Concept2 Forum

The figure above is taken from a paper published recently in a physiology science journal. I will discuss the paper below. But I like to start with a teasing questions that gets to the core of the paper:
The figure shows a rowing cycle. Suppose that for some reason you want to include a 2 sec pause in the cycle. You have the choice to pause either at the finish position (A in fig.1) or at the catch position (C in fig.1), but the aim is to get the best possible performance (time or distance) under this particular choise. In other words: which pause has the lowest performance penalty? Please write down your choise and the argument(s) for it.

The paper is titled 10% Higher Rowing Power Outputs after Flexion-Extension-Cycle Compared to an Isolated Concentric Contraction in Sub-Elite Rowers published in Frontiers in Physiology, 2020. The authors are three German scientists in Physiology and Exercise Training. They have published more papers recently with intriguing titels, like Low intensity rowing with blood flow restriction over 5 weeks increases V̇O2max in elite rowers: A randomized controlled trial, in the Journal of Science and Medicine in Sport (2020). These papers are peer-reviewed, so this is not some frankencrank stuff.

The paper can be downloaded freely, but I didn't find it easy to read. One of the reasons is that I am not familiar with the distinction between concentric contraction and eccentric contraction of muscles. Only recently I have learned about Plyometrics. Plyometrics is a term for exercises that stretch and then shorten the muscle to accelerate the body or limb. It is a buzz word in physiology and in training. It often helps understanding by giving an example:

In 2-leg jumping there is the squat jump and the countermovement jump. In the squat jump (bottom sequence in figure below), the movement starts from a stationary squatted position. The countermovement jump (top sequence) starts from a upright position, going rapidly through the knees followed directly by a jump. It turns out the the coutermovement jump is more forceful, leading to a greater jump height and a longer time of flight. Differences of 18-20% have been shown. The explanation is that the leg muscles behave elastically for rapid movements. The sequence of an eccentric contraction (leg muscle rapidly stretched) followed directly by a shortening to accelerate the body upward, is called a stretch-shortening cycle. We perform such a stretch-shortening cycle in the transition from recovery (slide in the Fig. 1) to the drive. In another topic, I have argued that the rowing cycle has more similarity to a (horizontal) countermovement jump than to a deadlift.



You cannot find the answer to my teasing question directly in the paper. The authors compared three different isolated rowing drives starting from a complete standstill of the flywheel. This is certainly not the case after a 2 sec pause. But the essence, if I read the paper correctly, is that the motions of the slide (recovery) and the drive should be uninterrupted to conserve energy and optimize performance.

In fact this paper is also relevant for another long-standing question : is the kinetic energy built up in the recovery (½ m v²) completely lost at the catch or can it be used to some extend in the drive? The paper shows that in a rapid stretch-shortening cycle muscles behave as springs and can store energy.

I am very interested to hear the argument(s) for your choise.

Easy: a pause at the release/finish. A pause at the catch would be absurd.

I agree a pause at the catch would make no sense, as there is a benefit in the quick transfer of kinetic power from a forward to a backward direction.

High jumpers always run to the bar, but how that energy gets transferred from horizontal to vertical is unclear, at least to me.

Pole jumpers go much higher, and there we can see the pole flexing and releasing; but the energy of the runner when approaching the bar will be similar.

Missed the point and decided pausing at back stops better as muscles and breathing less strained. I think there would actually be effort required to hold the catch position so definitely a bad idea!

Not read the paper, but from your description it suggests that accelerating into the catch might be of benefit!

iain wrote: ↑

March 1st, 2021, 10:13 am

Not read the paper, but from your description it suggests that accelerating into the catch might be of benefit!

It is a short acceleration, but I do exactly that with lower stroke rate sessions. It's a natural instinct for me.

Why not a pause mid-recovery? This is a common rowing (OTW) drill to work on sequence and balance. Actually, drills involving pauses at every phase of the stroke (except mid-drive) are done for those reasons. In a race situation, no pause is good; transitions as smooth as possible to get the most "run" on the boat.

I assume your question is an academic one, so a pause at the finish would have less penalty. Comparing the catch to your vertical jump example, a slight acceleration into the catch would compress the springs, if you will, and provide a more powerful drive out of the catch. No pause there.

Stopping between eccentric and concentric takes two extra actions, stop and restart. This is less efficient and also slower than the continuous transition we use at the catch when erging. Same effect in jumps with and without pause.

Elasticity is a property of matter, and properties cannot be switched off and on at will. Muscles are drivers, and their action is chemistry, so whenever used burn something. Thinking we can bounce could be a fatal delusion.

iain wrote: ↑

March 1st, 2021, 10:13 am

Not read the paper, but from your description it suggests that accelerating into the catch might be of benefit!

Yes, I also think that a quick deceleration before the catch and a steep acceleration thereafter is beneficial, or a high rating.


The participants in the study were asked to generate maximum power for each measurement trial. Each measurement was a single stroke. Figure 3C in the paper shows about 1200J per stroke (= 20 W min/stroke).

jamesg wrote: ↑

March 1st, 2021, 2:32 am

High jumpers always run to the bar, but how that energy gets transferred from horizontal to vertical is unclear, at least to me.

Pole jumpers go much higher, and there we can see the pole flexing and releasing; but the energy of the runner when approaching the bar will be similar.

This video should explain the high jump power transfer. Watch it to the end, even if you can’t understand German you’ll get the point.

https://youtu.be/HspzxKXhpzk

Closeup of the Fosbury technique indicates the human pogo stick is a real ankle cruncher. Looked up the associated pathology. Laundry list of striking force injuries feet and torsional injury knees.

A pause at the catch would be the best. The reason is at the finish, there would be a tendency to continue to contract the power generating muscles, interfering in their rest. Pausing at the catch would allow those muscle additional rest so they could generate more power during the power phase, all things being equal.

eccentric contraction of a muscle is contraction while lengthening. Concentric contraction is contraction while shortening. You are doing concentric contraction bringing the drink up to your lips and eccentric contraction putting the drink down.

That is an interesting paper. There are a couple of ways to explain that data. The most obvious one to me is not what I proposed before reading the paper but that the "precontraction" allows for an earlier application of power when the efficiency of the hip joint is higher. A rapid catch is better than a mushy one it would seem.

frankencrank wrote: ↑

March 24th, 2021, 11:16 pm

A pause at the catch would be the best. The reason is at the finish, there would be a tendency to continue to contract the power generating muscles, interfering in their rest. Pausing at the catch would allow those muscle additional rest so they could generate more power during the power phase, all things being equal.

eccentric contraction of a muscle is contraction while lengthening. Concentric contraction is contraction while shortening. You are doing concentric contraction bringing the drink up to your lips and eccentric contraction putting the drink down.

This is contradictory to one of the first sporty thing I recall being taught, and proved time and again since. If a pause at the catch is best then why can everyone jump higher by ‘bouncing’ into a vertical jump rather than starting in a static crouched position?

Tony Cook wrote: ↑

March 25th, 2021, 6:45 am

frankencrank wrote: ↑

March 24th, 2021, 11:16 pm

A pause at the catch would be the best. The reason is at the finish, there would be a tendency to continue to contract the power generating muscles, interfering in their rest. Pausing at the catch would allow those muscle additional rest so they could generate more power during the power phase, all things being equal.

eccentric contraction of a muscle is contraction while lengthening. Concentric contraction is contraction while shortening. You are doing concentric contraction bringing the drink up to your lips and eccentric contraction putting the drink down.

This is contradictory to one of the first sporty thing I recall being taught, and proved time and again since. If a pause at the catch is best then why can everyone jump higher by ‘bouncing’ into a vertical jump rather than starting in a static crouched position?

Indeed, a pauze will remove some of the stored elastic energy and waist energy. A pauze will also slow the rate down, which has to e compensated by either using a more forcefull stroke or increesing the movement of the other part of the stroke. Both will not be efficient.