Differences in pre-season balance among student athletes based on level of contact, age, and sex

BACKGROUND

Assessing postural control is important for the assessment of motor function after concussion. Data used for postural control assessment typically do not take the sport played, age, or sex of the athlete into consideration. It is plausible these variables may be significant when making return-to-play decisions.

RESEARCH QUESTION

This study used the BTrackS database to examine differences in postural control in athletes playing different types of sports and across sex and age.

METHODS

BTrackS data from 9093 high school to college-aged athletes (aged 14-22 years) were examined employing a One-way ANOVA with a post-hoc test to compare CoP path length between sport types. A moderation analysis was used to test interaction effects of sex and age on a CoP/BMI ratio.

RESULTS

Significant differences were observed between sport types, F(3,9089) = 42.4, p <.001, η2 = 0.014. Post hoc tests indicated that collision (M = 25.0, SD = 7.6) sport athletes exhibited significantly higher CoP measures compared to the contact (M = 23.4, SD = 7.4), limited contact (M = 22.9, SD = 6.9), and non-contact (M = 23.0, SD = 7.4) athletes. There was no difference between other sport types (p >.20). A significant mean sex difference (Mmale = 0.924, Mfemale = 0.898, p <.001) and a quadratic association with age, (β = -0.042, p <.001) was observed. Further, magnitude of those age differences decreased with age (β = 0.011, p <.001). An interaction of age and sex was significant for linear (β = 0.020, p <.001) and quadratic terms (β = -0.006, p <.001).

SIGNIFICANCE

Athletes exhibited different postural control when the type of sport, age, and sex was taken into consideration. This data possess clinical significance as this suggests that normative postural control data for collision sport athletes should be derived from data based upon type of sport played, age, and sex of the athlete.

Understanding the effects of a sudden directional shift in somatosensory feedback and increasing task complexity on postural adaptation in individuals with and without chronic ankle instability

BACKGROUND

Individuals with chronic ankle instability (CAI) present somatosensory dysfunction following an initial ankle sprain. However, little is known about how individuals with CAI adapt to a sudden sensory perturbation of instability with increasing task and environmental constraints to maintain postural stability.

METHODS

Forty-four individuals with and without unilateral CAI performed the Adaptation Test to a sudden somatosensory inversion and plantarflexion perturbations (environment) in double-, injured-, and uninjured- limbs. Mean sway energy scores were analyzed using 2 (group) × 2 (somatosensory perturbations) × 3 (task) repeated measures analysis of variance.

RESULTS

There were significant interactions between the group, environment, and task (P=.025). The CAI group adapted faster than healthy controls to a sudden somatosensory inversion perturbation in the uninjured- (P=.002) and injured- (P<.001) limbs, as well as a sudden somatosensory plantarflexion perturbation in the double- (P=.033) and uninjured- (P=.035) limbs. The CAI and healthy groups presented slower postural adaptation to a sudden inversion perturbation than a sudden somatosensory plantarflexion perturbation in double-limb (P<.001). Whereas both groups demonstrated faster postural adaptation to a sudden somatosensory inversion perturbation compared to somatosensory plantarflexion perturbation while maintaining posture in the injured- (P<.001) and uninjured- (P<.001) limbs. The CAI and healthy groups adapted faster to a sudden somatosensory inversion perturbation in the injured- (P<.001) and uninjured- (P<.001) limbs than in double-limb, respectively.

DISCUSSION

Postural adaptation in individuals with and without CAI depended on environmental (somatosensory perturbations) and task constraints. The CAI group displayed comparable and faster postural adaptation to a sudden somatosensory inversion and plantarflexion in double-, injured-, and uninjured- limbs, which may reflect a centrally mediated alteration in neuromuscular control in CAI.

The Impact of Differential Knee Laxity on Brain Activation During Passive Knee Joint Loading

Although higher anterior knee laxity is an established risk factor of ACL injury, underlying mechanisms are uncertain. While decreased proprioception and altered movement patterns in individuals with anterior knee laxity have been identified, the potential impact of higher laxity on brain activity is not well understood. Thus, the purpose of this study is to identify the impact of different magnitudes of knee laxity on brain function during anterior knee joint loading. Twenty-seven healthy and active female college students without any previous severe lower leg injuries volunteered for this study. Anterior knee laxity was measured using a knee arthrometer KT-2000 to assign participants to a higher laxity (N=15) or relatively lower laxity group (N=12). Functional magnetic resonance images were obtained during passive anterior knee joint loading in a task-based design using a 3T MRI scanner. Higher knee laxity individuals demonstrated diminished cortical activation in the left superior parietal lobe during passive anterior knee joint loading. Less brain activation in the regions associated with awareness of bodily movements in females with higher knee laxity may indicate a possible connection between brain activity and knee laxity. The results of this study may help researchers and clinicians develop effective rehabilitation programs for individuals with increased knee laxity. This article is protected by copyright. All rights reserved.

Modified proximal thigh kinematics captured with a novel smartphone app in individuals with a history of recurrent ankle sprains and altered dorsiflexion with walking

BACKGROUND

We examined sagittal-plane thigh angular kinematics in individuals with and without recurrent ankle sprains using a clinical smartphone app called AccWalker. Sagittal-plane ankle kinematics were also compared to ascertain that altered ankle dorsiflexion, which is typically displayed with chronic ankle instability, is also present in individuals with recurrent ankle sprains.

METHODS

Participants with (n = 22) and without (n = 22) recurrent ankle sprains were evaluated on average sagittal-plane ankle kinematics during walking and average sagittal-plane thigh angular kinematics during stepping-in-place with AccWalker.

FINDINGS

Significant group-by-limb interactions were found for sagittal-plane ankle kinematics (F_(1,42) = 63.786, P < .010) during walking and sagittal-plane average thigh angular range-of-motion (F_(1,42) = 6.166, P = .017) with AccWalker. Individuals with recurrent ankle sprains displayed more ankle dorsiflexion in affected (P < .001) and unaffected (P = .001) limbs during walking than healthy controls and exhibited more ankle dorsiflexion in their affected-limb compared to their unaffected-limb (P < .001). The average sagittal-plane thigh angular range-of-motion was lower in the unaffected-limb for recurrent ankle sprains compared to their affected-limb (P = .038) and the assigned unaffected-limb of healthy controls (P = .035).

INTERPRETATION

Increased dorsiflexion was present in both limbs of the recurrent ankle sprain group with walking. AccWalker does not assess ankle movement, but uniquely identified thigh motion impairments associated with recurrent ankle sprains in their unaffected-limb, potentially identifying central deficits associated with recurrent ankle sprains. This app has clinical implications for assessing potential pathological movement that can be corrected through rehabilitation.

Neuromotor changes in participants with a concussion history can be detected with a custom smartphone app

Neuromotor dysfunction after a concussion is common, but balance tests used to assess neuromotor dysfunction are typically subjective. Current objective balance tests are either cost- or space-prohibitive, or utilize a static balance protocol, which may mask neuromotor dysfunction due to the simplicity of the task. To address this gap, our team developed an Android-based smartphone app (portable and cost-effective) that uses the sensors in the device (objective) to record movement profiles during a stepping-in-place task (dynamic movement). The purpose of this study was to examine the extent to which our custom smartphone app and protocol could discriminate neuromotor behavior between concussed and non-concussed participants. Data were collected at two university laboratories and two military sites. Participants included civilians and Service Members (N = 216) with and without a clinically diagnosed concussion. Kinematic and variability metrics were derived from a thigh angle time series while the participants completed a series of stepping-in-place tasks in three conditions: eyes open, eyes closed, and head shake. We observed that the standard deviation of the mean maximum angular velocity of the thigh was higher in the participants with a concussion history in the eyes closed and head shake conditions of the stepping-in-place task. Consistent with the optimal movement variability hypothesis, we showed that increased movement variability occurs in participants with a concussion history, for which our smartphone app and protocol were sensitive enough to capture.

Direction-Specific Signatures of Sport Participation in Center of Pressure Profiles of Division I Athletes

BACKGROUND

Descriptive and comparative studies of human postural control generally report effects for component or resultant dimensions of a measured signal, which may obscure potentially important information related to off-cardinal directionality. Recent work has demonstrated highly specific balance behavior that is often not easily reconciled with conventional theories of postural control.

PURPOSE

The purpose of this study was to quantify the effects of sport-specific training history on directional profiles of center of pressure (COP) displacement and velocity among collegiate athletes.

STUDY DESIGN

Cross-Sectional Study.

METHODS

One-hundred sixty-seven NCAA Division-I varsity athletes (80 female: 19.12±1.08 years, 169.79±7.03 cm, 65.69±10.43 kg; 87 male: 19.59±1.33 years, 181.25±9.06 cm, 76.40±12.73 kg) representing four sports (basketball, soccer, tennis, and cross county) participated in this study. Participants balanced barefoot with eyes closed on a force plate for 10-s. in double leg and single leg stance. Effects of sport on mean COP velocity and total displacement were assessed within eight non-overlapping directions (i.e. heading bins).

RESULTS

Greater double leg COP displacement and velocity were observed within specific heading bins in cross country athletes when compared to soccer athletes. Greater double leg COP velocity was also observed in multiple heading bins in basketball athletes when compared to soccer athletes. Greater single leg (non-dominant limb) COP displacement was observed in the 135° heading bin in basketball athletes when compared to soccer athletes.

CONCLUSIONS

The observed effects are likely attributable to sport-specific sensorimotor adaptations, including lower extremity strength/power, proprioceptive acuity, and efficiency of integrating vestibular information. Other potential mechanism-namely the involvement of cutaneous feedback and/or muscle synergies-deserve consideration. Directional profiling of spontaneous COP motion may improve understanding of sport-related balance behavior, enhancing its application in therapeutic and performance monitoring contexts.

LEVEL OF EVIDENCE

3b.

Relationship of Anterior Cruciate Ligament Volume and T2* Relaxation Time to Anterior Knee Laxity

Background:

High anterior knee laxity (AKL) has been prospectively identified as a risk factor for anterior cruciate ligament (ACL) injuries. Given that ACL morphometry and structural composition have the potential to influence ligamentous strength, understanding how these factors are associated with greater AKL is warranted.

Hypothesis:

Smaller ACL volumes combined with longer T2* relaxation times would collectively predict greater AKL.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

College-aged active male (n = 20) and female (n = 30) participants underwent magnetic resonance imaging (MRI) and AKL testing. T2-weighted MRI scans were used to assess ACL volumes, and T2* relaxation times were used to assess ACL structural composition. AKL was measured via a commercial knee arthrometer. Forward stepwise linear regression with sex and weight (first step; suppressor variables) as well as ACL volume and T2* relaxation time (second step; independent variables) was used to predict AKL (dependent variable).

Results:

After initially adjusting for sex and weight (R² = 0.19; P = .006), smaller ACL volumes combined with longer T2* relaxation times collectively predicted greater AKL (R² = 0.52; P < .001; R²_Δ = 0.32; P_Δ < .001). A smaller ACL volume was the primary predictor of greater AKL (R²_Δ = 0.28; P < .001), with a longer T2* relaxation time trending toward a significant contribution to greater AKL (R²_Δ = 0.04; P = .062). After adjusting for ACL volume and T2* relaxation time, sex (partial r = 0.05; P = .735) and weight (partial r = 0.05; P = .725) were no longer significant predictors.

Conclusion:

AKL was largely predicted by ACL volume and to a lesser extent by T2* relaxation time (and not a person’s sex and weight). These findings enhance our understanding of how AKL may be associated with a structurally weaker ACL. The current study presents initial evidence that AKL is a cost-effective and clinically accessible measure that shows us something about the structural composition of the ACL. As AKL has been consistently shown to be a risk factor for ACL injuries, work should be done to continue to investigate what AKL may tell a clinician about the structure and composition of the ACL.

ACL Size and Notch Width Between ACLR and Healthy Individuals: A Pilot Study

BACKGROUND

Given the relatively high risk of contralateral anterior cruciate ligament (ACL) injury in patients with ACL reconstruction (ACLR), there is a need to understand intrinsic risk factors that may contribute to contralateral injury.

HYPOTHESIS

The ACLR group would have smaller ACL volume and a narrower femoral notch width than healthy individuals after accounting for relevant anthropometrics.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Magnetic resonance imaging data of the left knee were obtained from uninjured (N = 11) and unilateral ACL-reconstructed (N = 10) active, female, collegiate-level recreational athletes. ACL volume was obtained from T2-weighted images. Femoral notch width and notch width index were measured from T1-weighted images. Independent-samples t tests examined differences in all measures between healthy and ACLR participants.

RESULTS

The ACLR group had a smaller notch width index (0.22 ± 0.02 vs 0.25 ± 0.01; P = 0.004; effect size, 1.41) and ACL volume (25.6 ± 4.0 vs 32.6 ± 8.2 mm³/(kg·m)^-1; P = 0.025; effect size, 1.08) after normalizing by body size.

CONCLUSION

Only after normalizing for relevant anthropometrics, the contralateral ACLR limb had smaller ACL size and narrower relative femoral notch size than healthy individuals. These findings suggest that risk factor studies of ACL size and femoral notch size should account for relevant body size when determining their association with contralateral ACL injury.

CLINICAL RELEVANCE

The present study shows that the method of the identified intrinsic risk factors for contralateral ACL injury could be used in future clinical screening settings.

Sex Comparisons of In Vivo Anterior Cruciate Ligament Morphometry

CONTEXT

Females have consistently higher anterior cruciate ligament (ACL) injury rates than males. The reasons for this disparity are not fully understood. Whereas ACL morphometric characteristics are associated with injury risk and females have a smaller absolute ACL size, comprehensive sex comparisons that adequately account for sex differences in body mass index (BMI) have been limited.

OBJECTIVE

To investigate sex differences among in vivo ACL morphometric measures before and after controlling for femoral notch width and BMI.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty recreationally active men (age = 23.2 ± 2.9 years, height = 180.4 ± 6.7 cm, mass = 84.0 ± 10.9 kg) and 20 recreationally active women (age = 21.3 ± 2.3 years, height = 166.9 ± 7.7 cm, mass = 61.9 ± 7.2 kg) participated.

MAIN OUTCOME MEASURE(S)

Structural magnetic resonance imaging sequences were performed on the left knee. Anterior cruciate ligament volume, width, and cross-sectional area measures were obtained from T2-weighted images and normalized to femoral notch width and BMI. Femoral notch width was measured from T1-weighted images. We used independent-samples t tests to examine sex differences in absolute and normalized measures.

RESULTS

Men had greater absolute ACL volume (1712.2 ± 356.3 versus 1200.1 ± 337.8 mm³; t₃₈ = -4.67, P < .001) and ACL width (8.5 ± 2.3 versus 7.0 ± 1.2 mm; t₃₈ = -2.53, P = .02) than women. The ACL volume remained greater in men than in women after controlling for femoral notch width (89.31 ± 15.63 versus 72.42 ± 16.82 mm³/mm; t₃₈ = -3.29, P = .002) and BMI (67.13 ± 15.40 versus 54.69 ± 16.39 mm³/kg/m²; t₃₈ = -2.47, P = .02).

CONCLUSIONS

Whereas men had greater ACL volume and width than women, only ACL volume remained different when we accounted for femoral notch width and BMI. This suggests that ACL volume may be an appropriate measure of ACL anatomy in investigations of ACL morphometry and ACL injury risk that include sex comparisons.

Potential Mediators of Load-Related Decreases in Movement Quality in Young, Healthy Adults

CONTEXT

Predicting and promoting physical performance are important goals within the tactical professional community. Movement screens are frequently used in this capacity but are poor predictors of performance outcomes. It has recently been shown that prediction improved when movement quality was evaluated under load, but the mechanisms underlying this improvement remain unclear. Because balance, range of motion, and strength are mutually relevant to physical performance and movement quality, these attributes may mediate load-related decreases in movement quality and account for the resulting increase in performance prediction.

OBJECTIVE

To quantify the roles of balance, range of motion, and strength in mediating load-related decreases in clinical movement-screen scores.

DESIGN

Crossover study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-five male (age = 23.96 ± 3.74 years, height = 178.82 ± 7.51 cm, mass = 79.66 ± 12.66 kg) and 25 female (age = 22.00 ± 2.02 years, height = 165.40 ± 10.24 cm, mass = 63.98 ± 11.07 kg) recreationally active adults.

INTERVENTION(S)

Participants completed a clinical movement screen under a control condition and while wearing an 18.10-kg weighted vest as well as tests of balance, range of motion, and strength.

MAIN OUTCOME MEASURE(S)

Item score differences were assessed using Wilcoxon signed rank tests for matched pairs. Interactions between (1) balance, range of motion, and strength and (2) load condition were modeled using penalized varying-coefficients regression with item scores as the dependent measure.

RESULTS

Except for the hurdle step, item scores were lower in the weighted-vest than in the control condition for all tests ( P < .05). Except for rotary stability, F statistics were significant for all models ( P values < .05, R² values = 0.22-0.77). Main effects of balance, range of motion, and strength on Functional Movement Screen scores were observed ( P < .05); however, little evidence was found to suggest that these attributes mediated load-related decreases in Functional Movement Screen item scores.

CONCLUSIONS

Balance, range of motion, and strength affected movement quality but did not mediate the effect of the load treatment.

Potential Mediators of Load-Related Changes in Movement Complexity in Young, Healthy Adults

CONTEXT

Movement screening has become increasingly popular among tactical professionals. This popularity has motivated the design of interventions that cater to improving outcomes on the screens themselves, which are often scored in reference to an objective norm. In contrast to the assumptions underlying this approach, dynamical systems theory suggests that movements arise as a function of continuously evolving constraints and that optimal movement strategies may not exist. To date, few data address behavioral complexity in the fundamental movement tasks commonly used in clinical screenings.

OBJECTIVE

To provide evidence of complex variability during movement screens and test the role of modifiable-that is, trainable-constraints in mediating loss of complexity during experimental-task manipulations.

DESIGN

Crossover study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-five male (age = 23.96 ± 3.74 years, height = 178.82 ± 7.51 cm, mass = 79.66 ± 12.66 kg) and 25 female (age = 22.00 ± 2.02 years, height = 165.40 ± 10.24 cm, mass = 63.98 ± 11.07 kg) recreationally active adults.

INTERVENTION(S)

Participants performed tests of balance, range of motion, and strength. Additionally, they performed cyclical movement tasks under a control (C) condition and while wearing an 18.10-kg weight vest (W).

MAIN OUTCOME MEASURE(S)

Ground reaction forces were sampled at 1000 Hz and used to calculate center of pressure during cyclical movement tests. Multivariate multiscale entropy (MMSE) for the center-of-pressure signal was then calculated. Condition effects (C versus W) were analyzed using paired t tests, and penalized varying-coefficients regression was used to identify models predicting entropy outcomes from balance, range of motion, and strength.

RESULTS

The MMSE decreased during the W condition (MMSEC > MMSEW; t49 range = 3.17-5.21; all P values < .01).

CONCLUSIONS

Moderate evidence supported an association between modifiable constraints and behavioral complexity, but a role in mediating load-related loss of complexity was not demonstrated.

Changes in Posture Following a Single Session of Long-Duration Water Immersion

Transitioning between different sensory environments is known to affect sensorimotor function and postural control. Water immersion presents a novel environmental stimulus common to many professional and recreational pursuits, but is not well-studied with regard to its sensorimotor effects upon transitioning back to land. The authors investigated the effects of long-duration water immersion on terrestrial postural control outcomes in veteran divers. Eleven healthy men completed a 6-hour thermoneutral pool dive (4.57 m) breathing diver air. Center of pressure was observed before and 15 minutes after the dive under 4 conditions: (1) eyes open/stable surface (Open-Stable); (2) eyes open/foam surface (Open-Foam); (3) eyes closed/stable surface (Closed-Stable); and (4) eyes closed/foam surface (Closed-Foam). Postdive decreases in postural sway were observed in all testing conditions except for Open-Stable. The specific pattern of center of pressure changes in the postdive window is consistent with (1) a stiffening/overregulation of the ankle strategy during Open-Foam, Closed-Stable, and Closed-Foam or (2) acute upweighting of vestibular input along with downweighting of somatosensory, proprioceptive, and visual inputs. Thus, our findings suggest that postimmersion decreases in postural sway may have been driven by changes in weighting of sensory inputs and associated changes in balance strategy following adaptation to the aquatic environment.

A 6-week warm-up injury prevention programme results in minimal biomechanical changes during jump landings: a randomized controlled trial

PURPOSE

To examine the extent to which an ACL injury prevention programme modifies lower extremity biomechanics during single- and double-leg landing tasks in both the sagittal and frontal plane. It was hypothesized that the training programme would elicit improvements in lower extremity biomechanics, but that these improvements would be greater during a double-leg sagittal plane landing task than tasks performed on a single leg or in the frontal plane.

METHODS

Ninety-seven competitive multi-directional sport athletes that competed at the middle- or high-school level were cluster randomized into intervention (n = 48, age = 15.4 ± 1.0 years, height = 1.7 ± 0.07 m, mass = 59.9 ± 11.0 kg) and control (n = 49, age = 15.7 ± 1.6 years, height = 1.7 ± 0.06 m, mass = 60.4 ± 7.7 kg) groups. The intervention group participated in an established 6-week warm-up-based ACL injury prevention programme. Three-dimensional biomechanical analyses of a double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and external joint moments were analysed for group differences using 2 (group) × 4 (task) repeated measures MANOVA models of delta scores (post-pre-test value) (α < 0.05).

RESULTS

Relative to the control group, no significant biomechanical changes were identified in the intervention group for any of the tasks (n.s.). However, a group by task interaction was identified for knee abduction (λ = 0.80, p = 0.02), such that participants in the intervention group showed relative decreases in knee abduction moments during the SAG-DL compared to the SAG-SL (p = 0.005; d = 0.45, CI = 0.04-0.85) task.

CONCLUSION

A 6-week warm-up-based ACL injury prevention programme resulted in no significant biomechanical changes during a variety of multi-directional jump landings. Clinically, future prevention programmes should provide a greater training stimulus (intensity, volume), more specificity to tasks associated with the mechanism of ACL injury (single-leg, non-sagittal plane jump landings), and longer programme duration (> 6 weeks) to elicit meaningful biomechanical changes.

LEVEL OF EVIDENCE

I.

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women's basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women's soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.

Biomechanical Differences of Multidirectional Jump Landings Among Female Basketball and Soccer Players

Taylor, JB, Ford, KR, Schmitz, RJ, Ross, SE, Ackerman, TA, and Shultz, SJ. Biomechanical differences of multidirectional jump landings among female basketball and soccer players. J Strength Cond Res 31(11): 3034-3045, 2017-Anterior cruciate ligament (ACL) injury prevention programs are less successful in basketball than soccer and may be due to distinct movement strategies that these athletes develop from sport-specific training. The purpose of this study was to identify biomechanical differences between female basketball and soccer players during multidirectional jump landings. Lower extremity biomechanics of 89 female athletes who played competitive basketball (n = 40) or soccer (n = 49) at the middle- or high-school level were analyzed with 3-dimensional motion analysis during a drop vertical jump, double- (SAG-DL) and single-leg forward jump (SAG-SL), and double- (FRONT-DL) and single-leg (FRONT-SL) lateral jump. Basketball players landed with either less hip or knee, or both hip and knee excursion during all tasks (p ≤ 0.05) except for the SAGSL task, basketball players landed with greater peak hip flexion angles (p = 0.04). The FRONT-SL task elicited the most distinct sport-specific differences, including decreased hip adduction (p < 0.001) angles, increased hip internal rotation (p = 0.003), and increased relative knee external rotation (p = 0.001) excursions in basketball players. In addition, the FRONT-SL task elicited greater forces in knee abduction (p = 0.003) and lesser forces in hip adduction (p = 0.001) and knee external rotation (p < 0.001) in basketball players. Joint energetics were different during the FRONT-DL task, as basketball players exhibited less sagittal plane energy absorption at the hip (p < 0.001) and greater hip (p < 0.001) and knee (p = 0.001) joint stiffness. Sport-specific movement strategies were identified during all jump landing tasks, such that soccer players exhibited a more protective landing strategy than basketball players, justifying future efforts toward sport-specific ACL injury prevention programs.

Development of a Portable Tool for Screening Neuromotor Sequelae From Repetitive Low-Level Blast Exposure

Blast exposure is a prevalent cause of mild traumatic brain injury (mTBI) in military personnel in combat. However, it is more common for a service member to be exposed to a low-level blast (LLB) that does not result in a clinically diagnosable mTBI. Recent research suggests that repetitive LLB exposure can result in symptomology similar to symptoms observed after mTBI. This manuscript reports on the use of an Android-based smartphone application (AccWalker app) to capture changes in neuromotor functioning after blast exposure. Active duty U.S. Navy personnel (N = 59) performed a stepping-in-place task before repetitive LLB exposure (heavy weapons training), and again immediately after, 24 hours after, and 72 to 96 hours after the completion of the training. The AccWalker app revealed that there are changes in neuromotor functioning after LLB exposure (slower self-selected movement pace and increased stride time variability) in participants who experienced neurocognitive decline. These data suggest that neurocognitive and neuromotor decline can occur after repeated LLB exposure.

Prevalence of headshaking within the equine population in the UK

REASON FOR PERFORMING STUDY

Headshaking in horses has been reported to be most commonly due to idiopathic neuropathic facial pain (trigeminal-mediated headshaking). The prevalence of headshaking in horses in the UK is unknown.

OBJECTIVES

To estimate owner-reported prevalence of headshaking in horses in the UK and to report their case background and disease characteristics, as reported by owners.

STUDY DESIGN

Cross-sectional web based owner questionnaire.

METHODS

The questionnaire was advertised online via social media, horse forums, veterinary websites and equestrian magazines from 17th June 2016, until >1000 responses had been obtained. All UK horse owners were eligible to complete the questionnaire, however only one questionnaire could be completed per owner.

RESULTS

The estimated prevalence of owner-reported headshaking in the sample population of horses (n = 1014), within the last year, was 4.6% (95% confidence interval 3.5-6.1), whereas 6.2% (95% confidence interval 4.9-7.9) of horses were reported by their owners to have shown signs of headshaking at any time-point since ownership. There was no association of sex or breed. Nineteen percent of headshaking horses were reported to show headshaking at rest. Fewer than one-third (30.2%, n = 19) of headshaking horses had been examined by a veterinarian for headshaking. Of horses seen by a veterinarian, the cause for headshaking remained unknown in the majority of cases (57.9% responses) and trigeminal-mediated headshaking was reported as a diagnosis in just one case.

MAIN LIMITATIONS

The accuracy in data reporting by horse owners was not verified in this study. There may be a potential for bias towards over-reporting due to the nature of survey participation.

CONCLUSIONS

Within this sample, owner-reported prevalence of signs of headshaking within the last year, in horses in the UK was 4.6%. Over two-thirds of owners of headshaking horses did not seek veterinary intervention for headshaking. Trigeminal-mediated headshaking was rarely reported by owners as a diagnosis.

LOAD-ENHANCED MOVEMENT QUALITY SCREENING AND TACTICAL ATHLETICISM: AN EXTENSION OF EVIDENCE

BACKGROUND

Military organizations use movement quality screening for prediction of injury risk and performance potential. Currently, evidence of an association between movement quality and performance is limited. Recent work has demonstrated that external loading strengthens the relationship between movement screens and performance outcomes. Such loading may therefore steer us toward robust implementations of movement quality screens while maintaining their appeal as cost effective, field-expedient tools.

PURPOSE

The purpose of the current study was to quantify the effect of external load-bearing on the relationship between clinically rated movement quality and tactical performance outcomes while addressing the noted limitations.

STUDY DESIGN

Crossover Trial.

METHODS

Fifty young adults (25 male, 25 female, 22.98 ± 3.09 years, 171.95 ± 11.46 cm, 71.77 ± 14.03 kg) completed the Functional Movement Screen™ with (FMS™W) and without (FMS™C) a weight vest in randomized order. Following FMS™ testing, criterion measures of tactical performance were administered, including agility T-Tests, sprints, a 400-meter run, the Mobility for Battle (MOB) course, and a simulated casualty rescue. For each performance outcome, regression models were selected via group lasso with smoothed FMS™ item scores as candidate predictor variables.

RESULTS

For all outcomes, proportion of variance accounted for was greater in FMS™W (R² = ;0.22 [T-Test], 0.29 [Sprint], 0.17 [400 meter], 0.29 [MOB], and 0.11 [casualty rescue]) than in FMS™C (R² = ;0.00 [T-Test], 0.11 [Sprint], 0.00 [400 meter], 0.19 [MOB], and 0.00 [casualty rescue]). From the FMS™W condition, beneficial performance effects (p<0.05) were observed for Deep Squat (sprint, casualty rescue), Hurdle Step (T-Agility, 400 meter run), Inline Lunge (sprint, MOB), and Trunk Stability Push Up (all models). Similar effects for FMS™C item scores were limited to Trunk Stability Push Up (p<0.05, all models).

CONCLUSIONS

The present study extends evidence supporting the validity of load-enhanced movement quality screening as a predictor of tactical performance ability. Future designs should seek to identify mechanisms explaining this effect.

LEVEL OF EVIDENCE

3.

Altered Kinematics and Time to Stabilization During Drop-Jump Landings in Individuals With or Without Functional Ankle Instability

CONTEXT

It has been proposed that altered dynamic-control strategies during functional activity such as jump landings may partially explain recurrent instability in individuals with functional ankle instability (FAI).

OBJECTIVE

To capture jump-landing time to stabilization (TTS) and ankle motion using a multisegment foot model among FAI, coper, and healthy control individuals.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Participants were 23 individuals with a history of at least 1 ankle sprain and at least 2 episodes of giving way in the past year (FAI), 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (copers), and 23 individuals with no history of ankle sprain or instability in their lifetime (controls). Participants were matched for age, height, and weight (age = 23.3 ± 3.8 years, height = 1.71 ± 0.09 m, weight = 69.0 ± 13.7 kg).

INTERVENTION(S)

Ten single-legged drop jumps were recorded using a 12-camera Vicon MX motion-capture system and a strain-gauge force plate.

MAIN OUTCOME MEASURES

Mediolateral (ML) and anteroposterior (AP) TTS in seconds, as well as forefoot and hindfoot sagittal- and frontal-plane angles at jump-landing initial contact and at the point of maximum vertical ground reaction force were calculated.

RESULTS

For the forefoot and hindfoot in the sagittal plane, group differences were present at initial contact (forefoot: P = .043, hindfoot: P = .004). At the hindfoot, individuals with FAI displayed more dorsiflexion than the control and coper groups. Time to stabilization differed among groups (AP TTS: P < .001; ML TTS: P = .040). Anteroposterior TTS was longer in the coper group than in the FAI or control groups, and ML TTS was longer in the FAI group than in the control group.

CONCLUSIONS

During jump landings, copers showed differences in sagittal-plane control, including less plantar flexion at initial contact and increased AP sway during stabilization, which may contribute to increased dynamic stability.

Multiplanar Knee Laxity and Perceived Function During Activities of Daily Living and Sport

CONTEXT

Greater knee-joint laxity may lead to a higher risk of knee injury, yet it is unknown whether results of self-reported outcome measures are associated with distinct knee-laxity profiles.

OBJECTIVE

To identify the extent to which multiplanar knee laxity is associated with patient-reported outcomes of knee function in healthy individuals during activities of daily living and sport.

DESIGN

Descriptive laboratory study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty healthy individuals (20 men, 20 women; age = 18-31 years).

MAIN OUTCOME MEASURE(S)

All participants were given the Knee Outcome Survey Activities of Daily Living Scale (KOS-ADL) and Sports Activities Scale (KOS-SAS) and subsequently measured for knee laxity in the sagittal, frontal, and transverse planes. Separate backward stepwise regression analyses were performed to determine the extent to which multiplanar knee-laxity values predicted KOS-ADL and KOS-SAS scores within each sex.

RESULTS

Women had higher magnitudes of anterior, posterior (POST(LAX)), varus (VAR(LAX)), valgus (VAL(LAX)), and internal-rotation laxity than men and trended toward greater external rotation (ER(LAX)) laxity. Greater POST(LAX), less VAL(LAX), and greater VAR(LAX) was associated with lower KOS-ADL scores (KOS-ADL = -4.8 [POST(LAX)], + 3.3 [VAL(LAX)] - 2.2 [VAR(LAX)] + 100.4, R2 = 0.74, P < .001) and greater POST(LAX) and less VAL(LAX) was associated with lower KOS-SAS scores (KOS-SAS = -8.2 [POST(LAX)], + 3.6 [VAL(LAX)] + 96.4, R2 = 0.67, P < .001) in women. In men, greater POST(LAX) and less ER(LAX) was associated with lower KOS-SAS scores (KOS-ADL = -4.7 [POST(LAX)], + 0.9 [ER(LAX)] + 96.4, R2 = 0.49, P < .001).

CONCLUSIONS

The combination of POST(LAX) with less relative VAL(LAX) (women) or less relative ER(LAX) (men) was a strong predictor of KOS scores, suggesting that a self-reported outcome measure may be beneficial as part of a preparticipation screening battery to identify those with perceived functional deficits associated with their knee laxity.

MODIFIED FUNCTIONAL MOVEMENT SCREENING AS A PREDICTOR OF TACTICAL PERFORMANCE POTENTIAL IN RECREATIONALLY ACTIVE ADULTS

BACKGROUND

Failure to meet minimum performance standards is a leading cause of attrition from basic combat training. A standardized assessment such as the Functional Movement Screen™ (FMS™) could help identify movement behaviors relevant to physical performance in tactical occupations. Previous work has demonstrated only marginal association between FMS™ tests and performance outcomes, but adding a load challenge to this movement assessment may help highlight performance-limiting behaviors.

PURPOSE

The purposes of this investigation were to quantify the effect of load on FMS™ tests and determine the extent to which performance outcomes could be predicted using scores from both loaded and unloaded FMS™ conditions.

STUDY DESIGN

Crossover Trial.

METHODS

Thirteen female and six male recreationally active college students (21 ± 1.37 years, 168 ± 9.8 cm, 66 ± 12.25 kg) completed the FMS™ under (1) a control condition (FMS™C), and (2) an 18.10kg weight vest condition (FMS™W). Balance was assessed using a force plate in double-legged stance and tactical physical performance was evaluated via completion times in a battery of field tests. For each condition, penalized regression was used to select models from the seven FMS™ component tests to predict balance and performance outcomes. Data were collected during a single session lasting approximately three hours per participant.

RESULTS

For balance, significant predictors were identified from both conditions but primarily predicted poorer balance with increasing FMS™ scores. For tactical performance, models were retained almost exclusively from FMS™W and generally predicted better performance with higher item scores.

CONCLUSIONS

The current results suggest that FMS™ screening with an external load could help predict performance relevant to tactical occupations. Sports medicine and fitness professionals interested in performance outcomes may consider assessing movement behaviors under a load.

LEVEL OF EVIDENCE

3.

Noise-Enhanced Eversion Force Sense in Ankles With or Without Functional Instability

CONTEXT

Force sense impairments are associated with functional ankle instability. Stochastic resonance stimulation (SRS) may have implications for correcting these force sense deficits.

OBJECTIVE

To determine if SRS improved force sense.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twelve people with functional ankle instability (age = 23 ± 3 years, height = 174 ± 8 cm, mass = 69 ± 10 kg) and 12 people with stable ankles (age = 22 ± 2 years, height = 170 ± 7 cm, mass = 64 ± 10 kg).

INTERVENTION(S)

The eversion force sense protocol required participants to reproduce a targeted muscle tension (10% of maximum voluntary isometric contraction). This protocol was assessed under SRSon and SRSoff (control) conditions. During SRSon, random subsensory mechanical noise was applied to the lower leg at a customized optimal intensity for each participant.

MAIN OUTCOME MEASURE(S)

Constant error, absolute error, and variable error measures quantified accuracy, overall performance, and consistency of force reproduction, respectively.

RESULTS

With SRS, we observed main effects for force sense absolute error (SRSoff = 1.01 ± 0.67 N, SRSon = 0.69 ± 0.42 N) and variable error (SRSoff = 1.11 ± 0.64 N, SRSon = 0.78 ± 0.56 N) (P < .05). No other main effects or treatment-by-group interactions were found (P > .05).

CONCLUSIONS

Although SRS reduced the overall magnitude (absolute error) and variability (variable error) of force sense errors, it had no effect on the directionality (constant error). Clinically, SRS may enhance muscle tension ability, which could have treatment implications for ankle stability.

Trunk-rotation differences at maximal reach of the star excursion balance test in participants with chronic ankle instability

CONTEXT

Functional reach on the Star Excursion Balance Test is decreased in participants with chronic ankle instability (CAI). However, comprehensive 3-dimensional kinematics associated with these deficits have not been reported.

OBJECTIVE

To determine if lower extremity kinematics differed in CAI participants during anteromedial, medial, and posteromedial reach on the Star Excursion Balance Test.

DESIGN

Case-control study.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty CAI participants (age = 24.15 ± 3.84 years, height = 168.95 ± 11.57 cm, mass = 68.95 ± 16.29 kg) and 20 uninjured participants (age = 25.65 ± 5.58 years, height = 170.14 ± 8.75 cm, mass = 69.89 ± 10.51 kg) with no history of ankle sprain. We operationally defined CAI as repeated episodes of ankle "giving way" or "rolling over" or both, regardless of neuromuscular deficits or pathologic laxity. All CAI participants scored ≤26 on the Cumberland Ankle Instability Tool.

INTERVENTION(S)

Star Excursion Balance Test reaches in the anteromedial, medial, and posteromedial directions. The CAI participants used the unstable side as the stance leg. Control participants were sex, height, mass, and side matched to the CAI group. The 3-dimensional kinematics were assessed with a motion-capture system.

MAIN OUTCOME MEASURE(S)

Group differences on normalized reach distance, trunk, pelvis, and hip-, knee-, and ankle-joint angles at maximum Star Excursion Balance Test reach.

RESULTS

No reach-distance differences were detected between CAI and uninjured participants in any of the 3 reach directions. With anteromedial reach, trunk rotation (t(1,38) = 3.06, P = .004), pelvic rotation (t(1,38) = 3.17, P = .003), and hip flexion (t(1,38) = 2.40, P = .002) were greater in CAI participants. With medial reach, trunk flexion (t(1,38) = 6.39, P = .05) was greater than for uninjured participants. No differences were seen with posteromedial reach.

CONCLUSIONS

We did not detect reach-distance differences in any direction. However, participants with CAI rotated the trunk and pelvis more toward the stance leg than did stable-ankle participants during anteromedial and medial reach, possibly to help maintain a proximal stable posture and compensate for distal instability. These joint-angle differences with Star Excursion Balance Test performance may represent unique compensatory patterns for those with CAI.

Recalibration and validation of the Cumberland Ankle Instability Tool cutoff score for individuals with chronic ankle instability

OBJECTIVE

To independently recalibrate and revalidate the Cumberland Ankle Instability Tool (CAIT) cutoff score for discriminating individuals with and without chronic ankle instability (CAI). There are concerns the original cutoff score (≤27) may be suboptimal for use in the CAI population.

DESIGN

Case control.

SETTING

Research laboratory.

PARTICIPANTS

Two independent datasets were used (total N=200). Dataset 1 included 61 individuals with a history of ≥1 ankle sprain and ≥2 episodes of giving way in the last year (CAI group) and 57 participants with no history of ankle sprain or instability in their lifetime (uninjured group). Dataset 2 included 27 uninjured participants, 29 participants with CAI, and 26 individuals with a history of a single ankle sprain and no subsequent instability (copers).

INTERVENTIONS

All participants completed the CAIT during a single session. In dataset 1, a receiver operating characteristic (ROC) curve was calculated using the CAIT score and group membership as test variables. The ideal cutoff score was identified using the Youden index. The recalibrated cutoff score was validated in dataset 2 using the ROC analysis and clinimetric characteristics.

MAIN OUTCOME MEASURES

CAIT cutoff score and clinimetrics.

RESULTS

In dataset 1, the optimal cutoff score was ≤25, which is lower than previously reported. In dataset 2, the recalibrated cutoff score demonstrated a sensitivity of 96.6%, specificity of 86.8%, positive likelihood ratio of 7.318, and negative likelihood ratio of .039. There were 7 false positives and 1 false negative.

CONCLUSIONS

The recalibrated CAIT score demonstrated very good clinimetric properties; all properties improved compared with the original cutoff score. Clinicians using the CAIT should use the recalibrated cutoff score to maximize test characteristics. Caution should be taken with copers, who had a high rate of false positives.

Postural-stability tests that identify individuals with chronic ankle instability

CONTEXT

Chronic ankle instability (CAI) is characterized by repeated ankle sprains, which have been linked to postural instability. Therefore, it is important for clinicians to identify individuals with CAI who can benefit from rehabilitation.

OBJECTIVE

To assess the likelihood that CAI participants will exhibit impaired postural stability and that healthy control participants will exhibit better test performance values.

DESIGN

Case-control study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

People with CAI (n = 17, age = 23 ± 4 years, height = 168 ± 9 cm, weight = 68 ± 12 kg) who reported ankle "giving-way" sensations and healthy volunteers (n = 17, age = 23 ± 3 years, height = 168 ± 8 cm, weight = 66 ± 12 kg).

INTERVENTION(S)

Participants performed 7 balance tests: Balance Error Scoring System (BESS), time in balance, foot lift, single-legged stance on a force plate, Star Excursion Balance Test, side hop, and figure-of-8 hop.

MAIN OUTCOME MEASURE(S)

Balance was quantified with errors (score) for the BESS, length of time balancing (seconds) for time-in-balance test, frequency of foot lifts (score) for foot-lift test, velocity (cm/s) for all center-of-pressure velocity measures, excursion (cm) for center-of-pressure excursion measures, area (cm2) for 95% confidence ellipse center-of-pressure area and center-of-pressure rectangular area, time (seconds) for anterior-posterior and medial-lateral time-to-boundary (TTB) measures, distance reached (cm) for Star Excursion Balance Test, and time (seconds) to complete side-hop and figure-of-8 hop tests. We calculated area-under-the-curve values and cutoff scores and used the odds ratio to determine if those with and without CAI could be distinguished using cutoff scores.

RESULTS

We found significant area-under-the-curve values for 4 static noninstrumented measures, 3 force-plate measures, and 3 functional measures. Significant cutoff scores were noted for the time-in-balance test (≤25.89 seconds), foot-lift test (≥5), single-legged stance on the firm surface (≥3 errors) and total (≥14 errors) on the BESS, center-of-pressure resultant velocity (≥1.56 cm/s), standard deviations for medial-lateral (≤1.56 seconds) time-to-boundary and anterior-posterior (≤3.78 seconds) time-to-boundary test, posteromedial direction on the Star Excursion Balance Test (≤0.91), side-hop test (≥12.88 seconds), and figure-of-8 hop test (≥17.36 seconds).

CONCLUSIONS

Clinicians can use any of the 10 significant measures with their associated cutoff scores to identify those who could benefit from rehabilitation that reestablishes postural stability.

Clinical examination results in individuals with functional ankle instability and ankle-sprain copers

CONTEXT

Why some individuals with ankle sprains develop functional ankle instability and others do not (ie, copers) is unknown. Current understanding of the clinical profile of copers is limited.

OBJECTIVE

To contrast individuals with functional ankle instability (FAI), copers, and uninjured individuals on both self-reported variables and clinical examination findings.

DESIGN

Cross-sectional study.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Participants consisted of 23 individuals with a history of 1 or more ankle sprains and at least 2 episodes of giving way in the past year (FAI: Cumberland Ankle Instability Tool [CAIT] score = 20.52 ± 2.94, episodes of giving way = 5.8 ± 8.4 per month), 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (copers: CAIT score = 27.74 ± 1.69), and 23 individuals with no history of ankle sprain and no instability (uninjured: CAIT score = 28.78 ± 1.78).

INTERVENTION(S)

Self-reported disability was recorded using the CAIT and Foot and Ankle Ability Measure for Activities of Daily Living and for Sports. On clinical examination, ligamentous laxity and tenderness, range of motion (ROM), and pain at end ROM were recorded.

MAIN OUTCOME MEASURE(S)

Questionnaire scores for the CAIT, Foot and Ankle Ability Measure for Activities of Daily Living and for Sports, ankle inversion and anterior drawer laxity scores, pain with palpation of the lateral ligaments, ankle ROM, and pain at end ROM.

RESULTS

Individuals with FAI had greater self-reported disability for all measures (P < .05). On clinical examination, individuals with FAI were more likely to have greater talar tilt laxity, pain with inversion, and limited sagittal-plane ROM than copers (P < .05).

CONCLUSIONS

Differences in both self-reported disability and clinical examination variables distinguished individuals with FAI from copers at least 1 year after injury. Whether the deficits could be detected immediately postinjury to prospectively identify potential copers is unknown.

Customized noise-stimulation intensity for bipedal stability and unipedal balance deficits associated with functional ankle instability

CONTEXT

Stochastic resonance stimulation (SRS) administered at an optimal intensity could maximize the effects of treatment on balance.

OBJECTIVE

To determine if a customized optimal SRS intensity is better than a traditional SRS protocol (applying the same percentage sensory threshold intensity for all participants) for improving double- and single-legged balance in participants with or without functional ankle instability (FAI).

DESIGN

Case-control study with an embedded crossover design.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twelve healthy participants (6 men, 6 women; age = 22 ± 2 years, height = 170 ± 7 cm, mass = 64 ± 10 kg) and 12 participants (6 men, 6 women; age = 23 ± 3 years, height = 174 ± 8 cm, mass = 69 ± 10 kg) with FAI.

INTERVENTION(S)

The SRS optimal intensity level was determined by finding the intensity from 4 experimental intensities at the percentage sensory threshold (25% [SRS₂₅], 50% [SRS₅₀], 75% [SRS₇₅], 90% [SRS₉₀]) that produced the greatest improvement in resultant center-of-pressure velocity (R-COPV) over a control condition (SRS₀) during double-legged balance. We examined double- and single-legged balance tests, comparing optimal SRS (SRS(opt1)) and SRS₀ using a battery of center-of-pressure measures in the frontal and sagittal planes.

MAIN OUTCOME MEASURE(S)

Anterior-posterior (A-P) and medial-lateral (M-L) center-of-pressure velocity (COPV) and center-of-pressure excursion (COPE), R-COPV, and 95th percentile center-of-pressure area ellipse (COPA-95).

RESULTS

Data were organized into bins that represented optimal (SRS(opt1)), second (SRS(opt2)), third (SRS(opt3)), and fourth (SRS(opt4)) improvement over SRS₀. The SRS(opt1) enhanced R-COPV (P ≤ .05) over SRS₀ and other SRS conditions (SRS₀ = 0.94 ± 0.32 cm/s, SRS(opt1) = 0.80 ± 0.19 cm/s, SRS(opt2) = 0.88 ± 0.24 cm/s, SRS(opt3) = 0.94 ± 0.25 cm/s, SRS(opt4) = 1.00 ± 0.28 cm/s). However, SRS did not improve R-COPV over SRS₀ when data were categorized by sensory threshold. Furthermore, SRS(opt1) improved double-legged balance over SRS₀ from 11% to 25% in all participants for the center-of-pressure frontal- and sagittal-plane assessments (P ≤ .05). The SRS(opt1) also improved single-legged balance over SRS₀ from 10% to 17% in participants with FAI for the center-of-pressure frontal- and sagittal-plane assessments (P ≤ .05). The SRS(opt1) did not improve single-legged balance in participants with stable ankles.

CONCLUSIONS

The SRS(opt1) improved double-legged balance and transfers to enhancing single-legged balance deficits associated with FAI.

Functional ankle instability and health-related quality of life

CONTEXT

To our knowledge, no authors have assessed health-related quality of life (HR-QOL) in participants with functional ankle instability (FAI). Furthermore, the relationships between measures of ankle functional limitation and HR-QOL are unknown.

OBJECTIVE

To use the Short Form-36v2 Health Survey (SF-36) to compare HR-QOL in participants with or without FAI and to determine whether HR-QOL was related to functional limitation.

DESIGN

Cross-sectional study.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Sixty-eight participants with FAI (defined as at least 1 lateral ankle sprain and 1 episode of giveway per month) or without FAI were recruited (FAI group: n = 34, age = 25 ± 5 years, height = 1.71 ± 0.08 m, mass = 74.39 ± 12.78 kg, Cumberland Ankle Instability Tool score = 19.3 ± 4; uninjured [UI] group: n = 34, age = 23 ± 4 years, height = 1.69 ± 0.08 m, mass = 67.94 ± 11.27 kg, Cumberland Ankle Instability Tool score = 29.4 ± 1).

MAIN OUTCOME MEASURE(S)

All participants completed the SF-36 as a measure of HR-QOL and the Foot and Ankle Ability Measure (FAAM) and the FAAM Sport version (FAAMS) as assessments of functional limitation. To compare the FAI and UI groups, we calculated multiple analyses of variance followed by univariate tests. Additionally, we correlated the SF-36 summary component scale and domain scales with the FAAM and FAAMS scores.

RESULTS

Participants with FAI had lower scores on the SF-36 physical component summary (FAI = 54.4 ± 5.1, UI = 57.8 ± 3.7, P = .005), physical function domain scale (FAI = 54.5 ± 3.8, UI = 56.6 ± 1.2, P = .004), and bodily pain domain scale (FAI = 52.0 ± 6.7, UI = 58.5 ± 5.3, P < .005). Similarly, participants with FAI had lower scores on the FAAM (FAI = 93.7 ± 8.4, UI = 99.5 ± 1.4, P < .005) and FAAMS (FAI = 84.5 ± 8.4, UI = 99.8 ± 0.72, P < .005) than did the UI group. The FAAM score was correlated with the physical component summary scale (r = 0.42, P = .001) and the physical function domain scale (r = 0.61, P < .005). The FAAMS score was correlated with the physical function domain scale (r = 0.47, P < .005) and the vitality domain scale (r = 0.36, P = .002).

CONCLUSIONS

Compared with UI participants, those with FAI had less HR-QOL and more functional limitations. Furthermore, positive correlations were found between HR-QOL and functional limitation measures. This suggests that ankle impairment may reduce overall HR-QOL.

Balance assessments for predicting functional ankle instability and stable ankles

A number of instrumented and non-instrumented measures are used to detect balance deficits associated with functional ankle instability (FAI). Determining outcome measures that detect balance deficits associated with FAI might assist clinicians in identifying impairments that may otherwise go undetected with less responsive balance measures. Thus, our objective was to determine the balance measure that best predicted ankle group membership (FAI or stable ankle). Participants included 17 subjects without a history of ankle sprains (168±9 cm, 66±14 kg, 24±5 yr) and 17 subjects with FAI (172±9 cm, 71±11 kg, 22±3 yr). Balance trials were performed without vision and subjects stood on a single leg as motionless as possible for 20s. Balance was quantified with center-of-pressure measures (velocity, area) and error score. Measures were positively correlated with each other (r range: 0.60-0.76). The multifactorial model with all three measures best predicted group membership (F((3,30))=7.20, P=0.001; R(2)=0.42; percent classified correctly=77%), and was followed by the multifactorial model with resultant center-of-pressure velocity and error score (F((2,31))=8.73, P=0.001; R(2)=0.36; percent classified correctly=74%). The resultant center-of-pressure velocity (F((1,32))=13.46, P=0.001; R(2)=0.30; percent classified correctly=74%; unique variance=12.7%) and error score (F((1,32))=12.51, P=0.001; R(2)=0.28; percent classified correctly=71%; unique variance=12.0%) predicted group membership; however, 95th percentile center-of-pressure area ellipse did not (F((1,32))=4.16, P=0.05; R(2)=0.12; percent classified correctly=65%; unique variance=5.8%). A multifactorial single leg balance assessment is best for predicting group membership. COPV is the best single predictor of group membership, but clinicians may use error score to identify deficits associated with FAI if force plates are not available.

Concentric evertor strength differences and functional ankle instability: a meta-analysis

OBJECTIVE

To determine whether concentric evertor muscle weakness was associated with functional ankle instability (FAI).

DATA SOURCES

We conducted an electronic search through November 2007, limited to English, and using PubMed, Pre-CINAHL, CINAHL, and SPORTDiscus. A forward search was conducted using the Science Citation Index on studies from the electronic search. Finally, we conducted a hand search of all selected studies and contacted the respective authors to identify additional studies. We included peer-reviewed manuscripts, dissertations, and theses.

STUDY SELECTION

We evaluated the titles and abstracts of studies identified by the electronic searches. Studies were selected by consensus and reviewed only if they included participants with FAI or chronic ankle instability and strength outcomes. Studies were included in the analysis if means and SDs (or other relevant statistical information, such as P values or t values and group n's) were reported for FAI and stable groups (or ankles).

DATA EXTRACTION

Data were extracted by the authors independently, cross-checked for accuracy, and limited to outcomes of concentric eversion strength. We rated each study for quality. Outcomes were coded as either fast or slow velocity (ie, equal to or greater than 110 degrees /s or less than 110 degrees /s, respectively).

DATA SYNTHESIS

Data included the means, SDs, and group sample sizes (or other appropriate statistical information) for the FAI and uninjured groups (or ankles). The standard difference in the means (SDM) for each outcome was calculated using the pooled SD. We tested individual and overall SDMs using the Z statistic and comparisons between fast and slow velocities using the Q statistic. Our analysis revealed that ankles with FAI were weaker than stable ankles (SDM = 0.224, Z = 4.0, P < .001, 95% confidence interval = 0.115, 0.333). We found no difference between the fast- and slow-velocity SDMs (SDM(Fast) = 0.189, SDM(Slow) = 0.244, Q = 29.9, df = 24, P = .187). Because of the small SDM, this method of measuring ankle strength in the clinical setting may need to be reevaluated.

Thigh muscle activity, knee motion, and impact force during side-step pivoting in agility-trained female basketball players

CONTEXT

Improving neuromuscular control of hamstrings muscles might have implications for decreasing anterior cruciate ligament injuries in females.

OBJECTIVE

To examine the effects of a 6-week agility training program on quadriceps and hamstrings muscle activation, knee flexion angles, and peak vertical ground reaction force.

DESIGN

Prospective, randomized clinical research trial.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty female intramural basketball players with no history of knee injury (age = 21.07 +/- 2.82 years, height = 171.27 +/- 4.66 cm, mass = 66.36 +/- 7.41 kg).

INTERVENTION(S)

Participants were assigned to an agility training group or a control group that did not participate in agility training. Participants in the agility training group trained 4 times per week for 6 weeks.

MAIN OUTCOME MEASURE(S)

We used surface electromyography to assess muscle activation for the rectus femoris, vastus medialis oblique, medial hamstrings, and lateral hamstrings for 50 milliseconds before initial ground contact and while the foot was in contact with the ground during a side-step pivot maneuver. Knee flexion angles (at initial ground contact, maximum knee flexion, knee flexion displacement) and peak vertical ground reaction force also were assessed during this maneuver.

RESULTS

Participants in the training group increased medial hamstrings activation during ground contact after the 6-week agility training program. Both groups decreased their vastus medialis oblique muscle activation during ground contact. Knee flexion angles and peak vertical ground reaction force did not change for either group.

CONCLUSIONS

Agility training improved medial hamstrings activity in female intramural basketball players during a side-step pivot maneuver. Agility training that improves hamstrings activity might have implications for reducing anterior cruciate ligament sprain injury associated with side-step pivots.

Interest in health information exchange in ambulatory care: a statewide survey

OBJECTIVE

Assess the interest in and preferences of ambulatory practitioners in HIE.

BACKGROUND

Health information exchange (HIE) may improve the quality and efficiency of care. Identifying the value proposition for smaller ambulatory practices may help those practices engage in HIE.

METHODS

Survey of primary care and specialist practitioners in the State of Colorado.

RESULTS

Clinical data were commonly (always [2%], often [29%] or sometimes [49%]) missing during clinic visits. Of 12 data types proposed as available through HIE, ten were considered "extremely useful" by most practitioners. "Clinical notes/consultation reports," "diagnosis or problem lists," and "hospital discharge summaries" were considered the three most useful data types. Interest in EKG reports, diagnosis/problem lists, childhood immunizations, and discharge summaries differed among ambulatory practitioner groups (primary care, obstetrics-gynecology, and internal medicine subspecialties).

CONCLUSION

Practitioners express strong interest in most of the data types, but opinions differed by specialties on what types were most important. All providers felt that a system that provided all data types would be useful. These results support the potential benefit of HIE in ambulatory practices.

Ankle instability is associated with balance impairments: a meta-analysis

PURPOSE

Our primary purpose was to determine whether balance impairments were associated with functional ankle instability (FAI).

METHODS

Our literature search consisted of four parts: 1) an electronic search of PubMed, CINAHL, pre-CINAHL, and SPORTDiscus; 2) a forward search of articles selected from the electronic search using the Science Citation Index; 3) a hand search of the previously selected articles; and 4) a direct contact with corresponding authors of the previously selected articles. We initially identified 145 articles and narrowed these to 23 for inclusion in the meta-analysis. Identified outcomes were categorized by measurement units and balance task type (i.e., dynamic or static). Each study was coded based on whether inclusion or exclusion criteria were identified. Our statistical analysis included fixed, random, or mixed effect analyses based on the presence of within study heterogeneity and whether categories were being compared.

RESULTS

FAI was associated with poorer balance (standard difference of the mean [SDM] = 0.455, 95% confidence interval = 0.334-0.577, Z = 7.34, P < 0.001), but no difference existed between dynamic and static measure categories (Q = 3.44, P = 0.063). However, there was a significant difference between the dynamic measures (Q = 6.22, P = 0.013) with both time to stabilization and the Star Excursion Balance Test producing significant SDM and between static measures (Q = 13.00, P = 0.012) with the linear, time, velocity, and other measurement categories (but not area) producing significant SDM. Examination of individual outcomes revealed that time in balance and foot lifts produced very large SDM (3.3 and 4.8, respectively).

CONCLUSION

FAI is associated with impaired balance. Due to the relatively large effect sizes and simplicity of use of time in balance and foot lifts, we recommend that further research should establish their clinical validity and clinical cutoff scores.

Balance measures for discriminating between functionally unstable and stable ankles

PURPOSE

To identify force plate measures that discriminate between ankles with functional instability and stable ankles and to determine the most accurate force plate measure for enabling this distinction.

METHODS

Twenty-two subjects (177 +/- 10 cm, 77 +/- 16 kg, 21 +/- 2 yr) without a history of ankle injury and 22 subjects (177 +/- 10 cm, 77 +/- 16 kg, 20 +/- 2 yr) with functional ankle instability (FAI) performed a single-leg static balance test and a single-leg jump-landing dynamic balance test. Static force plate measures analyzed in both anterior/posterior (A/P) and medial/lateral (M/L) directions included the following: ground reaction force (GRF) SD; center-of-pressure (COP) SD; mean, maximum, and total COP excursion; and mean and maximum COP velocity. COP area was also analyzed for static balance. A/P and M/L time to stabilization quantified dynamic balance. Greater values of force plate measures indicated impaired balance. A stepwise discriminant function analysis examined group differences, group classification, and accuracy of force plate measures for discriminating between ankle groups.

RESULTS

The FAI group had greater values than the stable ankle group for A/P GRF SD (P = 0.027), M/L GRF SD (P = 0.006), M/L COP SD (P = 0.046), A/P mean COP velocity (P = 0.015), M/L mean COP velocity (P = 0.016), A/P maximum COP velocity (P = 0.037), M/L mean COP excursion (P = 0.014), M/L total COP excursion (P = 0.016), A/P time to stabilization (P = 0.011), and M/L time to stabilization (P = 0.040). M/L GRF SD and A/P time to stabilization had the greatest accuracy scores of 0.73 and 0.72, respectively.

CONCLUSION

Although 10 measures identified group differences, M/L GRF SD and A/P time to stabilization were the most accurate in discriminating between ankle groups. These results provide evidence for choosing these GRF measures for evaluating static and dynamic balance deficits associated with FAI.

Assessment tools for identifying functional limitations associated with functional ankle instability

CONTEXT

Assessment tools should identify functional limitations associated with functional ankle instability (FAI) by discriminating unstable from stable ankles.

OBJECTIVE

To identify assessment tools that discriminated FAI from stable ankles and determine the most accurate assessment tool for discriminating between FAI and stable ankles.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifteen individuals with FAI and 15 healthy individuals; participants with unilateral FAI reported "giving-way" sensations and ankle sprains, whereas healthy participants did not.

INTERVENTION(S)

Participants answered 12 questions on the Ankle Joint Functional Assessment Tool (AJFAT). They also performed a single-leg jump landing, which required them to jump to half their maximum jump height, land on a single leg, and stabilize quickly on a force plate.

MAIN OUTCOME MEASURE(S)

Receiver operating characteristic curves determined cutoff scores for discriminating between ankle groups for AJFAT total score and resultant vector (RV) time to stabilization. Accuracy values for discriminating between groups were determined by calculating the area under the receiver operating characteristic curves.

RESULTS

The cutoff score for discriminating between FAI and stable ankles was > or =26 (sensitivity = 1, specificity = 1) and > or =1.58 seconds (sensitivity = 0.67, specificity = 0.73) for the AJFAT total score and RV time to stabilization, respectively. The area under the curve for the AJFAT was 1.0 (asymptotic significance <.05), whereas the RV time to stabilization had an area under the curve of 0.72 (asymptotic significance <.05).

CONCLUSIONS

The AJFAT was an excellent assessment tool for discriminating between ankle groups, whereas RV time to stabilization was a fair assessment tool. Although both assessments discriminated between ankle groups, the AJFAT more accurately discriminated between groups than the RV time to stabilization did. Future researchers should confirm these findings using a prospective research design.

Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

Background

Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains.

Methods

This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea).

Results

Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 ± 0.4 cm/s vs. 2.7 ± 0.6 cm/s), M/L COPvel (2.6 ± 0.5 cm/s vs. 2.9 ± 0.5 cm/s), M/L COPsd (0.63 ± 0.12 cm vs. 0.73 ± 0.11 cm), M/L COPmax (1.76 ± 0.25 cm vs. 1.98 ± 0.25 cm), and COParea (0.13 ± 0.03 cm² vs. 0.16 ± 0.04 cm²) than the pooled means of the CCT and control groups (P < 0.05).

Conclusion

Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI.

Noise-enhanced postural stability in subjects with functional ankle instability

OBJECTIVE

To examine the effects of stochastic resonance (SR) stimulation on the postural stability of subjects with functional ankle instability (FAI).

DESIGN

Experimental research design.

SETTING

Sports medicine research laboratory.

PARTICIPANTS

12 subjects with FAI who reported a history of recurrent ankle sprains and "giving way" sensations at the ankle.

INTERVENTIONS

Subjects performed 20 s single-leg balance tests under SR stimulation at 0.05 mA and 0.01 mA and under control conditions. Testing order was randomised. Stimulators that delivered subsensory stimulation to ankle muscles and ligaments were worn. Subjects were blinded to the test conditions, as SR stimulation was subsensory and stimulators were turned off during the control condition.

MAIN OUTCOME MEASURES

Anterior/posterior and medial/lateral centre-of-pressure velocities (COPVs) were combined to form a resultant vector (COPV-R). The COPV-R differences between the optimal SR stimulation and control conditions were analysed. Optimal SR stimulation was defined as the SR stimulation input intensity level (0.05 mA or 0.01 mA) that produced the greatest percentage improvement in postural stability compared with the control condition. Slower velocities indicated enhanced postural stability.

RESULTS

The optimal input intensity was 0.05 mA for nine subjects and 0.01 mA for the other three. The optimal SR stimulation significantly (p<0.05) improved COPV-R compared with the control condition (6.60 (1.06) vs 7.20 (1.03) cm/s; mean (SD)).

CONCLUSION

SR stimulation may enhance signal detection of sensorimotor signals associated with postural stability. This result has clinical relevance as improvements in postural instability associated with FAI may decrease ankle sprain injury.

Functional balance training, with or without exercise sandals, for subjects with stable or unstable ankles

CONTEXT

Improving postural stability through balance training may prevent ankle sprains. Exercise Sandals may increase the demands placed on ankle muscles during rehabilitation, which could improve postural stability.

OBJECTIVE

To examine the effects of functional balance training, with and without the use of Exercise Sandals, on postural stability in subjects with stable or unstable ankles.

DESIGN

Prospective, nonrandomized clinical trial.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Sixteen subjects with functional ankle instability and 16 subjects with no history of ankle sprains.

INTERVENTION(S)

Subjects were assigned to an Exercise Sandal functional balance training group or a shoe functional balance training group. Subjects trained 3 times per week for 8 weeks and then performed a single-limb stance posttest.

MAIN OUTCOME MEASURE(S)

Subjects were required to remain as motionless as possible during a single-limb stance pretest. Anterior-posterior and medial-lateral center-of-pressure excursions were measured.

RESULTS

Exercise Sandal balance training improved anterior-posterior postural stability in both ankle groups ( P < .05). Both training interventions improved medial-lateral postural stability in stable and unstable ankles ( P < .05).

CONCLUSIONS

Postural stability improved after subjects performed functional balance training programs, both with and without Exercise Sandals. Training with Exercise Sandals might not be any more effective in improving postural stability than performing functional balance training without Exercise Sandals. However, Exercise Sandals did not impair postural stability and, consequently, might serve as an alternative therapy to improve postural stability.

Effect of coordination training with and without stochastic resonance stimulation on dynamic postural stability of subjects with functional ankle instability and subjects with stable ankles

OBJECTIVE

To examine the effects of coordination training with and without stochastic resonance (SR) stimulation on dynamic postural stability.

DESIGN

Experimental with repeated measures.

SETTING

Research Laboratory.

PARTICIPANTS

Thirty subjects with functional ankle instability (FAI) and 30 healthy subjects.

INTERVENTIONS

Subjects were assigned to a conventional coordination training group, SR stimulation coordination training group, or control group. Training groups performed coordination exercises for 6 weeks. Single leg jump-landing tests were performed before training began (pretest), and then once every 2 weeks. Jump-landing tests required subjects to land on a single leg on a force plate and stabilize quickly.

MAIN OUTCOME MEASURES

Anterior/posterior (A/P) and medial/lateral (M/L) time-to-stabilization (TTS).

RESULTS

The FAI group improved their A/P TTS over their pretest by 16% (test 2), 22% (test 3), and 22% (posttest). They also improved their M/L TTS over their pretest by 16% (test 3) and 22% (posttest). Control groups did not improve their TTS (P>0.05). SR stimulation did not statistically influence TTS (P>0.05). Effect sizes (ES), however, for our 3-way interaction analyses for A/P TTS (ES=0.40) and M/L TTS (ES=0.30) suggested that SR stimulation improved the FAI group's M/L TTS after 2 weeks of training, and improved their A/P TTS and M/L TTS to a greater degree after 4 weeks than coordination training alone.

CONCLUSION

Coordination training can improve dynamic postural instabilities associated with FAI. SR stimulation might be an alternative therapy for FAI, as this stimulation might improve dynamic postural stability more quickly and to a greater extent than coordination training without SR stimulation.

Single-leg jump-landing stabilization times in subjects with functionally unstable ankles

CONTEXT

Factors contributing to functional ankle instability may cause individuals with the condition to land from a jump differently than those with stable ankles.

OBJECTIVE

To determine stabilization time differences during single-leg jump landings between stable and unstable ankle groups and to report the reliability and precision of time-to-stabilization measures.

DESIGN

A mixed design with 1 between factor (ankle group) and 1 within factor (direction) was used to analyze the comparison between our 10 subjects with functional ankle instability and 10 subjects with stable ankles. Time to stabilization (seconds) was the dependent measure. Reliability for time-to-stabilization measures of our 12 additional subjects with stable ankles were assessed using intraclass correlation coefficients (ICC 2,7). Standard errors of measurements were also calculated for time-to-stabilization measures.

SETTING

Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANT(S): Ten subjects with functional ankle instability who reported at least 2 sprains and "giving way'' sensations at their ankles constituted the functional ankle instability group. Ten subjects without a history of ankle sprain injury served as healthy subjects. Twelve additional healthy subjects participated in the reliability study.

INTERVENTION(S)

Subjects performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height and then land on a single leg on a force plate. After landing, they stabilized quickly and remained as motionless as possible in a single-leg stance for 20 s.

MAIN OUTCOME MEASURE(S)

Anterior-posterior and medial/ lateral vibration magnitude curve fit time-to-stabilization.

RESULTS

Time to stabilization was longer for the functional ankle instability group (1.98 +/- 0.81 s) than for the stable ankle group (1.45 +/- 0.30 s) (P < .05). Reliability (standard error of the measurement) values for anterior/posterior and medial/lateral time-to-stabilization were 0.79 (0.15 s) and 0.65 (0.26 s), respectively.

CONCLUSIONS

Time to stabilization was longer for subjects with functional ankle instability than subjects with stable ankles. The ankle instability may have impaired the subjects' ability to stabilize after a single-leg jump landing. Reliabilities and standard errors of the measurements of time-to-stabilization measures were moderate and low, respectively.

Examination of static and dynamic postural stability in individuals with functionally stable and unstable ankles

OBJECTIVE

To determine static and dynamic postural stability differences between functional ankle instability and stable ankle groups.

DESIGN

Subjects were required to balance on a single leg and remain motionless for 20 seconds. After completing 3 trials, they performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height. They landed on a single leg, stabilized quickly, and remained motionless for 20 seconds.

SETTING

Sports Medicine Research Laboratory.

PARTICIPANTS

Subjects with functional ankle instability (n = 14) who reported at least 2 sprains and "giving way" sensations at their ankle joint within the year prior to testing. Fourteen subjects with no history of ankle sprain injury were matched to subjects with functional ankle instability.

MAIN OUTCOME MEASURES

Anterior/posterior and medial/lateral mean sway quantified static postural stability during single-leg stance. Dynamic postural stability was quantified with anterior/posterior and medial/lateral time to stabilization during single-leg jump landing.

RESULTS

Mean sway was not significantly different between groups in the anterior/posterior (P = 0.28) and medial/lateral (P = 0.65) directions. The functional ankle instability group took significantly longer to stabilize in the anterior/posterior (3.27 +/- 0.72 seconds vs. 2.33 +/- 0.33 seconds; P < 0.001) and medial/lateral (2.48 +/- 0.50 seconds vs. 2.00 +/- 0.65 seconds; P = 0.04) directions.

CONCLUSIONS

Individuals with functional ankle instability took significantly longer to stabilize than individuals with stable ankles after a single-leg jump landing. Differences between groups were not detected with mean sway measured during single-leg stance.