05 Apr Connie Draper – Why use Biomechanics ?
On the 26th of March 2017 we ran a workshop at Shiplake College in which Conny Draper discussed the power of telemetry. Conny also showed people how best to set up the system, explaining the common mistakes people make when using Telemetry.
Conny travels the world and works with many international teams and universities. Her insights and explanations were excellent. I certainly learned quite a bit.
Conny spoke about windows of opportunity in the rowing stroke. These are areas of the stroke where you can gain considerable speed without having to go to the gym.
The windows of opportunity are:
- At the catch
- At the finish
- When the boat begins to decelerate
It became very clear that power measured on the gate is a useful yet crude number. The better number is the net force on the boat.
“Net force is when the force on the gate is greater than the force on the foot stretcher”
On the recovery the force on the foot stretcher is greater than the force on the gate. This will be the case until you cover the blade in the water. But even then if you apply a lot of upward movement with your body near the beginning of the stroke you will increase the stretcher force so that it is temporarily greater than the force on the gate.
The consequence of the stretcher force being greater than the gate force you decelerate the hull.
“Deceleration on the hull occurs when the foot stretcher force is greater than the gate force”
Deceleration of the hull is something you need to minimize, especially on the recovery. By adding pressure onto your foot stretcher as late as possible you will minimize your negative effect on the hull. As soon as that force is on the stretcher the boat is decelerating.
Once you get to full compression, your legs will automatically fire down, this adds a lot of pressure onto your foot stretcher. If your blade is still in the air at this point you are not going to win many races.
The implication was that in order to achieve this you need good preparation on the recovery. Being in the correct positions at the right time is crucial.
Well not really as there are many factors that can affect the timing at the front. One that Conny was very keen on was handle speed on the recovery. If the speeds within the crew are not synchronized the effects are devastating. The challenge for this comes especially as the ratings increase. At r. 20 the ratio of the stroke is about 1:3, in racing it is more like 1:2. The change in time taken for the drive phase is negligible. But the recovery time is about half. So at race pace you have much less time to get your movement right on the recovery, but about the same time to sequence our drive.
Conny then proceeded to show the delegates how to use the power line system that Peach provides for analyzing the data.
By the end we had had our brains well and truly fried. It was hugely informative and enjoyable. The coaches who attended all said they found it useful.
We hope to run a few more of these in the future.