Eric Wiatt and Sean P. Flanagan
Edited by Tricia Hubbard
Rachel E. Brinkman and Todd A. Evans
Kristian M. O’Connor, Sarika K. Monteiro and Ian A. Hoelker
The purpose of this study was to compare the knee joint dynamics for males and females performing constrained cutting tasks to an unanticipated running and cutting maneuver. Sixteen male and 17 female recreational athletes were recruited to perform four cutting tasks; unanticipated run and cut (CUT), stride land and cut (SLC), far box-land and cut (FLC), and close box-land and cut (CLC). Three-dimensional knee joint kinematics and kinetics were recorded. Data were compared across gender and task with a 2 × 4 ANOVA (p < .05), and a factor analysis was performed to examine task relationships. There were significant group mean differences between the tasks and across genders. The factor analysis revealed high correlations between the three constrained tasks, but for variables typically associated with ACL injury risk there was a poor relationship to the CUT task. This was particularly true for the frontal plane variables. The constrained tasks were only moderately useful in predicting cutting mechanics.
Wendy I. Drechsler, John F. Knarr and Lynn Snyder-Mackler
Eighteen subjects participated in a randomized controlled clinical trial to compare the effectiveness of two physical therapy treatments for tennis elbow. The subjects were divided into two groups: In the neural tension group (NTG), the head of the radius was mobilized and specific physical therapy mobilizations were used to address hypomobility of the radial nerve. The standard treatment group (STG) received ultrasound, transverse friction massage, and stretching and strengthening exercises for the extensors of the wrist. All subjects were treated twice weekly for 6 to 8 weeks. Follow-up data were obtained at 3 months post-treatment. Subjects who received radial head mobilization improved over time (p < .05), while those who did not receive radial head mobilization did not improve. Results of the NTG treatment were linked to the radial head treatment, and isolated effects of the NTG treatment could not be determined. There were no long-term positive results in the STG.
Gilbert M. Willett, Jason B. Paladino, Kory M. Barr, Jill N. Korta and Gregory M. Karst
The purpose of this study was to determine the effect of weight-bearing terminal knee extension (WBKE) on normalized mean electromyographic (EMG) activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) and the VMO/VL ratio. Sixteen subjects with no history of knee dysfunction participated. Surface EMG data were recorded from the VMO and VL of subjects' test legs as they performed the WBKE exercise under four conditions, three involving elastic resistance and one involving no elastic resistance. EMG data were normalized relative to a maximal isometric quadriceps contraction, and overall mean VMO and VL activity and the VMO/VL ratio were determined for all conditions. The three conditions utilizing elastic resistance showed higher mean VMO and VL activity than the no-resistance condition. The VMO/ VL ratio was not significantly altered during any exercise condition as compared to maximal, quadriceps setting exercise. WBKE against elastic resistance was superior to the same exercise without resistance for generating mean VMO and VL activity. Performance of the WBKE, regardless of the position of lower extremity rotation, does not selectively activate the VMO apart from, or to a greater degree than, the VL.
Adam C. Knight and Wendi H. Weimar
The dominant and nondominant legs respond asymmetrically during landing tasks, and this difference may occur during an inversion perturbation and provide insight into the role of ankle-evertor and -invertor muscle activity.
To determine if there is a difference in the ratio of evertor to invertor activity between the dominant and nondominant legs and outer-sole conditions when the ankle is forced into inversion.
Repeated-measures single-group design.
15 physically active healthy volunteers with no previous history of an ankle sprain or lower extremity surgery or fracture.
An outer sole with fulcrum was used to cause 25° of inversion at the subtalar joint after landing from a 27-cm step-down task. Participants performed 10 fulcrum trials on both the dominant and nondominant leg.
Main Outcome Measures:
The ratio of evertor to invertor muscle activity 200 ms before and 200 ms after the inversion perturbation was measured using electromyography. This ratio was the dependent variable. Independent variables included outer-sole condition (fulcrum, flat), leg (dominant, nondominant), and time (prelanding, postlanding). The data were analyzed with separate 2-way repeated-measures ANOVA, 1 for the prelanding ratios and 1 for the postlanding ratios.
For the postlanding ratios, the fulcrum outer sole had a significantly greater (P < .05) ratio than the flat outer sole, and the nondominant leg had a significantly greater (P < .05) ratio than the dominant leg.
These results indicate that a greater evertor response is produced when the ankle is forced into inversion, and a greater response is produced for the nondominant leg, which may function better during a postural-stabilizing task than the dominant leg.
Anna M. Ifarraguerri, Danielle M. Torp, Abbey C. Thomas and Luke Donovan
ankle instability. Lateral ankle sprains (LAS) are the most frequently sustained musculoskeletal injury in sport and recreational activities. 1 , 2 Approximately 40% of individuals with a history of LAS develop a condition known as chronic ankle instability (CAI), 3 which is characterized by
Kevin McCurdy and John Walker
analyzing hamstrings activation during exercise have used 1 or 2 sites 1 , 2 for electrode placement to represent total hamstrings recruitment or to analyze differences in the medial versus lateral hamstrings activation. Magnetic resonance imaging studies have also been conducted during resistance exercise