de Zee, Mark

Klitgaard, Kent Kongsøre

Kristiansen, Mathias Vedsø

Lauridsen, Hanne Bloch

English

    Aalborg UniversitetUsing impulse to measure intensity during on-water kayakingde Zee, Mark; Kristiansen, Mathias Vedsø; Lauridsen, Hanne Bloch; Klitgaard, KentKongsørePublication date:2022Document VersionOther versionLink to publication from Aalborg UniversityCitation for published version (APA):de Zee, M., Kristiansen, M. V., Lauridsen, H. B., & Klitgaard, K. K. (2022). Using impulse to measure intensityduring on-water kayaking. Abstract from VIII International Congress of Coaches of Sprint Canoeing 2022,Pontevedra, Spain.General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            - Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            - You may not further distribute the material or use it for any profit-making activity or commercial gain            - You may freely distribute the URL identifying the publication in the public portal -Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: December 05, 2022Using impulse to measure intensity during on-water kayaking Mark de Zee1*, Mathias Kristiansen1, Hanne Bloch Lauridsen2, Kent Klitgaard1 1Sport Sciences – Human Performance and Technology, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark 2Team Danmark (Danish Elite Sports Institution), Copenhagen, Denmark. *Presenter Abstract BACKGROUND: Mobile power meters in cycling have been around since the 1980’s and provide a reliable and valid measure of the cyclists’ power output [1]. The cyclists’ power output is an objective measure of intensity and is independent of the weather conditions and slope. Moreover, it does not have a time delay like a physiological measure (e.g. heart rate). In cycling it is relatively straightforward to calculate the power by measuring the torque on the crank and the angular velocity given by cadence using the following equation: 𝑃 = 𝑇 ∙ 𝜔 Where P is the power, T is the torque on the crank and 𝜔 is the angular velocity. In kayaking, however, the measurement of power as an objective measure of intensity is a lot more complicated. Here, one would use the linear form of power: 𝑃 = 𝐹 ∙ 𝑣 Here, P is again the power, F could either be the paddle force or the force on the footrest. And v is the velocity. The question is though, the velocity of what? A logical choice would be the velocity of the kayak itself. However, the velocity of the kayak is heavily influenced by environmental conditions. Therefore, we would not obtain an objective measure of the athlete’s intensity. The company One Giant Leap claim to measure power in the paddle, but the algorithm used for determining velocity is confidential and not transparent, which makes it difficult to interpret their measures. An alternative could be to calculate the impulse of the paddle force or footrest force over a certain time period. Klitgaard et al. [2] showed a high correlation between the impulse over 10 seconds of the footrest forces and the velocity of the kayak.  In this work, we propose an alternative method to measure the intensity of a kayaking athlete using impulse. METHODS: One male national athlete (Age: 20; Body mass: 91.5 kg; Height: 179.5 cm) participated  in this study. The athlete did an all-out effort on a 500m on-water kayak sprint. Paddle forces, footrest forces, and velocity were obtained with a sample rate of 100 Hz using the E-kayak system (APlab, Rome, Italy). Bonaiuto et al. [3] has previously described this system in more detail. The paddle forces have both positive and negative values, where the negative values are from the right paddle and the positive ones are from the left. The impulse was calculated as a moving integral of the absolute paddle force values over a window of 5 seconds using the following equation: 𝑱𝟓𝒔 = ∑ |𝐹𝑖,𝑝𝑎𝑑𝑑𝑙𝑒|𝑖+𝑆∙∆𝑡𝑖∙1𝑆  Here,  𝑱𝟓𝒔 is the impulse over 5 seconds, S is the sample rate (in this case 100 Hz),  |𝐹𝑖,𝑝𝑎𝑑𝑑𝑙𝑒| is the absolute paddle force of the ith sample, and ∆𝑡 is the window we integrate over (in this case 5 s). In this way a vector is created, where each element is the impulse of the previous 5 seconds. The impulse will be reported in N⋅s. RESULTS: The athlete paddled the 500 meter in 115 s. Figure 1 shows how the impulse of the paddle forces over 5 seconds changes during the 500 m. Moreover, the velocity has been plotted.  Figure 1: The blue line indicates the development of the impulse of the paddle forces over a window of 5 seconds during an all-out effort over 500 meters. The red line is the velocity. DISCUSSION: In this study, we propose to use the impulse of the paddle forces integrated over a window of 5 seconds as a direct measure of the intensity of a kayak athlete. The advantage of using impulse is that the calculation is straightforward, transparent, and mechanically sound. The calculation of impulse is based on the forces delivered by the athlete and is, therefore, independent of environmental conditions. The velocity in figure 1 shows the same development as the 5-second impulse. In a future test setup the same athelete could produce the same impulse in headwind or tailwind, but the velocity would differ between the two conditions.  The impulse was calculated over a window of 5 seconds. Different time intervals where tested, however, it seems that 5 seconds is long enough to contain several strokes and it is short enough to reveal changes over time. The choice of the length of this window is something the kayak community should agree on to make comparisons over time and between athletes. The interpretation of power output is well developed and accepted by coaches in the cycling world. The interpretation and acceptance of impulse as an intensity measure will need time and more athlete data before kayak athletes and coaches will use it. However, we believe there is great potential that in the kayak community, impulse could be used as an intensity measure like power output is used in the cycling community using wearable devices. Acknowledgements The Novo Nordisk Foundation and Team Danmark funded this work. References 1. L. Passfield, JG. Hopker, S. Jobson, D. Friel & M. Zabala (2017) Knowledge is power: Issues of measuring training and performance in cycling, Journal of Sports Sciences, 35:14, 1426-1434, DOI: 10.1080/02640414.2016.1215504 2. Klitgaard, K. K., Rosdahl, H., Brund, R. B. K., Hansen, J., & de Zee, M. (2021). Characterization of Leg Push Forces and Their Relationship to Velocity in On-Water Sprint Kayaking. Sensors, 21(20), [6790]. https://doi.org/10.3390/s21206790  3. Bonaiuto V, Gatta G, Romagnoli C, Boatto P, Lanotte N & Annino G. (2020) A Pilot Study on the e-Kayak System: A Wireless DAQ Suited for Performance Analysis in Flatwater Sprint Kayaks. Sensors, 20(2): 542. https://doi.org/10.3390/s20020542  

Using impulse to measure intensity during on-water kayaking

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Using impulse to measure intensity during on-water kayaking

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