Biomedical subjects

Bruce M. Gansneder

Publications and source records attributed to Bruce M. Gansneder.

5 recordsLinked to original sources

PubMed2004

Performance on the Balance Error Scoring System Decreases After Fatigue.

OBJECTIVE: To determine the immediate effects of a whole-body fatigue protocol on performance of the Balance Error Scoring System (BESS), a postural-stability test commonly used as part of a concussion-assessment battery. DESIGN AND SETTING: Subjects were assigned to a fatigue or control group and were assessed before and immediately after a 20-minute fatigue protocol or rest period. SUBJECTS: Fourteen fatigue subjects and 13 control subjects participated in this study. All subjects were male and free of vestibular disorders, and none had suffered a mild head injury or lower extremity injury in the preceding 6 months, as described through self-report. MEASUREMENTS: We measured performance on the BESS for 9 stance-surface conditions and summed each condition to obtain a total score. Using the Borg scale, we also measured ratings of perceived exertion before, during, and after the fatigue protocol or rest period. RESULTS: We found a significant increase in total errors from pretest to posttest in the fatigue group (14.36 +/- 4.73 versus 16.93 +/- 4.32), a significant decrease in errors in the control group (13.32 +/- 3.77 versus 11.08 +/- 3.88), and a significant difference between groups on the posttest. The rating of perceived exertion scores were significantly different between the fatigue and control groups at the middle (13.29 +/- 1.59 versus 6.23 +/- 0.83) and end (15.86 +/- 2.38 versus 6.15 +/- 0.55) of the fatigue or rest period. CONCLUSIONS: The BESS error scores increased immediately after the fatigue protocol, demonstrating that balance ability diminished. Clinicians who use the BESS as part of their sideline assessment for concussion should not administer the test immediately after a concussion due to the effects of fatigue.

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PubMed2003

Subtalar Pronation Does Not Influence Impact Forces or Rate of Loading During a Single-Leg Landing.

OBJECTIVE: To identify the influence of static subtalar pronation (as measured by weight-bearing navicular drop [ND]) on ground impact forces and rate of loading during a single-leg landing. DESIGN AND SETTING: Subjects were grouped (n = 16 per group) on the basis of weight-bearing ND scores (supinators, <5 mm; neutral, 5-10 mm; pronators, >10 mm). Subjects performed 5 single-leg landings, dropping from a 0.3-m height onto a force platform. An electrogoniometer simultaneously recorded sagittal knee range of motion during the landing task. SUBJECTS: Forty-eight healthy volunteers participated. MEASUREMENTS: Peak vertical force was defined as the highest force recorded in the F(z) direction during landing. Rate of loading was defined as the peak vertical force divided by the time to reach the peak vertical force. Knee-flexion excursion was defined as the change in knee-flexion range from initial contact to peak vertical force. RESULTS: Peak vertical force (P =.769) and rate of loading (P =.703) did not differ among groups. Although secondary analyses identified significant negative correlations between peak force and rate of loading with knee excursion, the amount of knee excursion was similar among groups (P =.744). CONCLUSIONS: Our results de-emphasize the influence of static anatomical foot alignment on impact forces and absorption during a single-leg drop landing and provide further support for the role of knee flexion in dissipation of landing forces. Further investigations are needed to fully elucidate the role of subtalar pronation and other lower extremity alignment factors in force dissipation during dynamic functional activities.

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PubMed2003

Repeat Administration Elicits a Practice Effect With the Balance Error Scoring System but Not With the Standardized Assessment of Concussion in High School Athletes.

OBJECTIVE: To assess whether repeated administration of the Standardized Assessment of Concussion (SAC) and Balance Error Scoring System (BESS) demonstrates a practice effect in high school athletes. DESIGN AND SETTING: Subjects were assigned to either a control or practice group. Subjects in the control group were assessed twice, 30 days apart. Subjects in the practice group were assessed on 5 occasions. Four assessments were performed within a 7-day period and 1 more assessment 30 days after the initial test. SUBJECTS: Thirty-two uninjured high school athletes participated in this investigation. Sixteen were randomly assigned to a control group and 16 to a practice group. MEASUREMENTS: We measured performance on the SAC and on 6 test conditions of the BESS. RESULTS: We found a significant time-by-group interaction on BESS performance on the day-30 test session. A significant practice effect of the BESS was found during the course of repeated administrations in the practice group. After repeated testing, the number of BESS errors decreased with each test session, and error scores on day 5 (10.94 +/- 2.17) and day 7 (9.44 +/- 3.32) were significantly lower than the baseline score (12.88 +/- 3.34). We did not find group differences or a practice effect on the SAC (baseline score = 26.16). CONCLUSIONS: Our results revealed no practice effect with the SAC and a slight practice effect with repeated administrations of the BESS, especially with the single-leg stance on foam. Clinicians must acknowledge the potential for practice effects when readministering these concussion assessments to track recovery of an athlete or as a guide in return-to-play decision making.

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PubMed2001

Neuromuscular Response Characteristics in Men and Women After Knee Perturbation in a Single-Leg, Weight-Bearing Stance.

OBJECTIVE: We examined whether muscle response times and activation patterns in the lower extremity differed between men and women in response to a rotational knee perturbation while standing in a single-leg, weight-bearing stance. DESIGN AND SETTING: We used a lower extremity perturbation device to produce a sudden, forward, and either internal or external rotation moment of the trunk and femur relative to the weight-bearing tibia. Subjects completed 10 trials of both internal and external rotation perturbation; the first 5 acceptable trials were averaged and used for data analysis. Two separate, repeated-measures analyses of variance were used to compare myoelectric response times and activation patterns between men and women for both internal and external rotation perturbation. SUBJECTS: Thirty-two female (19 lacrosse, 13 soccer) and 32 male (lacrosse) healthy intercollegiate athletes participated in the study. MEASUREMENTS: We used surface electromyography to record long latency reflex times of the medial and lateral quadriceps, hamstring, and gastrocnemius muscles. RESULTS: Women responded faster than men, primarily due to a shorter latency in quadriceps activation. However, men and women exhibited no difference in muscle-recruitment order. CONCLUSIONS: Although men and women demonstrated similar muscle-recruitment patterns to an imposed lower extremity perturbation, women tended to activate their quadriceps earlier than men. Whether this earlier quadriceps activation diminishes the ability of the hamstrings to adequately stabilize the knee joint or subjects the anterior cruciate ligament to greater risk of injury is still unknown and requires further study. Furthermore, although surface electromyography and measurement of myoelectric response times are useful in evaluating the timing, activation order, and coactivity patterns of the knee musculature, future studies should evaluate sex differences across the complete response continuum, including measures of intrinsic muscle stiffness, electromechanical delay, and time to force production.

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PubMed2001

Duration of Maintained Hamstring Flexibility After a One-Time, Modified Hold-Relax Stretching Protocol.

OBJECTIVE: Previous research suggests proprioceptive neuromuscular facilitation (PNF) stretching techniques produce greater increases in range of motion than passive, ballistic, or static stretching methods. The purpose of our study was to measure the duration of maintained hamstring flexibility after a 1-time, modified hold-relax stretching protocol. DESIGN AND SETTING: The study had a 1 x 1 mixed-model, repeated-measures design. The independent variables were group (control and experimental) and time (0, 2, 4, 6, 8, 16, and 32 minutes). The dependent variable was hamstring flexibility as measured in degrees of active knee extension with the hip flexed to 90 degrees. Measurements were taken in a preparatory military academy athletic training room. SUBJECTS: Thirty male subjects (age, 18.8 +/- 0.63 years; height, 185.2 +/- 14.2 cm; weight, 106.8 +/- 15.7 kg) with limited hamstring flexibility in the right lower extremity were randomly assigned to a control (no-stretch) group or an experimental (stretch) group. MEASUREMENTS: All subjects performed 6 warm-up active knee extensions, with the last repetition serving as the prestretch measurement. The experimental group received 5 modified (no-rotation) hold-relax stretches, whereas the control group rested quietly supine on a table for 5 minutes. Posttest measurements were recorded for both groups at 0, 2, 4, 6, 8, 16, and 32 minutes. RESULTS: The repeated-measures analysis of variance revealed a significant group-by-time interaction, a significant main effect for group, and a significant main effect for time. Dunnett post hoc analysis revealed a significant improvement in knee-extension range of motion in the experimental group that lasted 6 minutes after the stretching protocol ended. CONCLUSIONS: Our findings suggest that a sequence of 5 modified hold-relax stretches produced significantly increased hamstring flexibility that lasted 6 minutes after the stretching protocol ended.

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