Quantifying Asymmetry and Performance of Lower Limb Mechanical Muscle Function in Varsity Athletes

• Author / Creator

  Stadnyk, Meredith M.

• In varsity sports, athletes are more susceptible to lower limb injury than the general population due to their continuous involvement in physically-demanding activity. Additionally, these athletes participate in high-level strength and conditioning training programs to ensure they are reaching their optimal performance in their sport. To better understand what should be expected when athletes either (1) have a lower limb injury, or (2) are not performing to their full lower limb function potential, we first need to understand what “normal” or “optimal” lower limb mechanical muscle function is in each sport. This project looked at a means of quantifying the lower limb mechanical muscle function instantaneously to provide information for rehabilitation and performance purposes in athletes of specific sports.

  Male and female varsity athletes from swim, volleyball, rugby, and soccer completed five trials of a counter movement jump (CMJ) on dual force plates. An analysis program was written in Wolfram Mathematica to analyze force-time jump data with minimal equipment and labor required. Various parameters of interest were generated, including: peak force, force-time curve shape classification, jump phase lengths (for eccentric and concentric phases), phase-specific kinetic impulse, asymmetry index, takeoff velocity, jump height, phase-specific center of mass displacements, and reactive strength index modified (RSImod).

  Male participants had a higher peak force than females, but no significant difference when peak force was normalized to body mass. Males took longer than females to takeoff, spent more time in the air, and had a higher takeoff velocity. Additionally, males had larger kinetic impulses compared to females. Males had a higher jump height and RSImod, which represents jump “explosiveness.” There were no differences between asymmetry indexes observed between the genders.

  The soccer athletes were able to exert the highest peak force per kilogram of body mass out of all the groups. The soccer group also spent the shortest time in the eccentric and concentric jump phases, and had the smallest impulses. The swim athletes had the lowest peak force out of all the group, and spent the most time in the jump phases. The swim athletes had the lowest RSImod out of all the sport groups. Volleyball players had the highest absolute peak force, spent the longest time in the air, and had the highest jump height and takeoff velocity out of all the groups. Volleyball players also had the largest kinetic impulses in both jump phases. The rugby group did not have any parameters that were significantly different from all the other sport groups, indicating that it may be difficult to determine what a “normal” rugby players’ jump performance is.

  A follow-up study was conducted to incorporate non-counter movement jumps (NCMJs) into assessing jump characteristics of the same sports as the CMJ study. In the NCMJ, swimmers had the lowest peak force normalized to body mass, and took the longest time to complete the jumps. Volleyball players spent the longest time in the air, had the highest takeoff velocity, the highest jump height, and the highest RSImod (although these were not significant with all other sport groups). Soccer players had the lowest body mass (although only significant with volleyball and rugby). Rugby players again lacked statistically significant results from the all other sport groups for any one specific variable for many of the NCMJ variables, and many of their results averaged somewhere in the middle of the other sport groups’. The results of these studies do not necessarily indicate that some athletes are “better” jumpers or have “stronger” lower limbs, but that differences do exist between sports for lower limb muscle usage.

• Subjects / Keywords

  • Asymmetry
  • Sports Performance
  • Plyometrics
  • Non-Counter Movement Jump
  • Counter Movement Jump

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-gb9f-pw27

• License

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