Influence of feedback schedule in motor performance and learning of a lumbar multifidus muscle task using rehabilitative ultrasound imaging: a randomized clinical trial.

BACKGROUND AND PURPOSE: Low back pain (LBP) may be associated with inadequate multifidus muscle function. Varying the frequency and timing of feedback may enhance acquisition and retention of multifidus muscle recruitment during exercise. SUBJECTS: Subjects without LBP (n=30) were randomly assigned to a constant (CON) or variable (VAR) feedback group. Twenty-eight subjects (mean age=28 years, SD=8.0; mean body mass index=24 kg/m(2), SD=0.70) completed training, and 23 completed retention testing. METHODS: Eight training sessions over 4 weeks included multifidus muscle exercise with rehabilitative ultrasound imaging (RUSI) feedback. Retention was assessed at 1 week and >or=1 month. RESULTS: At the start, both groups had similar performances of multifidus muscle recruitment (Fisher exact test, P=.26). Early in training, the CON group had good success (mean=80%) that was maintained at session 8 (mean=84%), with no difference between sessions 1 and 8 (Wilcoxon signed rank test, P=.19, 95% confidence interval [CI]=-9%, 42%). The VAR group gradually increased success (Wilcoxon signed rank test, P=.002, 95% CI=17%, 59%) between sessions 1 and 8. Both groups sustained their session 8 success when tested for short-term retention at 1 week (CON group: Wilcoxon signed rank test, P=.79; VAR group: Wilcoxon signed rank test, P=.36). At the long-term retention test, the VAR group outperformed the CON group (Wilcoxon score test, P=.04), indicating superior motor learning. DISCUSSION AND CONCLUSION: Variable feedback provided by RUSI resulted in greater success in lumbar multifidus muscle recruitment up to 3 to 4 months after training.

Between-day repeatability and symmetry of multifidus cross-sectional area measured using ultrasound imaging.

STUDY DESIGN: Prospective test-retest, intrarater reliability study. OBJECTIVES: To estimate the intrarater reliability, asymmetry, and associated error with measurement of the cross-sectional area (CSA) of the bilateral S1 multifidi when measured by a physical therapist following a short course of self-directed training in ultrasound imaging. BACKGROUND: There is increasing interest in the assessment of the lumbar multifidus during the recovery from low back injury. It is important to know the error associated with the CSA measurements obtained by a physical therapist with limited experience in ultrasound imaging when using a portable unit. METHODS AND MEASURES: Thirty healthy females (mean +/- SD age, 23 +/- 2 years; mean +/- SD mass, 63.1 +/- 9.2 kg; mean +/- SD height, 1.63 +/- 0.06 m) participated. Fourteen subjects returned within 1 to 4 days for repeated measurements. RESULTS: For all 30 subjects, the average (+/- SD) CSA of the left S1 multifidus (4.18 +/- 0.55 cm2) was larger (P<.05) than the right (4.11 +/- 0.57 cm2), with a standard error of the measurement (SEM) of 0.13 cm2 and average +/- SD asymmetry of 3.5% +/- 3.4%. For a subset of 14 subjects, the between-day intrarater reliability for the right S1 multifidus muscle was ICC3,1 = 0.80 (95% CI, 0.49-0.93), while the ICC for the left side was 0.72 (95% CI, 0.34-0.90). The day-to-day average differences for the left and right side were 0.02 cm2 and 0.04 cm2, respectively. For the most conservative estimate, the between-day SEM was 0.37cm2. CONCLUSIONS: A physical therapist, newly trained in ultrasound imaging, obtained reasonable between-day intrarater reliability when imaging the S1 multifidus. A high degree of symmetry was found between the bilateral S1 multifidi in a sample of healthy subjects, which is consistent with previous reports from measurements by skilled ultrasonographers.

The interrater reliability among physical therapists newly trained in a classification system for acute low back pain.

STUDY DESIGN: A prospective methodological interrater reliability study. OBJECTIVES: To calculate the interrater reliability among clinicians newly trained in a classification system for acute low back pain and to determine the level of agreement at key junctures within the classification algorithm. BACKGROUND: The utility of a classification system for patients with low back pain depends on its reliability and generalizability. To be practical, clinicians must be able to apply the system after a reasonable amount of training. Identifying key points in the classification algorithm where disagreement occurs can lead to better operational definitions. METHODS: Four physical therapists read an article and attended a 1-day training session in the classification system. Randomly paired therapists classified patients referred for treatment of acute low back pain and noted decisions at key junctures in the system algorithm. RESULTS: Forty-five patients were classified. Repeated examinations did not increase the patient's pain (P>.05). For 3 out of the 4 therapists, the interrater reliability showed a kappa value of 0.45. The fourth therapist, excluded from the overall analysis, exhibited a bias towards the immobilization classification. Among the 3 therapists, major disagreement occurred with the determination of symmetry with trunk side bending and the effects of repeated movements. CONCLUSIONS: Three out of 4 clinicians newly trained in the system showed moderate reliability. The reliability was slight when the fourth therapist was included. Refinement of the operational definitions and criteria for determining lumbar capsular patterns are needed. One day of training is probably not adequate for all therapists, especially for those biased towards specific low back pain syndromes.

Dynamics, stability, and control of stepping.

The dynamics, stability, and control of stepping are considered. The role of internal models is elaborated. The main objective of the paper is to provide a better understanding of the machinery and processing in the central nervous system (CNS) that relates to stepping. The role of the vestibular system in balance and balance recovery is described. Balance and balance recovery are essential in stepping, and guarantee the stability of the system before, during, and after stepping. In sagittal standing, humans use two distinct sets of control strategies to maintain their postural stability in response to external disturbance. In one set of strategies, the configuration of the base of support, namely, the position of the feet, remains unchanged. The ankle and hip strategies are examples of postural adjustments where the feet do not move. When the disturbances are large, and move the center of mass or pressure outside the support boundaries, stepping strategies are required. A simple control strategy is proposed for illustrative purposes. Its effectiveness is verified by computer simulation of a seven-link two-dimensional sagittal biped. The applications of the model in assessing trauma and injury are discussed.

Physical therapy on trial: the rationale, organization, and impact of a mock trial on physical therapy students' attitudes toward and confidence in research.

A learning activity, debate with a mock trial format, provides opportunities for physical therapy students to develop skill and confidence in learning to evaluate research critically, to formulate opinions regarding the credibility of the available evidence for a therapeutic approach to patient care, and to substantiate their choice of treatments with persuasive arguments and analytic rebuttals. The purposes of this study were to (1) describe the mock trial learning activity within a professional physical therapy curriculum and (2) determine whether the mock trial positively influenced students' attitudes toward research and confidence in their ability to interpret and apply research findings to clinical practice. A structured questionnaire was distributed to the 48 students at key points during the academic program to measure the overall effects of the physical therapy curriculum and the specific effects of the mock trial learning activity. There was an increase (p < 0.05) in the students' confidence in their ability to interpret and apply research after participating in the mock trial. The overall responses to the modified Attitudes-to-Research scale indicated that the physical therapy students generally held positive and optimistic attitudes toward research. These attitudes were maintained over the entire experience within the curriculum. If attitudes predict behavior, these future practitioners are more likely to be physical therapists who critically appraise and use evidence to determine practice.

Actions of the scalene muscles for rotation of the cervical spine in macaque and human.

STUDY DESIGN: Multiple single-subject design in 2 parts: 1 in anesthetized monkeys and a follow-up in human cadavers. OBJECTIVES: To determine whether anterior, middle, and posterior scalene muscles rotate the cervical spine to the same (ipsilateral to the muscle) or opposite (contralateral to the muscle) side. BACKGROUND: Some physical therapy and anatomy textbooks indicate that all 3 scalenes rotate the cervical spine to the same side, some indicate that all rotate to the opposite side, and the rest ascribe different functions to the different scalenes. METHODS AND MEASURES: While under anesthesia, macaques (n = 3) already scheduled for euthanasia were implanted with stimulating electrodes in each scalene muscle on one side, and then a neuromuscular junction blocker was administered to prevent confounding movement from brachial plexus stimulation. Three observers independently rated the direction of rotation produced by electrical stimulation. Postmortem dissection of the macaques was used to determine which direction of passive rotation stretched each scalene. Postmortem analyses in 2 human cadavers were also conducted to determine which direction of rotation stretched the human scalenes. RESULTS: Electrical stimulation in the macaque produced rotation to the same side for each of the 3 scalenes. Passive rotation to the opposite side put each scalene muscle of the macaque on stretch. In the human, rotation to the opposite side also stretched each scalene. CONCLUSIONS: All 3 scalene muscles produce rotation of the cervical spine to the same side. Maximum stretching of the scalenes should include rotation to the opposite side.

Effect of center of pressure and trunk center of mass optimization methods on the analysis of whole body lifting mechanics.

OBJECTIVE: This study evaluates methods to optimize the trunk center of mass position, the center of pressure position, or both to minimize the difference between horizontal location of the whole body center of mass estimated by the model and center of pressure measured during static postures. DESIGN: Within subjects repeated measures. BACKGROUND: Methods to optimize the trunk center of mass position have been proposed in the past, but have not been fully evaluated nor have accounted for errors in the location of the center of pressure. Accurately determining these locations affects the understanding of the control of balance. METHODS: Six methods were compared using kinematic and force plate data from 22 subjects. Static postures resembling both leg and back lifting techniques were used to optimize the center of mass. A typical lifting movement was used to evaluate the effectiveness of the methods in reducing the difference between external moment and time derivative of the angular momentum. RESULTS: Optimization of the center of pressure had a statistically significant effect on reducing errors (P<0.05), whereas optimization of the trunk center of mass alone had not (P>0.05). CONCLUSIONS: Optimizing the center of pressure was simple and compensated for systematic errors introduced from the model and instrumentation. The addition of the center of mass optimization improved some results but added much complexity to the experimental procedures. RELEVANCE: Reducing errors in determining the relative position of the center of pressure and center of mass enhances the understanding of balance control as this relationship reflects the dynamic stability of the system.

Balance loss when lifting a heavier-than-expected load: effects of lifting technique.

OBJECTIVES: To compare the lifting techniques of subjects who did and did not maintain their balance with an unexpectedly heavy load, and to examine whether the balance loss increased low back loading. DESIGN: Repeated-measures design. SETTING: A research laboratory. PARTICIPANTS: Fourteen healthy volunteers were assigned to 2 groups in the post hoc analysis. Group 1 (7 men; mean age, 25.6 +/- 4.2yr; height, 1.78 +/-.08m; weight, 83.0 +/- 8.5kg; lifting capacity, 63.2 +/- 8.0kg) maintained balance and was matched to group 2 (7 men; mean age, 26.3 +/- 4.1yr; height, 1.75 +/-.06m; weight, 78.2 +/- 5.3kg; lifting capacity, 64.7 +/- 4.9kg) who lost balance. INTERVENTIONS: Subjects lifted boxes of 5%, 20%, and 35% of their lifting capacity. Load magnitude was expected or unexpected. MAIN OUTCOME MEASURES: Center of mass (COM), lower body mechanics, ground reaction forces, and angular and horizontal momentum. RESULTS: Group 1 consistently showed greater lumbar flexion, less knee flexion, and a higher COM just before and after load liftoff. During the heavier-than-expected 35% lift, the trunk angular velocities lifts indicated that both groups experienced eccentric trunk extensor muscle contractions. CONCLUSIONS: The semisquat technique may protect against balance loss when lifting unexpectedly heavy loads. Eccentric muscle contractions and rapid increases in lumbar joint reaction moments may increase the risk of low back injury when there is a large, unexpected increase in the weight of the lifted load.