May 8 2017
Stroke Analysis of my 1000m singles race
Race Analysis
In this post I am looking at a few detailed metrics of the Masters 1x 1000m race I rowed yesterday. Data were collected with a SpeedCoach GPS 2 combined with a NK Empower Oarlock.
Here is the overview plot of catch and finish angles for the entire outing, including warming up and cooling down. The actual race starts at 1200m. Interesting to see that I seem to suddenly take length about 400m before the finish line. This is exactly the point where I finally passed my opponent and actually started to row at a lower power.
Here is a close-up of catch and finish angle for the race segment. We’re talking a 1 degree difference, but still it looks pretty consistent and significant.
So here is the power and average drive force. The start strokes are always at high power and force, as you are starting from a stop and rowing short strokes at high rate. I think I did a pretty good job getting the average force down to an average value and holding that for the rest of the race. It is interesting to see the power drop about half way, while the drive force remains constant, and the catch angle actually increases. That means that I either started to row at a lower stroke rate, or the actual stroke was shorter despite the catch angle being longer.
The plot thickens when we look at the “Work per Stroke” which drops with the drop in power. So it looks like the stroke rate remained constant, but something else was changing.
Funny enough, both the absolute drive length and the effective drive length remain constant for the entire race and at pretty good values. So the shift in catch angle was actually me focusing on length (after I had passed my opponent) and tap-down (which makes the stroke slightly shorter at the finish). Should be visible from Wash values.
Looking at Wash and Slip values, I cannot see a big difference:
Finally, the solution to the riddle seems to be the Peak Drive Force:
Interesting! I hadn’t expected that. The stroke profile plot for the first half of the race:
And here is the second half of the race. Almost identical to the first half, but the tiny difference do lead to a drop in power, while my pace didn’t drop as much as that of my opponent.
Here are power and pace in one plot:
And finally, stroke rate and power:
Monday – Tourism and travel home
Today was a holiday, so we made a few stops on the way home. Here are a few pictures:
May 11 2017
Two rest days and a hard session (lactate, lactate!)
Monday was a travel and tourism day, and tuesday was a very long day at work, and after the long weekend I was behind on a couple of important work related duties, as well as evening conference calls with final reviews of some project proposals, so I had to skip training. I didn’t mind much. I think a 2 day gap now and then, when life and work get in the way, is actually quite healthy and definitely not detrimental.
This also gave me a motivation to do a really hard training, although I chickened out of what our head coach had posted on the training plan board:
2x(7×50″/10″) @ 34-36 spm, 5 minutes rest between the 2 sets
That is like 30 strokes “on”, 3 strokes “rest”, for 7 minutes, at a stroke rate that I cannot hold for 4 minutes. Driving to the rowing club, I was thinking of what to do with these instructions. I was also curious to see how many of our Masters rowers would turn up on this Wednesday and what boat type I would row.
Turns out that through back injuries, work related duties, business travel, we had 4 rowers of our eight, plus 1 younger guy who rows with the Masters group occasionally. The issue, however, was that that one guy is not comfortable rowing a single, and one of the others is not a sculler. He only rows sweep. I got a little impatient when we hadn’t decided after 25 minutes so I announced that I would go in the single (which would also enable me to row my own session). The sweep rower Bulda teamed up with Krocan to take a pair, and the remaining two got out in a double.
We have the full Albano lanes out because of the International Youth Regatta of coming weekend, so I wanted to do 2x”something intensive at high stroke rates” in the 2k course. My training phase prescribes ANC training, which is short intervals with rest, and many of them, to get the body to produce lactate (as fuel, which I will condition the body to use in the subsequent phase).
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After 2k of warming up, I stopped to fiddle with my HR strap. I had the feeling that it was too lose and that I felt the strap on my back creeping down slowly. So I tried to adjust it back, which led to it snapping. The Wahoo Tickr straps connect with snap fasteners to the sensor “pod”. They call it the “two-snap” connection which is easy to get on and off. Well. It snapped. Under two layers of clothing (because it was cold), with me being in a single on cold water.
So I removed the upper part of my uni, clamped the scull handles between my belly and my legs, and tried to use two hands to snap on the HR strap. Initially, I failed, and I ended up holding only the sensor, with the strap being somewhere under my clothes, and discovering that my left blade had turned and was now perpendicular to the water, in flipping position. I corrected that, and proceeded to struggle. In the end I managed to snap everything back on and get my clothes in order as well. Without flipping.
Krocan proposed 20 strokes “on”, 10 strokes “off”, and that seemed a very good compromise. At this point, I was incorrectly remembering the training schedule and thinking that there were 3 series of 50″/10″, so I agreed with his proposal, thinking that we would 3 full 2k distances of them.
It was nice to row this next to the pair. I called out every eigth stroke of the paddle and grunted after the 20th (final) stroke of each interval. I managed to beat them by about a length over one entire 2k course. Looking at the graph, I see we did only 7 intervals per 2k. It felt more like 9 or 10. Anyway, after the first (headwind) and second (tailwind) 2k all three of us were so worn out that we couldn’t think of doing another series. So we just rowed the final 2k at steady state pace, followed by a cooling down.
During the intervals, I saw how I achieved fewer and fewer Watts as the intervals went on. Here, I am trying to see if that is a result of reduced force, length, stroke rate, or both. Stroke rate is excluded. You can already see from the overview chart above that the stroke rate didn’t drop. Here is a look at peak and average force.
In the these two plots, you can see that the effective drive length also drops, especially as I am shorter on the finish. I focused on not tapping down too late, because I noticed a very strong effect on “wash”, and also it makes it easier to keep the stroke rate high.
The next plot shows the same, but with effective drive length (taking into account slip and wash) instead of total drive length. I am running my effective drive length at 85% of total drive length. I would be interested to see the values of other people.
I also added a plot of the result, Work per Stroke, for the “on” intervals.
Here are some typical values according to Nielsen-Kellerman, compared to a summary for my “on” strokes. The values closest to my stroke are indicated with the colored cells. I guess I am just lacking in power and strength.
By sanderroosendaal • Uncategorized • 2 • Tags: ANC, ANC training, intervals, lake, OTW, rowing, single