Craig R. Denegar

Contributing factors to chronic ankle instability

Background: The development of repetitive ankle sprains and persistent symptoms after initial ankle sprain has been termed chronic ankle instability (CAI). There is no clear indication of which measures are most important in discriminating between individuals with and without CAI. Methods: Thirty subjects with unilateral CAI and controls had measures of ankle laxity and hypomobility, static and dynamic balance, ankle and hip strength, lower extremity alignments, and flexibility taken on both limbs. Results: Based on comparisons of CAI ankles and side-matched limbs in controls, the measures significantly predictive of CAI were increased inversion laxity (r 2 change = 0.203), increased anterior laxity (r 2 change = 0.11), more missed balance trials (r 2 change = 0.094), and lower plantarflexion to dorsiflexion peak torque (r 2 change = 0.052). Symmetry indices comparing the side-to-side differences of each measure also were calculated for each dependent variable and compared between groups. The measures significantly predictive of CAI were decreased anterior reach (r 2 change = 0.185), decreased plantarflexion peak torque (r 2 change = 0.099), decreased posterior medial reach (r 2 change = 0.094), and increased inversion laxity (r 2 change = 0.041). Conclusions: The results of this study elucidate the specific measures that best discriminate between individuals with and without CAI. Both mechanical (anterior and inversion laxity) and functional (strength, dynamic balance) insufficiencies significantly contribute to the etiology of CAI. Prevention of CAI may be possible with proper initial management of the acute injury with rehabilitation aimed at those factors that best discriminate between individuals with and without CAI.

Measurement of Scapular Asymmetry and Assessment of Shoulder Dysfunction Using the Lateral Scapular Slide Test: A Reliability and Validity Study

Background and Purpose. The Lateral Scapular Slide Test (LSST) is used to determine scapular position with the arm abducted 0, 45, and 90 degrees in the coronal plane. Assessment of scapular position is based on the derived difference measurement of bilateral scapular distances. The purpose of this study was to assess the reliability of measurements obtained using the LSST and whether they could be used to identify people with and without shoulder impairments. Subjects. Forty-six subjects ranging in age from 18 to 65 years (X=30.0, SD=11.1) participated in this study. One group consisted of 20 subjects being treated for shoulder impairments, and one group consisted of 26 subjects without shoulder impairments. Methods. Two measurements in each test position were obtained bilaterally. From the bilateral measurements, we derived the difference measurement. Intraclass correlation coefficients (ICC [1,1]) and the standard error of measurement (SEM) were calculated for intrarater and interrater reliability of the difference in side-to-side measures of scapular distance. Sensitivity and specificity of the LSST for classifying subjects with and without shoulder impairments were also determined. Results. The ICCs for intrarater reliability were .75, .77, and .80 and .52, .66, and .62, respectively, for subjects without and with shoulder impairments in 0, 45, and 90 degrees of abduction. The ICCs for interrater reliability were .67, .43, and .74 and .79, .45, and .57, respectively, for subjects without and with shoulder impairments in 0, 45 and 90 degrees of abduction. The SEMs ranged from 0.57 to 0.86 cm for intrarater reliability and from 0.79 to 1.20 cm for interrater reliability. Using the criterion of greater than 1.0 cm difference, sensitivity and specificity were 35% and 48%, 41% and 54%, and 43% and 56%, respectively, for 0, 45, and 90 degrees of abduction. Sensitivity and specificity based on the criterion of greater than 1.5 cm difference were 28% and 53%, 50% and 58%, and 34% and 52%, respectively, for the 3 scapular positions. Conclusion and Discussion. Our results suggest that measurements of scapular positioning based on the difference in side-to-side scapular distance measures are not reliable. Furthermore, the results suggest that sensitivity and specificity of the LSST measurements are poor and that the LSST should not be used to identify people with and without shoulder dysfunction.

Influence of a compression garment on repetitive power output production before and after different types of muscle fatigue

Compression shorts have become a very popular item of sports apparel. Few data exist about whether they influence athletic performance. The purpose of this study was to determine whether compression shorts affected vertical jump performance after different fatigue tasks (i.e., endurance, strength, and power). In addition, experiments on the influence of a compression garment on joint position sense at the hip and muscle movement velocity upon landing impact was also studied. Healthy college age men and women participated in the various studies. Subjects were thoroughly familiarized with the jump tests and all other experimental techniques. Jumps were performed on an AMTI force plate which was interfaced to a computer with customized software used to determine jump power. Ten consecutive maximal counter movement jumps with arms held at waist level were performed. The compressive garment had no effect on the maximal power of the highest jump in either men or women. The compressive garment significantly enha...

Static innominate asymmetry and leg length discrepancy in asymptomatic collegiate athletes

The objectives of the study were to assess: (1) static innominate asymmetry in the sagittal plane, (2) leg length discrepancy (LLD), and (3) the relationship between static innominate rotation and LLD in asymptomatic collegiate athletes. The study was an observational study by design which took place in a University athletic training research laboratory. The participants were twenty-four male and 20 female asymptomatic intercollegiate athletes who volunteered to take part in the study. Static innominate asymmetry was assessed with a caliper/inclinometer tool and LLD was measured with a tape measure using standard clinical methods. Results showed that forty-two subjects (95%) demonstrated some degree of static innominate asymmetry. In 32 subjects (73%), the right innominate was more anteriorly rotated than the left. Nearly all subjects were determined to have unequal leg lengths with a majority, 30 subjects (68%), showing a slightly longer left leg. Weak correlations (r=0.33 - 0.44) were identified between static innominate asymmetry and LLD. In Conclusion static innominate asymmetry and LLD are common among asymptomatic collegiate athletes. This information provides clinicians with normative data of common clinical measures in a physically active population.