Questions for Ric, Coggan, 2Lap etc...

dtla said:

This year I did the Transalp Challenge - 8 days of mountain bike stage racing across the Alps. My teammate and I were typically riding for about 4 hours each day, with lots of long (1-2 hour) climbs. After a few days, I was pretty much riding at a 'survival pace' every day. On climbs my heart rate was normally around 145 bpm - considerably lower than my LT heart rate, which is about 165 bpm. Even accounting for a decreased exercise HR from fatigue, my pace was therefore distinctly sub-threshold - much lower than I could maintain for a one-day event on the same kind of courses. Why is this? In day-on-day exercise, what is the physiology behind the fatigue? Is it simply depleted glycogen stores? Obviously if I get fitter my pace at the survival HR of 145 bpm should improve, but I'm wondering if there are things I can do to help access a higher HR when fatigued.

duncan

Ric has been out of town (as have I).
And since he is not available, and others have not chimed in, I'' tell you that there are a lot of possible answers to your question, as you may have guessed. However, aside from your training in preperation for your event, the most promenant issue in avoiding fatigue during stage racing is nutrition. This includes hydration, maintaining blood glucose levels during cycling and repleneshing glycogen stores before and after cycling.
As far as 'accessing' a higher heart rate, such a goal can be a bit dubious. What matters is how much power you are putting out and your perceived exertion at a particular HR (although I don't mean to say that power and RPE are a result of HR, as it is just the opposite). Higher HRs can be achieved in ways that do not increase power. Your extreme sense of fatigue is more telling and possibly due to a lack of glycogen stores.

Smartt/RST said:

Ric has been out of town (as have I).
As far as 'accessing' a higher heart rate, such a goal can be a bit dubious. What matters is how much power you are putting out and your perceived exertion at a particular HR (although I don't mean to say that power and RPE are a result of HR, as it is just the opposite). Higher HRs can be achieved in ways that do not increase power. Your extreme sense of fatigue is more telling and possibly due to a lack of glycogen stores.

Thanks for the answer. I have some more comments/questions in response. Firstly, I wouldn't describe it as "extreme fatigue", more that my speed was capped in some way. It wasn't that I felt weak, and I never hit the wall. (FYI we were in the top 5-10% of teams everyday, so, relatively, we were not slow.) Assuming this was due to glycogen depletion, would it be muscle or liver glycogen? How come my pace didn't get lower and lower everyday (since it would seem logical that the glycogen stores would get lower and lower everyday). How would this be consistent with being able to race fine for eight days straight, but then be extremely tired and fatigued for the next 10 days (when, as far as I know, glycogen repletion takes around 48 hours)?

duncan

dtla said:

Thanks for the answer. I have some more comments/questions in response. Firstly, I wouldn't describe it as "extreme fatigue", more that my speed was capped in some way. It wasn't that I felt weak, and I never hit the wall. (FYI we were in the top 5-10% of teams everyday, so, relatively, we were not slow.) Assuming this was due to glycogen depletion, would it be muscle or liver glycogen? How come my pace didn't get lower and lower everyday (since it would seem logical that the glycogen stores would get lower and lower everyday). How would this be consistent with being able to race fine for eight days straight, but then be extremely tired and fatigued for the next 10 days (when, as far as I know, glycogen repletion takes around 48 hours)?

duncan

Duncan, I can answer a few of your questions, but much of what you are looking for is a matter of long term coaching (i.e.: without knowing you and your training program, it's just impossible to say).
Depleted muscle glycogen dramatically reduces the power output you are able to sustain, whereas depleted liver glycogen would make you hypoglycemic (low blood sugar)...you would bonk, see stars, hardly be able to walk (never mind race!), etc.
Fatigue from glycogen depletion is indeed temporary; yes, muscle stores can be replaced in 12-48hrs with a high carbohydrate diet.
Long term fatigue as you describe is more a matter of systemic fatigue, simply from putting your body through more than it is accustomed to handling without any significant recovery mixed in; this effects/fatigues the central nervous system, your ability to recruit muscle, your hormonal system, your ability to sleep, etc, etc.....
These things do not fall an a specific timeline, as they are very individual and depend on far to many factors to set guidelines for.

Smartt/RST said:

Duncan, I can answer a few of your questions, but much of what you are looking for is a matter of long term coaching (i.e.: without knowing you and your training program, it's just impossible to say).
Depleted muscle glycogen dramatically reduces the power output you are able to sustain, whereas depleted liver glycogen would make you hypoglycemic (low blood sugar)...you would bonk, see stars, hardly be able to walk (never mind race!), etc.
Fatigue from glycogen depletion is indeed temporary; yes, muscle stores can be replaced in 12-48hrs with a high carbohydrate diet.
Long term fatigue as you describe is more a matter of systemic fatigue, simply from putting your body through more than it is accustomed to handling without any significant recovery mixed in; this effects/fatigues the central nervous system, your ability to recruit muscle, your hormonal system, your ability to sleep, etc, etc.....
These things do not fall an a specific timeline, as they are very individual and depend on far to many factors to set guidelines for.

Out of interest, would coaching account for these factors largely by scientifically-validated methods/understanding, or more from testing/general coaching experience?

duncan