Biomechanical Assessment of Countermovement Jumping Using Wearable Technologies

• Author / Creator

  Fathian, Ramin

• Monitoring and assessing physical performance, muscular fitness, and neuromuscular function are essential since they can help to reduce sports-related injuries, improve rehabilitation progress and develop more effective training strategies. Countermovement vertical jump (CMJ) is one of the frequently used means to practically monitor and assess athletic performance in athletic and non-athletic individuals. Previously, force-plate and motion-capture cameras were used in the lab to analyze CMJ-related parameters, including jump height, the main parameter describing the CMJ performance. Although these systems are accurate and precise, their application is time-consuming, expensive, and may not be practical outside of the lab environment. Vertec and jump mat are among the most used instruments to analyze the CMJ-related parameters in the field; however, they have limited precision, and their accuracy was questioned. Despite the potential of inertial measurement units (IMU) for estimating the CMJ-related parameters, their accuracy for this purpose has not been validated.
  The objective of this study was to investigate the accuracy and precision of a sacrum-mounted IMU to estimate the spatiotemporal parameters characterizing CMJ against both force-plate and motion-capture cameras as reference criteria during CMJs with and without arms swing. To this end, eleven adults without physical impairments performed six jumps each (four pre-exercise and two post-exercise) on a force-plate while an IMU was placed on the sacrum, and motion-capture system markers were placed on selected anatomical landmarks.
  First, the accuracy of the sacrum-mounted IMU to estimate the flight duration, jump duration and jump height during CMJ with and without arms swing was investigated. For the flight and jump duration, the mean errors (standard deviation) were 0.06 (0.17) sec and -0.03 (0.20) sec, respectively, for the CMJ with arms swing and 0.16 (0.22) sec and -0.07 (0.24) sec, respectively, for the CMJ without arms swing. Compared to both the force-plate and motion-capture system, the error of jump height estimated by the IMU was relatively small during the CMJ with and without arms swing. These errors were comparable to the difference between the jump height obtained by the force-plate and motion-capture system. Also, statistical correlations were observed between the jump height obtained by these three measurement systems. Flight duration, jump duration, and jump height obtained by IMU compared to force-plate showed that the IMU could not be used as a substitute for force-plate. Yet, errors in IMU measurements compared to force-plate were similar to the ones observed in motion-capture system. As a result, further studies might be conveyed to reduce the error of IMU compared to the force-plate. Second, the accuracy of the sacrum-mounted IMU in estimating flight-time to contraction-time (FT:CT) ratio and change was investigated. The relative mean error (standard deviation) of FT:CT ratio estimated using the IMU against the force-plate was 11.7% (13.3%) and 23.2% (11.7%) for CMJs with and without arms swing, respectively. The relative mean error (standard deviation) of change in FT:CT estimated using the sacrum-mounted against to force-plate was 7.6% (16.8%) and 9.5% (25.3%) for the CMJs with and without arms swing, respectively. Similarly, the IMU could not be used as a substitute for force-plate. Yet, further studies are needed to decrease the IMU error and investigate the IMU's potential to detect neuromuscular fatigue.

• Subjects / Keywords

  • Wearable Technologies
  • Countermovement jump

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-21he-zc95

• License

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