Endurance athletes and Hb A1c

[omicron1792]

Quick google search will provide lots of data on the topic. Here's one of many: https://pubmed.ncbi.nlm.nih.gov/17614026/

Right. But I’m not sure it means what you think it does.

Endurance exercise changes the way our bodies process sugars. Up to a point this appears to be a good thing.

Above a certain exercise threshold, the gains seen in studies plateau. At extended levels, the gains start to trend downwards.

Why is this? We don’t know fully, but there is something that flattens the curve. Glucose processing might be one of them. Keeping the body in an extended state of exercise may not allow the body time to do routine maintenance needed for healthy regulation.

Health coaches talking about increase rbc age causing increased a1c might be the answer. But it may not be, and my guess is it’s not. That YouTube video didn’t solve the riddle.

 

[ZachTullock]

Right. But I’m not sure it means what you think it does.

Endurance exercise changes the way our bodies process sugars. Up to a point this appears to be a good thing.

Above a certain exercise threshold, the gains seen in studies plateau. At extended levels, the gains start to trend downwards.

Why is this? We don’t know fully, but there is something that flattens the curve. Glucose processing might be one of them. Keeping the body in an extended state of exercise may not allow the body time to do routine maintenance needed for healthy regulation.

Health coaches talking about increase rbc age causing increased a1c might be the answer. But it may not be, and my guess is it’s not. That YouTube video didn’t solve the riddle.

For me - the available data speaks pretty clearly. Hba1c is a flawed biomarker viewed in isolation. It is useful when you use it as part of your comprehensive test results.

The data shows us that the value is skewed by RBC life and athletes who are metabolically healthy when you look at other biomarkers (insulin, fasted blood sugar, triglyceride /HDL ratio, etc etc) or a glucose tolerance test can often have elevated Hba1c.

So back to my original comment - Wouldn't worry about it too much as long as your other metabolic biomarkers are in line! Hope I was able to help out here. Not a medical professional - Just a hunter concerned about longevity so I can have as many seasons as possible in my life!

 

[Bobrobheimer]

For me - the available data speaks pretty clearly. Hba1c is a flawed biomarker viewed in isolation. It is useful when you use it as part of your comprehensive test results.

The data shows us that the value is skewed by RBC life and athletes who are metabolically healthy when you look at other biomarkers (insulin, fasted blood sugar, triglyceride /HDL ratio, etc etc) or a glucose tolerance test can often have elevated Hba1c.

So back to my original comment - Wouldn't worry about it too much as long as your other metabolic biomarkers are in line! Hope I was able to help out here. Not a medical professional - Just a hunter concerned about longevity so I can have as many seasons as possible in my life!

From what I can tell you might be right. And perhaps worrying tremendously in the circumstances you describe is uncalled for. However it also seems this is all just too new and not very well understood yet such that it might turn out either way for longevity. I would like to believe you are right for my own sake. I meet the triglycerides to HDL ratios generally well over the last few years but my LDL and appo b are too high.

 

[ZachTullock]

From what I can tell you might be right. And perhaps worrying tremendously in the circumstances you describe is uncalled for. However it also seems this is all just too new and not very well understood yet such that it might turn out either way for longevity. I would like to believe you are right for my own sake. I meet the triglycerides to HDL ratios generally well over the last few years but my LDL and appo b are too high.

Fair enough. Just trying to add some light on the discussion.

Regarding LDL and ApoB - Peter Attia has a lot of good information on this topic. Personally, I recommend finding a primary care doctor who is onboard with the "Medicine 3.0' concept outlined in Outlive.

 

[Huntingnorseman]

There is a lot to unpack here and I'll try to be succinct. To be clear I am not giving medical advice. Just providing some prospective as this is not an uncommon issue I deal with in athletes/ people who purposefully train. Part of this depends on your goal. Is it short-term performance or overall health?

1. An elevated A1C means over consuming carbs, increased stress hormones, or training is not structured well. For most people they have some of each. The over consuming carbs can be very individualized, there isn't a set number of carbs. People generally ignore the other lifestyle factors which contribute to elevated blood sugar: stress, poor sleep, ect.
2. A1C measurement has a relatively large margin of error. When performing serial measurement a change of at least 0.5 % is considered statistically significant. Inside that there is some ambiguity if the change is real.
3. A1C measurement is affected by various supplement, Vitamin C being a common one.
4. The normal ranges for fasting insulin and glucose are large and suboptimal for health. Many labs consider a fasting insulin into the mid-twenties to be normal and blood sugar up to the low 100's the normal range. If you calculate insulin resistance using HOMA-IR, these people have significant insulin resistance with "normal values".
If you look at the data a HOMA-IR Score of 2.0 or less is ideal, some studies would suggest 2.5. If you have the numbers you can calculate your score here, https://www.mdcalc.com/calc/3120/homa-ir-homeostatic-model-assessment-insulin-resistance
5. A1C doesn't tell you anything about postprandial glucose, both of which the absolute number and duration are important. I put a CGM on everyone I am concerned about, whether it be an A1C above goal, elevated HOMA-IR , or very low fat oxidation on their VO2 test. You can order these for home use now directly from Dexcom, https://www.stelo.com/en-us. This does introduce some bias as most everyone changes their habits slightly when they know they are being watched. You can do your workout and see what is happening your glucose when you carb up before, during, and after your workout.
6. A VO2 test is the most practical way to assess your metabolic health in addition to labs. If fat oxidation is low at your aerobic threshold, that is sign of poor metabolic health/flexibility. For example, if two people have the same AeT of 130 bpm, but one is using 80% fat and the other is using 20% fat these are not the same metabolic state or state of health in my view even though the may have the same AeT and VO2 Max. There will also be the situation where their AeT is very low as they have little ability to use fat as fuel at with even minimal activity. These are training, diet, and lifestyle issues.
7. Most people are spending way to much time in Zone 3-Zone 5. When I here people say I do moderate to intense cardio this is usually means they are above their AeT for most of their cardio. From a health standpoint I view this as metabolic purgatory. Your aren't improving your fat metabolism which is quite evident when you look at your the metabolic data from the test. This is where most people do all their cardio and it is counter productive for long-term health. The caveat to this is if you are wanting to perform better in race you have to spend time training in these zones since that is where you race. That training has to be structured and limited.
8. Total body fat by DEXA doesn't say much about your health and while FMI is better than BMI it doesn't tell you what you really want to know, which is where the fat is. I use VAT area as it has the best correlation to long-term risk of developing chronic disease. Goal is less than 100 cm sq and I consider optimal to be less than 90. You can have normal body fat with increased VAT area. This often goes with less than ideal ALMI in endurance athletes that don't lift.

You are asking some great questions about your health and you are unlikely to find a physician who understands how to put the tests together. Part of this is that there are not many places that offer all the testing in one place so you have to piecemeal the testing together over a period of time. I have some videos on our YouTube Channel you might find interesting. There is one specific to longevity vs performance.

 

[omicron1792]

There is a lot to unpack here and I'll try to be succinct. To be clear I am not giving medical advice. Just providing some prospective as this is not an uncommon issue I deal with in athletes/ people who purposefully train. Part of this depends on your goal. Is it short-term performance or overall health?

1. An elevated A1C means over consuming carbs, increased stress hormones, or training is not structured well. For most people they have some of each. The over consuming carbs can be very individualized, there isn't a set number of carbs. People generally ignore the other lifestyle factors which contribute to elevated blood sugar: stress, poor sleep, ect.
2. A1C measurement has a relatively large margin of error. When performing serial measurement a change of at least 0.5 % is considered statistically significant. Inside that there is some ambiguity if the change is real.
3. A1C measurement is affected by various supplement, Vitamin C being a common one.
4. The normal ranges for fasting insulin and glucose are large and suboptimal for health. Many labs consider a fasting insulin into the mid-twenties to be normal and blood sugar up to the low 100's the normal range. If you calculate insulin resistance using HOMA-IR, these people have significant insulin resistance with "normal values".
If you look at the data a HOMA-IR Score of 2.0 or less is ideal, some studies would suggest 2.5. If you have the numbers you can calculate your score here, https://www.mdcalc.com/calc/3120/homa-ir-homeostatic-model-assessment-insulin-resistance
5. A1C doesn't tell you anything about postprandial glucose, both of which the absolute number and duration are important. I put a CGM on everyone I am concerned about, whether it be an A1C above goal, elevated HOMA-IR , or very low fat oxidation on their VO2 test. You can order these for home use now directly from Dexcom, https://www.stelo.com/en-us. This does introduce some bias as most everyone changes their habits slightly when they know they are being watched. You can do your workout and see what is happening your glucose when you carb up before, during, and after your workout.
6. A VO2 test is the most practical way to assess your metabolic health in addition to labs. If fat oxidation is low at your aerobic threshold, that is sign of poor metabolic health/flexibility. For example, if two people have the same AeT of 130 bpm, but one is using 80% fat and the other is using 20% fat these are not the same metabolic state or state of health in my view even though the may have the same AeT and VO2 Max. There will also be the situation where their AeT is very low as they have little ability to use fat as fuel at with even minimal activity. These are training, diet, and lifestyle issues.
7. Most people are spending way to much time in Zone 3-Zone 5. When I here people say I do moderate to intense cardio this is usually means they are above their AeT for most of their cardio. From a health standpoint I view this as metabolic purgatory. Your aren't improving your fat metabolism which is quite evident when you look at your the metabolic data from the test. This is where most people do all their cardio and it is counter productive for long-term health. The caveat to this is if you are wanting to perform better in race you have to spend time training in these zones since that is where you race. That training has to be structured and limited.
8. Total body fat by DEXA doesn't say much about your health and while FMI is better than BMI it doesn't tell you what you really want to know, which is where the fat is. I use VAT area as it has the best correlation to long-term risk of developing chronic disease. Goal is less than 100 cm sq and I consider optimal to be less than 90. You can have normal body fat with increased VAT area. This often goes with less than ideal ALMI in endurance athletes that don't lift.

You are asking some great questions about your health and you are unlikely to find a physician who understands how to put the tests together. Part of this is that there are not many places that offer all the testing in one place so you have to piecemeal the testing together over a period of time. I have some videos on our YouTube Channel you might find interesting. There is one specific to longevity vs performance.

Man great post.

 

[Marbles]

I probably shouldn't have used myself as an example, but as that is already the case, I'll keep running with it.

Total body fat by DEXA doesn't say much about your health and while FMI is better than BMI it doesn't tell you what you really want to know, which is where the fat is. I use VAT area as it has the best correlation to long-term risk of developing chronic disease. Goal is less than 100 cm sq and I consider optimal to be less than 90. You can have normal body fat with increased VAT area. This often goes with less than ideal ALMI in endurance athletes that don't lift.

Good point, though my VAT is probably around 50 (using both anthropomorphic data and converting from total VAT mass on DEXA to a single slice area as would be obtained by an MRI).

So, no argument there to place stock in the Hb A1c.

Beyond that, in some studies, once BMI or body fat percentage is controlled for, VAT area is no longer a reliable predictor, so saying total body fat doesn't matter is to over state what is know at best.

Most people are spending way to much time in Zone 3-Zone 5. When I here people say I do moderate to intense cardio this is usually means they are above their AeT for most of their cardio.

On the 4-12 weeks a year were I train above aerobic threshold, I do less than 5% of my weekly time at that level, yearly time spent above aerobic threshold is probably less than 1%. If anything, given some of the data on HIIT, one might say I need more intensity (I would argue the data that favors HIIT does not come from people who move a lot, so doubt it is generalizable in this case).

The normal ranges for fasting insulin and glucose are large and suboptimal for health. Many labs consider a fasting insulin into the mid-twenties to be normal and blood sugar up to the low 100's the normal range. If you calculate insulin resistance using HOMA-IR, these people have significant insulin resistance with "normal values".
If you look at the data a HOMA-IR Score of 2.0 or less is ideal, some studies would suggest 2.5. If you have the numbers you can calculate your score here, https://www.mdcalc.com/calc/3120/homa-ir-homeostatic-model-assessment-insulin-resistance

My fasting insulin is below the labs detectable threshold (<10), so cannot calculate a precise HOMA-IR, but it is low. But, you can't fix to a number unless you know how and why the lab assigned those values as normal. Different assays cannot be compared 1:1 unless both techniques have been standardized.

A1C doesn't tell you anything about postprandial glucose, both of which the absolute number and duration are important. I put a CGM on everyone I am concerned about, whether it be an A1C above goal, elevated HOMA-IR , or very low fat oxidation on their VO2 test.

Why? Do a glucose challenge and get information that is clinically validated if you want to know glucose handling.

Interstitial glucose lags and is not validated as a diagnostic tool. Even capillary glucose doesn't always track with serum glucose (a well known issue in EM and CC environments).