Mechanical power output in rowing should not be determined from oar forces and oar motion alone

Hofmijster, Mathijs J.; Lintmeijer, Lotte L.; Beek, Peter J.; Soest, A. J. “Knoek” van

doi:10.1080/02640414.2018.1439346

Cited by 11 publications

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“…Acceptable levels of validity have been established for measures of rowing velocity from Catapult GPS units (Smith and Hopkins, 2012) and for force and oar angle by Peach instrumentation systems (Coker et al, 2009). Power provided by the Peach instrumentation system represents a proxy measure of the true mechanical power output (Hofmijster et al, 2018). Venue environmental conditions (collected at 1 min intervals from six weather stations positioned at water level along the 2,000 m course) were: 22.8 ± 2.1 • C air temperature (mean ± SD), 26.0 ± 1.3 • C water temperature, 59.0 ± 10.3% relative humidity, and 1.4 ± 0.6 m•s −1 wind speed, in a predominantly cross-tail direction on stroke side.…”

Section: Methodsmentioning

confidence: 99%

Technical Determinants of On-Water Rowing Performance

Holt

Aughey

Ball

et al. 2020

Front. Sports Act. Living

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Purpose: Research establishing relationships between measures of rowing technique and velocity is limited. In this study, measures of technique and their effect on rowing velocity were investigated.Methods: Ten male singles, eight female singles, three male pairs, and six female pairs participated. Data from each stroke for forty-seven 2,000 m races were collected using Peach PowerLine and OptimEye S5 GPS units. General linear mixed modeling established modifying effects on velocity of two within-crew SD of predictor variables for each boat class, with subsequent adjustment for power, and for power and stroke rate in separate analyses. Twenty-two predictor variables were analyzed, including measures of boat velocity, gate force, and gate angle. Results were interpreted using superiority and inferiority testing with a smallest important change in velocity of 0.3%.Results: Substantial relationships with velocity were found between most variables assessed before adjustment for power, and for power and stroke rate. Effect magnitudes were reduced for most variables after adjustment for power and further reduced after adjustment for stroke rate and power, with precision becoming inadequate in many effects. The greatest modifying effects were found for stroke rate, mean and peak force, and power output before adjustment, and for catch angle after adjustment for stroke rate and power. Substantial between-crew differences in effects were evident for most predictors in some boat classes before adjustment and in some predictors and some boat classes after adjustment for stroke rate and power.Conclusion: The results presented reveal variables associated with improvements in rowing performance and can be used to guide technical analysis and feedback by practitioners. Higher stroke rates and greater catch angles should be targeted to improve rowing performance, and rower force development for the improvement of power output. Relationships between rowing technique and velocity can be crew-dependent and are best assessed on an individual basis for some variables.

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Section: Methodsmentioning

confidence: 99%

Technical Determinants of On-Water Rowing Performance

Holt

Aughey

Ball

et al. 2020

Front. Sports Act. Living

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“…Kleshnev determined power output using forces at the foot stretcher and the oarlocks. Since those forces are high and opposing, this approach is very sensitive to errors in the measurements (Hofmijster et al, 2018). In order to reduce these potential errors we replaced foot stretcher forces and determined power output using the common proxy and the power term that is related to the rower's CoM acceleration (P residual ).…”

Section: Discussionmentioning

confidence: 99%

“…Simulation results suggest (Hofmijster et al, 2018) that P residual is a non-negligible part of P rower . However, the precise value of P residual is currently unknown, as well as its potential dependence on rower characteristics and rowing conditions.…”

Section: Introductionmentioning

confidence: 90%

“…However, as is addressed before by Kleshnev (Kleshnev, 2002), using this "common proxy" (Equation (2)) results in an underestimation of a rower's true average mechanical power output per stroke cycle. In a previous article (Hofmijster, Lintmeijer, Beek, & Van Soest, 2018), we have shown on theoretical grounds that this true power output of a rower averaged CONTACT Lotte L. Lintmeijer l.l.lintmeijer@vu.nl Amsterdam Movement Science, Vrije Universiteit Amsterdam, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands over a stroke cycle (P rower ) is related to the common proxy (P proxy ), but that it differs from the common proxy with an amount that we will refer to as the residual power output (P residual ). This P residual is related to the mass of the rower (m r ), the rower's centre of mass (CoM) acceleration (a rcom/w ), and the velocity of the boat (v b/w ) according to:…”

Section: Introductionmentioning

confidence: 93%

“…P rower was calculated according to classical Newtonian mechanics (see Hofmijster et al (2018) for an extended overview):…”

Section: W P Proxymentioning

confidence: 99%

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Improved determination of mechanical power output in rowing: Experimental results

Lintmeijer

Hofmijster

Fischedick

et al. 2018

Journal of Sports Sciences

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In rowing, mechanical power output is a key parameter for biophysical analyses and performance monitoring and should therefore be measured accurately. It is common practice to estimate on-water power output as the time average of the dot product of the moment of the handle force relative to the oar pin and the oar angular velocity. In a theoretical analysis we have recently shown that this measure differs from the true power output by an amount that equals the mean of the rower's mass multiplied by the rower's center of mass acceleration and the velocity of the boat. In this study we investigated the difference between a rower's power output calculated using the common proxy and the true power output under different rowing conditions. Nine rowers participated in an on-water experiment consisting of 7 trials in a single scull. Stroke rate, technique and forces applied to the oar were varied. On average, rowers' power output was underestimated with 12.3% when determined using the common proxy. Variations between rowers and rowing conditions were small (SD = 1.1%) and mostly due to differences in stroke rate. To analyze and monitor rowing performance accurately, a correction of the determination of rowers' on-water power output is therefore required.

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An accurate estimation of the horizontal acceleration of a rower's centre of mass using inertial sensors: a validation

Lintmeijer

Faber

Kruk

et al. 2018

European Journal of Sport Science

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For a valid determination of a rower's mechanical power output, the anterior-posterior (AP) acceleration of a rower's centre of mass (CoM) is required. The current study was designed to evaluate the accuracy of the determination of this acceleration using a full-body inertial measurement units (IMUs) suit in combination with a mass distribution model. Three methods were evaluated. In the first two methods, IMU data were combined with either a subject-specific mass distribution or a standard mass distribution model for athletes. In the third method, a rower's AP CoM acceleration was estimated using a single IMU placed at the pelvis. Experienced rowers rowed on an ergometer that was placed on two force plates, while wearing a full-body IMUs suit. Correspondence values between AP CoM acceleration based on IMU data (the three methods) and AP CoM acceleration obtained from force plate data (reference) were calculated. Good correspondence was found between the reference AP CoM acceleration and the AP CoM accelerations determined using IMU data in combination with the subject-specific mass model and the standard mass model (intraclass correlation coefficients [ICC] > 0.988 and normalized root mean square errors [nRMSE] 3.81%). Correspondence was lower for the AP CoM accelerations determined using a single pelvis IMU (0.877 < ICC < 0.960 and 6.11% < nRMSE < 13.61%). Based on these results, we recommend determining a rower's AP CoM acceleration using IMUs in combination with the standard mass model. Finally, we conclude that accurate determination of a rower's AP CoM acceleration is not possible on the basis of the pelvis acceleration only.

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Mechanical power output in rowing should not be determined from oar forces and oar motion alone

Cited by 11 publications

References 11 publications

Technical Determinants of On-Water Rowing Performance

Technical Determinants of On-Water Rowing Performance

Improved determination of mechanical power output in rowing: Experimental results

An accurate estimation of the horizontal acceleration of a rower's centre of mass using inertial sensors: a validation

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