Altered Movement Patterns Research Articles

Evaluating Eccentric Hip Torque and Trunk Endurance as Mediators of Changes in Lower Limb and Trunk Kinematics in Response to Functional Stabilization Training in Women With Patellofemoral Pain

Background: Altered movement patterns of the trunk and lower limbs have been associated with patellofemoral pain (PFP). It has been assumed that increasing the strength of the hip and trunk muscles would improve lower limb and trunk kinematics in these patients. However, evidence in support of that assumption is limited. Purpose: To determine whether increases in the strength of hip muscles and endurance of trunk muscles in response to functional stabilization training will mediate changes in frontal plane lower limb kinematics in patients with PFP. Study Design: Controlled laboratory study. Methods: Thirty-one female athletes were randomized to either a functional stabilization training group that emphasized strengthening of the trunk and hip muscles or a standard training group that emphasized stretching and quadriceps strengthening. Patients attended a baseline assessment session, followed by 8 weeks of intervention, and were then reassessed at the end of the intervention period. The potential mediators that were evaluated included eccentric torque of hip muscles and endurance of the trunk muscles. The outcome variables were the lower limb and trunk kinematics in the frontal plane assessed during a single-legged squat task. Results: The eccentric strength of the gluteus muscles showed a mediation effect ranging from 18% to 32% on changes to frontal plane kinematics (decreased ipsilateral trunk inclination, pelvis contralateral depression, and hip adduction excursions) observed in the functional stabilization training group after intervention. Conclusion: Although the mediation effects were small, the results suggest that improvements in the strength of the gluteus muscles can influence the frontal plane movement patterns of the lower limb and trunk in women with PFP. Clinical Relevance: Patients with PFP might benefit from strengthening of the hip muscles to improve frontal plane lower limb and trunk kinematics during functional tasks.

Lower Extremity Kinematics During a Drop Jump in Individuals With Patellar Tendinopathy.

Background:Patellar tendinopathy (PT) is a common degenerative condition in physically active populations. Knowledge regarding the biomechanics of landing in populations with symptomatic PT is limited, but altered mechanics may play a role in the development or perpetuation of PT.Purpose:To identify whether study participants with PT exhibited different landing kinematics compared with healthy controls.Study Design:Controlled laboratory study.Methods:Sixty recreationally active participants took part in this study; 30 had current signs and symptoms of PT, including self-reported pain within the patellar tendon during loading activities for at least 3 months and ≤80 on the Victorian Institute of Sport Assessment Scale–Patella (VISA-P). Thirty healthy participants with no history of PT or other knee joint pathology were matched by sex, age, height, and weight. Participants completed 5 trials of a 40-cm, 2-legged drop jump followed immediately by a 50% maximum vertical jump. Dependent variables of interest included hip, knee, and ankle joint angles at initial ground contact, peak angles, and maximum angular displacements during the landing phase in 3 planes. Independent-samples t tests (P ≤ .05) were utilized to compare the joint angles and angular displacements between PT and control participants.Results:Individuals with PT displayed significantly decreased peak hip (PT, 59.2° ± 14.6°; control, 67.2° ± 13.9°; P = .03) and knee flexion angles (PT, 74.8° ± 13.2°; control, 82.5° ± 9.0°; P = .01) compared with control subjects. The PT group displayed decreased maximum angular displacement in the sagittal plane at the hip (PT, 49.3° ± 10.8°; control, 55.2° ± 11.4°; P = .04) and knee (PT, 71.6° ± 8.4°; control, 79.7° ± 8.3°; P < .001) compared with the control group.Conclusion:Participants with PT displayed decreased maximum flexion and angular displacement in the sagittal plane, at both the knee and the hip. The altered movement patterns in those with PT may be perpetuating symptoms associated with PT and could be due to the contributions of the rectus femoris during dynamic movement.Clinical Relevance:Based on kinematic alterations in symptomatic participants, rehabilitation efforts may benefit from focusing on both the knee and the hip to treat symptoms associated with PT.

Anterior cruciate ligament injury about 20 years post-treatment: A kinematic analysis of one-leg hop.

Reduced dynamic knee stability, often evaluated with one-leg hops (OLHs), is reported after anterior cruciate ligament (ACL) injury. This may lead to long-standing altered movement patterns, which are less investigated. 3D kinematics during OLH were explored in 70 persons 23 ± 2 years after ACL injury; 33 were treated with physiotherapy in combination with ACL reconstruction (ACL(R)) and 37 with physiotherapy alone (ACL(PT)). Comparisons were made to 33 matched controls. We analyzed (a) maximal knee joint angles and range of motion (flexion, abduction, rotation); (b) medio-lateral position of the center of mass (COM) in relation to knee and ankle joint centers, during take-off and landing phases. Unlike controls, ACL-injured displayed leg asymmetries: less knee flexion and less internal rotation at take-off and landing and more lateral COM related to knee and ankle joint of the injured leg at landing. Compared to controls, ACL(R) had larger external rotation of the injured leg at landing. ACL(PT) showed less knee flexion and larger external rotation at take-off and landing, and larger knee abduction at Landing. COM was more medial in relation to the knee at take-off and less laterally placed relative to the ankle at landing. ACL injury results in long-term kinematic alterations during OLH, which are less evident for ACL(R).

Altered movement patterns and muscular activity during single and double leg squats in individuals with anterior cruciate ligament injury.

BackgroundIndividuals with Anterior Cruciate Ligament (ACL) injury often show altered movement patterns, suggested to be partly due to impaired sensorimotor control. Here, we therefore aimed to assess muscular activity during movements often used in ACL-rehabilitation and to characterize associations between deviations in muscular activity and specific altered movement patterns, using and further exploring the previously developed Test for substitution Patterns (TSP).MethodsSixteen participants (10 women) with unilateral ACL rupture performed Single and Double Leg Squats (SLS; DLS). Altered movement patterns were scored according to TSP, and Surface Electromyography (SEMG) was recorded bilaterally in six hip, thigh and shank muscles. To quantify deviations in muscular activity, SEMG ratios were calculated between homonymous muscles on injured and non-injured sides, and between antagonistic muscles on the same side. Correlations between deviations of injured/non-injured side SEMG ratios and specific altered movement patterns were calculated.ResultsInjured/non-injured ratios were low at transition from knee flexion to extension in quadriceps in SLS, and in quadriceps and hamstrings in DLS. On injured side, the quadriceps/hamstrings ratio prior to the beginning of DLS and end of DLS and SLS, and tibialis/gastrocnemius ratio at end of DLS were lower than on non-injured side. Correlations were found between specific altered movement patterns and deviating muscular activity at transition from knee flexion to extension in SLS, indicating that the more deviating the muscular activity on injured side, the more pronounced the altered movement pattern. “Knee medial to supporting foot” correlated to lower injured/non-injured ratios in gluteus medius (rs = −0.73, p = 0.001), “lateral displacement of hip-pelvis-region” to lower injured/non-injured ratios in quadriceps (rs = −0.54, p = 0.03) and “displacement of trunk” to higher injured/non-injured ratios in gluteus medius (rs = 0.62, p = 0.01).ConclusionsDeviations in muscular activity between injured and non-injured sides and between antagonistic muscular activity within injured as compared to non-injured sides indicated specific alterations in sensorimotor control of the lower limb in individuals with ACL rupture. Also, correlations between deviating muscular activity and specific altered movement patterns were suggested as indications of altered sensorimotor control. We therefore advocate that quantitative assessments of altered movement patterns should be considered in ACL-rehabilitation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0472-y) contains supplementary material, which is available to authorized users.

Factors associated with visually assessed quality of movement during a lateral step-down test among individuals with patellofemoral pain.

Cross-sectional. To determine what physical measures are associated with visually assessed quality of movement among patients with patellofemoral pain (PFP). An altered movement pattern has been implicated as a risk factor for PFP. An understanding of physical measures associated with an altered movement pattern could potentially help guide prevention and management efforts in patients with PFP. Seventy-nine (40 women) Israel Defense Forces soldiers referred to physical therapy with a diagnosis of PFP were included. Movement pattern was assessed visually during a lateral step-down test and rated as "good" or "moderate," based on previously established criteria. Weight-bearing and non-weight-bearing ankle dorsiflexion (DF) range of motion (ROM); hip internal and external rotation ROM; and hip abduction, hip external rotation, and knee extension strength were also assessed. Differences in physical measures between those with good versus moderate quality of movement were assessed. Weight-bearing DF ROM was more limited among participants with a moderate quality of movement compared to those with a good quality of movement (P<.01). Among men, non-weight-bearing DF ROM was more limited in those with a moderate quality of movement as well (P<.01). In addition, quality of movement was associated with weight-bearing DF ROM for both women (r = -0.39, P = .01) and men (r = -0.46, P<.01), and with non-weight-bearing DF ROM for men (r = -0.66, P<.01). When the subgroup of participants who exhibited more than 25° of non-weight-bearing DF ROM was assessed, those with a good quality of movement displayed greater hip external rotator and knee extensor muscle strength compared with those with a moderate quality of movement (P<.01). Ankle DF ROM should be assessed when patients with PFP demonstrate a lower quality of movement during a lateral step-down test. Lower hip muscle strength may be associated with lower quality of movement among patients with relatively greater ankle DF ROM.

Stair climbing – An insight and comparison between women with and without joint hypermobility: A descriptive study

Generalized joint hypermobility (GJH) is a frequent entity in rheumatology with higher prevalence among women. It is associated with chronic widespread pain, joint dislocations, arthralgia, fibromyalgia and early osteoarthritis. Stair climbing is an important functional task and can induce symptoms in hypermobile persons. The aim of this study was to compare ground reaction forces (GRF) and muscle activity during stair climbing in women with and without GJH. A cross-sectional study of 67 women with normal mobility and 128 hypermobile women was performed. The hypermobile women were further divided into 56 symptomatic and 47 asymptomatic. GRFs were measured by force plates embedded in a six step staircase, as well as surface electromyography (EMG) of six leg muscles. Parameters derived from GRF and EMG were compared between groups using t-test and ANOVA. For GRF no significant differences were found. EMG showed lower activity for the quadriceps during ascent and lower activity for hamstrings and quadriceps during descent in hypermobile women. For symptomatic hypermobile women these differences were even more accentuated. The differences in EMG may point towards an altered movement pattern during stair climbing, aimed at avoiding high muscle activation. However, differences were small, since stair climbing seems to be not demanding.

Contralateral Risk Factors Associated with Exertional Medial Tibial Pain in Women

This study aimed to prospectively analyze the role of factors on the contralateral side of the kinetic chain in the development of exertional medial tibial pain (EMTP). Eighty-one female physical education students were tested at the beginning of their first academic year. Within the testing protocol, contralateral isokinetic hip muscle strength and full-body kinematic parameters during a single-leg drop jump were evaluated. Online questionnaires were administered weekly, and personal interviews were conducted every 3 months to assess injury follow-up. EMTP was diagnosed by an experienced medical doctor. Cox regression analysis was used to identify the potential risk factors for the development of EMTP. After exclusion of subjects with diagnosed bilateral EMTP, 11 subjects were included in the EMTP group. Fifty-three subjects did not develop any lower extremity overuse injury and were included in the control group. The leg not at risk within subjects who developed EMTP was compared with an uninjured leg of those in the control group. Increased transverse plane motion for the contralateral lower leg segment during landing phase was found to be a significant predictor (P = 0.012) for EMTP. Analysis of the isokinetic data did not reveal altered hip muscle strength parameters for the leg not at risk within the EMTP group. Impaired dynamic joint stability or accessory movements were found in the transverse plane of the contralateral lower leg segment of EMTP subjects. This contralateral instability might have contributed to altered movement patterns within the kinetic chain function of EMTP subjects. No contralateral hip muscle strength parameters were found to predict EMTP in this study.

EXPLORATION OF CONTRALATERAL RISK FACTORS ASSOCIATED WITH THE DEVELOPMENT OF EXERTIONAL MEDIAL TIBIAL PAIN IN WOMEN

BackgroundThere is a significant lack of studies looking into the role of contralateral factors in the kinetic chain of subjects predisposed to exertional medial tibial pain (EMTP).DesignHip muscle strength and...

Effects of a 10-Week Resistance Exercise Program on Soccer Kick Biomechanics and Muscle Strength

The purpose of the study was to examine the effects of a resistance exercise program on soccer kick biomechanics. Twenty male amateur soccer players were divided in the experimental group (EG) and the control group (CG), each consisting of 10 players. The EG followed a 10-week resistance exercise program mainly for the lower limb muscles. Maximal instep kick kinematics, electromyography, and ground reaction forces (GRFs) as well as maximum isometric leg strength were recorded before and after training. A 2-way analysis of variance showed significantly higher ball speed values only for the EG (26.14 ± 1.17 m·s vs. 27.59 ± 1.49 m·s before and after training, respectively), whereas no significant differences were observed for the CG. The EG showed a decline in joint angular velocities and an increase in biceps femoris electromyography of the swinging leg during the backswing phase followed by a significant increase in segmental and joint velocities and muscle activation of the same leg during the forward swing phase (p < 0.05). The EG also showed significantly higher vertical GRFs and rectus femoris and gastrocnemius activation of the support leg (p < 0.05). Similarly, maximum and explosive isometric force significantly increased after training only for the EG (p < 0.05). These results suggest that increases in soccer kicking performance after a 10-week resistance training program were accompanied by increases in maximum strength and an altered soccer kick movement pattern, characterized by a more explosive backward-forward swinging movement and higher muscle activation during the final kicking phase.

Muscle activity and head kinematics in unconstrained movements in subjects with chronic neck pain; cervical motor dysfunction or low exertion motor output?

BackgroundChronic neck pain after whiplash associated disorders (WAD) may lead to reduced displacement and peak velocity of neck movements. Dynamic neck movements in people with chronic WAD are also reported to display altered movement patterns such as increased irregularity, which is suggested to signify impaired motor control. As movement irregularity is strongly related to the velocity and displacement of movement, we wanted to examine whether the increased irregularity in chronic WAD could be accounted for by these factors.MethodsHead movements were completed in four directions in the sagittal plane at three speeds; slow (S), preferred (P) and maximum (M) in 15 men and women with chronic WAD and 15 healthy, sex and age-matched control participants. Head kinematics and measures of movement smoothness and symmetry were calculated from position data. Surface electromyography (EMG) was recorded bilaterally from the sternocleidomastoid and splenius muscles and the root mean square (rms) EMG amplitude for the accelerative and decelerative phases of movement were analyzed.ResultsThe groups differed significantly with regard to movement velocity, acceleration, displacement, smoothness and rmsEMG amplitude in agonist and antagonist muscles for a series of comparisons across the test conditions (range 17 – 121%, all p-values < 0.05). The group differences in peak movement velocity and acceleration persisted after controlling for movement displacement. Controlling for differences between the groups in displacement and velocity abolished the difference in measures of movement smoothness and rmsEMG amplitude.ConclusionsSimple, unconstrained head movements in participants with chronic WAD are accomplished with reduced velocity and displacement, but with normal muscle activation levels and movement patterns for a given velocity and displacement. We suggest that while reductions in movement velocity and displacement are robust changes and may be of clinical importance in chronic WAD, movement smoothness of unconstrained head movements is not.

The short-term effects of a routine poisoning campaign on the movements and detectability of a social top-predator

Top-predators can be important components of resilient ecosystems, but they are still controlled in many places to mitigate a variety of economic, environmental and/or social impacts. Lethal control is often achieved through the broad-scale application of poisoned baits. Understanding the direct and indirect effects of such lethal control on subsequent movements and behaviour of survivors is an important pre-requisite for interpreting the efficacy and ecological outcomes of top-predator control. In this study, we use GPS tracking collars to investigate the fine-scale and short-term movements of dingoes (Canis lupus dingo and other wild dogs) in response to a routine poison-baiting program as an example of how a common, social top-predator can respond (behaviourally) to moderate levels of population reduction. We found no consistent control-induced differences in home range size or location, daily distance travelled, speed of travel, temporal activity patterns or road/trail usage for the seven surviving dingoes we monitored immediately before and after a typical lethal control event. These data suggest that the spatial behaviour of surviving dingoes was not altered in ways likely to affect their detectability, and if control-induced changes in dingoes' ecological function did occur, these may not be related to altered spatial behaviour or movement patterns.

Musculoskeletal screening to detect asymmetry in swimming

ObjectivesTo investigate the influence of asymmetry of clinical strength musculoskeletal screening measures and 3D kinematic movements on bilateral hand-force performance measures in swimmers. DesignCross-sectional. SettingInstitutional. Participants32 national-ranked junior swimmers, 100 m freestyle time (mean (SD), 60.68 s (4.81)). Main outcome measurementsScreened clinical strength, kinematic movements, and bilateral hand-force were measured. Asymmetry was defined as a percentage difference greater than 10 percent, either left (negative) or right (positive) for all variables. ResultsAsymmetry of the clinical strength measures was found in ∼85% of swimmers. Athletes with symmetry of all clinical strength measures displayed symmetrical bilateral hand force production. Approximately 50% of clinically asymmetrical swimmers were able to compensate, due to summated muscle symmetry and/or an altered kinematic movement pattern, and generate symmetrical hand force. ConclusionsSymmetry of clinical strength was directly related to symmetrical force output. It is important to connect the clinical screening results to the sport-specific performance measures to ensure functional and valid screening is undertaken. Clinicians should aim for symmetry of strength in order to minimise the requirement for compensatory strategies.

Measuring body weight distribution during sit-to-stand in patients with early knee osteoarthritis

People with severe degenerative conditions, such as osteoarthritis (OA), have been shown to have altered movement patterns during sit-to-stand. However it remains unclear whether such alterations exist in people with early OA, in the absence of pain. This study aimed to determine if a novel seat could be used to discriminate people with early OA compared with controls. The sit-to-stand task was performed by 20 people with early medial knee OA and 20 age and gender-matched control subjects, using an instrumented seat. OA subjects showed altered weight distribution in the transition phase from sit to stand, in that they placed more load through their unaffected side. Task duration was significantly longer for OA subjects, and ground reaction force integrals were significantly greater for both legs of OA subjects. OA subjects had significantly higher knee flexion and adduction moments in their unaffected compared with affected side. This study has demonstrated that a novel instrumented seat can be used to discriminate people with early medial knee OA during the sit-to-stand activity. These results may be relevant for early interventions to delay or prevent changes in muscle function of the affected limb as well as contralateral knee or hip osteoarthritis in these patients.

Does knee external rotation differ according to frontal plane knee alignment and the presence of patellofemoral osteoarthritis after anterior cruciate ligament reconstruction?

Does knee external rotation differ according to frontal plane knee alignment and the presence of patellofemoral osteoarthritis after anterior cruciate ligament reconstruction?

Can innominate motion be used to identify persons with ankylosing spondylitis? A pilot study

Innominate movements during hip abduction and external rotation have recently been described in healthy individuals. In the present study the aim was to determine whether these hip movement tests could discriminate altered movement patterns in people with specific pelvic girdle pain (PGP) disorder. This pilot study is the first step in determining the usefulness of prone hip abduction and external rotation in the differential diagnosis of PGP disorders. A cross-sectional comparison between a convenient sample of 6 individuals who had been referred for exercise and advice following diagnosis of ankylosing spondylitis (AS) via a Medical/Rheumatological pathway and 18 healthy age and gender matched controls. Transverse and sagittal plane innominate motion was measured using a palpation and digitizing technique with a magnetic tracking device. Data analysis involved applying best-fit equations to the data and visual inspection of the produced graphs as well as conditional logistical regression for each test position to determine our ability to predict group association. Graphical comparisons demonstrate a distinction between the patients with AS and the healthy controls. Further, for all three hip conditions the innominate angle was a significant predictor of group association (p = 0.002 for AB, p = 0.005 for AB + ER and p = 0.007 for ER).

Body mass index affects knee joint mechanics during gait differently with and without moderate knee osteoarthritis

Obesity is a highly cited risk factor for knee osteoarthritis (OA), but its role in knee OA pathogenesis and progression is not as clear. Excess weight may contribute to an increased mechanical burden and altered dynamic movement and loading patterns at the knee. The objective of this study was to examine the interacting role of moderate knee OA disease presence and obesity on knee joint mechanics during gait. Gait analysis was performed on 104 asymptomatic and 140 individuals with moderate knee OA. Each subject group was divided into three body mass categories based on body mass index (BMI): healthy weight (BMI<25), overweight (25≤BMI≤30), and obese (BMI>30). Three-dimensional knee joint angles and net external knee joint moments were calculated and waveform principal component analysis (PCA) was applied to extract major patterns of variability from each. PC scores for major patterns were compared between groups using a two-factor ANOVA. Significant BMI main effects were found in the pattern of the knee adduction moment, the knee flexion moment, and the knee rotation moment during gait. Two interaction effects between moderate OA disease presence and BMI were also found that described different changes in the knee flexion moment and the knee flexion angle with increased BMI with and without knee OA. Our results suggest that increased BMI is associated with different changes in biomechanical patterns of the knee joint during gait depending on the presence of moderate knee OA.

Shoulder morbidity after treatment for breast cancer is bilateral and greater after mastectomy

Background. A recent study in our laboratory found significant differences in scapular kinematics between the affected and unaffected sides of women reporting shoulder pain following treatment for breast cancer. An earlier smaller study from our laboratory found reduced muscle activity from four key muscles and an association with greater shoulder pain and disability. The aims of this study were to: correlate altered muscle activity from a larger sample with observed movement deviations; compare within subject movement and muscle deviations in survivors with healthy variation; explore the impact of a mastectomy vs. a wide local excision (WLE) on the observed deviations. Method. Cross-sectional study. One hundred and fifty-five women treated for unilateral carcinoma of the breast and 21 age-matched healthy women were included in the study. All patients filled out the Shoulder Pain and Disability Index (SPADI). Three-dimensional (3D)-kinematic data and EMG muscle activity were recorded during scaption on the affected and unaffected side. The association between kinematic data, EMG data, SPADI and covariates was determined using a two stage, random effects mixed multiple regression technique. Results. All scapula kinematic and muscle EMG parameters in both arms were altered in breast cancer survivors when compared to healthy participants. Altered movement patterns were different for left vs. right side affected. Mastectomy patients demonstrated greater movement deviations and reported significantly higher levels of pain than WLE patients. Conclusion. Shoulder morbidity is bilateral, greater in patients having a mastectomy and is present for up to six years post-surgery. This study and others now provide ample evidence to support prospective surveillance programmes that can be integrated into Survivorship Programmes.

Effects of the hallucinogenic drugs mescaline, phencyclidine and psilocybin on zebrafish behavior and physiology

Mescaline, phencyclidine (PCP) and psilocybin are potent hallucinogenic drugs strongly affecting both human and animal behavior. However, these compounds have not been previously investigated in zebrafish (Danio rerio), rapidly gaining popularity as a model in psychopharmacology research. Here, we examine the effects of mescaline, PCP and psilocybin in multiple behavioral paradigms. Mescaline (10–20 mg/L) generally displayed an anxiolytic effect in the novel tank test, while PCP (1–3 mg/L) reduced freezing behavior and elicited a pattern of erratic swimming. Mescaline‐treated fish markedly increased shoaling behavior and altered movement patterns in the open field test. Additionally, mescaline and PCP disrupted normal zebrafish exploratory behavior, as assessed by ethograms. Psilocybin at doses tested (0.5–3 mg/L) was inactive in all of the behavioral tests. Interestingly, both psilocybin and PCP raised whole‐body cortisol levels without affecting brain c‐fos expression, and mescaline did not alter cortisol or c‐fos levels. Overall, this confirms the high sensitivity of zebrafish models to various hallucinogenic compounds with complex behavioral and physiological profiles. This study was supported by the National Institute on Drug Abuse (NIDA) R03 grant to AVK.

Longitudinal changes in knee joint biomechanics during level walking following anterior cruciate ligament reconstruction surgery

Following anterior cruciate ligament reconstruction (ACL) patients have altered movement patterns in the reconstructed knee during walking. There is limited information about these alterations over an extended period of time. This study was designed to present a longitudinal analysis of gait patterns following ACL reconstruction surgery. Assessments of level walking were undertaken in 16 participants at a mean 10 months (initial assessment) and again at 3 years (follow-up assessment) after ACL reconstruction surgery. Kinematic and kinetic variables were analysed using a two factor (time, limb) repeated measures ANOVA. Kinematic data showed that patients were able to achieve greater extension about the reconstructed knee at follow-up than at initial assessment. The reconstructed knee was significantly less internally rotated than the contralateral knee at the initial assessment but not at follow-up. Kinetic data showed a significant increase in the external knee extension moment for the reconstructed limb over time. There were also significant increases in the external knee adduction moment for both limbs at the follow-up assessment. The external knee adduction moment was however smaller in the reconstructed knee than the contralateral knee at both assessments. The results indicate that gait variables do change over time and that measurement at a single time point may not reflect the long term outcome of ACL reconstruction surgery. The changes were however small and may not be clinically relevant. However, the consistently reduced external knee adduction moment seen about the reconstructed knee in this study may suggest that factors other than joint moments influence degenerative change over time.

Effects of experimentally induced low back pain on the sit-to-stand movement and electroencephalographic contingent negative variation.

It is becoming increasingly evident that people with chronic, recurrent low back pain (LBP) exhibit changes in cerebrocortical activity that associate with altered postural coordination, suggesting a need for a better understanding of how the experience of LBP alters postural coordination and cerebrocortical activity. To characterize changes in postural coordination and pre-movement cerebrocortical activity related to the experience of acutely induced LBP, 14 healthy participants with no history of LBP performed sit-to-stand movements in 3 sequential conditions: (1) without experimentally induced LBP; NoPain1, (2) with movement-associated LBP induced by electrocutaneous stimulation; Pain, and (3) again without induced LBP; NoPain2. The Pain condition elicited altered muscle activation and redistributed forces under the seat and feet prior to movement, decreased peak vertical force exerted under the feet during weight transfer, longer movement times, as well as decreased and earlier peak hip extension. Stepwise regression models demonstrated that electroencephalographic amplitudes of contingent negative variation during the Pain condition significantly correlated with the participants' change in sit-to-stand measures between the NoPain1 and Pain conditions, as well as with the subsequent difference in sit-to-stand measures between the NoPain1 and NoPain2 conditions. The results, therefore, identify the contingent negative variation as a correlate for the extent of an individual's LBP-related movement modifications and to the subsequent change in movement patterns from before to after the experience of acutely induced LBP, thereby providing a direction for future studies aimed to understand the neural mechanisms underlying the development of altered movement patterns with LBP.