Relationship between split time and stroke rate

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JotaBg
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Relationship between split time and stroke rate

Post by JotaBg » November 15th, 2020, 6:23 am

Hello all,

This is my first post on this forum! Last week I acquired my first Concept2 rower and I am very excited to become part of the community and learn as much as possible.

I am also new to rowing, so I am trying to learn as much as possible. But there is a specific question that I would appreciate if you can answer.

My understanding is that the two main numbers that I can look at are stroke rate (strokes per minute) and split time (time that it takes to row 500 m).

My question therefore is how these two metrics relate to each other. To ask it more specifically:

- Does an increased stroke rate result in a lower split time IF the power that I am applying to the flywheel (I guess Watts) is kept constant?

- Would this mean that there are two main ways of increasing my split time (speed): Either by increasing the power that I am applying but keeping the stroke rate constant or by increasing the stroke rate and keeping the power constant? Or, of course, also both: increasing both the applied force AND the stroke rate

- And my last question. What would the preferred way of increasing speed be? Increasing stroke rate and keeping force constant or keeping the stroke rate constant and increasing force production (I am guessing the latter)?
I also understand that at a higher stroke rate, it will be harder to keep the applied force constant, so increasing the stroke rate will be beneficial for speed but only up to a certain extent

Many thanks for taking the time to answer, guys! These are very newbie questions but I am just trying to get my head around all these

Thanks!
J

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Re: Relationship between split time and stroke rate

Post by Citroen » November 15th, 2020, 7:42 am

The only way to increase pace (which is time for 500m) is to put more work into the system (a higher watts number == lower pace time). That means driving harder with your legs. Stroke rate has little to do with it except for the limit of how often you can drive with your legs.

Rushing up and down the slide like a Duracell/Energiser bunny with a weak drive doesn't improve your time - it significantly reduces your recovery time. The ideal stroke is one where you get the best force with the least stress to your cardio-vascular system (with enough time for recovery before the next stroke).

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Re: Relationship between split time and stroke rate

Post by hjs » November 15th, 2020, 8:14 am

1 yes
2 yes and yes
3 beginners gain the most by building a stronger stroke. But at a certain point stronger is not needed.

Rowing is power endurance sport. The best rowers are tall, weight 90/105kg

Training for 2k and above is doing a lot of aerobic training with a strong enough stroke. This comes down to rating in the 18/22 range. On top of that speedtraining is done. But volumewise the speedwork is a lot less.

Racing is not using low ratings, but as high as is usefull. Toprowers often use 35 and above during 2k races.

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Re: Relationship between split time and stroke rate

Post by JotaBg » November 15th, 2020, 1:47 pm

Thanks both, that makes it much more clear

One follow up question, when training, is it then preferable to set a more or less fixed stroke rate (e.g. 22 spm) and modulate the split time (pace) by applying more or less power (Watts) during the session depending on how you are feeling?

An alternative could be aiming for a set split time but modifying strokes rates during the session, but I guess that doesn’t make that much sense compared to just keeping a more or less fixed spm and adjusting the applied force

Thanks again!

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Re: Relationship between split time and stroke rate

Post by hjs » November 15th, 2020, 1:55 pm

JotaBg wrote:
November 15th, 2020, 1:47 pm
Thanks both, that makes it much more clear

One follow up question, when training, is it then preferable to set a more or less fixed stroke rate (e.g. 22 spm) and modulate the split time (pace) by applying more or less power (Watts) during the session depending on how you are feeling?

An alternative could be aiming for a set split time but modifying strokes rates during the session, but I guess that doesn’t make that much sense compared to just keeping a more or less fixed spm and adjusting the applied force

Thanks again!
Mwe, in general rowers strive for a roughly fixed output per stroke in training, so speed up rate needs to go up and vice versa.

Re 22, that is more less the highest rating you can use during longer aerobic sessions. Any higher and you need to bleed the power a bit.

This is ofcourse not set in stone, everybody has personal things he/she likes or is better in. But you get the idea. Use a stroke to build a strong stable technique. So don’t vary the power to much.

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Re: Relationship between split time and stroke rate

Post by JotaBg » November 15th, 2020, 2:06 pm

Very clear, many thanks hjs!

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Re: Relationship between split time and stroke rate

Post by ampire » November 15th, 2020, 2:48 pm

Generally one might train aerobic long distances at R18 to R22 to build up the power you make with each stroke and also improve technique, efficiency, and form, and train your anaerobic HIIT workouts at R32-36 to build your ability to rate up: producing a high amount of strokes per minute and not being fatigued, meeting oxygen demand, improve mental toughness, and all while still producing a good amount of power with each stroke. The stroke on a stroke by stroke basis should be similar in wattage between both workouts but you would be doing more of them per minute while doing HIIT.

If you are doing time trials, you might use a stroke rate like 10K at R26-28, 5K at R30, 2K at R32-34, 500M at R36-40, but it really would vary per athlete.

If you do only one type of training, such as only HIIT you might not have the endurance for long distances, and if you do only long distance, you will lose the ability to rate high for any length of time, so ideally you would do both types of workouts with something like 80% long slow distance and 20% HIIT.

Example for the distance would be 90 minutes at UT2 pace.
Example for HIIT would be 8x500M /1 minute rest.
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Re: Relationship between split time and stroke rate

Post by Allan Olesen » November 15th, 2020, 3:39 pm

The answer to your first question is a clear "No".

Your pace is directly coupled to power. Actually, the ergometer measures your power and then converts it to pace using a fixed formula.

So when you row at for example 100 watt, you will see a pace of 2:31.8, no matter what your stroke rate is.

What you can change is the energy, that you put into each stroke. If you put twice the energy into each stroke, you only need half as many strokes per minute to produce the same power. You do that simply by pushing harder with your legs, and pulling harder with your arms.

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Re: Relationship between split time and stroke rate

Post by hjs » November 15th, 2020, 3:55 pm

hjs wrote:
November 15th, 2020, 8:14 am
1 yes
2 yes and yes
3 beginners gain the most by building a stronger stroke. But at a certain point stronger is not needed.

Rowing is power endurance sport. The best rowers are tall, weight 90/105kg

Training for 2k and above is doing a lot of aerobic training with a strong enough stroke. This comes down to rating in the 18/22 range. On top of that speedtraining is done. But volumewise the speedwork is a lot less.

Racing is not using low ratings, but as high as is usefull. Toprowers often use 35 and above during 2k races.
Did misread your first question. Watts = pace no matter what rate. I though your said power per stroke. :roll:

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Re: Relationship between split time and stroke rate

Post by Ombrax » November 15th, 2020, 6:31 pm

Welcome to the forum J.

I'll mention two additional things:

1) There's a direct relationship between power and split time (which is the same thing as boat pace, but inversely related, of course), and if you dig around a bit on the C2 web site you'll find the equation the PM uses. (I don't remember it off the top of my head.) The key point I want to make here is that there's a non-linear relationship between the split time and power, as you might expect due to the physics of drag, the power required to achieve a certain pace (or split time) goes up dramatically as your pace goes up. That's why it's so hard to go really fast (or even just faster) - you need A LOT more power to do it, and of course, your body is limited in what it can do and for how long it can do it.

2) All this speed and pace stuff is useful and interesting, but for someone just starting off on the erg the #1 most important thing is to get your technique right. Now is the time to make sure that you're rowing properly, before any bad habits get too ingrained in you stroke. There's lots of information on the C2 site for that, along with a number of videos on YouTube. Whatever else you do, don't neglect technique - doing it right is the simplest way to go faster, and may also help you avoid injury.

Good Luck

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Re: Relationship between split time and stroke rate

Post by Ombrax » November 15th, 2020, 11:04 pm

Re: More on power as I mentioned above

Here's one place where C2 gives you the equation for Watts:

https://www.concept2.com/indoor-rowers/ ... calculator

Formulas Used

distance = (time/split) * 500
split = 500 * (time/distance)
time = split * (distance/500)
watts = 2.8/(split/500)³

As you can see, watts are proportional to 1 / (split time)^3

So to get even small reductions in split time you have to significantly increase your power. (The force due to drag is proportional to the velocity squared, and the power required is proportional to the velocity cubed.)

Have fun !!!

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Re: Relationship between split time and stroke rate

Post by jamesg » November 16th, 2020, 2:29 am

What would the preferred way of increasing speed be?
Deliver more power to the handle.

Power is an engineering term that = Force x Speed. It's also = Force x Length / Time.

Afloat or on erg this power will be in the form of our stroke length, handle force and speed, and rating (spm). Start with length and style, it has to be learnt anyway, and is needed to make it relatively easy to do work on the handle, using the legs for maximum effect.

All the rest is very hard work and will come. Keep it easy on low drag to start with. This is what it looks like:

https://www.youtube.com/watch?v=Pf84O5cTWY4
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Re: Relationship between split time and stroke rate

Post by JotaBg » November 16th, 2020, 4:31 am

Hello guys,
I really appreciate all this feedback, it's really valuable. I have read all the posts a couple of times but I will have to come back to them from time to time to brush up on all the concepts! I will definitely concentrate on technique and taking things slowly, but I just had a few key questions that my curiosity needed answers for.

I only have a final question, that perhaps someone smarter would be able to infer from your replies, but I cannot seem to connect the dots. I will illustrate it with an example.

It's clear to me now that split time (pace) is directly related to power. Watts are converted into Split time using a formula. Everything good there.

But here my example:

Let's imagine that we have two rowers, A and B, that need to row 2000m.

- Rower A keeps a constant pace of 2:00/500 m (202.5 W)
- Rower B keeps the same constant pace, 2:00/500m (202.5W)

Since both rowers keep the same constant pace and power (every stroke they execute, they get the same W), they both would complete the 2000m in 8 minutes

However, let's imagine that Rower A applied that constant pace/power at a stroke rate of 20 strokes per minute, while Rower B applied it at a stroke rate of 30 strokes per minute.

The question is: how can it be that they complete that given distance at the same time? Wouldn't Rower B finish first since he applied the same power (202.5W) 30 times per minute vs 20?

I don't know if I am explaining it well so that you can understand where I want to get at, but for me, there is something counterintuitive in this example.

I promise that that's my last question, for now, :D
I really appreciate all the time that you guys are taking to answer.

Many thanks!
J

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Re: Relationship between split time and stroke rate

Post by hjs » November 16th, 2020, 4:41 am

Try it yourself. Use 1 min for example.

The point your missing is that the pm does not care about rating, yes it does show it but its of zero interest on the watts or pace.

In your example. Same pace at rate 30 and rate 20. This means the rower at 20 gives more energy per stroke.

Compare it to running, you can run and take short strides or longer ones, or you could even take jumps and in all cases go at tge same speed.

A good way to the feel is to do the following. Start rowing at a doable pace. Keep that pace contant, every 1 minute, keep the pace alike, but try to lower the rating with 1 some.
So say 28,27,26....etc. After you have done this you know exactly what is going on.

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Re: Relationship between split time and stroke rate

Post by Ombrax » November 16th, 2020, 4:42 am

Rower A will be applying much more force at the handle than Rower B.

The total work done will be the same (ignoring effects like drag on the person's body, that the erg can't measure).

A will apply a large force less often
B will apply a lower force more often

Pace will be the same.

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