Metabolic Acidosis (aka Bonking) on the Colorado Trail and Elsewhere

Mountain biking in Colorado
Mountain biking in the Tarryall Mountains

Ryan had never bonked before, at least in the metabolic shock overexertion sense of the word. When he started to bumble around and kept losing more and more of his edge, I knew that something was up and figured that’s what had happened. Not really realizing what was going on, he kept on trying to mountain bike further up the Colorado Trail, although with diminishing returns. The big patches of snow that still littered the trail, even though it was June, were probably a good thing since they ultimately turned us all around. His disrupted mental and physical state likely made the retreat more palatable to the 13-year-old, since he wasn’t one to be prone to turn around before his goal was reached, regardless of whatever difficulty he faced.

I’m sure that there’s some sort of scientific or medical description for just what bonking is, although I never really studied it from a medical standpoint. But, I had experienced it first-hand more than once by the time that Ryan was trying to figure out why his heart was beating so fast, and his legs felt like Jello, and so had my suspicions that it might be just that.

The symptoms—weakness, fast heart rate, and disorientation are a bit scary. Thankfully, bonking often rectifies itself eventually, assuming that whatever physical activity caused it in the first place is curtailed. And, it is ultimately less troubling than some other maladies with similar symptoms. But to rush to the bonking conclusion too quickly (and perhaps wrongly) can be dangerous and is not a thing I ever wanted to do. Seeing someone unable to do the physical tasks that they usually had no problem with, is disconcerting. But since I’d been in that state myself previously, as I listened to and observed his actions and saw how they almost perfectly mimicked what I remembered of my own experiences, I soon started to be able to predict what he was going to do next.

The fact that by the time he reached full bonk we were several miles from the trailhead was not ideal. But since it was downhill almost all the way back to the van, the stretch of trail that we were on was not particularly tricky, and the fact that I was carrying a lot of extra food (a treatment factor for bonking), I was optimistic about our situation. Besides, there weren’t a lot of options, other than going back, which was just what we were doing, anyway.

Soon after we turned around, I stopped the group for a bit, and we had a rest and some snacks. I got Ryan to eat all of the food that he had left and also noted that he’d consumed all of water in one bottle and about half of another up to that point. Good thing, I concluded, that he had at least stayed well hydrated and more than likely had plenty of water for the rest of the return.

Ultimately, we made it back to the trailhead, Ryan ate a bunch more food, and fully recovered within hours. He’d been introduced to one of the pitfalls of not fueling up enough during significant physical exertion at altitude and likely learned the lesson well.

I, on the other hand, had the same thing take place three times through the years and was thus apparently slower at learning the same lesson. The first time it occurred was mostly because of my ignorance regarding what could happen to a body without proper fuel intake. I’m not sure what my thinking was leading up to the second event, but for whatever reason, it just happened. And that takes us to the third time.

Several years after the Ryan event and even several more after my own first two, it happened to me again. As the symptoms began to develop, I brushed them off as just some sort of manifestation of weakness or lack of physical training. It occurred during a long mountain bike group ride in the Colorado mountains, which I’d actually done several times previously. I was careful to snack along the way and had a solid idea regarding the route and how it would likely all play out.

The length of the ride was 5 or 6 hours. While I typically didn’t tend to drink a lot of water while out riding, in this particular case, during the first part of the ride, I did. And by doing so, I stayed well hydrated, at least for a time. Even though the ride was long, I didn’t carry a lot of extra water with me since I knew that there was a Forest Service campground about two-thirds of the way along the route where I could refill.

The group was made up of strong riders, and the pace was consistently fast. By keeping myself well fueled and hydrated, I’d felt strong and been in the middle of the group throughout the first portion of the ride. About midway through the whole anticipated event and as we began riding the final stretch up to the campground, I polished off the last of my water. As I drank the last drop, I confidently started anticipating the long drink that I was going to take at the campground hand pump while I refilled my bottle. I’d gotten water out of the pump several times during the previous summer and was pleased with myself for coming up with a plan to reduce the load I was carrying because I would only need to carry one bottle that I would refill along the way.

I was feeling strong and was in high spirits as we rode into the Lost Park Campground until I looked at the concrete slab where the hand pump was supposed to be and saw that it’d been removed for the winter. I was speechless as I tried to think of somewhere else way out there in the middle of nowhere that had drinking water. When I came to the realization that there were no immediate options other than the untreated creek water trickling along nearby, I decided that I would just go the rest of the way with the zilch that I had and would just be thirsty.

We didn’t even bother to stop at the slab as we rode on toward the saddle between Topaz Mountain and North Tarryall Peak. I felt a bit sad and sickened as we passed the place where the water had once been, but within only minutes became focused on the climb at hand.

It didn’t take long after we passed the barren slab before I began to feel a bit less strong, but I ignored what my body was trying to tell me. About 15 minutes past the campground, the climb began. It wasn’t particularly steep, but it was a grind. I’d done it effortlessly several times before and had sometimes even had to wait for others to catch up at the gate near the top, so was figuring that it would be easy enough, this time around.

As the uphill began, I downshifted several times into successively easier gear combinations for climbing. As the pedaling continued to get more difficult, my first thought was that I was just in too big or “hard” of gear and needed to be in an easier one.

But alas, I eventually got down to my easiest one and was hardly going anywhere. By this time, I was struggling to stay upright given my slow forward movement, although in my mind I was riding along at normal cruising speed. Just how slow I was actually going dawned on me when the people that’d been riding behind me began to breeze past and looking as if they were on a leisurely ride in the park. Suddenly, it became difficult for me to push the pedals for more than a few seconds at a stretch. My mind was telling me that it wasn’t all that steep, but my high heart rate and leg weakness were each saying something else. Within minutes I was bringing up the rear and falling further behind all of the time.

By this point, still almost a half mile below the top of the pass, I realized that I’d bonked and that it was probably due to a lack of water and hydration. Right then, had there been any sort of water in a creek, rut on the ground, or elsewhere nearby, I would have gladly drunk it. But there wasn’t, and so that wasn’t even an option. While that fact didn’t help the bonk situation, it more than likely saved me from other, potentially compounding intestinal ones.

Up to this point, I’d just been riding with the group, but suddenly a sort of “group dynamic” pressure developed in my own mind as I realized that the other riders would likely be waiting for me up ahead at the gate. What was usually a leisurely fifteen-minute ride up the trail from there, now almost seemed like an impossibility.

And so, I rode, moving several feet forward every minute or so. Somehow, I did manage to continue to stay upright, even though I was riding at the ridiculously slow pace. It was all a blur.

Finally, the trail emptied me out into an open and previously logged area, and I could see the group waiting for me up at the far end of the clearing and the gate. It was only a hundred yards or so ahead, and I ridiculously attempted to look normal as I rode the last bit toward them, although I don’t imagine that there was doubt in anyone’s mind that things were not going all that well for me.

Eventually, I did reach them. The thing that riders sometimes do in such a situation is to declare that there was a “mechanical” that set you back. But, I couldn’t even figure all of that out and just said that I was feeling a bit off, but getting better. There were various offers of food and water, but I turned them all down, saying, and lying, that I had plenty.

I knew that the top of the pass was not far above the gate. I reasoned that once I got up to that point, it would be smooth sailing from there back to my Tarryall mountain Base Camp since it was mostly downhill. The ride from the gate on up to the top was not as pleasant as I outwardly tried to make it seem, but within 15 minutes we were all cresting the pass, and the downhill began.

It was a fast and painless descent for the others, but a slow and deliberate one for me as I rode at the back. While my speed (or lack of it) made the riding part reasonably doable, it also took me out of the route finding aspect. That typically wouldn’t have been a problem, except that in this case the trail we were following was somewhat vague as it entered the thick forest at the bottom of the first downhill section and I was the only one in the group who had any clue about where it actually went.

My friend Tom was at the front. Besides worrying with the fundamental issues associated with riding a bike in general, I was becoming concerned about how I was going to have to lead the group along the final part of the trail when I saw Tom reach the bottom of that first section and go the wrong way.

When he made the wrong turn, I immediately sped up and began yelling for everyone to stop. All of them did, except for him, since he was too far gone. Realizing that I needed to catch him, an adrenaline rush sped me up, and I somehow passed the stopped riders without crashing, telling them to cross the creek straight ahead, and then work their way from on back to the camp from there. I also yelled that I would go get Tom, we’d ride back down to the main road on our own, and then once they got back for one of them to drive down the road and pick us up. And so, they rode off in one direction as I continued in another.

I kept on going and finally did reach Tom at another creek crossing. We went on across and then the two of us began riding down a two-track road that we assumed would painlessly take us on down to the main road. We planned to get down there and then just wait for the others to pick us up and shuttle us back to the camp. It seemed simple enough, assuming that the road did what we thought it would do. But alas, it didn’t.

Riding the two-track road was pleasant, for a time, as it continued descending toward the paved county road, some three miles off in the distance. I was thankful for the smooth and easy riding as we quickly covered two or so of those miles. All was good, and I was confident that I could at least keep coasting and rolling downward until we came to a surprise uphill.

I was a bit disheartened to see and feel the road do what it did but assumed the uphill would be short, and so “attacked” the climb. My legs felt strong for the first couple of seconds, but the other five minutes that it took to get to the top were painful as my muscle-memory quickly remembered what’d been going on with my body less than an hour before. I would’ve cried, but I didn’t have enough fluid in my tear ducts to do so.

After a while, we did get to the summit of what I hoped was the final hill and we could see the main road off in the distance and down below. By this time, reaching the Tarryall Road had become my sole mission in life. I just wanted to get down to it and hoped that once there, one of the others would actually show up to drive me back. Worst case I figured, if that didn’t happen, I was confident that Tom would ride on back to the camp and then drive back in a vehicle to pick me up.

Whatever the case, I knew that I didn’t have the fuel in my system to ride all the way back to the lodge and completely disregarded that as even being an option. We finally did make it down to the pavement, and after only a short wait, one of the other riders showed up in his car to take me back to the lodge. Interestingly, I just stuck my bike behind a bush somewhat out of sight of the road and crawled into the passenger seat of the car. I planned to return and retrieve it later that day, although at the time I didn’t really focus on or even care about whether or not it was safe where I left it.

Once back at the camp lodge and after drinking three bottles of water, I began to regain my senses. Once mostly coherent, I began to wonder how the others had ever found their way back to the lodge on their own, and then almost immediately started worrying about my bike. After an hour of small talk and good-byes, everyone left, and I quickly drove off to get my bike. Thankfully it was still there. So, I didn’t lose much during the ordeal other than several pounds of water weight. And, as a bonus, I’d finally learned a good lesson about staying hydrated, the pitfalls of assuming things, and the benefits that come from being well prepared.

Vail Race 012
Riding Downhill

Author: David Appleton

I was born and raised in Texas and currently live in the Texas Hill Country, spent some 30 years living in the smack dab middle of Colorado, and have spent a lifetime adventuring and leading others on adventures in many parts of the wild world.