Pressure versus Splits

[pbear9990]

Hi Everyone

Please can anyone help with the following query?

Is there a method by which we can equate pressure to splits on an erg?

For example, if my fastest split for 500m is 2 minutes, then can I assume that to work at full pressure on an erg is to row 500m splits of 2 minutes (250m / 1 minute)?

Three quarter pressure would be to row 500m in 2.67 minutes (187m / 1 minute)

Half pressure would be to row 500m in 4 minutes (125m / 1 minute)?

Quarter pressure would be to row 500m in 8 minutes (62.5m / 1 minute)?

Does this make sense and is it comparable to varying pressures rowing on water?

Thanks, Dave

[jamesg]

"Pressure" equates to Power in Watts on the erg, not speed or pace.

So the pressure idea is similar on erg, thanks to the same hydrodynamic cube law that operates both afloat and also on the C2 air-braked ergometer.

On erg, Pace 2 minutes is 200W, so half pressure is 100W, if taken literally.

100W is pace 2:30.

3/4 would be 150W, pace 2:13.

On the erg, which measures Power, the applied Law to relate Power to Speed is Watts = 2.8 V³, with V in m/s.

On the PM you can switch Units as you wish so see it all.

[pbear9990]

@jamesg
Thank you for your reply.
So simplistically, if I want to use a measure on the erg which would equate 1/4 pressure, 1/2 pressure, etc. I should have the PM5 display the unit of measure as Watts?
Thanks

[Sakly]

So simplistically, if I want to use a measure on the erg which would equate 1/4 pressure, 1/2 pressure, etc. I should have the PM5 display the unit of measure as Watts?

Yes.
But the feeling is not linear - 100W feels like hardly rowing at all, 200W is challenging for most people, 300W many people will never reach.

[pbear9990]

@Sakly

Thank you for your reply.

What you have said chimes with my reason for asking the question.

If we are on the water and the cox / coach calls for ‘full pressure’ we pretty much know that we will be giving 100% effort. Then as the call is for reduced pressure (3/4, 1/2 & 1/4) we typically drop a percentage as we move from full to three-quarter to half to quarter. But does half pressure equal 50% of our maximum. It does not feel that we are dropping 25%, then 25%, then 25%. As you indicate, we get to a point where would we feel as though we are hardly rowing.

Do you think that, on the erg, dropping from 200W to 150W to 100W to 50W would be a good regime for training for full, three quarter, half and quarter pressure on the water? Would you recommend a different profile?

I hope this makes sense.

Many thanks, Dave

[Sakly]

Do you think that, on the erg, dropping from 200W to 150W to 100W to 50W would be a good regime for training for full, three quarter, half and quarter pressure on the water? Would you recommend a different profile?

Definitely a different profile.
As the wattage is highly individual based on your abilities, I would suggest following:
1. Row as hard as you can, full effort what you can hold on to as many strokes as it is requested on the water from your coach (at the same rate like OTW). Note your wattage.
2: Row at low pressure, like a steady state you could hold for an hour, again at the same rate. Note your wattage.
3: Based on above values you can evaluate the 50 and 75%, but not linearly.
In my case it would be probably around 360W (12W/stroke) and 230W (7,5W/stroke) at rate 30 (never rowed with low pressure at rate 30, so don't know. But my last HM at rate 20 was 224W, so the same wattage at rate 30 would be really easy). For lower rates the values are lower of course.
If 360W feel like 100% effort and 230W feel like "easy paddling" (rowing should never be really easy), I would think of 260-270W half power and 300-310W 75% - all at rate 30.

[pbear9990]

@Sakly
I will give it a try.
Thanks for the advice

[Sakly]

@Sakly
I will give it a try.
Thanks for the advice

Would be great if you share your experience when done

[Tsnor]

A different mostly subjective approach to paddle pressure / 1/4 pressure / 1/2 pressure / 3/4 pressure / full pressure / power(7,10,..) pressure / sprint pressure from OTW where you can't see the PM5.

Paddle pressure is no load but good looking strokes. What you'd use to cool down after a piece. Or to keep pace with boat that are waiting to dock or stage at the start line.

1/4 pressure is all day pressure. An output level you can row for over an hour, comfortable. Low HR.

1/2 pressure is the pace you can deliver for about an hour, max. You might only use 1/2 pressure for 5 or 10 mins, but if you kept going you'd run out of gas at about an hour.

3/4 pressure is about 20 mins then your done. You can use 3/4 pressure for an hour, but if you did 3/4 pressure for an hour the last 15 minutes would be much slower than the first 15 mins and people would be cooked.

full pressure is a little flexible. If the piece is 1500 meters full pressure then you use an effort level that works for 1500 m. If the piece is 2500 meters full pressure than you use a little less effort but it is still called full pressure. Likewise a 500 meter sprint at full pressure is the effort you can sustain for 500 meters.

power (7,10,...) is higher power for x many strokes "we'll take a power 7 in 2 strokes, there's 1 there's 2 BAM LEGS BAM". Generally you will be returning to your prior power output so you pick a power level that doesn't burn you out but makes a difference. The boat should move. Used for fun in longer practice pieces and to get ahead of another boat that has roughly the same race pace as you. "we're moving on them now, give me a power 10 in 2..." or leading into a sprint.

Sprint is final piece before rest and is empty the tank level output. Generally stroke rate goes up as well as pressure. Sometimes a sprint called for 20 strokes will actually last 25 or 30 strokes or more strokes, you gotta just hang on and keep power coming. Sometimes a sprint ends sooner than expected and you wish you'd gone harder. Judging the sprint start/duration is really hard because wind/current/distance/speed and how hard the rowers are actually going to pull are all problematic as are race competitive conditions.

As you get stronger your watts/splits at each of these will change, but the basic time parameters will stay the same. Also you can choose to go on the low end of 1/2 pressure or the high end depending how you feel, etc.

[jamesg]

So simplistically, if I want to use a measure on the erg which would equate 1/4 pressure, 1/2 pressure, etc. I should have the PM5 display the unit of measure as Watts?

Yes, but use Watts anyway, being a direct Power measurement it offers simple analysis.

You'd probably do best to start from the other end: when you say "Half", check what the crew actually does and why. And more to the point what happens at "Full".

A young crew with an oar in hand acts like a horse with the bit in its teeth. They want to keep their seats and will only slack when there's no option.

[KeithT]

I am glad to see the proper responses given here. I often find people trying to do the math with time and it doesn't work. A guy at my gym worked to improve his 500m and went from 1:40 to 1:30 - he was happy but thought that because 1:40 is 100 seconds and 1:30 is 90 seconds he improved by 10%. When I showed him the 37% increase he really did he was blown away.

[pbear9990]

Thank you for all replies. Really helpful & appreciated.
@Sakly - I will let you know how I get on.