Biomedical subjects

Bruce M Gansneder

Publications and source records attributed to Bruce M Gansneder.

At least 19 recordsLinked to original sources

PubMed2006

Validity and reliability of a new in vivo ankle stiffness measurement device.

This investigation was designed to test the validity and reliability of a new measure of inversion/eversion ankle stiffness on a unique medial/lateral swaying cradle device utilizing a test/retest with comparison to a known standard. Ankle stiffness is essential to maintaining joint stability. Most ankle injuries occur via an inversion mechanism. To date, very little information is available regarding stiffness of the evertor muscles in the prevention of excessive inversion joint rotation. Transient oscillation data representing inversion/eversion stiffness was obtained in a bipedal weight-bearing stance with an upright posture. Using commercially available springs with stiffness of 4.80N/cm the measured value recorded by the cradle was 4.87N/cm. Mean active stiffness values of the ankle were 35.70Nm/cm (SD 9.45). The trial-to-trial reliability ICC (2,1) coefficient was 0.96 with an SEM of 2.05Nm/rad, and the day-to-day reliability ICC (2,k) coefficient was 0.93 and an SEM of 3.00Nm/rad. The results demonstrate that inversion/eversion ankle stiffness measures on this device are a valid, repeatable and consistent measure. This is relevant because the ability to accurately quantify inversion/eversion ankle stiffness will improve our understanding of biomechanical stability and factors that influence it. It will also enable identification of ankle injury risk factors that will lead to more efficient rehabilitation programs and injury prevention strategies.

Adult↗

PubMed2006

Absolute serum hormone levels predict the magnitude of change in anterior knee laxity across the menstrual cycle.

This study aimed to determine whether absolute sex hormone concentrations predict the magnitude of knee joint laxity changes across the menstrual cycle. Twenty-two females (18-30 years, body mass index <or=30), who reported normal menstrual cycles for the previous 6 months were tested daily across one complete menstrual cycle for serum levels of estradiol (E=pg/mL), progesterone (P=ng/mL), and testosterone (T=ng/dL), and knee joint laxity (K(Lax)=mm displacement at 134N) measured with a standard knee arthrometer. The change in K(Lax) across the cycle (maximum-minimum), and minimum (early follicular) and peak (postovulatory) hormone concentrations were recorded for each subject. A stepwise linear regression determined if the minimum, peak, or absolute change in hormone concentrations would predict the magnitude of change in K(Lax) across the cycle. K(Lax) changed on average 3.2+/-1.1 mm across the menstrual cycle (range, 1.5-5.3 mm). Minimum levels of E (39.9+/-11.8 pg/mL) and P (0.61+/-0.27 ng/mL), coupled with peak concentrations of E (199.6+/-54.9 pg/mL) and T (22.5+/-10.5 ng/dL) explained 57.6% of the change in K(Lax) across the cycle. Greater absolute changes in K(Lax) were observed in response to peak E and T levels when minimum E concentrations were lower and minimum P concentrations were higher in the early follicular phase. The absolute minimum concentrations of E and P in the early follicular phase appear to be important factors in determining the sensitivity of the knee joint's response to changing hormone levels.

Adolescent↗

PubMed2005

Functional-Performance Deficits in Volunteers With Functional Ankle Instability.

Context: Although functional-performance tests are dynamic measures used to assess general lower body function, studies investigating these tests for ankle instability have yielded conflicting results.Objective: To determine if a relationship exists between a measure of functional ankle instability and deficits in functional performance.Design: A case-control study correlating subject performance on a set of lower extremity functional-performance tests with a measure of ankle instability.Setting: University athletic training research laboratory.Patients or Other Participants: We recruited 60 participants (43 females, 17 males, age = 22.4 +/- 4.9 years, height = 169.9 +/- 9.7 cm, mass = 72.6 +/- 16.3 kg; 42 injured, 18 uninjured) to participate in the study. Six questions were used to determine if functional ankle instability was present in each participant. A point was added for each yes response to produce an index that represents a continuous variable of functional ankle instability.Main Outcome Measure(s): Four unilateral hopping tests were used in this study: figure-of-8 hop, side hop, up-down hop, and single hop. For the first 3 tests, the total time was recorded with a handheld stopwatch to the nearest 0.01 second; for the single hop-for-distance test, the distance was recorded to the nearest 0.01 m. Correlations were computed with the functional ankle instability index and each of the 4 functional-performance tests.Results: No relationship was revealed between the functional ankle instability index and single hop for distance or up-down hop, with r values of -.008 and .245, respectively. A significant relationship was found between the functional ankle instability index and the side hop (r = .35, P </= .01) and the figure-of-8 hop (r = .31, P </= .02).Conclusions: A positive relationship existed between functional ankle instability and performance deficits on the side hop and figure-of-8 hop. Conversely, a relationship did not exist between functional ankle instability and frontal-plane functional-performance activities.

Journal Article↗

PubMed2005

Effects of Pronated and Supinated Foot Postures on Static and Dynamic Postural Stability.

Context: The foot is the most distal segment in the lower extremity chain and represents a relatively small base of support on which the body maintains balance (particularly in single-leg stance). Although it seems reasonable that even minor biomechanical alterations in the support surface may influence postural-control strategies, the implications of a hypermobile or hypomobile foot on balance have received little attention to date.Objective: To determine if supinated and pronated foot types influence measures of static and dynamic balance.Design: Participants were assigned to 1 of 3 groups depending on foot type, as defined by navicular-drop measures: pronated (>/=10 mm), neutral (5-9 mm), or supinated (</=4 mm). Measures of static and dynamic balance were obtained for each participant and compared across groups.Setting: Sports medicine and athletic training research laboratory.Patients or Other Participants: Sixteen individuals with pronated (navicular drop = 13.0 +/- 3.7 mm), neutral (navicular drop = 6.2 +/- 1.1 mm), or supinated (navicular drop = 2.2 +/- 1.7 mm) foot postures volunteered to participate in the study.Main Outcome Measure(s): We used the Chattecx Balance System to measure center of balance, stability index, and postural sway during static single-limb stance under eyes-open and eyes-closed conditions. Center of balance was defined as the point on the foot at which the body weight was equally distributed between the medial-lateral and anterior-posterior quadrants and was recorded in centimeters. Stability index was defined as the mean deviation in sway around the center of balance. Postural sway was expressed as the maximum sway distance recorded (cm) in the medial-lateral and anterior-posterior directions. The Star Excursion Balance Test was used to measure dynamic balance, which was reported as the reach distance (cm) in each of the 8 directions tested. The average of 3 trials of each measure was calculated and normalized to the subject's height.Results: We found no difference in center of balance or postural sway as a function of foot type. The stability index was greater in pronators than in supinators, but neither group was different from those with neutral foot types. Dynamic reach differed among groups but only in some directions. Generally, pronators reached farther in the anterior and anterior medial directions and supinators reached farther in the posterior and posterio-lateral directions. In the lateral direction, supinators reached farther than pronators but not farther than neutrals.Conclusions: Our results suggest that postural stability is affected by foot type under both static and dynamic conditions. These differences appear to be related to structural differences as opposed to differences in peripheral input. These effects should be considered when clinicians use such balance measures to assess injury deficits and recovery.

Journal Article↗

PubMed2004

Knee ligament behavior following a controlled loading protocol does not differ by menstrual cycle day.

BACKGROUND: Females experience a disproportionate number of anterior cruciate ligament injuries compared to males. Increased estradiol concentration has been suggested to alter ligament properties and strength. Determining whether the knee responds differently to an external load at various hormonal levels may be helpful in further explaining the gender disparity. METHODS: Estradiol, progesterone and testosterone were quantified at menses, near ovulation and at the mid-luteal phase. With one knee serving as the control limb and the other as the experimental limb, displacement at 134N and stiffness between 90 and 134N were recorded with a knee ligament arthrometer on both knees before and after a loading protocol. The protocol consisted of three, 3-min, posterior to anterior normalized loads directed to the posterior calf with a ligament testing device. FINDINGS: The loading protocol produced a measurable increase in displacement but not stiffness. Neither displacement nor stiffness measures however were affected by day of the menstrual cycle. No consistent relationships between hormonal concentrations and displacement or stiffness were evident. INTERPRETATION: Following a controlled, static external load, displacement and stiffness were not affected differently by day of the menstrual cycle.

Adolescent↗

PubMed2004

Relationship between two proprioceptive measures and stiffness at the ankle.

Previous research has investigated the role of proprioception and stiffness in the control of joint stability. However, to date, no research has been done on the relationship between proprioception and stiffness. Therefore, the purpose of this study was to determine the relationship between force sense, joint reposition sense, and stiffness at the ankle. A heterogeneous sample was obtained for this study; 20 of the 40 participants had a history of ankle sprains, and 13 of the 20 had been diagnosed by a physician (two mild ankle sprains, seven moderate sprains, four severe sprains). All subjects were asymptomatic and active at the time of the study. Active joint reposition sense was measured using a custom-built ankle goniometer, force sense was measured unilaterally and contralaterally with a load cell, and ankle muscle stiffness was measured via transient oscillation using a custom-built inversion-eversion cradle. We found no significant correlations between stiffness and joint reposition sense, with values of r ranging from 0.01 to 0.21. Significant correlations were found between stiffness and force sense. Specifically, contralateral force sense reproduction was significantly correlated to stiffness in the injured or "involved" ankle (r's ranging from 0.47 to 0.65; P< or =0.008). Whether the decreased ability to appropriately sense force (increased error) sends information to the central nervous system to increase muscle stiffness in response to an unexpected loss of stability, or whether these two phenomena function independently and both change concurrently as a result of injury to the system requires further investigation.

Adult↗

PubMed2004

Serial administration of clinical concussion assessments and learning effects in healthy young athletes.

OBJECTIVE: To determine if serial administration of the Standardized Assessment of Concussion (SAC) and Balance Error Scoring System (BESS) would elicit a learning effect in young athletes and to determine the intratester reliability of scoring the BESS. DESIGN: A prospective study of 50 healthy young athletes who were assigned to either the control or practice group. All subjects were administered the assessments on 2 occasions, 60 days apart. In addition, subjects in the practice group received serial administration of the assessments on 3 occasions in the week following the initial assessment. SETTING: University Sports Medicine/Athletic Training Research Laboratory. SUBJECTS: Fifty uninjured young athletes between 9 and 14 years of age. MAIN OUTCOME MEASURED: Scores on 2 clinical concussion assessments, the SAC and the BESS. RESULTS: We found a significant learning effect upon serial BESS testing in the practice group. BESS error scores were significantly lower than baseline (15.0 +/- 4.6) on days 5 (11.3 +/- 5.33), 7 (12.4 +/- 6.2), and 60 (12.6 +/- 6.2). We also found a significant learning effect upon the day 60 BESS administration across all subjects. We did not find a practice or learning effect with serial SAC test administration. The intratester reliability of the investigator's ability to score repeated observations of the same BESS test ranged from 0.87 to 0.98. CONCLUSIONS: Our results demonstrated that serial administration of the BESS elicited a learning effect, which was more prominent during the tandem conditions. Clinicians utilizing the BESS as a measure of postural stability should be aware of the potential for improvement with repeated testing. Clinicians should not expect improvement with the SAC, as scores remained relatively stable across all trials.

Adolescent↗

PubMed2004

Rate of force application during knee arthrometer testing affects stiffness but not displacement measurements.

STUDY DESIGN: Repeated-measures counterbalanced design. OBJECTIVES: To determine the effect of rate of force application on anterior tibial displacement and anterior tibial stiffness when measured with the KT-2000 knee arthrometer. BACKGROUND: Clinicians and researchers frequently use the KT-2000 to quantify anterior tibial displacement and stiffness. While many factors (ie, tibial rotation, alignment of the arthrometer, etc) have been identified to affect KT-2000 measurements, the effect of the rate of force application has not been studied. METHODS AND MEASURES: Seventeen recreationally active males between the ages of 19 and 36 years (mean age +/- SD, 27.8 +/- 5.3 years) with no previous history of knee injury participated. With the knee in 25 degrees of flexion, the KT-2000 was applied to the participants' anterior tibia. While the distal femur was stabilized, the first author applied a posterior-to-anterior force at a fast and slow rate. Three trials for the slow and fast rates of force application were averaged and used for statistical analysis. Anterior tibial displacement (mm) was measured at 133 N and the related anterior tibial stiffness (N/mm) values were calculated between 89 and 133 N. Separate paired t tests with Bonferroni adjustment were used to determine if differences in displacement and stiffness between rates of force application were present. RESULTS: Stiffness was significantly greater in the slow (mean +/- SD, 58 +/- 22 N/mm) as compared to the fast trials (mean +/- SD, 47 +/- 19 N/mm) (P = .005). Differences in displacement, however, were small and not significant (P = .132) between the slow (mean +/- SD, 3.9 +/- 1.5 mm) and fast (mean +/- SD, 4.0 +/- 1.6 mm) trials. CONCLUSION: The rate of force application affects anterior tibial stiffness but not anterior tibial displacement when measured with the KT-2000. This suggests that to ensure reliable results when using the KT-2000, the rate of force application must be controlled when measuring stiffness between 89 and 133 N, but not when measuring anterior tibial displacement at 133 N.

Adult↗

PubMed2004

Balance Recovers Within 20 Minutes After Exertion as Measured by the Balance Error Scoring System.

OBJECTIVE: To determine a balance recovery timeline after a functional exertion protocol using the Balance Error Scoring System (BESS). DESIGN AND SETTING: Five subject groups (4 test, 1 control) were tested 3 times during 1 session: once before the exertion protocol (pretest) and twice after the exertion protocol (posttest I and posttest II). Posttest I occurred at staggered intervals of 0, 5, 10, and 15 minutes, depending on experimental group assignment, and posttest II occurred at 20 minutes. SUBJECTS: One hundred subjects (80 test, 20 control) volunteered to participate in this study. None of the subjects had a balance disorder, mild head injury, or lower extremity injury in the 6 months before testing. MEASUREMENTS: We assessed balance using the BESS, assigning a score for each stance-surface condition. RESULTS: We found a significant decrease in BESS performance after the exertion protocol in all test groups, with exertion having the greatest effect on the tandem and single-leg stance conditions. All subjects recovered by posttest II, which was administered 20 minutes after cessation of the exertion protocol. CONCLUSIONS: Athletic trainers need to be aware of the effect of exertion when administering the BESS after physical activity. Athletic trainers can expect the BESS performance of healthy athletes to return to baseline levels within 20 minutes of rest.

Journal Article↗

PubMed2004

Functional Fatigue Decreases 3-Dimensional Multijoint Position Reproduction Acuity in the Overhead-Throwing Athlete.

OBJECTIVE: To determine the effects of functional fatigue on active multijoint position reproduction in overhead-throwing athletes. DESIGN AND SETTING: A standard, repeated-measures, randomized-ordered, counterbalanced, 2-period (crossover) design was used. During the first test session, we randomly assigned subjects to either the nonfatigue or fatigue condition. Subjects underwent pretest measurements and then either a functional fatigue protocol or rest period, followed by posttest measurements. After a recovery period, subjects crossed over to the opposing condition for the second testing session. SUBJECTS: Thirteen overhead-throwing athletes competing in National Collegiate Athletic Association Division I or club baseball, with no history of upper extremity or central nervous system disorders, volunteered for this study. MEASUREMENTS: We measured active multijoint position reproduction accuracy in 3 dimensions using an electromagnetic tracking device. We noted each subject's ability to reproduce 3 positions corresponding with distinct moments of his throwing motion. A variable error score was calculated to compare the locations of the reproduced points with reference to the target point. RESULTS: A significant difference occurred between the pretest and posttest error scores in the fatigue condition. Comparisons between positions indicated that more errors were seen in the arm-cocked position than in the follow-through position under both fatigue and nonfatigue conditions. CONCLUSIONS: Functional fatigue decreased joint position sense acuity in overhead-throwing athletes. Our findings using this novel testing measurement method are in agreement with past research, with one exception. The trend toward higher error scores in the arm-cocked position would appear to contradict findings that sensorimotor system acuity increases toward end ranges of motion.

Journal Article↗

PubMed2003

Reliability and validity of the Biodex system 3 pro isokinetic dynamometer velocity, torque and position measurements.

This study quantitatively assessed the mechanical reliability and validity of position, torque and velocity measurements of the Biodex System 3 isokinetic dynamometer. Trial-to-trial and day-to-day reliability were assessed during three trials on two separate days. To assess instrument validity, measurement of each variable using the Biodex System 3 dynamometer was compared to a criterion measure of position, torque and velocity. Position was assessed at 5 degrees increments across the available range of motion of the dynamometer. Torque measures were assessed isometrically by hanging six different calibrated weights from the lever arm. Velocity was assessed (30 degrees/s to 500 degrees/s) across a 70 degrees arc of motion by manually accelerating the weighted lever arm. With the exception of a systematic decrease in velocity at speeds of 300 degrees/s and higher, the Biodex System 3 performed with acceptable mechanical reliability and validity on all variables tested.

Humans↗

PubMed2003

Active knee joint velocity replication measures are stable and accurate in healthy individuals.

The purpose of this study was to determine the stability and accuracy of active knee joint velocity replication methods in healthy subjects. We used a repeated measures design with 14 healthy volunteers. Measures of velocity replication were performed in two ranges of knee joint flexion (0 degrees -30 degrees and 60 degrees -90 degrees ), across four testing velocities (5, 10, 15, and 30 degrees /s) in two movement directions (flexion and extension). Statistical analysis included intraclass correlation coefficients (ICCs; 2, k) and associated standard error of the measures calculated between day 1 and 2. We performed z-tests between all possible combinations of ICC pairs using Fisher's Z transformations to determine if any significant differences existed between observed ICCs. We also calculated correlation ratios (eta2) to explain the source of variability in the calculated ICCs. To assess measurement accuracy, we calculated constant error and absolute error between criterion and replication velocities. Results on ICCs and standard error of the measurements (SEMs) ranged from r = -0.44 +/- 7.00 to 0.88 +/- 0.72 degrees /s. Calculated z-tests indicated six paired ICCs were significantly different ( p < 0.1). In all six pairs, the faster test velocity had a lower ICC magnitude. The eta2 calculations demonstrated that inconsistent performance between day 1 and 2 caused the low ICC magnitudes observed with faster testing velocities. Significantly more absolute error occurred at 30 and 15 degrees /s compared with 5 degrees /s. Significantly less constant error was observed for 30 degrees /s compared with 15 degrees /s. A significant direction by range of motion interaction indicated less constant error for flexion movements in the 60 degrees -90 degrees range of motion (ROM) as compared with extension movements in either ROM. Healthy individuals could actively replicate slower criterion velocities in the mid and end ranges of knee joint motion in both movement directions with an acceptable amount of consistency and accuracy. The data support the use of velocity replication in future investigations on proprioceptive function.

Adult↗

PubMed2002

The differential effects of fatigue on reflex response timing and amplitude in males and females.

We examined the effects of fatigue on patellar tendon reflex responses in males and females. A spring-loaded reflex hammer elicited a standardized tendon tap with the knee positioned in an isokinetic dynamometer and flexed to 85 degrees. We recorded vastus lateralis activity (SEMG) and knee extension force production at the distal tibia (force transducer). Reflex trials were performed before and after (immediate, 2, 4, and 6 min) an isokinetic fatigue protocol to 50% MVC (90 degrees /s). For each event, pre-motor time (PMT), electromechanical delay (EMD), and total motor time (TMT) were obtained, as well as EMG amplitude (EMG(amp)), time to peak EMG (EMG(tpk)), peak force amplitude (F(amp)), time to peak force (F(tpk)), EMG:force ratio (E:F), and rate of force production (F(rate)=N/ms). TMT increased significantly in females following fatigue, while males showed no change. The increased TMT was due to an increased EMD with fatigue, while PMT was unaffected. EMG(amp) and F(amp) were somewhat diminished in females yet significantly augmented in males following fatigue, likely accounting for the differential changes in EMD noted. Results suggest males and females may respond differently to isokinetic fatigue, with males having a greater capacity to compensate for contraction force failure when responding to mechanical perturbations.

Adult↗

PubMed2002

Acute Orthotic Intervention Does Not Affect Muscular Response Times and Activation Patterns at the Knee.

OBJECTIVE: To evaluate the short-term effect of a semirigid foot orthotic device on response times and activation patterns of knee musculature in individuals with hyperpronation after a lower extremity perturbation in a single-leg, weight-bearing stance. DESIGN AND SETTING: We used a lower extremity perturbation device designed to produce a forward and either internal or external rotation of the trunk and femur on the weight-bearing tibia to evoke a reflex response. Subjects were tested both with and without orthotic devices. SUBJECTS: Seventeen (13 male, 4 female) volunteers (age, 20.6 +/- 1.8 years; height, 181.0 +/- 8.1 cm; weight, 87.4 +/- 19.5 kg; navicular drop, 12.1 +/- 1.8 mm) with a navicular drop greater than 10 mm volunteered for this study. MEASUREMENTS: Long latency reflex times were recorded via surface electromyography for the medial and lateral hamstrings, gastrocnemius, and quadriceps muscles. RESULTS: A dependent-sample t test revealed a significant decrease in navicular drop with orthotic intervention (P <.0001). With that confirmed, separate repeated-measures analyses of variance with 2 within factors (orthotic condition and muscle) revealed no significant difference in muscle response time between orthotic and nonorthotic conditions for either internal or external rotation perturbation. Although we found a main effect for muscle for both internal (P <.0001) and external (P <.0001) rotation, indicating a preferred muscle activation order, this activation order did not differ between orthotic and nonorthotic conditions (internal rotation P =.674, external rotation P =.829). CONCLUSIONS: Our findings suggest that a short-term application of a semirigid orthotic device does not alter muscle response times or activation patterns of the muscles that stabilize the knee. Further research is needed to determine whether changes in activation patterns may occur over time since mechanical adaptations occur with long-term wear.

Journal Article↗

PubMed2002

The Effect of a Neoprene Shoulder Stabilizer on Active Joint-Reposition Sense in Subjects With Stable and Unstable Shoulders.

OBJECTIVE: To compare the effects of shoulder bracing on active joint-reposition sense in subjects with stable and unstable shoulders. DESIGN AND SETTING: Two subject groups, with stable and unstable shoulders, participated in an active joint-reposition test of the shoulder under braced and unbraced conditions. SUBJECTS: Forty subjects (22 men, 18 women; age = 21.85 +/- 3.12 years; height = 173.97 +/- 10.08 cm; weight = 71.27 +/- 11.68 kg) were recruited to participate in this study. Twenty Division I athletes were referred to us for shoulder instability, which was subsequently confirmed with clinical assessment. The remaining 20 subjects were recruited from a similar student population and assessed as having stable shoulders. MEASUREMENTS: Each subject's ability to perceive joint position sense in space was tested by actively reproducing 3 preset angles (10 degrees from full external rotation, 30 degrees of external rotation, and 30 degrees of internal rotation) with and without a shoulder brace. Full, active external-rotation range of motion was assessed before active joint-reposition sense testing. RESULTS: While wearing the shoulder brace, the group with unstable shoulders demonstrated significant improvement in the accuracy of active joint repositioning at 10 degrees from full external rotation in comparison with the stable group. Furthermore, those with unstable shoulders demonstrated significantly less full external rotation than did those with stable shoulders, and the brace reduced full external rotation only for those with stable shoulders. CONCLUSIONS: Our findings suggest that shoulder active joint-reposition sense in subjects with unstable shoulders can be improved at close to maximal external rotation by wearing a shoulder brace. This effect does not appear to be related to restriction of shoulder external rotation.

Journal Article↗

PubMed2002

Chronic Ankle Instability Does Not Affect Lower Extremity Functional Performance.

OBJECTIVE: To determine if functional performance is impaired in individuals with self-reported chronic ankle instability. DESIGN AND SETTING: We used a between-groups design to assess 3 functional variables. All data were collected at a Division III college and a military academy. Before testing, all subjects performed a 5-minute warm-up, followed by a series of stretches for the lower extremity muscles. Subjects then performed cocontraction, shuttle run, and agility hop tests in a counterbalanced fashion. Three trials for each functional test were completed and averaged for analysis. SUBJECTS: Twenty men with a history of at least 1 significant ankle sprain and episodes of at least 1 repeated ankle injury or feelings of instability or "giving way" were compared with 20 men with no prior history of ankle injury. Subjects were matched by age, height, weight, and activity level. MEASUREMENTS: Time to completion was measured in seconds for the cocontraction and the shuttle run tests. The agility hop test was measured on an error point scale. RESULTS: Using 3 separate, independent, 2-tailed t tests, we found no significant difference between groups for the cocontraction (P =.452), shuttle run (P =.680), or agility hop (P =.902) tests. CONCLUSIONS: Chronic ankle instability is a subjectively reported phenomenon defined as the tendency to "give way" during normal activity. Although athletes commonly complain of subjective symptoms associated with chronic ankle instability, our findings suggest that these symptoms do not negatively influence actual functional performance. Future researchers should evaluate other, more demanding functional-performance tests to further substantiate these findings.

Journal Article↗

PubMed2002

Removal Tools are Faster and Produce Less Force and Torque on the Helmet Than Cutting Tools During Face-Mask Retraction.

OBJECTIVE: To investigate the retraction time, forces, and torques applied to the football helmet during removal of the face mask with different face-mask removal tools. DESIGN AND SETTING: Subjects retracted the face mask of a football helmet mounted to a force platform in a laboratory setting. They removed a standard face mask by cutting or removing (or both) the lateral plastic loop straps using 4 different tools: the Trainer's Angel (TA), FM Extractor (FM), power screwdriver (SD), and Quick Release System (QR) in a counterbalanced fashion. SUBJECTS: Eighteen certified athletic trainers participated in this study. MEASUREMENTS: We started measuring time when the subject picked up the tool and ended when the face mask was in a fully retracted position. Maximum forces and torques were measured from the force platform during the retraction process. RESULTS: The SD and QR retracted the face mask significantly faster than the TA and FM. Forces producing superior-inferior translation were least with the SD. The SD and QR produced less lateral translation and rotation and lateral flexion moment than the TA and FM. The FM produced less torque in the lateral flexion moment than the TA. CONCLUSIONS: Tools that removed the loop straps (SD, QR) were faster and produced less force and torque on the helmet than the tools that cut through the loop straps (TA, FM).

Journal Article↗

PubMed2002

Strength, Functional Outcome, and Postural Stability After Anterior Cruciate Ligament Reconstruction.

OBJECTIVE: To compare postural stability, single-leg hop, and isokinetic strength measurements in subjects after anterior cruciate ligament (ACL) reconstruction with an age- and activity-matched control group. DESIGN AND SETTING: Subjects reported to a sports medicine/athletic training research laboratory for testing. Subjects reported for one testing session for a total test time of 1 hour. SUBJECTS: Twenty subjects with ACL reconstructions (ACLRs) and 20 age- and activity-matched controls were selected to participate in this study. An arthroscopically assisted central one-third bone-patellar tendon procedure was used to repair the ACLs. MEASUREMENTS: We measured concentric and eccentric peak torque (Nm) measurements of the knee extensors and flexors at 120 degrees and 240 degrees /second on an isokinetic dynamometer. Unilateral and bilateral dynamic postural stability was measured as a stability index in the anterior-posterior and medial-lateral planes with the Biodex Stability System. We tested single-leg hop for distance to measure objective function. RESULTS: We found no significant difference between the ACLR and control subjects for stability index or knee-flexion peak torque scores. On the single-leg hop for distance, the ACLR subjects hopped significantly shorter distances with the involved limb than the uninvolved limb. Furthermore, the ACLR subjects' single-leg hop distance was significantly less when the involved limb was compared with the control-group matched involved limb, and the ACLR subjects performed significantly better when the uninvolved limb was compared with the control-group matched uninvolved limb. The ACLR subjects produced significantly greater torque in the uninvolved leg than in the involved leg. In addition, the peak torque was significantly less for the involved limb in the ACLR group when compared with the matched involved limb of the control group. CONCLUSIONS: After ACLR (mean = 18 +/- 10 months), single-leg hop-for-distance scores and quadriceps strength were not within normal limits when compared with the contralateral limb. Our results suggest that bilateral and single-limb postural stability in the ACLR group was not significantly different than the control group at an average follow-up of 18 months after surgery.

Journal Article↗