Energy dissipation differs between females with and without chronic ankle instability.

Chronic ankle instability (CAI) is associated with altered energy dissipation patterns, but comparisons to lateral ankle sprain (LAS) copers have not been explored. The purpose of this study was to examine differences in relative sagittal plane energy dissipation during a single-leg landing between female CAI and LAS coper participants. We separated 33 females (23.6 ± 4.6 years, 164.3 ± 6.2 cm, 69.4 ± 13.7 kg) into CAI (n = 17) and LAS coper (n = 16) groups. Participants completed 5 single-leg landings followed by a 5-second stabilization. We collected sagittal plane kinematics and joint moments at the ankle, knee, hip, and proximal joints (knee and hip) combined then calculated each joint's energy dissipation at 50, 100, 150, and 200 ms post-landing. We compared the percentage of total energy dissipated by the ankle, knee, hip, and proximal joints during each interval utilizing independent t tests and Cohen's d effect sizes. Statistical significance was set a priori at P < .05. The CAI group had lower relative energy dissipation from the ankle at 50 (24.7 ± 11.5% vs 39.2 ± 11.8%, P < .01, d = 1.25 [0.47, 1.95]), 100 (66.9 ± 19.4% vs 77.7 ± 6.5%, P = .04, d = 0.74 [0.01, 1.42]), and 150 ms (70.7 ± 17.8% vs 81.0 ± 5.7%, P = .03, d = 0.77 [0.04, 1.46]) compared to LAS copers. The CAI group had a greater hip contribution through 150 ms (17.9 ± 10.7% vs 11.7 ± 4.4%, P = .04, d =-0.75 [-1.44, -0.03]) and the proximal joints at 50 (75.3 ± 11.5% vs 60.8 ± 11.8%, P < .01, d = -1.25 [-1.96, -0.47]), 100 (33.1 ± 19.4% vs 22.3 ± 6.5%, P = .04, d = -0.74 [-1.42, -0.01]), and 150 ms (29.3 ± 17.8 vs 19.0 ± 5.7%, P = .03, d =-0.77 [-1.46, -0.04]) compared to LAS copers. Females with CAI may benefit from therapeutic exercises designed to correct a single-leg energy dissipation strategy that relies less on the ankle joint.

Quantifying levels of function between different subgroups of chronic ankle instability.

The purpose of this original investigation was to determine if selected sensorimotor, mechanical, and self-reported measures are different among chronic ankle instability (CAI) subgroups, healthy control participants, and lateral ankle sprain copers (LAS-Copers). Ninety-four participants volunteered and were categorized into perceived ankle instability (PI) alone (n = 13), recurrent ankle sprains (RAS) alone (n = 12), PI in combination with RAS (PI-RAS; n = 25), LAS-Copers (n = 18), and controls (n = 26). Participants completed self-assessed global, regional, and psychological health-related quality-of-life (HRQOL) questionnaires and assessments of sensorimotor function and mechanical joint laxity. One-way ANOVAs were performed with the intention of reducing the number of original outcomes into a smaller number of predictor variables. Discriminant functional analysis was used to establish which specific measures best differentiate between groups. Eight outcome measures from neural excitability, postural control, static postural control, and HRQOL showed a significant differentiation between five groups (Wilk's λ = 0.26, χ232  = 114 45, P < 0.001, canonical correlation = 0.80) and correctly determined only 58.1% of group membership, and the PI-RAS and control groups were the only fit in the proposed model. A different model or other sensorimotor outcomes from more dynamic and complex tasks may be needed for the PI, RAS, and LAS-Coper groups.

Quadriceps neural alterations in anterior cruciate ligament reconstructed patients: A 6-month longitudinal investigation.

The purpose of this investigation was to evaluate differences in quadriceps corticospinal excitability, spinal-reflexive excitability, strength, and voluntary activation before, 2 weeks post and 6 months post-anterior cruciate ligament reconstruction (ACLr). This longitudinal, case-control investigation examined 20 patients scheduled for ACLr (11 females, 9 males; age: 20.9 ± 4.4 years; height:172.4 ± 7.5 cm; weight:76.2 ± 11.8 kg) and 20 healthy controls (11 females, 9 males; age:21.7 ± 3.7 years; height: 173.7 ± 9.9 cm; weight: 76.1 ± 19.7 kg). Maximal voluntary isometric contractions (MVIC), central activation ratio (CAR), normalized Hoffmann spinal reflexes, active motor threshold (AMT), and normalized motor-evoked potential (MEP) amplitudes at 120% of AMT were measured in the quadriceps muscle at the specific time points. ACLr patients demonstrated bilateral reductions in spinal-reflexive excitability compared with controls before surgery (P = 0.02) and 2 weeks post-surgery (P ≤ 0.001). ACLr patients demonstrated higher AMT at 6 months post-surgery (P ≤ 0.001) in both limbs. No MEP differences were detected. Quadriceps MVIC and CAR were lower in both limbs of the ACLr group before surgery and 6 months post-surgery (P ≤ 0.05) compared with controls. Diminished excitability of spinal-reflexive and corticospinal pathways are present at different times following ACLr and occur in combination with clinical deficits in quadriceps strength and activation. Early rehabilitation strategies targeting spinal-reflexive excitability may help improve postoperative outcomes, while later-stage rehabilitation may benefit from therapeutic techniques aimed at improving corticospinal excitability.

Chronic ankle instability and fatigue create proximal joint alterations during performance of the Star Excursion Balance Test.

The combined effects of chronic ankle instability (CAI) and lower extremity fatigue on measures of neuromuscular control have not been well established. The purpose of this study was to investigate the influence of CAI on the performance of a dynamic postural control task, the Star Excursion Balance Test (SEBT), after fatiguing activities. Thirty subjects with (n = 14) or without (n = 16) unilateral CAI completed anterior, medial, and posterior reaching directions of the SEBT performed before and after a lunging fatigue protocol and an open chain ankle isokinetic fatigue protocol. Pre-post fatigue change scores were calculated for sagittal plane kinematics of the stance leg and the normalized reach distances (%MAXD). Using a regression model, group and kinematic data were used to explain between subject differences in %MAXD. For each reaching direction, a separate analysis was completed for the two fatigue conditions. When reaching anteriorly after the lunge fatigue condition, CAI and the changes in knee and hip flexion predicted approximately 49 % of the variance in %MAXD (R2 = .487; p = .001). When reaching medially under lunge fatigue, CAI predicted approximately 20 % of the variance in %MAXD (R2 = .198; p = .014). Isolated ankle fatigue did not cause significantly different responses between groups. For two of the reaching directions, CAI status significantly influenced the variances in %MAXD under the influence of lunge fatigue. Functional fatigue protocols

Parent and child views of parent-child relationship qualities and resilient outcomes among urban children.

Separate in-depth interviews were conducted with two groups of highly stressed 4th-6th grade urban children classified as stress-affected (SA) and stress-resilient (SR), and their parents. Judges identified interview items reflecting three components of a good parent-child relationship, i.e. positive parental attitudes, involvement and guidance. SR parents and children scored higher than their SA counterparts on all three relational dimensions. Additionally, SR parent-child dyads had more congruent views of their relationship than SA dyads. These findings suggest that positive parent-child relationship qualities play an important protective role that favors resilient outcomes, at ages 10-12, among children who have experienced major life stress.

Interviews with children who experienced major life stress: family and child attributes that predict resilient outcomes.

Demographically comparable groups of children exposed to major life-stress, with stress resilient (SR) and stress affected (SA) outcomes at ages 10 to 12, were interviewed to assess perceptions of their caregiving environments, peer relationships, and themselves. SR children compared with SA children reported more: (1) positive relationships with primary caregivers, (2) stable family environments, (3) inductive and consistent family discipline practices, and (4) positive expectations for their futures. SR girls viewed their mothers as more nurturing than did SA girls. Perceptions of fathers, quality of peer relationships, and global self-concept did not differentiate the groups. A discriminant function analysis identified four variables that correctly classified 74% of the subjects as SR or SA. Findings support the view that caregiver-child relationships play a key role in moderating children's developmental outcomes under conditions of high stress.

Cyanamide injections during alcohol deprivation increase alcohol drinking.

Long-Evans male rats were given 7 weeks of choice between 10% ethanol and water and then were divided into 6 matched groups, 3 of which were then deprived of alcohol for 6 days. Subcutaneous cyanamide injections (10 mg/kg, 3 times daily, for 4 days) during alcohol deprivation produced a long lasting, significant increase in subsequent alcohol selection, over and above the increase produced by alcohol deprivation alone. The same injections given to a group not deprived of alcohol caused a significant suppression of alcohol drinking during the treatment and had disappeared 4 days after the last injection. Thereafter the drinking remained at the control level and did not rise to that of the group given the injections during deprivation. The groups did not differ in their subsequent selection of saline solutions.