Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity
Striking velocity is a key performance indicator in striking-based combat sports, such as boxing, Karate, and Taekwondo. This study aims to develop a low-cost, accelerometer-based system to measure kick and punch velocities in combat athletes. Utilizing a low-cost mobile phone in conjunction with th...
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MDPI AG
2025-01-01
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| author | Lukas Pezenka Klaus Wirth |
| author_facet | Lukas Pezenka Klaus Wirth |
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| description | Striking velocity is a key performance indicator in striking-based combat sports, such as boxing, Karate, and Taekwondo. This study aims to develop a low-cost, accelerometer-based system to measure kick and punch velocities in combat athletes. Utilizing a low-cost mobile phone in conjunction with the PhyPhox app, acceleration data was collected and analyzed using a custom algorithm. This involved strike segmentation and numerical integration to determine velocity. The system demonstrated moderate reliability (intraclass correlation coefficient (ICC) <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo>,</mo><mn>1</mn></mrow></semantics></math></inline-formula> = <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.746</mn></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.786</mn></mrow></semantics></math></inline-formula>, standard error of measurement (SEM) = <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.488</mn></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.921</mn></mrow></semantics></math></inline-formula> m/s), comparable to commercially available systems. Biological and technical variations, as well as test standardization issues, were acknowledged as factors influencing reliability. Despite a relatively low sampling frequency, the hardware and software showed potential for reliable measurement. The study highlights the importance of considering within-subject variability, hardware limitations, and the impact of noise in software algorithms. Average strike velocities exhibited higher reliability than peak velocities, making them a practical choice for performance tracking, although they may underestimate true peak performance. Future research should validate the system against gold-standard methods and determine the optimal sampling frequency to enhance measurement accuracy. |
| format | Article |
| id | doaj-art-7cd552eab7b443959f9958cbcb6cebea |
| institution | Kabale University |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
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| series | Sensors |
| spelling | doaj-art-7cd552eab7b443959f9958cbcb6cebea2025-01-24T13:48:26ZengMDPI AGSensors1424-82202025-01-0125230710.3390/s25020307Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick VelocityLukas Pezenka0Klaus Wirth1Institute of Sport Science, University of Applied Sciences Wiener Neustadt, 2700 Wiener Neustadt, AustriaInstitute of Sport Science, University of Applied Sciences Wiener Neustadt, 2700 Wiener Neustadt, AustriaStriking velocity is a key performance indicator in striking-based combat sports, such as boxing, Karate, and Taekwondo. This study aims to develop a low-cost, accelerometer-based system to measure kick and punch velocities in combat athletes. Utilizing a low-cost mobile phone in conjunction with the PhyPhox app, acceleration data was collected and analyzed using a custom algorithm. This involved strike segmentation and numerical integration to determine velocity. The system demonstrated moderate reliability (intraclass correlation coefficient (ICC) <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo>,</mo><mn>1</mn></mrow></semantics></math></inline-formula> = <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.746</mn></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.786</mn></mrow></semantics></math></inline-formula>, standard error of measurement (SEM) = <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.488</mn></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.921</mn></mrow></semantics></math></inline-formula> m/s), comparable to commercially available systems. Biological and technical variations, as well as test standardization issues, were acknowledged as factors influencing reliability. Despite a relatively low sampling frequency, the hardware and software showed potential for reliable measurement. The study highlights the importance of considering within-subject variability, hardware limitations, and the impact of noise in software algorithms. Average strike velocities exhibited higher reliability than peak velocities, making them a practical choice for performance tracking, although they may underestimate true peak performance. Future research should validate the system against gold-standard methods and determine the optimal sampling frequency to enhance measurement accuracy.https://www.mdpi.com/1424-8220/25/2/307combat sportskinematicsreliabilityaccelerometry |
| spellingShingle | Lukas Pezenka Klaus Wirth Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity Sensors combat sports kinematics reliability accelerometry |
| title | Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity |
| title_full | Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity |
| title_fullStr | Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity |
| title_full_unstemmed | Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity |
| title_short | Reliability of a Low-Cost Inertial Measurement Unit (IMU) to Measure Punch and Kick Velocity |
| title_sort | reliability of a low cost inertial measurement unit imu to measure punch and kick velocity |
| topic | combat sports kinematics reliability accelerometry |
| url | https://www.mdpi.com/1424-8220/25/2/307 |
| work_keys_str_mv | AT lukaspezenka reliabilityofalowcostinertialmeasurementunitimutomeasurepunchandkickvelocity AT klauswirth reliabilityofalowcostinertialmeasurementunitimutomeasurepunchandkickvelocity |