CX fitness - apparently it's not the same thing

[s_curran]

I'm right there with you. I've perfected the late race fade.

After spending a good deal of time on the mountain bike this spring, and racing a few times, I found myself pondering just how different I find the mtb race from a cross race. The efforts are not equivalent, or at least they don't feel that way to me. In my very brief and inconsequential experience I've found places to rest or sit in in mtb races, the same cannot be said for cross. The sport races have all been right about at the 2 hour mark too, not very cross-like. I also suspect the level of competition in the local cross scene is higher. Not sure though.

Anyways, my excuse is a lack of base. I go into every cross season with less base than I should. I simply struggle to find the time to put in more than 4-5 hours a week. I'll do more in late summer to prep for cross (and I do use HR to try to hit some specific zones during targeted workouts, though I use it rather obtusely), but I just cannot get my head wrapped around spending the "off season" riding at night when I want to be with my wife, or getting up at 04:30 to ride the trainer.

Was there a point to my post? I'm not sure anymore. Just that I can commiserate.

Well its good to hear I'm not alone. It must be the same thing for me. My goal is 8 hours a week on the bike. But that's just because I really enjoy those weeks. I maybe only hit that goal once a month.

I have found MTB races the same, except short track. Short track I would say is really close (same length effort, same amount of laps, atleast for the after work series I have been doing). Also I was trying to chase down Paul Curley and crew, so that might have been part of it.

[BSUdude]

I hope some others chime in since there is a lot knowledge out there on this forum, but this makes sense to me.

***disclaimer this is not mine, just transposing what I gathered from this video: but it aligns with my training experience, and explains things in a helpful logical way.

Basically all efforts considered, raise your FTP, especially at this point in the season relative to the start of CX. To use the same example as the video, raising FTP lets you "drain the battery" slower...so everytime you go above FTP, which obviously happens a lot in a cross race, you deplete an energy source that largely can't be replenished during that race. So if you raise your FTP, when you have to accelerate out of corners, start the race, etc it drains your battery more slowly which in should give you more of that all-important above threshold energy source further into the race.

Example: say there's a straightaway in a course that you burn at 400 watts for 20s. If your FTP is 250w, @ 400w you are 150w over for 20s. If your FTP is 275w, @ 400w you are now only 125w over for 20s. So you leave a little bit more energy in the tank every time through there, leaving you more energy that should last later into the race.

Obviously there a lot of factors that go into this, but largely raising FTP, especially at this point in the year relative to CX season is not gonna do you wrong.

[Octave]

BSUdude is spot on here -

think of your total fitness like a hybrid car (stick with me, I swear..): when you're cruising around in your "endurance" or "tempo" zones, you're running off of an easily rechargeable energy source like a battery. It can recharge while you ride/drive, you can replenish it with a few calories here and there and you're not going to exhaust it in a single ride/drive. But when you want to hit the highway on-ramp and you need to go from 20-80mph in a quick burst you have to engage that bigger engine, which is going to dip into your gas tank. Your gas tank (in power terms, your W') is a much more limited resource and cannot be replenished while you drive. Every time that you dip into your gas tank you're tapping a limited resource. And especially during a race, you've gotta tap it a few times and still have gas left when you get to that finishing straight.

So, if you make your battery-powered engine more powerful (raise your FTP) then those hard efforts won't dip so hard into your gas tank (or rather, the efforts that DO dip into your gas tank start at a much higher level).


Your VO2Max is very hard to make substantial gains on - in a very real way, you get what you get. You can make it budge, but it's largely what you've got and it's not going anywhere in a big way. Your FTP however can be manipulated hugely, and that's where the focus should be.

But at the same time, excessive time in Zone 3 converts a lot of those sprinting and high-end muscle fibers into more endurance-oriented fibers. It's a trade-off, so don't overtrain the low-end stuff because on a muscular level it is detraining the higher-end fibers.

[s_curran]

BSUdude and Octave, great stuff. Now heres my question, raising FTP/CM. I tried to read up on it, seems a lot like different types of intervals, longer ones especially, riding either just below or above threshold depending on the day. Everything is in reference to watts and measured things though. Is there a a simpler way to talk about this, more like general ideas? Can I figure out the general area of my FTP is with HR data?

[Daschund]

Raising FTP to me is riding in z3 3x15min, 2x20min or something similar depending on whatever excuse I have. Sometimes I do it with HR monitor, sometimes without it. I try to feel the effort in my legs and keep it as it is rather than looking monitor constantly. It might not be very accurate, but afterwards I know (from feeling and by looking at HR avg.'s) that I have been going quite hard for 3x15min, the last 15min being the hardest one. This might be a totally screwed way to do this, but I keep telling myself I need to know how it feels rather than monitor telling me how my body is feeling. To mix this a bit more, I do these exercises with cross bike in the woods.

[Octave]

BSUdude and Octave, great stuff. Now heres my question, raising FTP/CM. I tried to read up on it, seems a lot like different types of intervals, longer ones especially, riding either just below or above threshold depending on the day. Everything is in reference to watts and measured things though. Is there a a simpler way to talk about this, more like general ideas? Can I figure out the general area of my FTP is with HR data?

No, you cannot figure out FTP using HR data - you can find where the two overlap or correlate, but one cannot be found using the other.

If you want to raise your FTP using HR data, there are a few ways to do it - you could try sweet-spot (SS) intervals of 15-20 minutes just below your lactate threshold. For your HR that's the very high end of Z3. You could also do shorter intervals at Z4. The point is sustained efforts sitting right round your lactate threshold.

Raising FTP to me is riding in z3 3x15min, 2x20min or something similar depending on whatever excuse I have. Sometimes I do it with HR monitor, sometimes without it. I try to feel the effort in my legs and keep it as it is rather than looking monitor constantly. It might not be very accurate, but afterwards I know (from feeling and by looking at HR avg.'s) that I have been going quite hard for 3x15min, the last 15min being the hardest one. This might be a totally screwed way to do this, but I keep telling myself I need to know how it feels rather than monitor telling me how my body is feeling. To mix this a bit more, I do these exercises with cross bike in the woods.

Most people, including myself, find that the monitor helps a lot to find what these zones feel like and to keep it honest, but in the end everything will be done by feel. I do plenty of intervals in a structured manner but rarely spend the entirety looking at a monitor. During a 15 minute interval I probably peek at the screen every 7-8 minutes.

[BSUdude]

BSUdude and Octave, great stuff. Now heres my question, raising FTP/CM. I tried to read up on it, seems a lot like different types of intervals, longer ones especially, riding either just below or above threshold depending on the day. Everything is in reference to watts and measured things though. Is there a a simpler way to talk about this, more like general ideas? Can I figure out the general area of my FTP is with HR data?

For FTP work 10, 15, & 20 minute intervals are bread and butter w/ rest time between each of approximately 1/3 of the length of the interval. Conceivably you should be able to do this type of work using HR. But you still have to establish your threshold HR to get the zones. However unlike power your HR zones won't change much as you get more fit, so you shouldn't have to retest every 6 weeks or so. HR will vary a bit day to day based on how rested your body is and the weather, but if you've been training with HR for awhile you've probably learned this.

More general terms? As I believe DOOFUS said 2 hard days a week and as many endurance hours as you can manage.

[twowheels]

You've also got to feel comfortable riding cross so you need to corner efficiently, mount and dismount smoothly, deal with the bumps efficiently, without wasting energy locking up your upper body, braking too hard, etc. And you need to acclimate your body to intense efforts and quick recovery. Do you ride mountain bikes? On the velodrome?

[Britishbane]

I very much appreciate the responses, as someone who has no clue this is a place to start.

[bcroslin]

I've always approached CX training like how you'd prepare for doing a time trial. You're essentially red lining right from the start and then having to suffer through the next 45-60 mins. You have to practice going out hard but not blowing yourself up. It's not easy and I have unfortunately suffered from the fade in the last lap or two of a race. Practicing 30 min hot laps usually helps you find your comfort level. A strategy that has worked well for me is to allow someone else to lead and you hold their wheel but you have to have great bike handling skills because if you make a mistake you're liable to have to kill yourself to get back on. Whatever you do, don't go chasing the guy who takes the hole-shot and then proceeds to disappear up the road because in Cat 4/5 I almost guarantee you're going to see him again as you pass him unless he's the local phenom and then you're not going to be able to hang any how. Always remember to ride your own race and you'll be fine.

[Britishbane]

I've always approached CX training like how you'd prepare for doing a time trial. You're essentially red lining right from the start and then having to suffer through the next 45-60 mins. You have to practice going out hard but not blowing yourself up. It's not easy and I have unfortunately suffered from the fade in the last lap or two of a race. Practicing 30 min hot laps usually helps you find your comfort level. A strategy that has worked well for me is to allow someone else to lead and you hold their wheel but you have to have great bike handling skills because if you make a mistake you're liable to have to kill yourself to get back on. Whatever you do, don't go chasing the guy who takes the hole-shot and then proceeds to disappear up the road because in Cat 4/5 I almost guarantee you're going to see him again as you pass him unless he's the local phenom and then you're not going to be able to hang any how. Always remember to ride your own race and you'll be fine.

I hear what you are saying with regards to duration. But the effort, at least to me seems totally different. You'd never TT where you coasted for 3 seconds every 39 seconds.

Edit: on the phone exude the errors. You get the pount

[s_curran]

Lesson learned last week. Don't try to race a 1:40min XC mtb race like a cross race. You will explode. On a more positive note, the Short Track race I did the day before was 40 minutes and I felt and did really well. I monitored my HR during the XC race, mostly as a learning experience. I averaged Lap 1 182, lap 2 184, and lap 3 186. (EDIT: note, it was 94 degrees during the race, I was dehydrated at the end). I hit a max of 199 on that last lap, this is the highest I have seen so I set it as my max, although maybe I'll see if it would go higher over 30 minutes. So, this seems to be the best heart rate data I have. So I should assume my threshold is somewhere around that range? Or is MTB racing just too different to really use this. According to what I thought my HR zones are, I spent 1:35 in zone 4. Does this really make any sense?

I just found a good place to do a little mini practice cross course, my thought is that I'll go out and start doing 10 minute intervals around it. and slowly work them into longer ones. I'm also trying to help my girlfriend train, so I think this will work for both of us.

[Octave]

According to what I thought my HR zones are, I spent 1:35 in zone 4. Does this really make any sense?

Nope. How did you determine your HR zones? Did you do this with a power-test? Theoretically you should have failed well before 1:35 if you were really holding steady in Z4.

[s_curran]

Nope. How did you determine your HR zones? Did you do this with a power-test? Theoretically you should have failed well before 1:35 if you were really holding steady in Z4.

Figured, I just did my zones off of my max and my resting. My max could be higher and I just haven't hit it yet. I'm honestly not looking to get super in depth with this, but I do like having an idea of what I'm doing.

I'm not going to lie though, it sure felt like I "failed". That was a level of exhaustion I have never felt.

[BSUdude]

My 20 min HR is about 188, depending on the day and temps.

I've done 3 XC mtb races this year:

1:32, 183HR
2:00, 177HR (cool day)
1:50, 182HR

In each of those events my highest 20min HR during the race was at or within a couple beats of 188. So using your best 20min from that race would probably be a better approximation, although your best 20min from the short track race might be even better since you theoretically would've been going harder.

Interesting that your HR got higher as the event went on. Were you consciously pacing/holding back at the beginning of the race? Without fail during mtb and CX races my highest HRs come in the first 1/3 of the event, but HR is highly individual..

[Britishbane]

For FTP work 10, 15, & 20 minute intervals are bread and butter w/ rest time between each of approximately 1/3 of the length of the interval. Conceivably you should be able to do this type of work using HR. But you still have to establish your threshold HR to get the zones. However unlike power your HR zones won't change much as you get more fit, so you shouldn't have to retest every 6 weeks or so. HR will vary a bit day to day based on how rested your body is and the weather, but if you've been training with HR for awhile you've probably learned this.

More general terms? As I believe DOOFUS said 2 hard days a week and as many endurance hours as you can manage.

So, is it reasonable that one day a week a person could do FTP work as described above, and another day high intensity intervals? If not, how and when do you integrate that into CX prep?

[hmai18]

Perhaps you'll find this useful? Cyclocross is Coming: Adam Myerson Lays Out the Ideal Training Week - Cyclocross Magazine - Cyclocross News, Races, Bikes, Photos, Videos

[BSUdude]

So, is it reasonable that one day a week a person could do FTP work as described above, and another day high intensity intervals? If not, how and when do you integrate that into CX prep?

As the CX season approaches the FTP work can start to take a back seat. 2-4 weeks out from your first race is the time to cut back to 1 day of FTP a week, then another day of CX specific (read: short and hard) intervals ...and then 1-2 of your endurance days become skills days.

[s_curran]

Just re-read the thread to figure out what i'm doing again. This year so far is interesting, I'm about 1000 miles/100 hours ahead of my pace from last year, but a lot of that was Z1-2 touring with my fiance. When I got back, the first weekend I did an MTB race, my body was not ready, I went out following the leaders (that I should be able to ride with), but was at my max. I dropped off, but then 10 min. later was good to go, and I felt better and better all the way through the 2 hour race, and most importantly had a lot of matches to burn. That said, my threshold felt really low, but my base felt good.

I've been working on raising my intensity, just started doing loose z4 10 min intervals, figure I'll work that up to 3x20's by the time race season comes around, plus as things get closer (maybe a month to go?) start to integrate 10-30 second intervals. Does this make sense? should I start doing the longer intervals earlier?

[BSUdude]

Your approach sounds solid to me. Starting with a few 10 minute intervals to get the body back into to that mode of FTP work is smart. Then once you get used to being tight in that zone, increase the interval count or length. If you are having issue with the 10 minutes at Z4 right out of the gate, you can do a starter workout where it is something like 2 rounds of 3 minutes Z3/2 minutes Z4 for 20 minutes. But if you can handle the 10 minutes Z4 straight right away then go with that. We are halfway through July so there's not a ton of time to burn yourself out on FTP before the season starts.