no sweat

Returning to fitness this year after a decade and a half of general sloth.

Reading Friel (CTB) now. Bought a HRM, trying to get a little smarter about this training thing. I have not yet set about trying to work out an actual plan, I'm just collecting data and trying to understand where I'm at and figure out where I want to go next.

At the moment, my unstructured riding is mostly at tempo and I ride about 100 mi a week. Tues. I busted out 90 minutes at an average HR of 145. I estimate my LT at 157. I came home from that ride feeling worked out, wonderful, ready to do it again. I stayed below LT for the entire ride except the last 400' climb where I cranked it up and crested the hill at about 170.

Wed, I did the same ride, held back, took about 10 minutes longer, avg HR 128 (bottom of Z2 per Friel). Managed to stay below 145 for the whole ride (a challenge, given my terrain!). The first half of this ride seemed trivially easy. The second half got increasingly difficult and when I got home, I was really glad to get off the bike. I don't understand this. Doing the same ride slower was ultimately more difficult. Am I imagining things? Was this simply cumulative fatigue? Or is there some different purpose to slower pacing that -- because I have largely ignored it -- is more difficult for me and therefore something I need to work on?

Friel is pretty clear on what he thinks needs to be done in a variety of training-for-racing situations and all of it includes a lot of miles at less than tempo. Friel is clear that he believes that this is essential, so presumably it has a physiological purpose, but he doesn't make clear what the purpose is. Insight?

achoo

What you probably did - since you were at a lower power level - is not stop pedaling as much. The longer continuous effort pushed you harder than what you did in prior rides.

The purposes are:

1. Get in more time on the bike. You can only do so much at z3 or higher - you'll either burn out or get really good at being mediocre if you spend too much time in higher zones.
2. Build endurance.
3. Build aerobic power
4. Increase your body's ability to burn fats instead of glycogen

linnefaulk

You are building a good base.
I think of it as a guitarist doing scales for hours before they can play songs.

CharlyAlfaRomeo

My guess is that you were a bit fatigued from doing that ride two days in a row. From the duration I'd estimate you did 60-80 miles combined between the two days, totalling a high percentage of your regular weekly mileage.

As far as the benefits of Z2 training go I've read in the past of a multitude of adaptations such as higher mitochondrial density, larger stroke volume of the heart (particularly the left ventricle), increased muscular capillary density and a few other things I can't remember off the top of my head.

All of these things add up to your body having a higher aerobic capacity, capable of higher output before going anaerobic.

FWIW I read most of this stuff in books years ago while training for road racing. I'm sure a bit of Googling and a lot of reading will confirm most of it, and possibly debunk some too.

Edit: add increased use of fat stores for energy to the list of benefits.

no sweat

The ride is just short of 25 miles, includes some dirt, pretty good sized hills and I'm on a mtb on dirt road tires.

I did the same again tonight (all in the interest of science, of course, but the fact it's a lovely rural NH ride doesn't hurt)... this time I just rode how I felt, finished in ~90 minutes again with avg HR 146. I think the difference between my hard & easy rides is adrenal hormones (which I like). I'm trying to get in tune with my bod and pay attention to things. Tonight the sprint to the top of a hill about 2/3 through got me about 10 above LT for the first time in the ride and the hormone rush was unmistakeable. Good? Bad? Dunno -- must read and learn more. I do know that after that sprint the rest of the ride got faster.

oespinoza83

You have to go slow before you can go fast.

chasm54

You might find this training peaks article useful.

As you'll see from the table, riding in zone 2 causes most of the neuromuscular adaptations that you get in zones 3 and 4, but - as you would expect - they happen slower. However, you can recover completely from from a Z2 ride in time for the next day's workout. So Z2 rides are extremely helpful for building a big aerobic base, because you are stressing the body sufficiently to promote those adaptations but doing so at a pace that allows you to tolerate high volumes. That's why lots of base training miles done at low intensities, one can build a huge base without getting exhausted - and, of course, once one has the base one recovers better anyway and can cope with more high-intensity work.

I think you've just proved this to yourself. Almost certainly you found the Z2 ride harder because you weren't fully recovered from the tempo ride form the previous day. if you'd done the Z2 ride first, you'd probably have been fairly fresh for the tempo effort on day 2.

From my own experience, spending the time on Z2 endurance work does exactly what Friel predicts and gives one a solid base on which to build.

I have tried the alternative. One year my training was interrupted and I did Carmichael's time crunched training program - which is pretty much all short intense workouts with little endurance work - as a "quick fix" to get me fit for the start of the racing season. It worked in that it got me pretty fast in about 8 weeks, but by the end of ten weeks I was suffering from burn-out and had to back off three weeks or so. I didn't have the aerobic base to allow me tolerate the high-intensity workouts for more than a short period.

Also, look at this sports science article. It appears that world-class runners, as well as cyclists, spend most of their training time at low intensity. They do it because it works - the sports scientists then come along to explain why.