Altered Multifidus Recruitment During Walking in Young Asymptomatic Individuals with a History of Low Back Pain

Study Design Cross sectional, laboratory study. Background Individuals with low back pain have impaired activation of multifidus during postural adjustments and increased activity of the erector spinae musculature during walking. However, it is unclear if these alterations in muscle activity are evident during locomotion in individuals with a history of low back pain when they are between symptomatic episodes. Objectives To compare paraspinal muscle activity in young healthy individuals and young individuals with a history of low back pain during walking turns. Methods 14 asymptomatic individuals with a history of low back pain and 14 controls performed 90° walking turns at both self-selected and fast speed. The duration and amplitude of activity in the deep fibers of multifidus and the lumbar and thoracic longissimus were quantified using intramuscular electromyography. Results There was a significant speed by group interaction for the duration of multifidus activity (p = .013). Duration of activity increased from the self-selected to the fast locomotor speed in the controls, but decreased in the individuals with a history of low back pain (p = .003). Self-selected speed was the same in both groups (p = .719). There was a trend towards a significant association between group and the direction of change in the duration of deep multifidus activity (χ2 = .058). Duration of thoracic longissimus activity and amplitude of multifidus and thoracic longissimus activity increased similarly in both groups from the self-selected to faster speed. Conclusion Even between symptomatic episodes, young individuals with a history of low back pain demonstrated altered recruitment of the deep fibers of lumbar multifidus in response to changing locomotor speed during walking turns

Trunk-Pelvis Coordination During Turning: A Cross Sectional Study of Young Adults With and Without a History of Low Back Pain

Background During steady-state locomotion, symptomatic individuals with low back pain demonstrate reduced ability to modulate coordination between the trunk and the pelvis in the axial plane. It is unclear if this is also true during functional locomotor perturbations such as changing direction, or if this change in coordination adaptability persists between symptomatic episodes. The purpose of this study was to compare trunk-pelvis coordination during walking turns in healthy individuals and asymptomatic individuals with a history of low back pain. Methods Participants performed multiple ipsilateral turns. Axial plane inter-segmental coordination and stride-to-stride coordination variability were quantified using the vector coding technique. Frequency of coordination mode and amplitude of coordination variability was compared between groups using Wilcoxon signed-ranks tests and paired t-tests respectively. Findings During stance phase of the turn, there was no significant difference in either inter-segmental coordination or coordination variability between groups. Inter-segmental coordination between the trunk and the pelvis was predominantly inphase during this part of the turn. During swing phase, patterns of coordination were more diversified, and individuals with a history of low back pain had significantly greater trunk phase coordination than healthy controls. Coordination variability was the same in both groups. Interpretation Changes in trunk-pelvis coordination are evident between symptomatic episodes in individuals with a history of low back pain. However, previously demonstrated decreases in coordination variability were not found between symptomatic episodes in individuals with recurrent low back pain and therefore may represent a response to concurrent pain rather than a persistent change in motor control

Does Insertion of Intramuscular Electromyographic Electrodes Alter Motor Behavior During Locomotion?

Intramuscular electromyography (EMG) is commonly used to quantify activity in the trunk musculature. However, it is unclear if the discomfort or fear of pain associated with insertion of intramuscular EMG electrodes results in altered motor behavior. This study examined whether intramuscular EMG affects locomotor speed and trunk motion, and examined the anticipated and actual pain associated with electrode insertion in healthy individuals and individuals with a history of low back pain (LBP). Before and after insertion of intramuscular electrodes into the lumbar and thoracic paraspinals, participants performed multiple repetitions of a walking turn at self-selected and controlled average speed. Low levels of anticipated and actual pain were reported in both groups. Self-selected locomotor speed was significantly increased following insertion of the electrodes. At the controlled speed, the amplitude of sagittal plane lumbo-pelvic motion decreased significantly post-insertion, but the extent of this change was the same in both groups. Lumbo-pelvic motion in the frontal and axial planes and thoraco-lumbar motion in all planes were not affected by the insertions. This study demonstrates that intramuscular EMG is an appropriate methodology to selectively quantify the activation patterns of the individual muscles in the paraspinal group, both in healthy individuals and individuals with a history of LBP

The Influence of Divided Attention on Walking Turns: Effects on Gait Control in Young Adults With and Without a History of Low Back Pain

The cognitive control of gait is altered in individuals with low back pain, but it is unclear if this alteration persists between painful episodes. Locomotor perturbations such as walking turns may provide a sensitive measure of gait adaptation during divided attention in young adults. The purpose of this study was to investigate changes in gait during turns performed with divided attention, and to compare healthy young adults with asymptomatic individuals who have a history of recurrent low back pain (rLBP). Twenty-eight participants performed 90° ipsilateral walking turns at a controlled speed of 1.5 m/s. During the divided attention condition they concurrently performed a verbal 2-back task. Step length and width, trunk-pelvis and hip excursion, inter-segmental coordination and stride-to-stride variability were quantified using motion capture. Mixed-model ANOVA were used to examine the effect of divided attention and group, and interaction effects on the selected variables. Step length variability decreased significantly with divided attention in the healthy group but not in the rLBP group (post-hoc p = 0.024). Inter-segmental coordination variability was significantly decreased during divided attention (main effect of condition p \u3c 0.000). There were small but significant reductions in hip axial and sagittal motion across groups (main effect of condition p = 0.044 and p = 0.040 respectively), and a trend toward increased frontal motion in the rLBP group only (post-hoc p = 0.048). These findings suggest that the ability to switch attentional resources during gait is altered in young adults with a history of rLBP, even between symptomatic episodes

Trunk Coordination in Dancers and Non-Dancers

Variability, or how a task changes across trials, may reveal differences between athletes of differing skill levels. The purpose of this study was to examine trunk and lower extremity (LE) single joint kinematic variability and inter-segmental coordination variability in dancers and non-dancers during bipedal vertical dance jumps (sautés). Twenty healthy females, ten with no formal dance training and ten professional dancers, performed 20 consecutive sautés. Single joint kinematic variability was assessed using mean standard deviation of angular displacement, and inter-segmental coordination variability was assessed using angular deviation of the coupling angle between segments. Within the context of the standard error of measure, there was no difference in single joint kinematic variability between dancers and non-dancers. Inter-segmental coordination variability in the trunk was higher than variability in LE couplings for both groups. Dancers had lower inter-segmental coordination variability than non-dancers for LE sagittal, frontal and transverse plane couplings and sagittal plane trunk couplings. Trunk adjustments may be important for successful performance, but lower inter-segmental coordination variability in expert dancers indicates a higher level of control. Trunk coordination and postural control may be important factors to investigate in skilled athletes

Factors Related to Intra-Tendinous Morphology of Achilles Tendon in Runners

The purpose of this study was to determine and explore factors (age, sex, anthropometry, running and injury/pain history, tendon gross morphology, neovascularization, ankle range of motion, and ankle plantarflexor muscle endurance) related to intra-tendinous morphological alterations of the Achilles tendon in runners. An intra-tendinous morphological change was defined as collagen fiber disorganization detected by a low peak spatial frequency radius (PSFR) obtained from spatial frequency analysis (SFA) techniques in sonography. Ninety-one runners (53 males and 38 females; 37.9 ± 11.6 years) with 8.8 ± 7.3 years of running experience participated. Height, weight, and waist and hip circumferences were recorded. Participants completed a survey about running and injury/pain history and the Victorian Institute of Sport Assessment-Achilles (VISA-A) survey. Heel raise endurance and knee-to-wall composite dorsiflexion were assessed. Brightness-mode (B-mode) sonographic images were captured longitudinally and transversely on the Achilles tendon bilaterally. Sonographic images were analyzed for gross morphology (i.e., cross-sectional area [CSA]), neovascularization, and intra-tendinous morphology (i.e., PSFR) for each participant. The factors associated with altered intra-tendinous morphology of the Achilles tendon were analyzed using a generalized linear mixed model. Multivariate analyses revealed that male sex was significantly associated with a decreased PSFR. Additionally, male sex and the presence of current Achilles tendon pain were found to be significantly related to decreased PSFR using a univariate analysis. Our findings suggested that male sex and presence of current Achilles tendon pain were related to intra-tendinous morphological alterations in the Achilles tendon of runners

Identification of potential neuromotor mechanisms of manual therapy in patients with musculoskeletal disablement: rationale and description of a clinical trial

<p>Abstract</p> <p>Background</p> <p>Many health care practitioners use a variety of hands-on treatments to improve symptoms and disablement in patients with musculoskeletal pathology.</p> <p>Research to date indirectly suggests a potentially broad effect of manual therapy on the neuromotor processing of functional behavior within the supraspinal central nervous system (CNS) in a manner that may be independent of modification at the level of local spinal circuits. However, the effect of treatment speed, as well as the specific mechanism and locus of CNS changes, remain unclear.</p> <p>Methods/Design</p> <p>We developed a placebo-controlled, randomized study to test the hypothesis that manual therapy procedures directed to the talocrural joint in individuals with post-acute ankle sprain induce a change in corticospinal excitability that is relevant to improve the performance of lower extremity functional behavior.</p> <p>Discussion</p> <p>This study is designed to identify potential neuromotor changes associated with manual therapy procedures directed to the appendicular skeleton, compare the relative effect of treatment speed on potential neuromotor effects of manual therapy procedures, and determine the behavioral relevance of potential neuromotor effects of manual therapy procedures.</p> <p>Trial Registration</p> <p><url>http://www.clinicaltrials.gov</url> identifier NCT00847769.</p

Biomechanical Characteristics of Lumbar Manipulation Performed by Expert, Resident, and Student Physical Therapists

Background Lumbar manipulation is a commonly used treatment for low back pain, but little research evidence exists regarding practitioner biomechanics during manipulation. Most existing evidence describes rate of force production through the hands into instrumented manikins and it is unclear how the practitioner moves their body and legs to generate this force. Objectives To identify and characterize important kinetic and kinematic factors in practitioners of varying experience performing lumbar manipulation in order to identify which factors distinguish experts from less experienced practitioners. Study design This was a cohort observational laboratory study. Methods 43 male physical therapists (PT) and PT students (4 experts, 11 residents, 13 third year, and 15 first year students) performed 4 manipulations each on asymptomatic patient models. Angular and linear kinematics of the pelvis were measured using motion capture, and ground reaction forces were measured with force plates under the practitioner\u27s feet. Results Peak pelvic angular velocity was greater and in the opposite direction in experts compared to other groups in the frontal plane (p = 0.020) and transverse plane (p = 0.000). Experts had greater downward pelvic linear velocity than third year students and first year students (p = 0.000). Experts also demonstrated faster rate of vertical ground reaction force unloading during the manipulation (p = 0.002). Conclusions Expert performance of manipulation was characterized by increased speed of linear and angular pelvic motion, and increased modulation of vertical ground reaction force. These results help to inform educators and practitioners that teach and use this complex manual skill

Within-day test-retest reliability of transcranial magnetic stimulation measurements of corticomotor excitability for gastrocnemius and tibialis anterior muscles

Background: Manual therapy interventions targeting the talocrural joint can improve gait and balance functions in individuals following ankle sprains. Less is known about the underlying mechanisms of functional improvements after manual therapy. One hypothesis involves change in corticomotor excitability (CE) following manual therapy procedures. Transcranial magnetic stimulation (TMS) is a brain imaging method that could provide important information regarding potential changes in CE associated with manual therapy techniques applied to the talocrural joint. However, within-day reliability of TMS to measure CE must first be established in order to measure CE changes associated with manual therapy procedures. Objective: To determine the within-day test-retest reliability of TMS CE measures for gastrocnemius (GAS) and tibialis anterior (TA) for use in test-retest designs assessing corticomotor excitability in manual therapy and exercise studies. Method: TMS measures, including motor evoked potential (MEP) amplitude and cortical silent period (CSP), were completed twice on the same day under resting and active conditions in n = 6 nondisabled participants. The absolute reliability (coefficient of variation), relative reliability (intraclass correlation coefficient), standard error of measures, and minimal detectable change outside the 95% confidence interval were calculated for both GAS and TA muscles in each experimental condition. Results: There were no statistically significant differences between the first and second TMS measurements. TMS measurements for GAS and TA demonstrated good absolute and relative test-retest reliability under the active condition, but not the resting condition. Discussion: TMS under the active condition can be reliably used to assess CE even in postural muscles with a small cortical representation area, such as GAS