Abstract
IntroductionThe Concept 2 (C2) rowing ergometer is used worldwide for home-based training, official competitions, and performance assessment in sports and science. Previous studies reported a disparate underestimation of mechanical power output positively related to an unclearly defined stroke variability. The aim of this study was to quantify the accuracy of the C2 while controlling for the potentially influencing variables of the rowing stroke by using a test rig for air-braked rowing ergometers and thus excluding biological variability.MethodsA unique motorized test rig for rowing ergometers was employed. Accuracy was assessed as the difference in mechanical power output between C2 and a reference system during steady (i.e., minimal variations of stroke power within a series of 50 spacemark, no -strokes) and unsteady simulated rowing (i.e., persistent variations during measurement series) while manipulating the stroke variables shape, force, or rate.ResultsDuring steady simulated rowing, differences between C2 and the reference system ranged 2.9–4.3%. Differences were not significantly affected by stroke shapes (P = 0.153), but by stroke rates ranging 22–28 min−1 (P < 0.001). During unsteady simulated rowing with alterations of stroke force and rate, mean differences of 2.5–3.9% were similar as during steady simulated rowing, but the random error increased up to 18-fold. C2 underestimated mechanical power output of the first five strokes by 10–70%. Their exclusion reduced mean differences to 0.2–1.9%.ConclusionDue to the enormous underestimation of the start strokes, the nominal accuracy of the C2 depends on the total number of strokes considered. It ranges 0.2–1.9%, once the flywheel has been sufficiently accelerated. Inaccuracy increases with uneven rowing, but the stroke shape has a marginal impact. Hence, rowers should row as even as possible and prefer higher stroke rates to optimize C2 readings. We recommend external reference systems for scientific and high-performance assessments, especially for short tests designs where the start strokes will have a major impact.
Highlights
The Concept 2 (C2) rowing ergometer is used worldwide for home-based training, official competitions, and performance assessment in sports and science
The C2 was designed as a training device, but is used by training centers and rowing federations around the world (Smith and Hopkins, 2012) for performance testing to reduce the influence of environmental conditions, which are difficult to control and greatly affect on-water performance (Kleshnev, 2009; Smith and Hopkins, 2011; Malcata and Hopkins, 2014)
A 100 Hz odometer (Limes L120/B1, Kübler, Villingen-Schwenningen, Germany) captures the displacement of the chain. These sensors allow for the exact calculation of mechanical work, which— divided by the duration of the rowing cycle—allows to calculate mechanical power output of the reference system (PREF)
Summary
The Concept 2 (C2) rowing ergometer is used worldwide for home-based training, official competitions, and performance assessment in sports and science. The direction of movement is reversed and the rower moves forward to the starting position (i.e., recovery phase). During this phase the flywheel decelerates due to the resistance of the circulated air, but it does not stop immediately. That is due to the rotating mass of the flywheel and the energy stored This phenomenon is similar to the momentum of an already accelerated rowing boat. In an air-damped ergometer such as the C2, it is the rower who determines resistance via stroke force, rate, and length and thereby the accuracy of the targeted mechanical output
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