Practical implications of seat synchronisation
Did you know that: Lack of synchronization is counterproductive for the entire crew, as it increases total inertial losses, makes force application less comfortable, and decreases overall efficiency, power production, and rowing speed of the crew.
After our two previous newsletters in February and March 2024 on the synchronization of seat movements, we've received several questions with a common theme: 'How should rowers feel when they are out of sync with their crew? For instance, if they are late, does it make it harder for them to pull through?”
The Handle Drag Factor (HDF) was developed as a universal 'burden factor': a higher HDF indicates that more force/power is required to pull the handle at a certain velocity, or at a fixed force/power, the handle velocity is lower. The correlation of HDF with seat timing during recovery (T1) and at the catch (T3) within the crew was negative and significant. This means that it feels lighter to pull the handle for rowers who start later, and for 'early starters,' it feels heavier.
However, a lighter HDF for later rowers does not necessarily means that rowing is easier for them. It means that they apply force later during the drive, when the handle velocity is already high, requiring more power from them.
Later rowers should feel like they are 'losing ground' under their feet during the catch, which requires more effort from them to change direction and accelerate their mass, making it more difficult to apply force to the handle. This additional stretcher force is transferred through the boat and applied to the oars of 'early starters', who feel 'firm ground' at the stretcher during the catch and experience a faster increase in force at lower handle velocity, resulting in less power expended.
The amount of extra energy required to overcome inertia (Einert) increases with the stroke rate. The lowest values of Einert were found at stroke rates of 20-28 spm (6-8% of WpS), and at higher rates, it increases to 10-11%. This is likely a factor limiting the increase of racing stroke rates. Sweep rowers spend 1.3% more energy to overcome inertia than scullers. Interestingly, longer catch angles had a positive effect on inertial efficiency, while finish angles had no effect.
'How does synchronization affect rowing technique, such as the force curve?' A comparison of the force curves of the stroke rower reveals that rowers are much more 'front-loaded' in a well-matched pair, produce higher average force and work per stroke (WpS). Lack of synchronisation leads to 30%: higher inertial losses in late rowers. These losses are not balanced by higher inertial efficiency of “early starters”: each rower lost 1% more energy in overcoming inertia as a consequence of poor seat synchronization.
In recent times, measurement systems have become increasingly prevalent in rowing, as well as in other sports. Frequently, the data obtained from these systems is utilized for selecting rowers for a crew. However, the information above clearly underscores the need for coaches to exercise caution when relying solely on telemetry data for crew selection. While it's true that significantly stronger rowers would typically exhibit good numbers regardless of timing within a crew, this should be common knowledge for coaches, with or without telemetry. However, in cases where there's only a marginal difference between rowers (which is often the scenario), 'early starters' can unintentionally or intentionally manipulate their data, especially if they are privy to information such as that found in our newsletters. Biomechanical measurements should primarily serve the purpose of improving rowing technique, and selection should be based on races in small boats and objective 'seat racing'.
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©2024 Dr. Valery Kleshnev