Step-down Task Research Articles

Cinnamic acid rescues behavioral deficits in a mouse model of traumatic brain injury by targeting miR-455-3p/HDAC2

AimsTraumatic brain injury (TBI) not only induces physiological disabilities but also leads to cognitive impairment. However, no effective therapeutic approach for TBI-related memory decline exists. In this study, we treated TBI mice with cinnamic acid (CNA) to detect whether CNA is able to rescue the memory deficits induced by TBI and to explore the potential mechanisms. Main methodsMice were divided into the following groups: the sham group, the TBI group, the TBI + CNA group and the CNA group. Basic physiological parameters, neurological severity score and brain water content were analyzed. The Morris water maze and inhibitory avoidance step-down task were used to determine learning and memory. Golgi staining was used to measure alterations in dendritic spines. Western blot analysis and a commercial kit were used to detect the content and activity of HDAC2. qPCR was used to detect the relative level of miR-455. Key findingsCNA did not affect physiological function but effectively restored neurological function and brain edema. CNA alleviated the memory impairments induced by TBI in both the Morris water maze and step-down task. CNA also recovered abnormalities in the synapses of TBI mice by suppressing the activity of HDAC2. Furthermore, CNA did not alter HDAC mRNA because it promoted the expression of miR-455-3p, a miRNA that regulates HDAC2 at the posttranscriptional level. SignificanceThe application of CNA effectively treats TBI-induced memory deficits by increasing miR-455-3p and by inhibiting HDAC2.

Between session reliability of intramuscular electromyography for segments of gluteus medius and minimus during gait and stepping tasks

Between-session reliability of electromyographic data is important for confidence in interpreting the role of muscles in functional tasks but critical if these data are to be compared before and after an intervention that seeks to change pathological patterns of muscle activity. The gluteus medius (GMed) and minimus (GMin) are known to have functionally discrete segments that are highly active during stance phase of gait and stepping tasks. This study measured the between-session reliability of activity patterns, mean amplitudes and time to peak (TTP) activity of these muscle segments. Intramuscular electrodes were placed in 3 segments of GMed and 2 segments of GMin in 10 healthy young adults for each of two testing sessions held two weeks apart. Participants completed six repetitions of comfortable speed walking trials, step-up and step-down tasks with activity patterns for each muscle segment time- and amplitude-normalized and averaged across trials. Re-test reliability for was high for activity patterns (coefficient of mean correlation ranging from 0.890 to 0.998) across all tasks and muscle segments and only two pairwise comparisons showing differences in amplitude between sessions. With standardized data collection and analysis procedures, GMed and GMin muscle segment activity patterns show good between-session reliability for weightbearing tasks.

Physical and psychological predictors on pain intensity in conscripts with plantar fasciitis

BackgroundPlantar fasciitis is commonly found among the physically active population, including conscripts. Some studies have reported that being overweight and having psychological symptoms contribute to pain from plantar fasciitis. However, there is a lack of information regarding the physical predictors, and more research is needed to determine the relationship between such predictors and pain intensity from plantar fasciitis in conscripts. ObjectiveTo determine which physical and psychological variables act as predictors of pain intensity among Thai novice conscripts with plantar fasciitis. MethodsTwo hundred and seventy Thai novice conscripts without musculoskeletal pain completed the Depression, Anxiety and Stress Scale short version and then received baseline assessment of ankle dorsiflexion angle, ankle plantarflexor strength, and quality of lower extremity movement from a physical therapist. After 10 weeks of military training, 71 of these Thai conscripts developed pain from plantar fasciitis. Multiple linear regression analysis with the forward stepwise method was used to explore the predictors of pain intensity due to plantar fasciitis. ResultsUsing a forward regression analysis, anxiety (B=0.13; 95% CI, 0.06–0.20; p<0.01) and quality of movement score (B=0.87; 95% CI, 0.28–1.47; p=0.01) were significant predictors of pain intensity. The regression model with these predictors explained 25% of the variability in pain intensity from plantar fasciitis. ConclusionHigher scores of anxiety and movement quality on the lateral step-down task were associated with pain intensity from plantar fasciitis after the completion of a 10-week military program. However, lower ankle dorsiflexion angle and ankle plantarflexor strength did not predict pain intensity.

How does acute pain influence biomechanics and quadriceps function in individuals with patellofemoral pain?

ObjectivesBeside pathophysiological factors, pain is believed to play a crucial role in the progression of patellofemoral pain (PFP). However, the isolated effect of pain on biomechanics and quadriceps function has not been investigated in PFP. Thus, this study aimed to investigate the effect of pain on quadriceps function and lower limb biomechanics in individuals with PFP. MethodsTwenty-one individuals with PFP (11 males and 10 females, age: 29.76 ± 6.36 years, height: 1.74 ± 0.09 m, mass: 70.12 ± 8.56 kg) were measured at two different occasions: when not and when experiencing acute pain. Peak quadriceps torque (concentric, eccentric and isometric) and arthrogenic muscle inhibition (AMI) were assessed. Three-dimensional motion analysis and surface electromyography of the quadriceps and hamstring muscles were collected during running, a single-leg-squat and step-down task. The normality was assessed using the Shapiro–Wilk test and a MANOVA was performed at the 95% confidence interval. ResultsAMI increased significantly in acute pain. The net muscle activation of the knee extensors and flexors decreased during running in acute pain. The lower limb biomechanics and the quadriceps torque did not change in acute pain. DiscussionIt appears that even if individuals with PFP experience pain they can still deliver maximal quadriceps contractions and maintain their moving patterns without biomechanical changes. However, the overall reduced activation of the quadriceps and the increased AMI indicate the presence of quadriceps inhibition in acute pain.

Efficacy of Kinesio Taping and McConnell Taping Techniques in the Management of Anterior Knee Pain

Anterior knee pain also known as patellofemoral pain syndrome is a frequently encountered musculoskeletal disorder that worsens with activity. The multifactorial etiology of patellofemoral pain syndrome alters lower-extremity mechanics, increasing patellofemoral joint stresses during weight-bearing tasks. Kinesio and McConnell tapings are often incorporated into the treatment, but their efficacy is still unclear. To test the efficacy of Kinesio taping, McConnell taping, and sham taping in improving knee mechanics and reducing pain during activity. Cross-sectional design. Clinical biomechanics laboratory. Ten participants (age: 20.3 [1.5]y, height: 169.9 [10.4]cm, and mass: 70.17 [13.1]kg) with anterior knee pain and no history of trauma. Three trials each of squat, drop jump, and step-down tasks with 3 taping conditions in a counterbalanced order. Two-dimensional motion capture data of lower-extremities in frontal and sagittal planes were recorded and analyzed using 3 iPads and Spark Motion® application. Pooled effect sizes (Hedges' g), 95% confidence intervals, and repeated-measures analysis of variance (P < .05) compared baseline and taping conditions during exercises for pain Visual Analog Scale and knee flexion in all exercises, hip abduction during step-down and drop jump, frontal plane projection during step-downs, and knee translation in sagittal plane during squats. Significant reductions in Visual Analog Scale were recorded during squats between tapes (F2.505,12.867 = 3.407, P = .04, Hedges' g = -0.70). Pairwise comparison showed a decrease in Visual Analog Scale for sham taping (mean difference = 1.14cm, P = .01) and Kinesio taping (mean difference = 1.54cm, P = .02) compared with baseline during squats. A variety of taping methods can potentially reduce perceived pain in individuals with patellofemoral pain syndrome, allowing clinicians to perform rehabilitation exercises. Sensory effects associated with short-term taping may be sufficient enough to modify knee pain acutely by afferent input blocking nocioceptive pain before the participants could adapt. Most interestingly, the sham taping technique demonstrated promise for enhancing functional outcomes, depending on the length of the tape and area covered.

The decline step-down test measuring the maximum pain-free flexion angle: A reliable and valid performance test in patients with patellofemoral pain

ObjectivesPatients with patellofemoral pain (PFP) experience pain while descending stairs. To date no reliable and valid performance-test exists to assess the maximum pain-free knee flexion angle (MPFFA) as outcome measure during a step-down task. Therefore, the intra- and inter-observer reliability and construct validity of the decline step-down test (DSDT) measuring the MPFFA in patients with PFP were evaluated. DesignReliability and construct validity. SettingPrivate practices in Nijmegen and Utrecht, the Netherlands. ParticipantsPatients with PFP. Main outcome measuresThe reliability was assessed by repeated measurements of the MPFFA during the DSDT. The construct validity was assessed by correlating the measurements on the DSDT with the Anterior Knee Pain Scale Dutch Version (AKPS-DV) based on a pre-set hypothesis. ResultsThirty-two participants (forty-eight knees) were eligible for inclusion. The intraclass correlation coefficient (ICC) for intra-observer reliability was ICC2,1 = 0.83 and ICC2,1 = 0.85 for inter-observer reliability. The 95% limits of agreement (LoA) showed a width of 27.56° for intra-observer reliability and a width of 24.42° for inter-observer reliability. There was an average positive correlation between the DSDT and the total score on the AKPS-DV (rs = 0.31, p = 0.030). ConclusionThe DSDT measuring the MPFFA is reliable and valid in patients with PFP.

Can the use of proprioceptive knee braces have implications in the management of osteoarthritic knees: An exploratory study.

Use of proprioceptive knee braces to control symptomology by altering neuromuscular control mechanisms has been shown in patellofemoral pain. Although their potential in patients with knee osteoarthritis is vast, little research has examined their efficacy. This study examines the effect of a proprioceptive knee brace on lower limb kinematics and kinetics in healthy participants and in participants with OA. Thirteen healthy participants were asked to perform a 10-cm step-down task with and without a proprioceptive brace. Data were collected using a 10-camera Qualisys system. Individuals with osteoarthritis completed the Knee injury and Osteoarthritis Outcome Score before and after 4 weeks of intervention. During step-down reductions in knee maximum internal rotation, transverse range of movement, transverse plane angular velocity and maximum internal rotation angular velocity was seen. Ankle plantar flexion and inversion angular velocity decreased while inversion and maximum supination angular velocity increased. Improvements in Knee injury and Osteoarthritis Outcome Score were noted across all parameters with brace use. Positive changes in kinematic variables in multiple planes can be achieved with proprioceptive bracing alongside improved patient outcome. These changes occur at the knee but analysis of other weight bearing joints should not be overlooked in future studies. This study supports the concept of neuromuscular reinforcement and re-education through proprioceptive bracing and its application in the management in knee osteoarthritis. Proprioception can alter symptoms and biomechanics embraced and adjacent lower limb joints. The results of this study highlights the potential uses of non-mechanical bracing in the treatment of osteoarthritis and other potential to bridge the osteoarthritis treatment gap. Furthermore, large-scale research is needed to match disease subset to brace type.

Step-Down Task Identifies Differences in Ankle Biomechanics Across Functional Activities.

Currently, there is no clinical exam to evaluate ankle frontal plane kinematics. The purpose of this study was to determine whether individuals identified as "lateral" landing during a video-recorded step-down task have differences in ankle inversion as measured with 3-dimensional motion capture during walking, step-down, and jump-landing tasks compared to individuals identified as "non-lateral". Fifty-seven recreationally active adults completed the descriptive laboratory study. During walking, step-down, and jump-landing tasks, participants had their ankle frontal plane kinematics measured using a 3-dimensional motion capture system. In addition, during the step-down task, participants had a posterior view video of their foot recorded using a commercial camera. Following testing, a blinded-investigator scored the step-down video of all participants by classifying them as "lateral" landing or "non-lateral" landing. Ankle frontal plane kinematics during the walking, step-down, and jump-landing tasks were compared between the two groups (lateral (N=24) and non-lateral (N=33) using a binary logistic regression and time-series confidence interval analysis. During walking, stepping-down, and jump-landing, the lateral group had significantly more inversion at initial contact and during various other phases specific to each task. This study found that a clinical screening tool could identify individuals who have significantly more inversion during three tasks.

Assessing Mongolian gerbil emotional behavior: effects of two shock intensities and response-independent shocks during an extended inhibitory-avoidance task.

Despite step-down inhibitory avoidance procedures that have been widely implemented in rats and mice to study learning and emotion phenomena, performance of other species in these tasks has received less attention. The case of the Mongolian gerbil is of relevance considering the discrepancies in the parameters of the step-down protocols implemented, especially the wide range of foot-shock intensities (i.e., 0.4–4.0 mA), and the lack of information on long-term performance, extinction effects, and behavioral patterning during these tasks. Experiment 1 aimed to (a) characterize gerbils’ acquisition, extinction, and steady-state performance during a multisession (i.e., extended) step-down protocol adapted for implementation in a commercially-available behavioral package (Video Fear Conditioning System—MED Associates Fairfax, VT, USA), and (b) compare gerbils’ performance in this task with two shock intensities – 0.5 vs. 1.0 mA—considered in the low-to-mid range. Results indicated that the 1.0 mA protocol produced more reliable and clear evidence of avoidance learning, extinction, and reacquisition in terms of increments in freezing and on-platform time as well as suppression of platform descent. Experiment 2 aimed to (a) assess whether an alternate protocol consisting of a random delivery of foot shocks could replicate the effects of Experiment 1 and (b) characterize gerbils’ exploratory behavior during the step-down task (jumping, digging, rearing, and probing). Random shocks did not reproduce the effects observed with the first protocol. The data also indicated that a change from random to response-dependent shocks affects (a) the length of each visit to the platform, but not the frequency of platform descends or freezing time, and (b) the patterns of exploratory behavior, namely, suppression of digging and rearing, as well as increments in probing and jumping. Overall, the study demonstrated the feasibility of the extended step-down protocol for studying steady performance, extinction, and reacquisition of avoidance behavior in gerbils, which could be easily implemented in a commercially available system. The observation that 1.0 mA shocks produced a clear and consistent avoidance behavior suggests that implementation of higher intensities is unnecessary for reproducing aversive-conditioning effects in this species. The observed patterning of freezing, platform descents, and exploratory responses produced by the change from random to periodic shocks may relate to the active defensive system of the gerbil. Of special interest is the probing behavior, which could be interpreted as risk assessment and has not been reported in other rodent species exposed to step-down and similar tasks.

Suppression of microRNA-9-5p rescues learning and memory in chronic cerebral hypoperfusion rats model.

Chronic cerebral hypoperfusion has been associated with cognitive impairment in dementias, such as Alzheimer's disease (AD) and vascular disease (VaD), the two most common neurodegenerative diseases in aged people. However, the effective therapeutic approaches for both AD and VaD are still missing. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in the epigenetic regulation in many neurological disorders; the critical roles of miRNAderegulation had been implicated in both AD and VaD. In the current study, we reported that miR-9-5p is elevated in the serum and cerebrospinalfluid of patientswith VaD. The miR-9-5p wasalso increased in both the hippocampus and cortex of rats with 2-vessel occlusionsurgery. Furthermore, application ofmiR-9-5p antagomirs attenuated the memory impairments in rats with 2-vessel occlusion surgery both in the Morris water maze and inhibitory avoidance step-down tasks. Furthermore, miR-9-5p antagomirs reducedthe inhibition oflong-term potentiation and loss of dendritic spines in chronic cerebral hypoperfusionrats. Additionally, the cholinergic neuronal function was rescued by miR-9-5p antagomirs, as well as the neuronal loss and the oxidative stress. We concluded that miR-9-5p inhibition may be a potential therapeutic target for the memory impairments caused by chronic cerebral hypoperfusion.

Quercetin ameliorates chronic unpredicted stress-induced behavioral dysfunction in male Swiss albino mice by modulating hippocampal insulin signaling pathway

Chronic stress is associated with impaired neurogenesis, neurodegeneration and behavioral dysfunction, whereas the mechanism underlying stress-mediated neurological complications is still not clear. In the present study, we aimed to investigate whether chronic unpredicted stress (CUS) mediated neurological alterations are associated with impaired hippocampal insulin signaling or not, and studied the effect of quercetin in this scenario. Male Swiss albino mice were subjected to 21day CUS, during which 30mg/kg quercetin treatment was given orally. After 21days, behavioral functions were evaluated in terms of locomotor activity (Actophotometer), muscle coordination (Rota-rod), depression (Tail Suspension Test (TST), Forced Swim Test (FST)) and memory performance (Passive-avoidance step-down task (PASD)). Further, hippocampal insulin signaling was evaluated in terms of protein expression of insulin, insulin receptor (IR) and glucose transporter 4 (GLUT-4) and neurogenesis was evaluated in terms of doublecortin (DCX) expression. 21day CUS significantly impaired locomotion and had no effect on muscle coordination. Stressed animals were depressed and showed markedly impaired memory functions. Quercetin treatment significantly improvement stress-mediated behavior dysfunction as indicated by improved locomotion, lesser immobility time and greater frequency of upward turning in TST and FST and increased transfer latency on the day 2 (short-term memory) and day 5 (long-term memory) in PASD test. We observed significantly higher IR expression and significantly lower GLUT-4 expression in the hippocampus of stressed animals, despite of nonsignificant difference in insulin levels. Further, chronic stress impaired hippocampal neurogenesis, as indicated by the significantly reduced levels of hippocampal DCX expression. Quercetin treatment significantly lowered insulin and IR expression and significantly enhanced GLUT-4 and DCX expression in the hippocampus, when compared to CUS. In conclusion, quercetin treatment efficiently alleviated stress mediated behavioral dysfunction by modulating hippocampal insulin signaling and neurogenesis.

Dynamic Trunk Stability During A Step-down Task In Baseball Players

Trunk stability is critical for the transfer of energy from the lower extremity to upper extremity during throwing. Defining lower extremity kinematics during dynamic tasks will enable understanding of their contribution to trunk stability. PURPOSE: To examine the effects of trunk stability on lower extremity kinematics during a step-down task (SDT). METHODS: Professional baseball players (n=70; 22.6 ± 2.2 years; 91.8 ± 9.9kg; 185.8 ± 6.6cm) volunteered. A SDT was performed on their lead leg from a 20.3cm box, lowering their contralateral heel to the ground and then returning to the starting position. Participants were filmed in the frontal and sagittal planes. Data were analyzed at heel strike using Dartfish. Trunk stability was defined as ‘poor’ when trunk motion (sum of trunk flexion and lean) was >24.9°, the median of the sample. ‘Good’ stability was defined as <24.9°. A one-way ANOVA was performed to determine if kinematics were different between participants with poor and good trunk stability. Pearson Product correlations characterized the relationship between trunk motion and lower extremity kinematics. RESULTS: See Table 1. Knee flexion (p=0.04) and hip flexion (p=0.03) were significantly greater in participants with good trunk stability. Significant negative correlations between trunk motion and knee (r=-0.323) and hip flexion (r=-0.360) were observed. CONCLUSION: Participants with poor trunk stability had significantly less knee and hip flexion during the SDT. Correlations indicate that as lower extremity motion decreases, trunk stability decreases. Deficits in knee and hip motion may have contributed to trunk instability, or they are a compensation strategy for the increased trunk motion in those classified with poor trunk stability. Research is needed to assess the impact of altered lower extremity kinematics and trunk stability on energy transfer during throwing.Table 1: SDT data in participants with good and poor trunk stability. Mean (SD).

Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during step-down task

BackgroundStrengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight-bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step-down task in women. MethodsThirty-four young women who demonstrated dynamic knee valgus during step-down were divided into two groups. The experimental group underwent three weekly sessions of strengthening exercises for eight weeks, and the control group continued their usual activities. The following evaluations were carried out: (a) isokinetic maximum concentric and eccentric work of hip lateral rotators, (b) isokinetic hip passive torque of lateral rotation and resting transverse plane position, and (c) three-dimensional kinematics of the lower limb during step-down. FindingsThe strengthening program increased concentric (P<0.001) and eccentric (P<0.001) work of hip lateral rotators, and changed hip resting position toward lateral rotation (P<0.001). The intervention did not significantly change hip passive torque (P=0.089, main effect). The program reduced hip (P=0.002), thigh (P=0.024) and shank (P=0.005) adduction during step-down task. Hip, thigh and knee kinematics in transverse plane and foot kinematics in frontal plane did not significantly modify after intervention (P≥0.069, main effect). InterpretationHip and trunk strengthening reduced lower limb adduction during step-down. The changes in hip maximum work and resting position may have contributed to the observed kinematic effects.

An Ecological Study of Anterior Cruciate Ligament Reconstruction, Part 2: Functional Performance Tests Correlate With Return-to-Sport Outcomes.

Background:Additional high-quality prospective studies are needed to better define the objective criteria used in relation to return-to-sport decisions after anterior cruciate ligament (ACL) reconstruction in active populations.Purpose:To investigate prospectively the relationship between functional performance test results at 24 weeks postoperative and return-to-sport activity (Tegner activity score) at 12 and 24 months, respectively, after synthetic (ligament advanced reinforcement system [LARS]) and autograft (doubled semitendinosus/gracilis [2ST/2GR]) ACL reconstructions.Study Design:Case series; Level of evidence, 4.Methods:A total of 64 patients who underwent ACL reconstruction (32 LARS, 32 2ST/2GR autograft; mean age, 27.9 years; body mass index [BMI], 24.9 kg/m2) were assessed preoperatively and at staged intervals postoperatively up to 24 weeks for isokinetic testing of quadriceps and hamstring average power per repetition at 60 deg/s and 180 deg/s, a battery of hop tests, peak vertical ground-reaction force (vGRF), and time to peak vGRF (in seconds) during a step- and jump-down task onto a force platform and peak speed (m/s) using a global positioning system (GPS unit) during a running task. A cohort of 32 healthy matched participants (mean age, 26.31 years; BMI, 25.7 kg/m2) were also tested to act as reference. Pearson correlation was calculated to assess correlation of each performance measure at 24 weeks postoperative with activity outcomes (Tegner score) at 12 and 24 months.Results:The strongest correlation between physical performance tests and return-to-sport outcomes was observed with peak speed during running. Large correlations were also observed for hamstring isokinetic power and hop test for distance. Moderate correlations were observed for timed hop, peak vGRF during a jump-down task, and quadriceps isokinetic power. No statistical correlations were observed for time to peak vGRF during a step-down and jump-down task as well as peak vGRF during a step-down task. When the performance tests were pooled together, mean postoperative improvements of 24% were observed from preoperative to 24 weeks within the surgical cohort. For each performance test, preoperative level of function strongly correlated with performance levels on the same test at 24 weeks.Discussion:The results of this study indicate that clinicians might seek to prioritize these tests and the rehabilitation themes they imply when seeking to maximize postoperative ACL activity outcomes. The observed strength between pre- and postoperative performance tests and return-to-sport outcomes within this study highlights the potential value of preoperative conditioning before undergoing ACL reconstruction. Future research should examine absolute predictive criterion thresholds for functional performance-based tests and reinjury risk reduction after ACL reconstruction.

Cross State-dependent Learning Interaction Between Scopolamine and Morphine in Mice: The Role of Dorsal Hippocampus.

Introduction:The current study aimed at investigating the existence of the cross state-dependent learning between morphine and scopolamine (SCO) in mice by passive avoidance method, pointing to the role of CA1 area.Methods:The effects of pre-training SCO (0.75, 1.5, and 3 μg, Intra-CA1), or morphine (1, 3, and 6 mg/kg, intraperitoneal (i.p.) was evaluated on the retrieval of passive avoidance learning using step-down task in mice (n=10). Then, the effect of pretest administration of morphine (1.5, 3, and 6 mg/kg, i.p.) was examined on passive avoidance retrieval impairment induced by pre-training SCO (3 μg/mice, Intra-CA1). Next, the effect of pretest Intra-CA1 injection of scopolamine (0.75, 1.5, and 3 μg/mice) was evaluated on morphine (6 mg/kg, i.p.) pre-training deficits in this task in mice.Results:The pre-training Intra-CA1 injection of scopolamine (1.5 and 3 μg/mouse), or morphine (3 and 6 mg/kg, i.p.) impaired the avoidance memory retrieval when it was tested 24 hours later. Pretest injection of both drugs improved its pre-training impairing effects on mice memory. Moreover, the amnesia induced by the pre-training injections of scopolamine (3 μg/mice) was restored significantly (P<0.01) by pretest injections of morphine (3 and 6 mg/kg, i.p.). Similarly, pretest injection of scopolamine (3 μg/mice) restored amnesia induced by the pre-training injections of morphine (6 mg/kg, i.p.), significantly (P<0.01).Conclusion:The current study findings indicated a cross state-dependent learning between SCO and morphine at CA1 level. Therefore, it seems that muscarinic and opioid receptors may act reciprocally on modulation of passive avoidance memory retrieval, at the level of dorsal hippocampus, in mice.

THE POWERSTM STRAP MODIFIES HIP AND KNEE MOVEMENT DURING THE SINGLE LEG SQUAT AND THE SINGLE LEG STEP DOWN TASK

Previous research has shown that excessive hip internal rotation can lead to abnormal patellar maltracking and thereby to lower limb injuries, such as patellofemoral pain and non-contact ACL injuries. Researchers...

Precision Grip Control while Walking Down a Stair Step.

The aim of this study was to determine whether the internal model regulating grip force (GF)/load force (LF) coordination during a brisk load increase is preserved when the lower extremities produce a perturbation during a single step-down task. We observed the coordination of the vertical ground reaction force (vGRF), GF and LF while holding a handheld object during a single step-down task. The 3 forces (vGRF, GF and LF) decreased during the start of the task. While the subject was descending, LF and GF became dissociated from vGRF and increased in value, probably to anticipate the first foot contact. Coordination of LF and GF was maintained until the maximal vGRF (knee extension). LF peaked in the same time window as vGRF, whereas GF peaked about 70 ms later. This desynchronization, which was previously observed in direct load increase on a handheld object, was interpreted to be a predictive action to ensure the smooth management of the brisk increase in load induced by the lower extremities. Incidentally, in this group, kinematic and dynamic differences were observed between men and women, which may highlight a gender-specific strategy to perform the step-down task. In conclusion, these results suggest that the internal model of precision grip is able to integrate a brisk load change, whatever its origin, and regulate the forces to provide an ideal GF to dampen a brisk load increase and secure the object.

Comparison of Muscle Activation Levels Between Healthy Individuals and Persons Who Have Undergone Anterior Cruciate Ligament Reconstruction During Different Phases of Weight-Bearing Exercises.

Study Design Cross-sectional, controlled laboratory study. Background Quantification of muscular activation during different phases of functional activities is important to understand activation deficits in individuals who have undergone anterior cruciate ligament reconstruction (ACLR). Objectives To compare activation levels of the vastus medialis (VM), medial hamstrings (MH), and gluteus medius (GMed) muscles during the different phases of weight-bearing tasks between individuals who had undergone ACLR and healthy controls. Methods Surface electromyography was used to measure the activation levels of the VM, MH, and GMed muscles in 16 participants who had undergone ACLR (average time since surgery, 4 years) and 15 healthy participants during the reach and return phases of the Star Excursion Balance Test (SEBT) and the ascending and descending phases of a step-down task (SDT). Repeated-measures analyses of variance were performed to determine whether muscle activation levels differed between groups during different phases of the tasks. Results There were significant group-by-phase interactions for the GMed during both the SEBT and SDT. Gluteus medius activation was lower for the ACLR group during the return phase of the posteromedial direction of the SEBT compared to the control group (P = .03). During the SDT, GMed activation was higher for the ACLR group during the ascending phase than during the descending phase (P<.001), while the control group showed no difference between phases (P = .71). Conclusion Individuals who had undergone ACLR have similar VM and MH activation compared to healthy individuals during different phases of the SDT and SEBT. However, phase differences for GMed activity and decreased GMed activity relative to healthy individuals were observed among ACLR participants. J Orthop Sports Phys Ther 2016;46(11):984-992. Epub 11 Oct 2016. doi:10.2519/jospt.2016.5896.

The Association of Ankle Dorsiflexion Range of Motion With Hip and Knee Kinematics During the Lateral Step-down Test.

Study Design Controlled laboratory study. Background Altered hip and knee kinematics have been associated with several knee disorders, including anterior cruciate ligament tear, patellofemoral pain, and iliotibial band syndrome. Limited ankle dorsiflexion (DF) range of motion (ROM), which has been linked with some of these disorders, has also been associated with altered knee kinematics. Objective To explore the association of ankle DF ROM with hip and knee kinematics during a step-down task. Methods Thirty healthy participants underwent a 3-D analysis of hip and knee kinematics during a lateral step-down test, followed by measurement of ankle DF ROM in weight bearing (WB) and non-weight bearing (NWB). Participants were dichotomized using the median values into low- and high-DF subgroups within both WB and NWB. Hip and knee kinematics were compared between the low- and high-DF subgroups. Results Participants in the low-DF subgroups exhibited greater peak hip adduction (WB, P = .02; NWB, P<.01) and greater peak knee external rotation (WB, P = .02; NWB, P<.01) compared with participants in the high-DF subgroups. In addition, participants in the low-DF WB subgroup exhibited decreased peak knee flexion compared with participants in the high-DF WB subgroup (P<.01). Conclusion Individuals with lower ankle DF ROM exhibited hip and knee kinematics previously associated with several knee disorders, suggesting that this impairment may be involved in the pathogenesis of the same disorders. Assessment of ankle DF ROM may be useful as part of a preparticipation screening. Furthermore, deficits in ankle DF ROM may need to be addressed in individuals with altered movement patterns. J Orthop Sports Phys Ther 2016;46(11):-1. Epub 29 Sep 2016. doi:10.2519/jospt.2016.6621.

Minocycline ameliorates d-galactose-induced memory deficits and loss of Arc/Arg3.1 expression

Dysfunction of learning and memory is widely found in many neurological diseases. Understanding how to preserve the normal function of learning and memory will be extremely beneficial for the treatment of these diseases. However, the possible protective effect of minocycline in memory impairment is unknown. We used the well-established D-galactose rat amnesia model and two behavioral tasks, the Morris water maze and the step-down task, for memory evaluation. Western blot and PCR were used to examine the protein and mRNA levels of Arc/Arg3.1. We report that minocycline supplementation ameliorates both the spatial and fear memory deficits caused by D-galactose. We also found that Arc/Arg3.1, c-fos, and brain-derived neurotrophic factor levels are decreased in the D-galactose animal model, and that minocycline reverses the protein and mRNA levels of Arc in the hippocampus, suggesting the potential role of Arc/Arg3.1 in minocycline's neuroprotective mechanism. Our study strongly suggests that minocycline can be used as a novel treatment for memory impairment in neurological diseases.