When does body start burning fat/muscle to replace glycogen?
 

I usually do a long and hard 3-4 hour ride (with 150-200 calories/hour in-flight) and then do a 1 hour easy ride home. During that 1 hour easy ride, has my body already started converting fat/muscle to replace the depleted glycogen? Should I begin recovery in-take as soon as I start riding easy, or is it OK to do that after the 1 hour easy ride?

Also, when my body is replacing the depleted glycogen, does it burn fat or muscle to do that (in the event that I don't in-take enough carb)?

I think you can wait until you get home. Usually the body prefers to use fat to replenish glycogen. You have to be really undernourished to start catabolizing muscle.

Carbohydrates are the only thing that can replenish glycogen. Fat and muscle do not burn to replace it, but you can burn fat for energy. As soon as you get home have a recovery drink, consisting of Carbs, protein, electrolytes, and L-glutamine. About an hour later have a good solid food meal. I also suggest having a carb and BCAA drink or some gels while riding. If you allow your fuel stores to get too low during a ride, it will effect your performance.

If you are still taking in glycogen during the easy ride, so you should be okay. Your body can break down muscle to replace glycogen stores if it needs to, but if you have calories coming in and get your recovery nutrition after you're done I think you'll be okay.

Uh, no.
Your basic understanding of how the body utilizes energy during exercise is not accurate.

You don't take in glycogen. Glycogen is the storage form of glucose in animals and humans which is analogous to the starch in plants. Glycogen is synthesized and stored mainly in the liver and the muscles. It is synthesized from carbohydrate intake. Muscles only store small amounts of glycogen; enough glycogen for ~90 minutes of intense exercise. Glycogen, glucose, lactate, fatty acids, ketones and protien can be used as energy to meet metabolic demand when exercising.

Under most circumstances, fats and carbohydrates are the fuels utilized during exercise. Primary (typically carbohydrates-our most efficient energy source) or secondary sources (like fat or protein-relatively inefficient as compared to carbs) of energy are determined by prior nutrition state and the intensity and duration of the exercise. At low levels of prolonged exercise most energy needs come from fat. At higher intensities, carbohydrates plays a greater role. Protein plays only a minor role at very high levels of energy utilization.

During low intensity exercise, muscles utilize fat for fuel (determined by respiratory quotient (RQ) on VO2 max testing). The advantage of fat as a fuel: it provides extensive stores of calories in a easily portable form. Protein only provides about 6% of energy needs. With high intensity endurance exercise, the production of glucose from amino acids can be significant, up to about 10 or 15% of total energy needs. When glycogen stores have been depleted, gluconeogenesis build glucose from protein (which = depletion of muscle mass), one must maintain carbohydrate intake to avoid this from happening.

One part of your statement above is correct in that calories coming in during exercise are necessary beyond about 90 minutes of intense exercise, and a correct ratio of Carbs:Protein to recover are necessary to replenish glycogen stores and repair damaged muscles (micro-fiber damage).

RATBOY
Exercise Physiologist

Ratboy, great dissertation.

Does diabetes affect any of that process? Specifically Type 2?

CCrew:

One important thing to remember with persons with Type II diabetes...your blood sugar CAN be controlled (in most cases) with exercise and proper diet and having Type II diabetes most certainly does affect the process of utilizing carbohydrates.

Some important points to remember...the amount and type of carbohydrate affects blood glucose levels. Choose most of your foods with a lower glycemic response as a way to fine tune your carb counting. Also, keeping track of how many carbohydrates you eat and setting a limit for your maximum amount to eat, you can help to keep your blood glucose levels on track. Exercise will mobilize the the blood sugar more rapidly and help bring your levels back into check.

Hope this helps,

RATBOY

Thanks for the response.
I've been able to get off virtually all meds with the aid of riding and carefully watching what I eat. Glucose numbers run a tad high, but well within acceptable limits. Three days off the bike is my limit before the numbers spike.

Biggest issue I have is that I ride extensively.. 50 miles a day as a commuter, and frequent weekend rides of longer distances. I have issue fueling enough to sustain a more "energetic" level of riding/training without hitting the wall. Putzing along @ 12-14mph no problem. Not pure bonk mind you, but just a quite obvious hit in stamina and endurance. Most of the energy products are effective but are hardly designed for diabetics, and any requests to mfg's are met with the quick response "consult your primary care physician". I also have to be excruciatingly careful as they will spike my numbers. I try not to use them.

Consulting the Dr. is so well and good, but frankly I can't find one that has any clue how to deal with a patient that is interested in amateur competitive level training, much less is exercising as to not take meds. I flat asked one if they're used to writing scrips for people so they can go home and sit on the couch and got "that's what most do" as a response. If I take meds and ride I will get low crashes quickly, and it's an ugly place to be for me.

I'm really trying to get a handle on the physiological changes due to the Type 2 and how to best cope with the way my body is now processing glucose. If nothing else I'd just love to be able to find a Dr that doesn't gloss over when he has to process what we do cycling.

Aim for me is to get into TT and Cyclocross beginning next season and at the moment I feel like I've hit a plateau that I can't get past. Don't even ask how badly a Dr's eyes gloss over when he ses training mapped to HR zone/distance/pace/glucose level :P

Any suggestions appreciated. I can't be the only one out here trying, although I know I'm in a distinct minority.

Regards,
Roger

Ratboy, I'm just getting into serious exercise after decades of sedentary existence. Can you recommend an entry level book on exercise physiology?

CCrew: Interesting post.
I was diagnosed T2 after a poor response to a Glucose Tolerance Testand placed on the "appropriate" meds. I have a family history but suspected my GTT fail was due to a recent operation and rejected outright the "come back in a year and we will re-check your levels".
Basically...you are now T2, get over it, live with it.
I pulled the long forgotten MTB out and started exercising. Traded up to a decent road bike and upped the ante after about 4 months and now do 700+ kms a month, average 22-23 kms/hr. Read lots on the subject...made my own road cookies...took glucose levels before and after the ride as well as the usual fasting and 2 hour post-prandial reads. After maybe 2-3 months I changed Doctors and asked for a repeat GTT....doctor was "astonished" at the results which were low range of normal. No meds as a result.
I have continued taking glucose readings post-ride...5.0-5.5 mmol/L (90-99 mg/dl)...are typical.
I vary the ride intensity and time of food input to see if there is anything to note in the subsequent readings...nothing much in way of variation.
My opinion from lots of reading: Statin drugs were causing high glucose readings. Doctor initially said no way. Changed the statin type as they insisted I needed them but at 10mg rather than 80 mg. I am not sure but continue exercising because I see many more benefits now that previously never got passed my DNA embedded laziness.
Will this help you?
Don't know.
But making your own road cookies is a great start.
Make them to your particular dietary needs.
Log it.
Keep a post-ride spreadsheet...I use MS Excel, a Polar Heart Watch,Omron digital Blood Pressure
device and digital Glucose Monitor.
This gives me ...max/min/average heart rate, distance/time/max and average speed, blood pressure,HR post-ride, glucose, food intake.
As good as a Powertap...almost.
Even if this does not get you off the meds you will know EXACTLY where you are at.

Regards

The textbook: "Exercise Physiology : Energy, Nutrition, and Human Performance" by William D McArdle, Frank I. Katch, & Victor L. Katch is largely considered to be the most comprehensive compilation on the subject. It is what I used in school as my text. There are many others, but this is the one I refer to most often.

You can find it here: http://books.barnesandnoble.com/sear...ise+physiology

It isn't cheap, but any good textbook will cost.

Hope this is helpful.

RATBOY

Roger:

No dobut that exercising as a diabetic poses numerous hazards and challenges. Its a constant monitoring of your before AND after glucose readings and understand how you personally respond to certain types of activity. Some good ideas can include: wear an ID bracelet that indicates your diabetic condition and, whenever possible, exercise with a partner (just in case).

Since I do not have an M.D. behind my name I will make the disclaimer that you should at least make your Physician aware or your exercising intentions. It is a true statement that many doctors are just not as well educated with the effects of exercise and certain conditions, but they still take the responsibility to monitor your health. The idea is to be safe AND reasonable.

There are estimated calorie expenditure and strategies to lessen the risk of hypoglycemia and large spikes if you do consume too much sugar. I agree that the current energy solutions are not well suited for diabetics. But, food intake both before and after exercise should be reviewed carefully. Because approximately 50% of the calories burned during exercise come from a carbohydrate source (assuming you are exercising at an intensity where carbohydrates are being used as the primary energy source, with the remainder coming from fat), you can calculate that in a 30 minute exercise session, wherein an activity like cycling merely at 8mph burns about 10 cal/min, a person would need to consume about 38g of carbohydrates (50% of 300kcal =150 kcal or 37.5 g of carbohydrate). I certainly am not an expert with this population, so I apologize for not giving more concrete solutions for you at this point. It may be helpful to work with a dietician and exercise physiologist who are local to you so they can monitor your condition more carefully.

Just a few ideas,

RATBOY

Except for "Glycogen is the storage form of glucose in animals and humans which is analogous to the starch in plants." Which is true, but an analogy that is only really useful to those people who don't need it.

But a very nice summary, yes!

Again, thanks for all the responses. One of the better BF threads imho.

I think there's one thing I'm missing here though, and can't seem to get what I feel is a "non-waffling" answer from the medical community on is..

The human body utilizes insulin to recharge glycogen stores in tissue. Since a Type 1 doesn't make insulin, and a Type 2 may well make it but the body doesn't properly utilize it, what effect does that have on recovery and/or proper glycogen storage for a diabetic, and what's the best way to track it? Glucose levels in the bloodstream notwithstanding, it isn't necessarily an indicator that it's properly being stored and/or utilized.

One of my major issues is maintaining stamina levels across a longer course. I commute 50 miles a day. Day 1 (Monday) is wonderful, then it gets progressively worse through the week until sometimes I'm just happy to get back on Friday. Very DOMS similar in presentation, but hard to describe. I eat well, my glucose levels are wonderful, and I get decent sleep. I'm more interested in how to track so that I can then go to a DR and say "See!" this is what I'm talking about!

Thanks again..
Roger
.

I'm not a doctor, nor a medical professional - but I play one on these forums and I think I know what's missing here. It's a lack of understanding regarding the complexity of metabolism and the concepts surrounding biological feedback loops.

Much of the processes described, are not regulated discreetly, nor do they operate independently. They are all part of a "mix of competing biochemical instigators and detractors" that often blur any attempt to read a given value of a blood component . There are many proteins and other factors that control or otherwise affect the efficiency of a given metabolic pathway.

When things go wrong, as in disease, a particular drug may treat one aspect of the disease perfectly, but that hardly means that there are not other physiological consequences to the condition.

You'll have to keep experimenting and paying attention to continue your progress. But realize that it isn't quite as easy as "this does that" and eat this and all's well.

What you likely are experiencing is general muscle fatigue rather than nutrition. 50 miles a day is a lot; enough to cause the fiber tissue to tear down some. Instead of giving your body some time to rest and the fibers to repair, you are tearing them down further. By Friday and 250 miles, they just don't have the strength they do on Monday.

You obviously have a big enough endurance base to do that, but I would ride Monday and Tuesday, take a break on Wednesday, and ride Thursday and Friday.

Totally agree that there is general muscle fatigue with that amount of exercise. I did some non-biking exercise on Saturday and Sunday, did my 22 mile commute on Monday, had a tough non-bike workout on Tuesday, and did my commute again on Wednesday. That's five days in a row of exercise. There was no way I was going to make it commuting today, and I am taking tomorrow's commute real slow and having a big lunch to power me up.

Even if I was eating like a horse, I still don't think I could make it more than 5 days in a row with vigorous exercise, I just turned 40 and don't have diabetes. Funny thing about bonking on the commute home is that rarely am I shot in a cardio sense, that is I am not terribly out of breath--I think I get that way from my non-bike interval training. However, my legs get sore and the pouding from the crappy MUP surfaces takes a toll on me.

That sounds familiar... I'm usually fine... My quads hate life though :). And IIRC, you and I are pounding some of the same trails...

Thanks!