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Bonk vs Fatigue(13 posts)

Bonk vs Fatiguekyvdh
Dec 17, 2001 7:11 PM
Anyone know if there is a way to tell the difference between bonking and just plain old fatigue? I was out riding Saturday with my son. I'm riding mountain tires and had on wind pants and baggy windbreaker on a 30 mile ride I've done plenty of times before and by the end I was completely out of steam. I'm riding the MTB tires to get more workout when riding with my son (15 and getting far too strong too quickly). I'm trying to tell if I'm just losing fitness with my cross training and less riding or if I just bonked. I don't usually eat during that ride. I did have gatorade. It seems to be that ever since switching to ATB tires and colder weather (more clothes) I have been struggling a lot more. Does colder air hurt the ability to go as fast or sustain effort? I remember last year when it turned colder my benchmark times got slower but I didn't know why then either. Any thoughts out there?
bonk, fatigue, dehydration...Dog
Dec 17, 2001 7:35 PM
Hmm. Bonk pretty much wipes you out until you get food. Bonk is the depletion of glycogen in your muscles and blood stream (and liver). For me, it starts with muscle ache, and declines to not being able to go 12 mph on flat ground. It usually takes at least a couple of hours for anyone to bonk, but it might happen sooner if you were glycogen depleted to begin. I usually feel sort of depressed, like I never want to bike again, when bonking. That's a real brain thing. Bonking occurs even if you have not been riding hard, not breathing hard, but will occur faster if riding hard, particularly up long hills.

Fatigue is a harder concept. What is fatigue? It could be the damage to muscle cells and nerves caused by activity, along with lactic acid accumulation and effects (acid irritates the muscles), bruising, and bonking, too. Fatigue could also be related to having sore muscles from a prior workout from which you have not recovered (repaired).

Here is how I basically distinguish. If you are breathing hard and just can't go faster, you are fatigued. If you are not breathing hard and can't go faster, it's bonk.

Now, to introduce another variable - dehydration. I'm learning from experience and from my ultra coach that many times we mistake bonk for what is really dehydration. Dehydration will slow you down just as dramatically and certainly as bonking. Many people don't drink enough, some even more so when it's cold out and there isn't as much of an urge to drink. Even in cold weather, try to drink at least a bottle an hour.

How did you feel when the slowing down hit?

"Even in cold weather, try to drink at least a bottle an hour."Ahimsa
Dec 17, 2001 7:48 PM
No problem mate. Cheers!


Must be something wrong with me...D. Breath
Dec 17, 2001 10:27 PM
I have been doing 4 1/2 - 5 hour rides in near freezing temps. spinning a 42x16 with just one bottle of water and a PowerBar.

I find that when I drink more, I have to take a pee break at least twice during the ride, and my discharge is quite clear. I do try to drink (and eat) lots before a long ride and afterwards.
You are fit...allervite
Dec 18, 2001 10:46 PM
The fitter you are the less calories and water you need to go as far as the less fit rider. Your body is running efficiently. You're a stud dude.
re: Bonk vs FatigueScottfBlanchard
Dec 17, 2001 7:36 PM
Fatigue is merely the depleation of muscle energy over a period of time. This could be lack of fitness, over working, anaerobic metabolism or just plain tired. Bonking is a depleation of glycogen stored in the liver and muscles. When you completly exhust your glycogen supplies you are through. The only way to replenish them is through time and sugar (carbs). The key is to replace your stores while you exercise with a carbohydrate substance every 30 -40 min on the bike and immediately following the workout. You have a 1-2 hr window after exercise where your body is capable if replacing almost all of its lost stores. If you wait outside your golden hour it can take up to 24 hrs to have the same level of replacement. Cold weather can also cause the body to consume more calories as can inefficiency and extra weight. Remember, fat burns in a carbohydrate flame, if you have no carbs left, you have a harder time accessing fat stores. Fat stores are a grat source of energy. Once you are out of fuel you are done. Take care of your machine and it will take care of you. If you do not you will have long-term negative consequences.
Bonk, AKA "Hitting the wall"Bernie
Dec 17, 2001 10:16 PM
Someone has already said it. Hitting the wall, the marathon term for bonk, is when your muscles and liver are depleted of glycogen (storage form of glucose). When your muscles and liver are depleted of glycogen, your body has to rely on the metabolization of free fatty acids and protein. Your body does not metabolize fat and protein as effeciently as cabohydrates. When you hit the wall, you cramp up. Everyone has had a hamstring cramp at one time. When hitting the wall, your active muscles experience this type of cramping. When you hit the wall, you can avoid making things worse by resting and taking it easy. I liken my ride after hitting the wall to a car only running on a couple cylinders. My advice is plan ahead, and don't hit the wall. If you hit the wall hard, it can be very uncomfortable. Being out of shape, pushing real hard, poor nutrition, (not eating enough before or during a ride)lack of recovery time or "bartender legs" can lead to hitting wall.
re: Bonk vs FatigueScottfBlanchard
Dec 17, 2001 7:38 PM
You can also check my website for more information.

Scott Blanchard
Bonk vs. Fatigue?....Bonk by knockoutAhimsa
Dec 17, 2001 7:40 PM
Hard to tell really. If you run this route all the time then it might be a "bonk", but in many cases the two are interchanged and "bonk" is overused due to it's hep athletic slang appeal.

I suppose the definition of "bonk" is completely depleting your stores of glycogen with no available carb input to replete it (comments from the experts welcomed).

Fatigue being obviously lack of sleep, lack of conditioning, bad hair day, etc.

No one can say for sure what happenened to you that day. I surely would not stress over it. I ride every day and some days are just difficult for no apparent worries...I just ride harder next time.

ATB tires + more clothes does certainly = more effort

Cold weather and lessened ability? YGMT


Bonk vs. Fatigue?....Bonk by knockoutcyclaholic
Dec 17, 2001 8:09 PM
I bonked once this year on a long century (I had completed a long century the day before) and the feeling was something I'd never experienced before.

It all happened very fast. The first symptom was a severe burning in my legs on small rollers that I would not have normally noticed. Within two miles, I started feeling lightheaded - like I was a little high - and I was conscious that I was not real steady on the bike. I pulled over and ate a couple of granola bars and drank some more, but I was completely wiped from that point on. Thankfully I had only a few miles to go, but it was a real struggle to finish.

I've been fatigued on bike rides and on half-marathons but nothing quite like that. It really was like hitting a wall.
re: Bonk vs Fatiguelongfellow68
Dec 18, 2001 3:56 AM
You'll know if your bonking. Its like your about to pass out, can't turn the cranks over with any power at all and maybe a tingly sensation on the skin. And it all happens suddenly.
I've had it happen to me once during a MTB race and damn, its one of the worst feelings in the world. I could barely walk my bike and finish. You just want to stop completely and rest.
You'll know if you bonk.
my symptomsdzrider
Dec 18, 2001 5:25 AM
With fatigue I feel myself gradually slowing down and I can continue for a very long time if I eat and drink. I call this state the other side of the wall. Mentally I feel a short period of depression and then become resigned to being out there a long time and certain that I can do it.

My first sign of bonking is feeling like I don't want to eat or drink anything. Next my legs stop doing what my mind tells them to do. I become impatient and almost panicky about finishing. If I succeed in getting food - energy gel in particular - down and drink some water the bonk subsides and I get to the other side of the wall by this much more miserable route. If I fail at eating and drinking my legs cramp and I'm done for the day. Luckily this has only happened twice.
my symptomsallervite
Dec 18, 2001 10:50 PM
I bonked so hard once that I could not ride my bike down a slight downhill. I was weaving all over the place and had to stop beside the road and take a nap. When I finally got to food, I had to sip juice slowly. Everything else would come right back up. I came close to this again after finishing a 219 mile ride.