Tuesday: 4×15’/4′ (7′ @ 5KP, 8′ @ MP) Marathon Training OTW

Weather:  Lovely.  Sunny.  Temperature was around 60F.  There was a moderate 5-10mph breeze from the WNW.  This was a cross/tail wind heading down river and the cross/head wind going upriver.  (But since I was going to row to power, that didn’t matter!)

Plan:  This was the first time I would be doing one of the Fletcher Marathon Plan sessions on water.  I figured I would need to be a little flexible to make it work.

  • 4 x 15′ / 4′ rest
  • In each 15′ interval
    • 7′ @ 5KP (which is 220 to 235W on the erg)
    • 8′ @ MP (which is 180 to 195W)

As for adaptations.

  • I have about 3000m of river that I can row at high pressure.  This takes me a little bit less than 15 minutes.  I decided to keep the 7′ at 5KP and then just stop short of 8′ if I ran out of river.  This would be more of problem downstream than upstream, both because of current and also the headwind.
  • Power:  I decided to try to row to my erg power specs.  I suspected that this would be really hard, and it was.  After I rowed, I listened to a great podcast about rowing with power meters which said the average difference between erg and OTW powers was in the range of 13% to 16%.  Interesting tidbit.  If I had know that, the targets would have been substantially reduced.

Screen Shot 2017-05-17 at 8.26.07 AM

  • Rate:  I have somewhat arbitrarily decided to match rate to these powers as follows
    • 5KP: 24-26
    • 10KP: 22-24
    • HMP: 20-22
    • MP: 19-21

So, how’d did it go?  It was a really tough, but awesome workout.  I dug very deep to get it done and I definitely faded in the later reps, but I stayed focused and got it done.  From a TRIMP perspective, it was the hardest workout I’ve done since the end of January (HR based TRIMP of 195)


Here’s the interval summary from rowsandall

Workout Summary - media/20170516-135626-SpdCoach 2182533 20170516 0639amo.csv
Workout Details
01|01613|07:00.0|02:10.2|224.6|24.3|164.0|170.0|09.5 - 255-240W
02|01258|05:51.0|02:19.5|190.8|20.1|165.0|170.0|10.7 - 180-195W

So, I tried hard, but I couldn’t hit the erg based targets.  But I was ahead of the 15% derated targets.  For now, I will aim at the top end of the OTW target range.

I’m using the impeller on the speedcoach to try to avoid stream effects on the live pace display.  I’ve tried to calibrate the impeller input, but based on a comparison of the speedcoach and GPS data today, I think my cal factor might be a bit slow.

Workout Summary - media/20170517-123357-87478o.csv
Workout Details

I compared the paces.


So, based on this data, I think my impeller is reading about 4.5 seconds slow.

This row gave me a treasure trove of data to look at the state of my rowing technique.  Here is a gallery of the plots that I did.

  • Power and pace vs stroke rate:  pace is bimodal due to headwind.  Power is not.  Pretty wide spread because of the way I started faster and faded
  • Effective length vs stroke rate:  Slightly longer at r24 than at r20.  This is pretty consistent with what I’ve read in Kleshnev and other places
  • Wash:  Wash got a little bit worse as I got more tired, but I think it is pretty good.  I guess my finishes are in OK shape.
  • Slip:  Lower slip values at r24.  This is where the better length is coming from.  I am attacking the catch with more enthusiasm at the higher stroke rate.  Not sure if that is a good thing or a bad thing.  I need to figure out if it is resulting in a more fficient generation of boat speed relative to the effort (power).  That will be a longer term project.
  • Catch:  consistent.  A little degradation in the last interval.  Certainly more variation from stroke to stroke.
  • Finish:  Better and more consistent at r24.  You can see how I was really struggling at the beginning of each of the r20 sections.  I dug a deep hole with the higher power segments, and when I gear shifted I struggled to take full strokes.
  • Effective length vs time:  You can see the effect of me gasping for breath at the beginning of the MP sections, especially in the later intervals
  • Work per stroke vs time:   I filtered the data to do two plots.  One for r24 and the other for r20. Very clear reduction in r24 WPS over the workout.  I was rowing to lower power and slightly higher rate.   This is physiological, not technique.  In the r20 sections, you can see me digging out of the lactate hole through each of them and finishing stronger.


Now I am flying out to LAX.  I will take today as a rest day.  Tomorrow morning, I have two possible plans.  If I stay over I’m planning to visit Crossfit Anaerobic in Irvine and do this session…

M2 4 x 20′ / 2′ MP, 10KP, HMP, MP 90.0% (167)

I might take the red eye home.  If I do that, I have my rowing gear in my car and my plan would be to stop and row on my way home from the airport.  The plan would then be to do a version of this OTW.  Each section would probably be closer to 15 minutes.

7 thoughts on “Tuesday: 4×15’/4′ (7′ @ 5KP, 8′ @ MP) Marathon Training OTW

  1. stelph82 says:

    “I listened to a great podcast about rowing with power meters which said the average difference between erg and OTW powers was in the range of 13% to 16%.”

    I haven’t got to that podcast yet as I’m working my way through them in chronological order (which I would recommend, they are all excellent) – but just a note of caution that personally I am not finding that fade between erg and water, infact I am able to hold more watts on the water at the same HR/Relative Perceived Effort than I am on the erg – reading around this is pretty well established in cycling as well where some cyclists are find it easier to hit set wattages on the trainer and others on the road so its certainly something you should test to see your own results


    • sanderroosendaal says:

      I am adding a feature to set the mentioned percentage drop on rowsandall.com.
      Discussing with NK, they see this drop in all the rowers they work with. Of course, the actual power you measure is quite sensitive to the calibration you do with the NK calibration tool. If you don’t get the angles calibrated right, the oarlock will think that you pull a longer arc, and as work W = F x ds, with F the force and ds the distance, you are then stuck.
      When you have some time, redo the calibration, and see if the values are still higher.

      Liked by 1 person

      • stelph82 says:

        Interesting, i will have a go at calibrating again – incidentally I am actually on my second gate as the first one was sent back so they could see if they could work out what was going on with the Bluetooth dropouts so I have run the angle calibration 2-3 times in the time I have had it and I tend to calbrate the force value every other outing before I put the blades in – the angles tend to come out where I expect (approx 110 – 114 degrees depending on rate and conditions) – both gates show increased watts compared to ergo (the trial I run was with the old gate, still seeing the higher numbers now with the new one)

        Im sure NK have tested a lot of Rowers but to be honest i would guess this will be a fraction of the numbers of cyclists who have been tested with a power meter, so I suspect it does happen although its not completely understood why it happens


        The only way to be sure what kind of rower you are (an innie or an outie  ) would be to test

        Liked by 1 person

  2. sanderroosendaal says:

    The explanation is that the erg measures the energy you put into the chain, while the gate only measures the horizontal force at the gate, then uses the calibration and your inboard/scull length setting to calculate the handle power. There is a couple of steps where a bad setting or calibration can give you off values, so you have to make sure you calibrate well before you compare values between rowers with different gates.
    That said, if you don’t fuzz about the absolute value, then the power number is a gift from heaven in terms of quantifying your training and racing.


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