Climbing Muscles? Perhaps
When I began to do long hilly rides, I acquired a nemesis: the Mysterious Pain. This pain would get me even when my legs were strong and my energy levels were high. It would get me when least expected, ruining countless rides and limiting my progress.
I have never experienced anything quite like it before. It wasn't so much of a pain even, as an alarming sensation of seizing, not so much in my lower back as below it. If you draw an imaginary horizontal line perpendicular to the top of the butt crack, the sensation was along that line, in two distinct spots on the left and right, symmetrical.
The first time I experienced it in earnest was during a 100 mile overnight ride to Maine early last summer. It came on around mile 70 and was so debilitating I had to stop on the side of the road and stretch every 10 miles to keep going.
Mystery pains are a source of fascination to cyclists, and I talked about mine with a slew of local riders. At the time the consensus was that I had increased my milage too quickly and hadn't the upper body strength to handle it. So I spent the rest of the summer sticking to sub-100K rides, but doing them with more frequency to build up strength and muscle tone. I am not sure this had any effect. It may have worked subtly, but at the time I felt somewhat stagnant and dispirited. I wanted, very badly, to do longer rides. And I felt strong; my legs would seldom get tired on a bike. But this strange pain/ seizing sensation was like a brick wall I kept hitting: No sooner would I attempt a long ride with lots of climbing, it would return.
This Spring I began riding more than ever. Short rides, long rides, paved rides, dirt rides, club rides, brevets... I thought I was riding a lot before, but now I was practically living on my bike. Disappointingly, the mystery pain was still there - though I'd now learned to manage it with strategically timed stops and stretching. On the 200K brevet, I'd pull over on the side of the road every so many miles so that I could bend over backwards and do some quick twists before continuing. That was all it took to stop the discomfort for the next so many miles, so stopping was better than not stopping: If I did nothing about it and continued riding it would only slow me down.
Having witnessed this riding next to me on the 200K, my friend Pamela suggested that the problem could be insufficiently developed "climbing muscles" - something she herself had experienced at one time. Rather than related to distance, the discomfort could be brought on by long stretches of climbing - which are of course more likely to occur on long distance rides.
There were other suggestions from riding companions at this time: That my gears were too high. That my saddle was too hard. That my position on the bike was too aggressive. And that climbing seated was the real issue.
At that point I decided to take an aggressive approach and try everything. The suggestion that my roadbike position was causing the discomfort worried me, because I otherwise found it so comfortable. But a few strategic rides helped me eliminate that as the cause: I was able to bring about the same pain on more upright bikes (even my Brompton) if I used higher gears when climbing for a prolonged period of time. So gearing had a lot more to do with it than position. I now also knew for certain that the source of the problem wasn't the long distance, but the long, repeated climbs. In Ireland I found that I could bring about the pain within as little as 20 miles, if they were "quality miles" with respect to elevation gain.
In short, the climbing muscles diagnosis seemed the most probable. But how to develop them? I was not willing to go to the gym to work on my "core," and so far just continuing to ride the way I'd been wasn't helping.
Staying in Ireland took care of the problem. Here I did not continue to ride the way I'd been, but, with some guidance, began to do more focused riding - both faster and with more climbing - on a more or less daily basis. I learned how to use gears more efficiently. And I also finally learned how to stand out of the saddle and began practicing that every ride.
One result of all this has been a subtle, but significant transformation to my body within a very short time period. The changes to my legs did not surprise me - after all, that is what we expect from cycling. But I did not expect the changes to my midriff. My abdomen has gone flat and there are these weird thin horizontal muscles wrapping around the sides of my torso, front and back - where the "love handles" used to be, if you will. I have never had muscle definition in this area before, and it all looks and feels absolutely bizarre, as if my body isn't really mine. But existential analyses aside, whatever's happened it has solved the mystery pain problem. No more. It's just gone - regardless of whether I climb standing or seated, in a low gear or high. Just to make sure, this past week I've made it a point to do hilly rides without getting out of the saddle at all, like in the old days (meaning entire months ago). But that seizing sensation below the lower back is now just a memory.
So... climbing muscles. What are they exactly? I imagine some combination of abdominal and lower back muscles. For some they might be naturally well developed. For most they are probably average. And for some, like myself, they could be underdeveloped - requiring lots of work to get up to par. Happily, I love riding and doing this "work." And I love it that this limitation is finally gone.