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Bryan L. Riemann

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Bryan L. Riemann and George J. Davies

Context: Previous investigations have examined the reliability, normalization, and underlying projection mechanics of the seated single-arm shot-put (SSASP) test. Although the test is believed to reflect test limb strength, there have been no assessments determining whether test performance is directly associated with upper-extremity strength. Objective: To determine the relationship between isokinetic pushing force and SSASP performance and conduct a method comparison analysis of limb symmetry indices between the 2 tests. Design: Controlled laboratory study. Setting: Biomechanics laboratory. Patients (or Other Participants): Twenty-four healthy and physically active men (n = 12) and women (n = 12). Intervention(s): Participants completed the SSASP and isokinetic pushing tests using their dominant and nondominant arms. Main Outcome Measures: SSASP distance and isokinetic peak force. Results: Significant moderate to strong relationships were revealed between the SSASP distances and isokinetic peak forces for both limbs. The Bland–Altman analysis results demonstrated significantly (P < .002) greater limb symmetry indices for the SSASP (both medicine balls) than the isokinetic ratios, with biases ranging from −0.094 to −0.159. The limits of agreement results yielded intervals ranging from ±0.241 to ±0.340 and ±0.202 to ±0.221 from the biases. Conclusions: These results support the notion that the SSASP test reflects upper-extremity strength. The incongruency of the limb symmetry indices between the 2 tests is likely reflective of the differences in the movement patterns and coordination requirements of the 2 tests.

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Bryan L. Riemann and Kevin M. Guskiewicz

Mild head injury (MHI) represents one of the most challenging neurological pathologies occurring during athletic participation. Athletic trainers and sports medicine personnel are often faced with decisions about the severity of head injury and the timing of an athlete's return to play following MHI. Returning an athlete to competition following MHI too early can be a catastrophic mistake. This case study involves a 20-year-old collegiate football player who sustained three mild head injuries during one season. The case study demonstrates how objective measures of balance and cognition can be used when making decisions about returning an athlete to play following MHI. These measures can be used to supplement the subjective guidelines proposed by many physicians.

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Randy J. Schmitz, Bryan L. Riemann and Timothy Thompson

Objective:

To determine whether gluteus medius (GM) activity increases in response to isometric closed-chain external hip rotation.

Design:

Subjects performed single-leg stances in 3 different conditions: 0° knee flexion, 0° hip flexion (C1); 0° knee flexion, 20° hip flexion (C2); and knee flexed 20–30°, 20° hip flexion (C3). Posteriorly directed forces of 8.9 N (F1), 17.8 N (F2), and 26.7 N (F3) were applied at the lateral pelvis of the nonstance side during each condition.

Subjects:

20 college students.

Measurements:

Surface EMG RMS amplitude from the GM and kinematic data from the trunk, hip, and knee.

Results:

Statistical analyses revealed a significant Condition 3 Force interaction and significant increases of EMG activity from C1F1 and C1F2 to C1F3 and from C3F1 to C3F2 and C3F3. F2 and F3 of C2 were significantly less than F2 and F3 of both C1 and C3.

Conclusions:

GM activity increases in response to isometric, closed-chain, external hip-rotation forces, and forward movement of the upper body with respect to the base of support decreases GM activity.

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Bryan L. Riemann, Nancy Caggiano Tray and Scott M. Lephart

Objectives:

To determine the physiological adaptations that might occur with a 4-week unilateral multiaxial training program in lower leg kinesthesia, peak torque, and postural control.

Study Design:

True experimental pretest-posttest control-group design.

Setting:

Research laboratory.

Subjects:

26 healthy, active subjects (14 men, 12 women).

Interventions:

Subjects were assigned to an experimental or control group. The experimental group performed multiaxial coordination training 3 days/wk for 4 weeks.

Main Outcome Measures:

Both groups were tested 3 times, pretest and 2 and 4 weeks after training was initiated. Outcome measures included conscious appreciation of ankle kinesthesia, eversion and dorsiflexion isokinetic peak torque, and static and functional postural control.

Results:

Results revealed a significant Group × Test interaction only for inversion kinesthesia.

Conclusions:

Four weeks of multiaxial coordination training did not significantly improve any of the dependent variables in healthy individuals. Further research should consider the effects of such a program on injured subjects.

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Bryan L. Riemann, Kelsey Piersol and George J. Davies

Context: Single leg balance testing is a commonly used tool in sports medicine; however, there has been no consensus on trial duration needed to obtain reliable measures. Objective: This investigation sought to determine the minimum trial duration required to obtain the highest intrasession single and average trial reliability for single leg balance testing on stable and unstable surfaces using dominant and nondominant limbs. Design: Intrasession reliability.Setting:Biomechanics laboratory. Participants: 70 healthy (35 men, 35 women), physically active young adults aged 22.8 ± 2.8 y divided into 3 subgroups (n = 10, 30, 30) across a 3-phase study. Methods:3 phases of single leg balance testing were performed. For phase 1, the duration of time each participant could maintain posture on each limb/surface were computed. Phase 2 considered performance for 6 cumulative time intervals (5s, 10s, 15s, 20s, 25s, 30s). Phase 3 served to solidify results of phase 2 by computing reliability of 15s trials. Main outcome measures: Overall stability index of the center of pressure and platform tilt. Results: Intraclass correlation coefficients for phase 2 ranged from .74 (5s interval for nondominant limb on unstable surface) to .94 (20s interval for nondominant limb on stable surface). Phase 3 intraclass correlation coefficients ranged from .66 to .78 for single trial and .85 to .92 for 3 trial average with coefficients of variation ranging from 23.9% to 40.4% for single trial and 13.8% to 23.0% for 3 trial average. Conclusions:These results ultimately suggest 15s as the optimal trial duration to provide reliable measures while reducing compensatory event occurrence.

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Bryan L. Riemann, Kevin M. Guskiewicz and Edgar W. Shields

Although sophisticated forceplate systems are available for postural stability analyses, their use is limited in many sports medicine settings because of budgetary constraints. The purpose of this investigation was to compare a clinical method of evaluating postural stability with a force-platform sway measure. Participants completed a battery of three stance variations (double, single, and tandem) on two different surfaces (firm and foam) while standing on a force platform. This arrangement allowed for simultaneous comparisons between forceplate sway measures and clinical assessments using the Balance Error Scoring System (BESS). Significant correlations were revealed for the single-leg and tandem stances on the firm surface and for double, single, and tandem stances on the foam surface. These results suggest that the BESS is a reliable method of assessing postural stability in the absence of computerized balance systems.

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Bryan L. Riemann, Nancy A. Caggiano and Scott M. Lephart

Postural control and functional performance tests are often used separately during orthopedic postinjury assessments. The purpose of this investigation was to examine a clinical method of assessing postural control during a functional performance task. Thirty participants were divided into two groups. The first group was tested three times, the second group only once. The same tester evaluated each participant's performance during all testing sessions, and during the first two testing sessions (Group 1) two additional testers evaluated each performance. Intraclass correlational coefficients between the three testers ranged from .70 to .92. Session 1 (Group 1) scores were pooled with Group 2 scores, and correlational analyses were conducted between participant height and performance; no significant relationships were revealed. The scores from Group 1 were analyzed using between-days repeated-measures ANOVAs. Results revealed significant improvement between Sessions 1 and 3 for the static portion of the test. The results suggest that the multiple single-leg hop-stabilization test offers a method of assessing postural control during a functional performance task.

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Joshua M. Drouin and Bryan L. Riemann

Column-editor : Carl G. Mattacola