. Around 20 minutes in, I felt a hypo ep coming on. I tried to keep going, but had to stop pause the workout, go and eat some peanut butter and jam (jelly for the Americans) on bread, and a couple of home made rice cakes. I then got back on, and after about 15 minutes started to come out of it.
What is weird is that I based on previous experience, I can often smash out a longer and harder HIIT set with the same amount of fuel in the tank and be fine.
This made me wonder if Zone 2 is not leading to glycogenolysis (or gluconeogenesis) in the same was that harder workouts do. Therefore the glucose gets pulled into the muscles quickly, but isn’t replaced fast enough.
Anyone else get something like this or have thoughts on it?
This is not medical advice, but have you ever checked your blood sugar during one of these episodes? If low you need a work up. It’s not normal to go low in the first hour of a ride of any intensity. Do you have these symptoms when not exercising? You need to give your doctor more information. Although continuous glucose monitors aren’t perfect, it might give you the data you need to convince your doctor to do a work up or send you to an endocrinologist. In any event, documenting that you actually are low is important. Again not medical advice, just some educational material.
Hi Mecons, yeah I have done a couple of simple finger prick tests at home. I didn’t do one this time, but in the past I do recall a low reading (around 3 - 3.5 mmols / L I think).
My gut (pun intended) feeling is it is a reactive hypoglycaemia. I think I remember on one of the sports knowledge podcasts there was mention of it happening when your body over reacts by producing too much insulin which is compounded by doing exercise. I try to avoid high GI / GL foods unless required for recovery, but it still happens sometimes.
I am probably due for another general medical check up anyway, so I will bring it up again (maybe with a different GP at the same clinic). Good idea regarding the continual monitoring. I will have a look into that too.
I get exactly this from time to time and have been through numerous tests, latest being a mixed meal test. I did go low after the test but not very low so it wasn’t conclusive. They have ruled out all the more sinister causes that can affect pancreatic function, and appears it may just be the way my body is, so also have just ended up with the advice to to carry some jelly babies. I try not to eat massive meals as find that can be a trigger, appears my body just over reacts to a large intake of food, and instead I eat little and often which seems to stabilise my blood sugar and, fingers crossed, I haven’t had an episode for quite a while.
This part may be key: “I try not to eat massive meals as find that can be a trigger, appears my body just over reacts to a large intake of food, and instead I eat little and often which seems to stabilise my blood sugar and, fingers crossed, I haven’t had an episode for quite a while”
I’ve had this happen to me once or twice, pretty rarely but it was disconcerting when it happened. There was a fast talk podcast about the same, they called it “rebound hypoglycemia”, something about the carb bomb causes your body to produce insulin (rest and digest) and if the timing works out juuuust right (or just “wrong” lol) you’re in the low blood sugar state for the exercise
After saying this hadn’t happened for a while in my post above, I had an episode whilst mountain biking on Wednesday. Out with a group, did an easy hour or so, stopped in the cafe, enjoyed a delicious flap jack and cup of tea, then headed out for another lap. About ten minutes in felt a bit faint and weak. Handful of fruit pastilles sorted me out, then felt fine for the rest of the ride and did some of the best descending I’ve done in a while. Maybe a very sugary flap jack was a bad idea but it was flipping lovely and I’d be lying if I said I wouldn’t do it again!