Thursday, April 1, 2010

Oceanside Bike and Run Data

Before starting my bike (over) analysis, I noticed that I had the 108th fastest bike time overall and the 5th fastest in my AG. Kinda crappy, I think. Normally my bike ranking is quite a bit higher in the overall, although that's for full-IMs where I feel my strength lies. Oh well, plenty of room for improvement.

Anyhow, I forgot to press "Stop" on my Garmin upon entering T2, so instead of recording 2:30 of power data the CPU ended up recording for 4:30 with zero power for the last two hours. In order to view proper averages, I needed to modify the power file (as Garmin's pathetic software doesn't allow one to recalculate averages for portions of a ride, and also because Saris' much more robust Power Agent has an error reading the file). After downloading the file in Garmin's software, exporting the file as a .tcx file, importing that .tcx file into Golden Cheetah, exporting the file as a .csv file, opening the .csv file with Excel, manually deleting the last two hours of the ride to create a modified .csv file, and importing the modified .csv file back into Golden Cheetah, I finally got some usable data.

Without further ado, here's the data:
Duration: 2:30
Average power: 240 W (zeros included)
Average HR: 144 bpm (more on this below)
xPower: 250 W (this is essentially the same as normalized power in WKO+)
Variability index: 1.04 (i.e., xPower/average power, more on this below)
Average cadence: 83 rpm (zeros included, I typically rode at 85 rpm with a variation of around 5 rpm)

Power line graph:

This graph has smoothing set to 20 seconds so the graph is a bit easier to read.

Notice here that for almost the first 120 minutes that my power was either slightly above 250 W or far below 250 W. Since most power below 250 W is far below that value, it appears that these recordings took place while I was coasting or soft pedaling(downhill, grabbing a bottle at an aid station, dropping back after being passed, etc.). Also, like I mentioned in my race report I didn't push myself at the end of the ride. That power drop is apparent as my power after 120 minutes is primarily below 250 W.

What can I take from the graph? That when pedaling I should aim for 250 to 260 W for a HIM. Since I ran well, I can be confident that this is a sustainable power for me during a half. Oh, and I am also adjusting my FTP based on this ride to be right around 300 W (this estimation being based on my power, 240 to 250 W, divided by 0.80 to 0.85, the typical portion of FTP at which one can ride a HIM).

As any power user knows, average power is far from the most relevant piece of info. xPower, Raceday & Golden Cheetah's substitute for WKO+'s proprietary normalized power, is basically the average power that I rode at when not surging or soft pedaling. That's a simplification, but I think it's the most useful way to consider xPower because the implication is that xPower is the power I should actually target during my ride.

My 250 W xPower supports riding at 250-260 W as discussed above, but xPower is further useful because it tells me after the fact how good of a job I did at holding a constant effort. WKO+ refers to the ratio of xPower (Pnorm, as they call it) to average power as variability index (VI). A VI of 1.00 indicates a perfectly steady output (good), while something like 1.10 would indicate widely varying power outputs (bad). A high VI is bad because it is likely that a high VI rider spends a lot of time way above his intended power output, and this is likely to take its toll on the run.

For a hilly course like CA 70.3, a VI of 1.03-1.04 is pretty good (from what I've heard, anyhow). My VI is 250/240, or 1.04. While that seems pretty good, I think with a bit more discipline I could ride even steadier. (I'm also happy with this value because it gives me a bit of authority to rant about the way most AGers ride, which I will do in a future post.)

Power bar graph:


Zone Description Low (W) High (W) Time
Z1 Active Recovery 0 165 14:48
Z2 Endurance 165 225 33:17
Z3 Tempo 225 270 52:53
Z4 Threshold 270 315 33:32
Z5 VO2Max 315 360 11:49
Z6 Anaerobic 360 450 3:39
Z7 Neuromuscular 450 MAX 00:20


I'm sure my astute readers will immediately notice a problem with the bar graph -- the total time adds up to 3.0 hours, not the 2.5 hours that my ride actually lasted. This appears to be a yet another quirk of my Garmin. Regardless, I'd guess the distribution is properly proportioned and just scaled incorrectly.

What to take from this info? I did a good job minimizing very high power output (>360 W). I bet most of the nearly 4 minutes spend above 360 W came from accelerating (out of turns, after soft pedaling, etc.). Looking at the 315 to 360 W interval, I think a good portion of that came during the climb near 30 miles. I remember my power hovering around 315 W for most of that climb. If I'm going to put out a high power, the best place to do it is when my speed is low because this gives the most bang for the buck. Ideally, though, I'd spend no time above 315 W. Another possible area of improvement is reducing the amount of time spent not pedaling. Even putting out 150 W on a downhill is better than coasting.

Heart Rate Graph


This is about the oddest HR graph I've seen. My power was pretty constant with a slight decrease at the end, yet my HR steadily increases throughout the ride. My aerobic decoupling was an astounding 22%!!! (Aerobic decoupling is basically a ratio of two other ratios, a first power/HR ratio for the first half of the ride and a second power/HR ratio for the second half of the ride. Power/HR is expected to stay nearly constant throughout a ride, and aerobic decoupling measures how much the ratio changes throughout the ride. See here and here for more info.)

Is my 22% decoupling a sign of dehydration? That'd be odd for a 2.5 hour ride on a 55 to 70 degree day. Is my aerobic fitness in the crapper right now? That, too, would be surprising given my ~20 hours per week training volume. Or, was I just not strong enough muscularly to maintain 250 W? That's my best guess. It's also possible that my HR monitor was simply wrong. However, I do not suspect this is the case because typically a bad HR monitor produces lots of jumps in HR, whereas I only have one clearly wrong piece of data when my HR jumps to nearly 200 at 80 minutes or so (rest assured that my heart never actually beat that fast). I'll keep looking at this metric for future rides to try to learn what's going on.

Bike conclusion: Overall, a well paced and even ride. I don't think I'd change anything on race day except maybe push a bit harder at the end of the ride. Pushing a bit harder may have saved a minute or two on the bike, which potentially could have moved me up in the standings. On the other hand, would that have cost my run?

Run graph:


Run data:
5:58/mile average
171 bpm average, 177 bpm max


I didn't start my watch until 3 minutes into the run, so the first segment is missing. I ran the fastest during those first few minutes, but after that my pacing is dead on. I slowed just a few seconds/mile (based on the dashed line representing my average pace) over the course of the run. At the end, I started getting some slight side cramps. I could have picked up the pace for the last mile or two, but doing so would have risked the cramps getting worse. During the race I weighed the potential time savings from picking up the pace against the risk of having to slow greatly if my cramping got worse, and then decided to go the quickest pace that kept my cramping at bay instead of the fastest pace I could muster.

Anyhow, not much to comment on here other than that this is probably my best paced triathlon run ever. Oh, and the fastest amateur run split and 10th fastest overall, just 4 seconds/mile behind race winner and 70.3 world champ Michael Realert (though he put a tad bit of time into me on the bike...).

Transistions
Bet you didn't see this one coming! But look at my transitions: T1 = 3:44; T2 = 1:18. A good T1 would have been <2:30. I took my time putting on arm warmers and didn't hurry getting my other gear on, either. On the positive side, I got my wetsuit off faster than ever. This was my first swim in a new Zoot Zenith 2.0, and it must have larger ankle openings because I have never had an easier time getting a suit off. Usually this is a problem for me with my size 11 feet and extremely inflexible angles.

I guess it's time to start practicing transitions. I should also think about my strategy a bit more. For example, in the future I'll keep my arm warmers on my base bar's ends in transition, then put the warmers on once I start riding. I'll also probably wait to put my sunglasses on until I'm moving, too. Why work so hard to cut a minute or two off my swim and then just give that time right back with a sloppy transition?

2 comments:

  1. At the end of the day Evan, SPEED is the sole goal; that is how fast you can get from the start line to the finish line, regardless of all else. So a comment like this...

    "Even putting out 150 W on a downhill is better than coasting."

    ...is not entirely accurate. If, for example, you're coasting down a hill at 40mph or putting out 150w to maintain that same speed, you'd be better off coasting. And at 40mph 150 watts is almost always wasted energy, and wasted energy is what haunts us most at the finish line.

    All told, you did well; but yes...there are places to improve, both on the bike and, believe it or not, in the run. (Don't tell the pros this!)

    But the truth is we know your swim to be the big culprit, and that's what needs the most attention, as per your last blog. A wetsuit/salt water swim should have you MUCH faster, so before you go looking where you could've made up seconds or *possibly* a minute or two, let's look to the water and the elements within in.

    Of course, pool time is not the same as open water swimming, so while your swimming is perhaps improving in the pool it may not relate to the tactics required in swimming without lane-lines and around hordes of others. Let's work on this this summer...as there's work to do!

    Transitions: Use plastic bags (over your hands) to put your arm-warmers on *before* hopping on the bike; there's plenty of seconds spared there. And practice transitions once a week for the last few weeks prior to your next race.

    -CV

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  2. Evan,

    On a bike course like Oceanside, how much aerodynamic savings do you think your calves produced? Also, with that speed on the run, do you think your calves produced an aerodynamic advantage over others too?

    ha!


    In addition to what CV said - fold/roll your arm warmers inside out half way, and when you stick your hand/bag through, you can essentially roll it up, rather than tug it. As for the sunglasses - I leave them open and upside down in my helmet when I get to transition (I used to master transitions to the point where I could look more for my transition rankings, rather than total time rankings), and put them on first. It takes about .2 seconds - then put the helmet on. Buckle, and you're set to rock.

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