Saturday, October 25, 2008

The Most Common Ironman Mistake

In Kona this year I met an age-group athlete the day before the race. Nice guy. After the race he wrote me with a question about his race. He also sent me his WKO+ power-data file. You can see it below. What I saw is typical of most Ironman athletes. It’s easy to fix but requires dedication as it isn’t what you want to do in a race. The other chart you see farther down is explained in my answer.

Question: I have been training with power (bike) and GPS (run) throughout this year and have felt as though I had nailed my plan down. On my bike, I did a bunch of rides 4:30-6:00 and was able to maintain 200-220 watts (I usually don’t use normalized power because I can’t see it on my computer). Also, my critical power is around 290. I use the 20 minute all out and the 3 minute all out to calculate this. I had registered for Ironman Florida as well so I really didn’t want to push too hard and have nothing left. I figured I would stay around 200-210-ish to be safe. Coming out of the swim and going to the bike my legs felt pretty tired. I was able to keep the watts up in the beginning but it really felt like I was pushing a lot harder than what my watts were showing. By mile 40 I started cramping in my VMO on both legs. This went on for the next several miles and got worse. At this point all goals went out the window and it was a race of survival at that point. My average power was 169 and normalized power was 179 (which is the lowest long ride I have done in months). I was hoping to finish the bike in 5:30 but only managed 5:57...which I was actually happy with considering the conditions of the race and my body. I felt good from a nutrition standpoint. I think I was a little dehydrated but not by much (i urinated before the bike and 2x on the bike and none on the run). Of course, the bike killed my run as well. I was hoping for a 3:45 run (which I have done before). In my previous ironman races I have been sore for the whole week. Two days after the race I was stiff but not bad and think it may have been due to my flight home more than the race. Four days out I felt great.
I was totally baffled by this result and wondered am I asking too much out of myself? Could the conditions of heat and wind have that much of an effect on my performance or am I missing something here?

Answer: It’s always a bit difficult to draw conclusions from just one piece of data even if it is over nearly 6 hours. Having heart rate in addition to power would have been good to see what you were experiencing effort-wise and to get some idea of what the heat was doing to you, also. I would like have seen how much cardiac drift/decoupling was going on. That can be found on the “graph” view of WKO+ where it says “Pw:HR.” But I’m fairly confident I see the cause of your demise on the bike. It has to do with variability index. I see this a lot and spend months teaching the athletes I train how to control it by working on pacing while staying very focused on power in training and races.

Variability index (VI) is normalized power divided by average power. The resulting ratio should be less 1.05 I’ve found in long course racing. Your average VI for the entire race was 1.08. Much too high. Looking at it by quarters reveals even more. That’s what the chart attached shows. In Q1 VI was 1.08, Q2 it was 1.07 and in Q3 climbing to Hawi and descending it was 1.11. For 84 miles of the race you were averaging 1.09 for VI. It didn’t drop back down into the goal range of less than 1.05 until the final quarter when fatigue set in and forced you to ride steady.

What these VI numbers tell me is that you were surging a lot—in and out of corners in town, into head wind, up and down small hills, when someone passed you or you passed others, etc. Surges sap you of energy very quickly and also play havoc with your gut’s processing of fluid and fuels. Steady state pacing is a far better use of your energy. I expect your long rides did not have nearly this high of a VI. They, just like your race, should have a VI less than 1.05. Until you can do that it is unlikely that you will ever produce your best possible long course ride.

Also attached is a chart from an athlete I used to coach who was the best I’ve ever worked with for low VI scores. Here he does 112 miles in training in 4:44 with a VI of 1.01. He raced exactly the same as he trained. There was never any question that he would have a good IM ride. This is exactly what you need to work on doing also. Make your rides exactly like what you expect to do in the race – as much as possible. Terrain and weather may confound the preparation a little but you need to decide how to handle those also relative to your power. Once you learn to ride this same way you’ll have good races without issues, at least not on the bike.

You mentioned that you didn’t see any way to ride normalized power in the race. Actually, you can. If you ride at a steady power output of VI less than 1.05 the average power on your device will be almost the same as normalized power. In fact, what you should do is to set a race power goal based on the NP from your long rides in the last several weeks before the race. So if you determine that an appropriate NP is, say, 200w then you just ride steadily trying to average 200w. At less than 5% VI your range would wind up being +/- 10w or less. But realize that the goal number you come up with must be based on actual training data, not what you think you are capable of. That’s a whole other discussion.


At October 25, 2008 7:52 PM , Blogger Dinger said...

Joe, how do you copy graphs out of WKO+ and embed them in your blogger posts? I've given up trying to figure it out.

At October 26, 2008 9:05 AM , Blogger Joe Friel said...

Hi Dinger--Go to and check out Snagit. A great tool. I use it daily.

At October 26, 2008 3:27 PM , Blogger Dinger said...

Thanks Joe, I'll check it out.

One more question. When you have your athletes manually logging swim workouts into WKO+, do you have them estimate TSS and Intensity Factor, or do you just have them leave those fields blank?

If you are having them estimate, what sort of guidelines do you give them in terms of setting a scale? The subjectivity of an estimate scares me, but it is better than nothing.

I'd be very interested to see how my CTL line changes if I could incorporate my swim workouts.

I love the WKO+ tool. Thanks...

At October 26, 2008 4:33 PM , Anonymous Anonymous said...

I'm not sure I agree with your post in a couple of areas

First, if we buy in to the Normalized power construct and equation, a VI of 1.09 means that normalized power and estimated metabolic cost is 9% more than the average power... if the athlete had done multiple rides at the target average wattage, it seems unlikely that a normalized wattage of only 9% higher would cause meltdown after just 40miles... particularly as presumably the previous rides have been done a VI of greater than 1, so the real increment over what we know is achieveable would be lower.

Second, I think your maths is off. Keeping within +/- 10W of target wattage would result in a VI of pretty much close to 1 (and btw would be sub-optimal on anything other than a pancake flat course). You could actually spend 50% of your time at target wattage +20% and 50% at target wattge -20% and get a VI of 1.05.


At October 27, 2008 3:54 AM , Blogger Bahzob said...

One of the nice features of the Ergomo head unit is(was) that it displays normalised power, TSS and intensity factor along with average power. Great for long ride pacing and training.

Shame its gone bust.

Know the Powertap hasnt got these features, do any of the others?

At October 27, 2008 4:11 AM , Blogger Bahzob said...

Very interesting.

I wonder if you have similar view on VI for a cycling sportive like the Etape. Think it will be greater on these due to high power up long climbs followed by long descents at close to zero. I find my VI is around 1.18 on these. By coincidence this is exactly the same as Adam Hansens on stage 17 of tour this year (when he was aiming just to finish within time so guess he was riding conservatively).

At October 27, 2008 6:42 AM , Blogger Joe Friel said...

Dinger--The athletes I coach almost always enter data by uploading it from a device. Rarely do they do it manually. On those rare occasions when they do I have use a 30-100 scale to estimate _average_ TSS per hour. 30 is as easy as possible; 100 is as hard as possible. Then they multiply the estimate by the duration of the workout in hours and record that workout TSS. No need to estimate IF as TSS is based on IF.

I don't put much value in a combined, 2- or 3-sport CTL. But I do in a combined ATL.

At October 27, 2008 7:11 AM , Blogger Joe Friel said...

Wilf--I've viewed scores of such files for athletes who had long course bike rides worse than they thought they were capable of based on their training. Each of them had a VI greater than 1.05. Most were close to 1.1. Constantly accelerating requires more energy to average a given power than riding that power steady state. If you check the power files for these same riders you'll find their long training rides had a low VI. Now had they trained for a high a high VI (as many pros do) they may have been ok in the race because they would have prepoared to race that way.

As for hilly courses, I've had athletes do VI <1.05 and still have their optimal races. Yes, VI will be some what higher due to climbing. The key is to limit the metabolic cost on the uphills, especially long climbs. While not a climbers' course, Hawaii has a lot of elevation gain. The rider in the lower chart of this post did it three times with VI of 1.04 with times of 4:58, 4:51, 5:03.

The key here, Wilf, is really how you train relative to how you race. You can do a race with a lot of variability if you prepare for it. Then you will learn what the limits of your variation should be. This is essentially what many of the pros do. So it's a matter of deciding how you will race and training accordingly. I'd recommend that most people would be wise to race steady state (low VI) rather than frequently accelerate and decelerate (high VI).

At October 27, 2008 8:46 AM , Blogger Joe Friel said...

Bayzob--Yes, that is a nice feature to have. But I know of no other power meters that have it. Even nicer, though, would be GPS/accelerometers that provide real time normalized graded pace.

At October 27, 2008 8:50 AM , Blogger Joe Friel said...

Hi Bahzob--Bike races will almost always have much higher VIs than TTs/triathlons. In fact, it may even be good in that case as it can mean that the rider is coasting and soft pedaling a lot and using energy only when called upon to cover/make moves that determine race outcome.

At October 28, 2008 11:15 AM , Anonymous Ted Darling said...

Joe, it appears that the reasons this athlete may have experienced such a high VI is that he was targeted 210-220 average, when clearly his body would not allow him to do it. He would have been much better off targeting 180-190 (60-65% of FTP), remaining as aero as possible and leaving something in the tank for the run. Do you think this is more of a case of him targeting too high a race pace for power rather an a pure VI problem?

At October 28, 2008 1:50 PM , Blogger Joe Friel said...

Hi Ted--I certainly agree that it is possible he set his sights too high. Especially given that in the first quarter of the ride his average power dropped from about 210 to about 170. That's a sure sign something is wrong which could be unrealistic expectations. But since we don't have HR it's not possible to know what his effort was here. That would have been nice to know. But based on his email he had been doing long rides in the range of 200-220 for 4.5-6 hours. If that's the case then there would be every reason to believe he could do it in a race. So if that is true then I have to believe it is something else. A very high VI is the likely culprit - as usual. After I posted this he wrote back to me and said his VI in those training rides was much lower than it had been in the race. So he agrees that was probably the issue. It's very common. Almost everyone does it. I spend a great deal of time talking with my client-athletes about this issue and preparing them to handle it correctly, which means to remain calm and steady.

At October 29, 2008 10:16 PM , Anonymous Jeff said...

Joe - Knowing that your VI may be elevated due to a hilly course is there a way to prepare to "limit the metabolic cost on the uphills, especially long climbs" and desents as you mentioned. I raced IMC this year and held VI to 1.04 until Richter at mile 45ish. From that point on the VI shot up to 1.14 for the remainder of the ride. Another possibilty for an increased VI in the last 60+ mi could be from the long descents. When coasting (Avg Pw = 0) so VI = NP/Avg PW goes out the window.
Sorry for the long winded question...
Thanks Joe,

At October 30, 2008 2:52 PM , Blogger Joe Friel said...

Hi Jeff--That's a good question. One of the pros I coach did IM Canada this year. His bike VI was 1.05. That's a little higher than he would have normally had for a flat course. He held his peak power to less than FTP on all climbs and coasted the downhills whenever he was spun out. So it can be done.


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