A characteristic of scapulothoracic dysfunction is the tendency for the upper regions of the trapezius to hypertrophy in relation to its middle and lower portions. This creates a muscular imbalance that can alter scapular position and subsequently the length–tension relationship of the shoulder muscles. Tape was applied over the right upper trapezius to inhibit electrical activity in the muscles of 10 uninjured subjects. EMG activity was recorded in two locations of the upper trapezius and one location in the middle to lower trapezius region while each subject maintained an isometric contraction designed to activate both muscles. With the tape applied, there was a statistically significant reduction in EMG activity of the upper trapezius with a corresponding increase in the middle/lower trapezius. The ability of the tape to alter trapezius activity in this fashion may help correct muscular imbalances in the trapezius muscle.
Gary E. Morin, David Tiberio and Gary Austin
Michael F. Joseph, Kristin L. Holsing and David Tiberio
Kinematic differences have been linked to the gender discrepancies seen in knee injuries. A medially posted orthotic decreases frontal and transverse plane motions in the lower extremity during ambulation, squatting and landing. This study investigated the effect of a medial post on amount and timing of lower extremity motions during a single-leg squat in male and female athletes. We hypothesized there would be differences in these kinematic variables dependent upon sex and post conditions. Twenty male and female athletes performed single-leg squats with and without a five degree full-length medial post. Maximum joint angles were analyzed using a two-way, repeated-measures analysis of variance to determine if the differences created by post condition were statistically significant, whether there were gender differences, or interactions. Differences in maximum motion values and the time at which they occurred were found between men and women at the hip, knee and ankle. The post decreased all frontal plane measures in both sexes and resulted in earlier attainment of maximum ankle eversion and delayed maximum knee valgus. A medially posted orthotic may be beneficial not only in limiting motion, but in affecting the time in which stressful motions occur.
Timothy A. Hanke, Bruce Kay, Michael Turvey and David Tiberio
Lateral stability and weight transfer are important for successful stepping and are associated with falls in older adults (OAs). This study assessed the influence of step pacing frequency during medial–lateral stepping in place on body center of mass and lower limb movement in young adults, middle-aged adults, and OAs. Medial–lateral center of mass and stepping limb motion and lower limb loading data were collected. Center of mass motion decreased with increasing pacing frequency and increased to a lesser extent with decreasing pacing frequency. Step length was relatively resistant to changes in pacing frequency. OAs exhibited reductions in whole body and stepping motion compared with younger adults. OAs exhibited greater support limb loading. OAs adapt both postural and stepping strategies to successfully step under time-critical conditions.