One potential ACL injury situation is due to contact with another person or object during the flight phase, thereby causing the person to land improperly. Conversely, athletes often have flight-phase collisions but do land safely. Therefore, to better understand ACL injury causation and methods by which people typically land safely, the purpose of this study was to determine the effects of an in-flight perturbation on the lower extremity biomechanics displayed by females during typical drop landings. Seventeen collegiate female recreational athletes performed baseline landings, followed by either unexpected laterally-directed perturbation or sham (nonperturbation) drop landings. We compared baseline and perturbation trials using paired-samples t tests (P < .05) and 95% confidence intervals for lower-extremity joint kinematics and kinetics and GRF. The results demonstrated that perturbation landings compared with baseline landings exhibited more extended joint positions of the lower extremity at initial contact; and, during landing, greater magnitudes for knee abduction and hip adduction displacements; peak magnitudes of vertical and medial GRF; and maximum moments of ankle extensors, knee extensors, and adductor and hip adductors. We conclude that a lateral in-flight perturbation leads to abnormal GRF and angular motions and joint moments of the lower extremity.
Jae P. Yom, Kathy J. Simpson, Scott W. Arnett and Cathleen N. Brown
Kathy J. Simpson, Jae P. Yom, Yang-Chieh Fu, Scott W. Arnett, Sean O’Rourke and Cathleen N. Brown
The objective of the study was to determine if prophylactic ankle bracing worn by females during landings produces abnormal lower extremity mechanics. Angular kinematic and ground reaction force (GRF) data were obtained for 16 athletically experienced females who performed brace and no-brace drop landings. The brace condition displayed reduced in/external rotation and flexion displacements about the ankle and knee joints and increased vertical and mediolateral GRF peak magnitudes and rate of vertical GRF application (paired t test, P < .05). The ankle and knee joints landed in a less plantar flexed and more flexed position, respectively. No significant ab/adduction outcomes may have occurred due to interparticipant variability and/or a lack of brace restriction. Conclusion: During typical landings, this lace-up brace increases vertical GRF, decreases ankle and knee joint displacements of flexion and int/external rotation, but minimally affects ab/adduction displacements.
Gina Sobrero, Scott Arnett, Mark Schafer, Whitley Stone, T. A. Tolbert, Amanda Salyer-Funk, Jason Crandall, Lauren B. Farley, Josh Brown, Scott Lyons, Travis Esslinger, Keri Esslinger and Jill Maples
High intensity functional training (HIFT) emphasizes constantly varied, high intensity, functional activity by programming strength and conditioning exercises, gymnastics, Olympic weightlifting, and specialty movements. Conversely, traditional circuit training (TCT) programs aim to improve muscular fitness by utilizing the progressive overload principle, similar movements weekly, and specified work-to-rest ratios. The purpose of this investigation was to determine if differences exist in health and performance measures in women participating in HIFT or TCT after a six-week training program. Recreationally active women were randomly assigned to a HIFT (n = 8, age 26.0 + 7.3 yrs) or TCT (n = 11, age 26.3 + 9.6 yrs) group. Participants trained three days a week for six weeks with certified trainers. Investigators examined body composition (BC), aerobic and anaerobic capacity, muscular strength, endurance, flexibility, power, and agility. Repeated-measures ANOVA were used for statistical analyses with an alpha level of 0.05. Both groups increased body mass (p = .011), and improved muscular endurance (p < .000), upper body strength (p = .007), lower body power (p = .029) and agility (p = .003). In addition, the HIFT group decreased body fat (BF) %, while the TCT group increased BF% (p = .011). No changes were observed in aerobic or anaerobic capacity, flexibility, upper body power, or lower body stair climbing power. Newer, high intensity functional exercise programs such as HIFT may have better results on BC and similar effects when compared with TCT programs on health and fitness variables such as musculoskeletal strength and performance.