Christopher E. Ordway, Bridget McFadden, Alan J. Walker, David J. Sanders, Harry Cintineo, Brittany Bozzini, Marissa Bello, Ryan Curtis, PhD, Robert Huggins, PhD, Douglas Casa, PhD, Shawn M. Arent, PhD, CSCS*D
Background: Monitoring athlete movement patterns during the competitive season may be a useful tool for identifying injury risk factors in athletes. During conference play, competitive stress can be more pronounced, which could increase fatigue. Unfortunately, lab-based biomechanics equipment is typically required for assessment.
Purpose: To track changes in Single Leg Squat (SLS) and Landing Error Scoring System (LESS) assessments over the course of conference play in female college soccer players using a commercially available optical tracking system.
Methods: Female (n=21; Mage= 19.7±1.5yrs; Mweight=66.3±6.2kg) Division I college soccer players were monitored throughout conference play. Training Load (TL) was measured using the Polar TeamPro system. Athletes participated in performance testing every 4-weeks including SLS and LESS tests using the TRAZER computer simulation and full-body sensing technology to track the hips, knees, ankles and torso. The SLS test has subjects place their hands on their hips, extend one leg in front and squat down to maximal knee flexion. The test is then repeated on the other leg. The LESS test has subjects start on top of a 30cm plyometric box with hands on hips. Subjects then performed a drop jump by stepping off the box and landing on a mark on the ground at a distance from the box equivalent to 50% of the subject’s height, followed by a maximal vertical jump. A total of 5 trials were completed for each assessment. RM MANOVAs and univariate follow-ups were conducted with significance set at P<. 05.
Results: Compared to early season play, TL decreased throughout the conference schedule (P<. 05). For the SLS test, a significant main effect was seen for hip abduction on the right (P<. 05) and a trend for left knee movement (P=.06). Hip adduction increased from T1 to T2 (ΔHip abduction= 2.01°; P<. 05) and then decreased from T2 to T3 (ΔHip abduction= -1.66°; P<.05). Knee movement decreased from T1 to T3 (ΔKnee Movement = -0.49° ; P<. 05). For the LESS test, right knee movement, left knee movement, and stance width all changed over time(P<. 05). There was no significant change from T1 to T2 in the left knee, but a significant increase occurred by T3 (ΔL knee movement = 4.2°; P<. 05). There was a significant decrease from T1 to T2 in the right knee movement (ΔR knee movement = -3.3°; P<0. 5), but returned to baseline at T3. Stance width narrowed from T1 to T2 (ΔStance width = 3.29cm; P<. 05) and remained narrower at T3.
Conclusions: Inconsistent changes occurred for left and right knee movement between tests. Throughout conference play, SLS showed either no changes or improvements in knee movement, while the LESS test revealed greater changes in the movement of both knees. Given the incidence of knee injury in the female athlete, these findings may have relevance for identifying biomechanical changes in landing kinematics. Furthermore, these changes occurred despite decreases in TL, perhaps suggesting the importance of considering accumulation of training stress.
Practical Applications: The LESS assessment may be a more useful tool than the SLS for assessing these athletes as it appeared to be more sensitive to change and more closely mirrors aspects of competitive play. However, further validation of this technology is necessary before implementing it as part of a systematic monitoring strategy.