NK's Partnership with BioRow
The EmPower Oarlock is the result of a collaboration between NK and Valery Kleshnev, founder and director of BioRow. BioRow is a rowing biomechanics research and consultancy firm known for producing both in-depth rowing technique analysis and dozens of medals in international competitions. NK has worked with Dr. Kleshnev since 2014 to merge BioRow approaches to measuring and quantifying complex rowing biomechanics with NK's industry-leading rugged rowing technology and user-friendly SpeedCoach GPS. NK will continue to work with Dr. Kleshnev to take full advantage of BioRow technology, knowledge, and analysis tools as the EmPower Oarlock progresses.
How do we measure force?
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The EmPower Oarlock core is a specially designed load cell incorporating multiple strain gauges. The force of the oar during the drive on the face of the oarlock deforms the load cell, generating a strain measurement. This measurement is converted to a Force (Fgate), based on factory calibration values. The Wheatstone Bridge strain gauge configuration helps compensate for temperature variations.
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Force at the handle (Fhandle) is calculated using the equation shown, and is a function of the oar length, inboard length, location of force on the handle and location of force on the blade.
Sculling: a=6cm | b=22.5cm
Sweep: a=15cm | b=27.5cm |
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How do we measure work?
Work is force times distance. In rowing, work per stroke is the average force times the arc length of the oar's travel. We calculate this by integrating work measurements over very short periods of time during the drive. For these short intervals, we multiply the average force times the arc length covered by the oar handle. Work per Stroke is the sum of these work measurements during the drive.
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How do we measure power?
Power is work per unit of time. In rowing, power is the Work per Stroke divided by the Time per Stroke. While we use Work per Stroke as calculated on the drive, we use the Time per Stroke for the entire stroke cycle. This is done to account for physiological recovery which occurs during the stroke cycle, whereas the work is done primarily on the drive.
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How do we measure angle?
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1. The catch is defined as the location where the oar changes direction.
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2. Lock occurs when the force reaches 200N for sweep or 100N for sculling. Slip is the difference between Catch and Lock angles.
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3. The location of Peak Force is the angle at which the maximum force occurs during any given stroke.
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4. Unlock occurs when the force drops below 200N for sweep or 100N for sculling. Wash is the difference between Unlock and Finish angles.
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5. The finish is defined as the location where the oar changes direction.
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6. An angle of 0° is defined as when the oar handle is perpendicular to the boat. By convention, the oar handle rotated toward the stern is considered a negative angle (typical for the catch), and the oar handle rotated toward the bow is considered a positive angle (typical for the finish).
