Understanding the Biomechanical Factors in Performing a Pre-planned Versus Reactive Agility Drill

Date of Award


Degree Name

M.S. in Mechanical Engineering


Department of Mechanical and Aerospace Engineering and Renewable and Clean Energy


Advisor: Kimberly Bigelow


There is emerging interest in reactive agility. In comparison to traditional agility with a pre-planned path, reactive agility drills and tests include uncertainty of where to run as an athlete responds to a stimulus. These better represent the "open skills" needed for dynamically changing environments. Research studies that have compared reactive agility to pre-planned tests have mainly focused on examining reaction times. The overall aim of this study was to determine how factors including biomechanics and cognitive ability contribute to differences in performance on reactive agility tests compared to pre-planned tests.Eighteen college-aged athletic males completed two pre-planned tests, two reactive agility tests, and two cognitive tests. For the primary reactive agility test, we utilized an assessment known as the D4 Open with five programmable lights arranged in an arc with a center light acting as the trigger light. In the assessment, all lights illuminated and the participant had to identify the odd light out as quickly as possible and run to it, incorporating the elements of visual scanning and then adding in color recall afterwards. For the primary pre-planned version of this test, the D4 Closed, the athlete was simply told which lights to run to in advance. Computerized cognitive tests were used to measure reaction time and cognitive flexibility. Initially, the study population was divided into "Faster" (n=9) and "Slower" (n=9) groups based off their D4 Closed best trial time. The "Faster" group exhibited faster times on average for the D4 Closed, but not the D4 Open. These differences, however, were not statistically significant. We then calculated total excursions (TOTEX) of center of mass (CoM) as captured by a wearable motion capture system to assess overall movement efficiency. It was found that the TOTEX values observed a strong correlation (r=0.777) between the D4 Closed and D4 Open tests, but the difference between the "Faster" athletes was not statistically significant than that of the "Slower" athletes for either test (P=0.788 and P=0.290). Overall, the D4 Open TOTEX values were higher for both "Faster" and "Slower" groups, suggesting that individuals were not as direct or efficient in their movements with the added uncertainty. Cognitive tests results did not correlate to performance on the D4 Open. Overall, these findings suggest that "Faster" athletes, according to the D4 Closed, did not necessarily perform well on the D4 Open. We then extended the work to analyze which variables measured would effectively predicted completion times on the D4 Closed and D4 Open. For this, athletes were ranked on a scaled of 1-18 on both the D4 Close and D4 Open to assess how the added uncertainty changed their performance in relation to the other athletes. Then in generating models through stepwise multiple linear regressions, the results supported that reactive agility tests are different than pre-planned agility tests. Reaction time was a statistically significant factor in predicting the D4 Closed while reaction time, weight, and cognitive flexibility were statistically significant factors for predicting D4 Open times. This further supports the role of open skill assessment.


Mechanical Engineering, Biomechanics, Biomechanics, Pre-planned, Reactive, Agility, open skills

Rights Statement

Copyright 2019, author