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Technical and Rhythmical Rowing in Zagreb

Measuring the Rowing Performance of the Best

Last week our Quiske field-testing team consisting of Pentti and myself visited the oldest rowing club in Croatia to measure their talented rowers on the 2km course on Lake Jarun in Zagreb.

The 2km rowing course on Lake Jarun

We met the rowers at the boat house at 7am on Friday morning and started setting up our Rowing Performance system without further ado as soon as we had introduced ourselves to Nikola Bralic, the well respected coach, most famous for having coached the Sinkovic brother's from junior rowers all the way to Olympic Gold.

Setting up the Rowing Performance system on the boat and oars

The phone running the Quiske Rowing Performance App needs to be attached rigidly to ensure high quality data and here we're doing it in about a minute while Nikola is watching. The oar sensor must also be attached carefully but strapping it on to the oar takes less than a minute.

First we measured Teuta Stojakovic, and incredibly strong promising young female rower.

our first rowing technique measurement in Croatia

Next we met with Martin Sinkovic himself and we were pretty much in awe when we saw the agile way he is handling his boat and oars. Martin Sinkovic pulled off to do a piece on Lake Jarun but soon returned to have us swap the sensor, the connection of which for some reason was lost... Martin is a truly inspiring rower with awesome patience too. A minute later and Martin and his fixed sensor were off for a 4km session back and forth on the course.

Martin Sinkovic and the Quiske Rowing Performance sensor on his oar

We measured how Martin was handling his right oar and the timing of his catch as a function of the boat acceleration.

The Rowing Performance sensor sits right next to the oarlock

Measuring sweep rowing was a first for the Quiske team and we're lucky to get to measure two junior pairs. It was really interesting for us to get to see the shape of the oar flight path and to compare it with that of a sculling oar.

The Rowing Performance system can measure also sweep rowing technique

The rower can choose to have one or two sensors placed on either oar or the seat. However, due to the high frequency of the data collected by the sensor, each sensor requires a phone of their own for receiving (BLE) and crunching the data. Below Mihael whose both oars were measured simultaneously and hence two phones two receive the data, and a SpeedCoach to verify the basic SPM, distance and speed data also measured by our App ;-).

Having sensors on right and left oars means that two phones are needed

When rowing you can choose between seeing a set of numerical metrics, or then you can see graphs showing the oar, seat or boat behavior during the time of each previous stroke. Based on discussions with rowers who have tried our system, it seems that most prefer the main numerical metric screen with very simple information, and that the graphs are more useful to analyze in detail afterwards. Below the main numerical metric screen, showing basic feedback on SPM and speed but also the total stroke angle of the left and right oars in the bottom right tiles of the screen. The stroke angle decreases as a function of SPM but seeing the angle in real time can help the rower make sure each stroke is as long as possible, every single consecutive stroke.

broken image

The oar, seat and boat graphs are available for closer analysis after uploading the recorded session to the web portal. There you can study for example how the flight path changes in shape and how the total (horizontal) angle decreases as the SPM increases as shown below (blue at low SPM, red at high SPM).

The oar flight path shows the angles that the oar makes in the horizontal and vertical directions. The total horizontal angle decreases with rising stroke rate

It is interesting to compare rowing technique of one rower at different rate or speed but it is also enlightening to compare different rowers with each other, especially if they are meant to row together in one boat. The below shows the angular velocity of the oars of four different rowers all rowing single sculls at same rate. The x-axis shows the time of one stroke and positive velocity means the oar is moving towards the bow (drive direction) and negative means that the oar is in recovery. The catch happens when the velocity is 0 before the drive and it happens at different time for different rowers when measured with our cycle detection as reference. There's quite a lot to learn from this graph but I'll leave that for a separate post.

The performance graph shows the angular velocity of the oar during drive and recovery

We at Quiske are not coaches but merely rowers and physicists/engineers but after having compared the data from many different rowers we've picked up a thing or two. It really seems that the rowing stroke is a kind of a fingerprint of a rower and that a trained eye can recognize who is the rower behind a particular rowing graph. Also it seems that the best rowers do not necessarily have "text-book" acceleration graphs. It is especially interesting to do comparisons of data measured from multiple oars, be it left and right of the same rower, or two oars from members in a crew. We can pinpoint differences in timings of the catch, or in the shapes of the flight path, or the rhythm of the seat movements. We in the Quiske field testing team (Pentti and myself) compete as a crew in races ourselves and we've indeed found it useful to overlay oar and seat graphs of our own rowing to help us in our hunt for as synchronous technique as possible.

Looking at the results in the web portal after rowing

We had a quick look at the measured data in our web portal after measuring the rowers at Lake Jarun. We compared the oar lengths and oar angular motion of individual rowers at different SPM as well as different rowers with each other at same SPM.

It was enjoyable for two Finnish rowers being transferred from the subzero icy Helsinki to +23deg C sunny Zagreb, and also to just sit on the pier for a moment and watch the vibrant rowing community at Lake Jarun with junior crews aged 13 and upwards taking out their boats under the watchful eyes of their coaches and maneuvering them in the midst of a large number of more experienced crews. On our second day of our visit we had a chance to see the world's most talented rowers take measure of each other at a Regatta where the most awaited race was the Mens 1x with Martin Sinkovic taking the victory.

To make the trip perfect we also managed to borrow a double and do some quick outings ourselves. Rowing is a luxury for us during the season when the lakes are frozen back home, and this Winter our team has already managed to go rowing in the UK, Italy, Denmark and finally in Croatia so we're feeling quite lucky. During a few spare minutes in Zagreb we also put together our first tutorial video on how to install the Rowing Performance system before going on water:

Well, that was a video done with no preparation whatsoever and our team promises to produce a better tutorial as soon as we next time manage to go on water (this might take a while though...) Also at that time we promise to create an introduction into the analytics that our web portal can deliver.

During our two day trip we also managed to sneak in some time on the Ergo.

A world record Concept2

We visited the gym where the Sinkovic brothers train and Pentti hopped on the particular Concept2 which was used for the 6km world record: a stunning 18:03.1. Also we did some measurements with our Beta Rowing Performance system on the Ergo, measuring the rhythm of the seat and handle and Pentti was excitedly explaining how he is always looking to make the next stroke perfect :-). Below the analysis of a short indoor rowing piece showing quite nice rhythm (the dotted line shows the seat speed and the handle line is solid).

The Indoor Rowing Performance system gives feedback on rowing rhythm
The handle and seat speeds are shown overlaid to help find correct rowing rhythm

No matter if you're rowing indoors or are fortunate enough to do it outdoors the quest for getting into the right rhythm is similar, hunting for that feeling you get when you think you achieve a stroke which is rhythmically and technically close to perfection. And then trying to hang on to that feeling, and repeating stroke after stroke. We've discussed this feeling with many rowers, the feeling of finding the right rhythm and the hunt for that feeling...

Martin Sinkovic going rowing

Thank you Mladost HAVK for hosting us. We feel inspired. Would be a pleasure to be back as soon!