More Data-mongering: Long Rides, Cycing Cadence and Nutrition

Yep, that's the course profile, and yep,
we have to do that mountain twice

On Friday, I did my third five-hour CompuTrainer ride in preparation for Ironman St. George (IMSG). This time, four hours of it were using the IMSG Real Course Video - my third time through the full 67.4 mile course. I expected to once again see improvement in my power output and heart rate for the IMSG course, but that wasn't what actually happened. Instead, I gained a completely new set of data. And I had to figure out how it fit into the grand scheme of things that is my Ironman training.

The last time I rode the IMSG course, my average power increased while my average heart rate decreased - a good indication that my hard work on the bike was paying off. But two data points don't make a trend, so of course, I had to follow it up with another data set. Unfortunately, the third data set - Friday's ride - did not continue the trend. But it DID give me some new information to work with.

I don't like to make excuses for why this long ride wasn't better than the last because we all have off days. What I will say is that the night before my long ride included two- and one-minute repeats at anaerobic power levels. To date, it was the hardest (read: most painful and muscle-fatiguing) workout I have done on the bike, and I spent most of it out of the saddle to stop my quads from screaming. (Seriously, I hate myself for saying this, but if I were on a hill, I would have got off and walked.) Less than 24 hours later, I was back on the bike for my five-hour ride.

And, surprisingly, my legs didn't feel massively fatigued when I started. I kept an eye on my power and heart rate during the ride, but to avoid getting psyched out from the upcoming hills, I spent the rest of the time watching food shows on the Travel Channel. It's a strange choice of programming, I know, but I actually enjoy watching Man v. Food while I'm on the trainer because nothing makes me want to ride harder than watching Adam Richman destroy his body. It also helps that I don't eat meat so it doesn't make me hungry (unless, like one of the episodes this time, he eats blueberry pancakes - grrr! and he was in Hawaii while doing it!).

By the time my ride was over, to my dismay, the important variables had gone in the wrong direction:

• average heart rate increased by 4% over my last ride on this course: 143 compared to 137
• average power decreased by almost 2%: 160 compared to 163

Poor performance numbers were accompanied by change in another variable to which I've not paid much attention: cadence. The reason I've not paid much attention to it is because it changes very little during my long rides - it always hovers around 95-97 RPM. On THIS ride, it changed. A LOT - my cadence value remained over 100 and sometimes went as high as 110 for the duration of my ride (except on the climbs). By the end, there it was, an average cadence value of 101 - a major increase over my last three rides (see chart below).

Cadence per mile on the IMSG course
(Green line is most recent ride)

Why, all of a sudden, was I spinning at a much higher RPM? Was I in a hurry? And of what importance is cadence? Is there an optimal value? What cadence SHOULD I be riding at? (Face it people, I've never claimed to be a cycling expert.) I went to Google and found these:

• an article on Beginner Triathlete from Rich Strauss  describing the "match analogy" from Cycling Peaks
• an article on TriFuel from Ken Mierke explaining Lance Armstrong's extremely high cadence and that it's not necessarily the way everyone should ride
• an article from Joe Friel about whether triathletes' cycling cadence has payoffs on the run: The Effect of Cycling Cadence on Running in Triathlon

So, yes, I learned that cadence is important (duh!). And to get back to analyzing my training ride, I think that not being rested and tearing up my quads the night before might explain some of what happened. My quads were more comfortable in a state of fast spinning and my body naturally drifted to that state. Higher cadence kept my speed up while my power was down and caused my heart rate to go up (apparently, something I can handle for five hours).

But here comes the real learning experience. I noticed one more effect during this ride - and this is perhaps the most important thing given my history of nutrition disasters. I fueled the way I've been practicing: about 250 calories per hour with First Endurance's EFS liquid shot and drink and SportQuest Direct's CarboPro. I also took one Thermolyte electrolyte capsule (330 mg sodium) and drank about 20 ounces water per hour. Unlike my previous rides, by the time I reached four hours, I was having trouble taking in more carbos and my stomach was distressed, as if nothing were digesting. I was sweating much more than usual and by the end, my knees had become miniature salt mines.

Thus, assuming my digestive problems had nothing to do with what I was watching on TV, I am relatively sure now that in addition to not getting enough sodium, my nutrition problems are directly linked to my heart rate. So I'm defining a new heart rate zone. I'm calling it the "digestive zone." And it seems to be somewhere below 143. If I keep my heart rate in the 130s or lower during the Ironman bike, I will likely be able to fuel without difficulty.

Well, that's my take on it anyway.

Finally, this winter in Cleveland has been very harsh, especially on the weekends. And with nine weeks to go, hopefully my next long ride will be more than five hours and outdoors.