I'm not sure what I'm trying to get at. Trying to figure out the science of it all I guess. Tying in what Dancinbr said, about BG going up if you wait too long to eat...the reason for that is because the liver has sensed BG dropping too low so releases glucose to compensate...
I have to eat something very shortly after waking up or this happens to me, my BG will climb till I eat something.
So I thought spiking with exercise could be a similar problem... the liver sensing the depletion of inner muscular energy stores and releasing glucose to replenish them.
Wondering if eating will stop that then too?
What science is at work when eating something stops your BG from rising?



I did some more research on this, and you are correct, Bernstein says you need to keep exercising if this happens. Because during exercise you begin to accept insulin and to burn up carbs. As you get lower your liver begins releasing glucose into the blood. To have your sugars drop you have to continue exercising.


SIGH.... are you sure I cant' fix it with more eating, rather than more exercise?
lol

He also says that over time, your liver will get better at providing the proper amount of glucose as your body adjusts to lower scores.

It's a miracle I'm getting myself to do what amount of exercise I'm doing. I'm doing what I can do for right now. I guess I'll just have to hope my liver catches on sooner rather than later.

The whole body mechanism and glucose is quite complex. We learn from each other and that is terrific. I know I am learning more each day as I listen to experiences shared here.

Now to do what I promised myself to do. Take Bernsteins' book off my shelf and read it again, slowly with a whole lot more understanding

My walking time is morning, an hour after breakfast. My breakfast is always low to no carbs. I take my supplements (vit, min, acids, herbs) 30 mintues prior to breakfast. If I check FBG and post walking BG, I usually have a drop of 10 to 15 points after walking. FBG is usually between 95 to 115. On some occasions, I do have a rise and it is always surprising to see the rise. After much thought, I think it has something to do with the way I ate the night before as to the time and amount of carbs. Just my simple thinking, but I think my evening meal should be very low carb so I'm in a fat burning mode by morning, therefore with a low/no carb breakfast, after exercise I'm still in a fat burning mode, therefore liver is not converting protein to glucose for energy, thus, no spike in BG reading after exercise... Anyone with different thoughts, please correct me.... I'm just reading this thread for the first time and find it interesting how we're seeing and noticing impact in BG from diet and exercise.... One thing I am sure we all realize is timing of everything is everything....

Well, I have my doubts, but I've been wrong before

Hi Kitty,

I think that it's quite true that as glucose in the blood becomes depleated that the liver can over-compensate and cause elevated blood glucose levels, which in turn stimulates an insulin response in people that have one. However, there is a lot of published science on the subject of exercise, and unfortunately it does not appear to be as simple as just that single explanation.

According to the study linked below, (much of which is over my head) insulin has little or no effect during very intense exercise. It gets quite complicated, and of course not all the scientists/experts agree on all points. That being said, as a layman let me attempt to interpret the portions of the study that I think I understand.

Intense Exercise Has Unique Effects on Both Insulin Release and Its Roles in Glucoregulation

We've all been taught to think of insulin response as being the primary hormone in regulating our blood glucose levels, and in most of our daily activities, including low and moderate exercise, it is. However, the study shows that both fit non-diabetic and fit diabetic subjects will suffer from hyperglycemia after just 20 minutes of very intense exercise. Even with subjects with normal metabolisms it still takes them 40 - 60 minutes to restore their normal pre-exercise blood glucose levels, and in doing so first hyperinsulinemic conditions are induced.

The study also tested type I diabetics. Not surprisingly, lacking an insulin response, this induced a sustained hyperglycemic condition that had to be reversed with increased dosages of fast acting insulin. Although the study did not test type II diabetics, since their insulin response is somewhere between a non-diabetic subjects and a type I diabetic subjects, it is not unreasonable for us to conclude that they would also become hyperglycemic and that it would take longer than 60 minutes to restore their pre-exercise blood glucose levels.

During these bouts of intense exercise, despite the increased production of plasma glucose, insulin production remains uneffected. During these intervals, other hormones, not insulin, are mediating the body's metabolism. It is only after several minutes into recovery does insulin regain it's control.

Now with regard to Dr. Bernstein's advice to keep exercising to reduce the elevated blood glucose, if this study is correct, then the doctor's advice will only work if the exercise is not truely in a sustained anaerobic state. The body requires adequate amounts of insulin to transport glucose from the blood into body tissues, and insulin apparently is only produced in an aerobic state. The measurements in the study clearly show that even in non-diabetic subjects insulin is simply not being released during intense excercise despite the existing hyperglycemic conditions.

So to me the take home message is that sustained (lasting several minutes) true anaerobic exercise (>80% VO2max) should not be pursued on a regular basis by diabetics because it WILL induce unneccessary blood glucose spikes.

I don't think Dr. Bernstein's advice is harmful for sustained vigorous aerobic exercises, even if they occasionally peak into the anaerobic range for a few minutes. However, there appears to be other studies that present a better way for diabetics to exercise vigorously with less loss of glucose control. (By the way, I know Dr. Bernstein advocates anaerobic exercise, but I believe that if someone can sustain these intense levels of exercise for more than 20 minutes then, regardless of what their so-called theoretical target heart rate, they can't actually be in anaerobic mode. What has happened is that through conditioning a person has extended his/her actual target heart rate beyond their age group.)

Enhancement of fat metabolism by repeated bouts of moderate endurance exercise

Here's the abstract:



Here's a layman's discussion of the above study.

Repeated sessions of exercise burn more fat than a single, long session

You'll notice the author of the article puts emphasis on the improved fat loss of resting between workout sessions, versus one long continuous workout. However, as I mentioned, in addition this approach should be of particular interest to diabetics who wish to exercise vigorously with minimal elevation of blood glucose levels.

I had occasion to try this method out very recently. In the past after a strenuous weight lifting workout I found my blood glucose spiking up to 190. Earlier this week I had too much carbs for breakfast and found my blood glucose to be 201. Here's my log for the day:

10:26 AM fasting BG 133.
11:00 AM Brunch oatmeal, blueberries, banana.
12:04 PM BG 201.
12:37 PM BG 160.
1:09 PM BG 96 following 6 minute 00 second mile warm-up run on elliptical & 26 minutes of weights.
1:28 PM BG 92 following 19 minutes of rest.
1:45 PM BG 94 following 17 minutes of weights. (Finished 1st set total 43 minutes)
2:20 PM BG 102 following 35 minutes of weights (Finished 2nd set 35 minutes)
2:39 PM BG 99 following 19 minutes of rest.
3:37 PM BG 99 following 43 minutes of weights (3rd set) plus resting during 15 minute drive home.
4:16 PM BG 108.
5:50 PM BG 88.
7:03 PM BG 92.
7:30 PM dinner salmon, brocoli, string beans.
Metformin XR 500 mg.
8:39 PM BG 97.
9:37 PM BG 94.

[Please pardon a digression]
To put the above readings in perspective, before I discuss them perhaps I should provide a bit of background regarding my personal situation. I'm a 60 year old, thin type II diabetic recovering from colon cancer. I'm 6'0" tall and last year my weight dropped down to 144 pounds during treatment. During recovery I had no trouble regaining body weight, but unfortunately I found I had lost a lot of muscle weight and replaced it with fat. So at 157 pounds I was out of shape, skinny and flabby. I joined a gym run by a local hospital and starting researching bodybuilding, nutrition and exercise. For 5 months I've been weight training, I tripled my caloric intake and recently I started a low carb diet. I haven't had much success in increasing my body weight, only a two pound increase, but my Body Fat % has decreased from 17.2% to 12.3%, and my abdominals are just beginning to show.

Anyway the whole point of this is that I've started to more carefully monitor my blood glucose levels and I find 1) my control isn't all that great, and 2)despite the strenuous exercise, it's a lot harder to maintain glucose control while I'm taking in 2,700 calories daily. Hence all the daily records.
[End of digression]

So getting back to my blood glucose readings, I got up a late with a not to good fasting reading. Then I had a high carbo breakfast (not realizing at the time that oatmeal and a banana had so much carbos), and an hour later my blood glucose is at 201. Not good. It was my weight lifting day, so I drive to the gym, but this time I take my monitor with me. By the time I'm ready to start exercising my blood glucose is down to 160. So I start my warm-up run on the elliptical. With all that sugar I break a personal record running a mile in 6 minutes flat. Most of the run was aerobic, toward the end for the last five minutes or so I was close to my maximum heart rate for my age (160 BPM), so maybe I'm in the anaerobic mode for a few minutes.

I start my weight routine. After working out for roughly 30 minutes I rest for about 20 minutes, workout for 30+min, rest 20 min., etc. I do three complete sets on 13 machines for a total lift of more than 64,800 pounds, a 25% increase over my previous best day.

All during my workout my GB stays between 92 and 102, when normally if I had attempted a single strenous workout it would have spiked at about 190.

Following the workout the reading stayed between 88 and 108 for the remainder of the evening.

In summary resting between workout sets managed my blood sugar spikes and helped increase my total weight lifted. Of course having started the workout with an usually high amount of blood sugar no doubt contributed to the good performance, but regardless the improved control, both during the workout and after, is a big plus and I plan on making this a part of my normal routine.

I hope this long-winded post (my first) helps you in pursuing vigorous exercise without jeopardizing glucose control.

Larry

You seem to have me confused with someone who wants to exercise.

LOL!

Thanks for that good info. It makes sense. So the take-away message I'm getting, to avoid more episodes like the day i was doing strenuous yardwork and tested and found my BG was way up to 176, a number I hadn't seen in months, I should work/rest/work/rest. Testing frequently will let me know how long those work periods can be. And this actually does just as good a job of burning fat as pushing on non-stop.

Welcome to the board, and congratulations on your recovery and achievements!

If I take a half hour walk after dinner I seem to get good glucose levels the next morning. 83 the other morning, though I am averaging 92 - 94 without the walk. I will walk tonight to test again.

Hi all,
An earlier poster claimed that "Type 1"s seem to have an easier time with am exercise. This is absolutely not true! I wake up- am I too low / too high to exercise? I lower my basal rate, trying to predict when I'll be able to exercise, and for how long. Whoops- exercise delayed and basal rate too low and now running high! Oh and low carbing too- not enough insulin floating around to support the exercise, I better counterintuitively bolus before am exercise.
I could go on. Not a big deal, but I'm always wary of sentences that begin with "Type 1s have an easier fill in the blank" Nothing is easier.
V.

Hi Kitty,

Thanks for the welcome.

Yes, by alternating strenuous workouts with rests we can do more exercise, minimize blood glucose spikes and, according to the study, it actually increases the rate of fat burning versus a single non-stop workout.

By the way, if you are doing strenous yardwork in a warm climate, dehydration can also be contributing to your high blood glucose reading.


Sorry for the long-winded treatise, but you did say you were trying to "figure out the science of it all".

Larry

lfchanin - i just found this, then realised it's the same study you posted

-----------------
http://health.yahoo.com/news/177955

"To investigate, the researchers had seven healthy men complete one long workout and then two shorter workouts [with a 20 minute rest in between] on exercise bicycles.
...
The men showed lower levels of insulin and blood glucose during the second phase of the two-part exercise session."
------------------

i might try it, intense aerobic-alternating-with-anaerobic exercise (15-20 mins total) normally gives me a 40-point increase in BG, which exceeds what i get from any (low-carb) meal and it also takes a while to drop afterwards. i would be happy if a rest and second exercise period could bring down that increase more quickly.

Hi Pauleo,

Yes, based on the research I quoted earlier, and our own personaly experiences, sustained (15-20 minutes) anaerobic exercise will induce hyperglycemia, and that's true for fit non-diabetics as well as diabetics. To get to 15 to 20 total minutes, the anaerobic exercise bouts in these studies are usually achieved by some sort of high intenisty interval training, such as sprinting alternating with a slower "resting" pace. However, the rest period is short enough that the heart rate doesn't drop into the aerobic range, for very long if at all.

I believe that occasional, short anaerobic exercise can benefit a diabetic. An example might be a mile run for a fit diabetic. Obviously this depends on the conditioning of the individual. I recently ran a mile in 6 minutes flat. This started out at a moderate pace in the aerobic range and toward the end, I'm guessing the last minute, I was running at a faster pace at maximum heart rate for my age.

However, I don't think that repeatedly exercising at true anaerobic intensities for sustained periods of time (15 - 20 minutes) will lead to better blood glucose control, because we will find ourselves continually requiring several additional hours to recover our pre-exercise blood glucose levels.

With regard to my remark about "true" anaerobic intensities, it should be noted that generally most of us use the simple formula:

Maximum Heart Rate (MHR) = 220 - age

So in my case my MHR is 160. However, that is only valid if I have average fitness. If I am more fit than the average 60 year old then my MHR will be higher, and conversely if I am less fit, it should be lower.

When Dr. Berstein suggests continuing exercise to reduce exercise induced higher blood glucose levels, it certainly can't be at anerobic intensity levels. There are two reason for this. 1) Only world class athletes can sustain true anaerobic exercise for more than 20 minutes, 2) as long as an individual is in a true anaerobic state, insulin response is shut off and blood sugars continue to rise. The fact that Dr. Berstein can continue to exercise at > 80% of 152 beats per minute for sustain durations, doesn't mean he is in a true anaerobic state. It just means that he is much more fit than the average 68 year old. His real maximum heart rate is probably greater than 160 and he is undoubtedly exercising in the aerobic range for him where there is an insulin response.

Larry

Has anybody used fast acting insulin to control BG highs before weightlifting. In just the past couple months I have gone from about 115 to 130 after either weight lifting or HIIT

Larry,

Thanks for your thoughts. About me, I am trying a few types of interval training at the moment, with variations on how far I let my heart-rate drop in the aerobic period. Typically I do two of the following three things as a warm-up before weights -

Firstly 10 mins on a treadmill, starting on a level gradient, but increasing to gradient between 7% and 10% for 40 seconds at the 3, 5, 7, 9 minute points. My heart rate is 150-160 at high gradient and drops to 130s for level gradient. More importantly I guess, it feels like a good heart rate, in that I feel like I'm tiring at the end of the 40 second high-gradient stages.

Secondly is 500m sprints on a rowing machine. I start with a pace of about 2.05, then 2.00, then 1.55, then whatever I can manage below 1.55 (not much). In between each sprint, I rest completely and let my heart rate drop from 140-150 to about 100. I throw in an occasional 30 second all-out sprint at a pace of about 1.35.

Finally on spin bicycle, I do ten mins, in 20 second units of medium speed (pedal rotations), high speed, and then zero effort (zero means spinning the wheels but no resistance), and I vary the resistance at each new one minute set, including doing high resistance where it's hard to move the pedals. Heart rate is 130-140s and drops to 120s. I don't seem to hit 140-150s on a spin cycle unless I really work at it for some reason.

I just made these routines up, but I was partly inspired by Dr Bernstein's book. Also Art de Vany has a web-page, if you do not know it - if I summed up my understanding of his philosophy, it would be that changing heart rate during exercise is hugely more important than steady-state heart rate,
For that reason, I'm not wanting to do anaerobic exercise for 20 mins, amy more than wanting to do aerobic exercise for 20 mins, I am concentrating on variation in heart rate.

One thing I did not experiment much with is interspersing weights with sprints - currently all my 'moving' exercise is at the start, followed by weights.

I wish I understood a bit more abut the BG increase during exercise. I can easily believe that the overall effect of such exercise is good. But I would like to be able to use exercise to control whatever glucose store is being released during exercise, I feel in the dark about the actual process that's happening,

Paul.

Hi Rob,

The first study I referenced earlier states that for intense exercise:



Not the most helpful response to say "try experimenting". I think they are reluctant to suggest taking insulin before a workout due to the increased likihood of having a hypoglycemic incident.

Frankly I'm surprised that your blood glucose didn't go a lot higher with High Intensity Interval Training. I recommend that you discontinue HIIT. Do you have any insulin response whatsoever? If so, it might be helpful to rest between weight lifting sets.

Larry

Hi Paul,

You're welcome.

I would suggest that you do what I did, take your blood glucose monitor with you to the gym and take readings at key intervals to see what is happening, especially after those 150 - 160 stints.



I haven't read any science on changing heart rate, but many bodybuilders recommend varying the routine on a regular basis. From a diabetic standpoint I don't think extended aerobic exercise would hurt glucose control unless it exceeded about two hours. As I mentioned I do think 20 minutes of true anarobic exercise would be harmful to glucose control.



I think this depends on your goals. Since I'm thin, and trying to gain lean body weight, I think it would be counter-productive if I did a lot of cardio on my weight training days, other than as a warm-up. However, I'm trying to do get into a routine whereby I do cardio on my "off" days.



Here's my layman's interpretation.

Regardless of whether you are non-diabetic or diabetic, if you do any kind of low intensity exercise, where the heart rate is averaging an aerobic rate, then your blood glucose will gradually decrease until some point where the liver kicks in and throws glucose back into the blood stream. So say you're running at an easy pace, your blood glucose will decrease as circulating insulin pulls glucose out of your plasma while glucogen is pulled out of your muscles. Then, at some point determined by the amount and intensity of the exercise, when a good deal of muscular glucogen is depleted, your liver kicks in, over-compensates, and converts its glucogen back into sugar causing a spike.

Now if you are exercising in an anaerobic state, your insulin response is turned off (this is true of non-diabetics and diabetics), and as glucogen in your muscle becomes depleted the liver starts dumping glucose, but there's no insulin response to moderate the increase so the glucose keeps rising. It only take 15 to 20 minutes of anaerobic exercise to cause a very significant spike in even fit non-diabetic subjects. (When all the available glucose is depleted exhaustion sets in, exercise ceases, and you are forced into an aerobic state.)

So in a way non-diabetics, and type II diabetics, become type I diabetics during the period of intense exercise, because they don't have an insulin response. It is only during recovery, when insulin response is resumed, do the distinctions between normal, type II and type I reappear. So after intense exercise the non-diabetics require 40 - 60 minutes to regain their pre-exercise blood glucose levels, the type II's require more than an hour, and the type I's can't regain control without additional dosages of insulin.

Any kind of exercise improves insulin sensitivity AFTER the exercise. There have been studies showing that for weight training this improved sensitivity lasts longer than typical low to medium "cardio" exercise. By resting between weight lifting sets, we are able to do more weight lifting exercise without spiking our blood sugars. So doing weight lifting is my priority in trying to improve blood glucose control. Since the body needs to rest from weight lifting, I think less strenous "cardio" exercise on the off days makes sense to keep the metabolism and insulin sensitivity up, albeit at a lower level that the weight training days.

Larry