Understanding the Biering-Sørensen test: Contributors to extensor endurance in young adults with and without a history of low back pain.

The Biering-Sørensen test is commonly used to assess paraspinal muscle endurance. Research using a single repetition of the test has provided conflicting evidence for the contribution of impaired paraspinal muscle endurance to low back pain (LBP). This study investigated how Sørensen test duration, muscle activation, and muscle fatigability are affected by multiple repetitions of the test and determined predictors of Sørensen test duration in young adults with and without a history of LBP. Sixty-four young individuals performed three repetitions of the Sørensen test. Amplitude of activation and median frequency slope (fatigability) were calculated for the lumbar and thoracic paraspinals and hamstrings. Duration of the test was significantly less for the 3rd repetition in individuals with LBP. In individuals without LBP, test duration was predicted by fatigability of the lumbar paraspinals. In individuals with LBP, Sørensen test duration was predicted by fatigability of the hamstrings and amplitude of activation of the thoracic and lumbar paraspinals. Our findings demonstrate that it is necessary to amplify the difficulty of the Sørensen test to reveal impairments in young, active adults with LBP. Training programs aiming to improve lumbar paraspinal performance should monitor performance of other synergist muscles during endurance exercise.

Comparison of electromyographic activity of the gluteal muscles and tensor fascia lata in persons with patellofemoral pain: evaluation of selected, hip-targeted exercises using indwelling fine-wire electrodes.

INTRODUCTION: Excessive hip adduction and internal rotation are common movement impairments associated with patellofemoral pain (PFP). As such, strengthening of the hip abductors and external rotators commonly is recommended. Because tensor fascia latae (TFL) is a hip internal rotator in addition to being an abductor, it is important to select exercises that target the superior gluteus maximus (SUP-GMAX) and gluteus medius (GMED) while minimizing activation of the TFL. OBJECTIVE: To identify hip-targeted exercises resulting in greater activation of the SUP-GMAX and GMED relative to the TFL in persons with PFP. METHODS: Twelve individuals with PFP participated. Electromyographic (EMG) signals were obtained from the GMED, SUP-GMAX, and TFL using fine-wire electrodes while participants performed 11 hip-targeted exercises. Normalized EMG of GMED and SUP-GMAX was compared to that of the TFL for each exercise using repeated measures ANOVAs and descriptive statistics. RESULTS: Of the 11 hip exercises evaluated, only the clam exercise with elastic resistance resulted in significantly greater activity of both gluteal muscles (SUP-GMAX = 24.2 ± 14.4%MVIC, p = .05; GMED = 37.2 ± 19.7%MVIC, p = .008) relative to the TFL (12.5 ± 11.7%MVIC). Five exercises exhibited significantly lower activation of SUP-GMAX relative to TFL: 1) unilateral bridge: SUP-GMAX = 17.7 ± 9.8%MVIC, TFL = 34.0 ± 17.7%MVIC, p = .01; 2) bilateral bridge: SUP-GMAX = 10.0 ± 6.9%MVIC, TFL = 14.0 ± 7.5%MVIC, p = .04; 3) abduction: SUP-GMAX = 14.2 ± 11.1%MVIC, TFL = 33.0 ± 11.9%MVIC, p = .001; 4) hip hike: SUP-GMAX = 14.8 ± 12.8%MVIC, TFL = 46.8 ± 33.7%MVIC, p = .008; and 5) step-up: SUP-GMAX = 15.0 ± 5.4%MVIC, TFL = 31.7 ± 19.9 %MVIC, p = .02). No differences in gluteal activation relative to TFL were found for the remaining 6 exercises (all p > .05). CONCLUSION: The clam with elastic resistance exercise was effective at activating the SUP-GMAX and GMED greater than TFL. No other exercises achieved a similar level of muscular recruitment. When attempting to strengthen the gluteal muscles in persons with PFP, care should be taken in assuming that common hip-targeted exercises result in the desired recruitment patterns.

Understanding the Biering-Sørensen test: contributors to extensor endurance in young adults with and without low back pain.

Impaired paraspinal muscle endurance may contribute to persistent low back pain (LBP) and is frequently assessed using a single repetition of the Biering-Sørensen test. This study investigated how Sørensen test duration, muscle activation, and muscle fatigability are affected by multiple repetitions of the test, and determined predictors of Sørensen test duration in young, active adults with and without a history of LBP. Sixty-four individuals with and without persistent LBP performed 3 repetitions of the Sørensen test. Amplitude of activation and median frequency slope (fatigability) were calculated for the lumbar and thoracic paraspinals and the hamstrings. Duration of the test was significantly less for the 2nd and 3rd repetitions in individuals with LBP. In individuals without LBP, fatigability of the lumbar paraspinals was the best predictor of test duration. In individuals with LBP, Sørensen test duration was predicted by fatigability of the hamstrings and amplitude of activation of the thoracic and lumbar paraspinals. Our findings demonstrate that it is necessary to amplify the difficulty of the Sørensen test to elucidate impairments in young, active adults with LBP. Training programs aiming to improve lumbar paraspinal performance in individuals with LBP should monitor performance of other synergist muscles during endurance exercise.

Persons with patellofemoral pain exhibit altered hip abductor muscle recruitment while performing hip abductor exercises.

INTRODUCTION: Strengthening of the hip abductors has been advocated for persons with patellofemoral pain (PFP). It is not clear if these individuals activate the hip abductor muscles appropriately to achieve the desired therapeutic effects. OBJECTIVE: To compare activation of the hip abductor muscles between persons with and without PFP during the performance of hip abductor exercises. METHODS: Thirty-two individuals participated (12 with PFP and 20 without PFP). The average age (± standard deviation) was 29.7 ± 5.9 years for the PFP group and 28.1 ± 6.9 for the control group. Electromyographic (EMG) signals from the gluteus medius (GMED), superior gluteus maximus (SUP-GMAX), and tensor fascia lata (TFL) were obtained using fine-wire electrodes while participants performed 11 different exercises. Normalized EMG activity of each muscle was compared between groups across all exercises. RESULTS: When averaged across all exercises, persons with PFP exhibited significantly greater EMG activity of TFL (mean = 25.3% MVIC; 95% CI = 19.2, 31.3) compared to those without PFP (mean = 17.6% MVIC; 95% CI = 12.8, 22.4) and significantly lower EMG activity of SUP-GMAX (mean = 16.4% MVIC; 95% CI = 11.0, 22.0) compared to those without PFP (mean = 25.4% MVIC; 95% CI = 21.0, 29.8). Persons with PFP exhibited lower EMG activity of GMED, but only for 3 out of the 11 exercises evaluated (hip abduction, hip hike, step-up). CONCLUSION: Compared to persons without PFP, those with PFP exhibited activation differences during the performance of exercises used to target the hip abductors. Our results highlight the need for activation training prior to the initiation of strengthening exercises to achieve desired therapeutic effects.

Survey of Physical Therapists' Attitudes, Knowledge, and Behaviors Regarding Diagnostic Imaging.

OBJECTIVE: The purpose of this study was to describe physical therapists' attitudes, knowledge, and behaviors regarding the use of diagnostic imaging. METHODS: Physical therapists in the United States were recruited from July 2018 through May 2019 to complete a web-based, cross-sectional survey. Participants were asked about demographics, their perceived knowledge base and skills for recommending or ordering different imaging modalities, and their behaviors regarding diagnostic imaging. Descriptive statistics were used to characterize the participants' demographics and responses to all questions. Chi-square tests were performed to compare responses by characteristics of survey participants and Wilcoxon signed-rank tests to compare levels of agreement. RESULTS: The mean age was 43 years, and of the 739 respondents, 58% (n = 417) were female. Ninety-two percent of respondents (n = 595) reported having recommended diagnostic imaging to another provider at least once. Only 11.6% (n = 75) reported having ever directly ordered diagnostic imaging. Participants' attitudes about their knowledge base and skills for recommending or ordering plain radiographs were stronger compared with any other imaging modalities followed by magnetic resonance imaging (MRI) over other imaging techniques. Participants' attitudes on recommending plain radiographs or MRI differed by professional education level, board-certification status, fellowship completion, and years since graduation. CONCLUSION: It is common for physical therapists to recommend imaging, but few have directly ordered imaging. Most survey participants believed that they have an adequate knowledge base and skills for recommending and ordering plain radiographs and MRI. IMPACT: These results can serve as a benchmark for future comparison as policies and educations evolve. Understanding physical therapists' attitudes, knowledge, and use of diagnostic imaging is important to inform research, policy, and education.

Postural cueing increases multifidus activation during stabilization exercise in participants with chronic and recurrent low back pain: An electromyographic study.

Persons with low back pain (LBP) have demonstrated altered morphology and function of the deep multifidus (DM). This study examined the effects of postural cueing for increased lumbar lordosis on DM and longissimus thoracis (LT) activation during lumbar stabilization exercises (LSE) performed by persons with LBP. Nine adults with a history of chronic or recurrent LBP were recruited. Fine-wire EMG data was collected while participants performed 10 LSE's in neutral posture and with postural cueing. Percent maximum voluntary isometric contraction of L5 DM and T12 LT, and ratios of activation (DM/LT) were analyzed. There was a significant main effect for posture on DM activation (p < 0.001), indicating greater activation levels during exercises performed with postural cueing vs. neutral posture. LT activation did not increase significantly with postural cueing. Following a significant 1-way repeated measures ANOVA (p = 0.034) for the postural cueing condition, pairwise comparisons demonstrated significantly higher DM/LT activation ratios for prone leg lift, variable-angle Roman chair at 15°, bridging, and bilateral arm and leg lift. These results suggest postural cueing can be used across a range of LSE intensities to increase DM activation without a significant increase in LT activation in patients with chronic or recurrent LBP.

The influence of pelvic rotation on clinical measurements of hip flexion and extension range of motion across sex and age.

OBJECTIVE: The purpose of this study was to identify the amount of pelvic rotation associated with hip motion during passive hip flexion and extension goniometric measurements. DESIGN: Cross-sectional study. SETTING: University laboratory. PARTICIPANTS: One hundred healthy adults (males = 45, females = 55) aged 18-66 years participated. OUTCOME MEASURES: Clinical range of motion measurements of hip flexion, and extension during the modified Thomas test, and pelvic sagittal position measured using a device, attached from the PSIS to ASIS, and a fluid-filled inclinometer. RESULTS: When pelvic rotation was subtracted from the clinical measurements, hip flexion measurements were significantly reduced in both sexes (males: 110.8 ± 7.4 to 93.8 ± 7.8°, P < 0.001; females: 121.3 ± 7.2 to 107.3 ± 8.6°, P < 0.001). However, subtracting pelvic rotation from hip extension measurements only significantly reduced the measurements in females (15.5 ± 6.0 to 6.2 ± 6.8°, P < 0.001). No significant differences were found across age groups. CONCLUSIONS: Clinical measurements of hip flexion exaggerated the range of motion in both sexes. The modified Thomas test appeared to control for rotation of the pelvis during hip extension in men. However, in women, hip extension measurements were exaggerated.

Spondylolisthesis Identified Using Ultrasound Imaging.

57-year-old woman was recruited for a research study of muscle activation in persons with low back pain. She described a progressive worsening of left lower lumbar pain, which began 5 years prior without any precipitating incident, and intermittent pain at the left gluteal fold (diagnosed as a proximal hamstring tear 2 years prior). Ultrasound revealed marked anterior displacement of the L3-4 and L4-5 facet joints. The subject was recommended for a radiograph using a lateral recumbent view, which demonstrated a grade II spondylolisthesis. J Orthop Sports Phys Ther 2017;47(12):970. doi:10.2519/jospt.2017.7363.

Children require less gait kinematic adaptations to pull a trolley than to carry a backpack.

To transport school materials, trolleys have been proposed for children as an alternative to carrying a backpack. However, there is limited evidence comparing the adaptations associated with carrying school trolley versus backpack. This study compared the effects of carrying a backpack and pulling a trolley on gait kinematics in children. Fifty-three students were evaluated. Children walked at self-selected speeds across a walkway with no bag (control), carrying a backpack with the 15% of child́s body weight (%BW) and pulling a trolley with the same load. Spatiotemporal gait parameters and 3D kinematics of lower extremities and thorax were computed. No significant differences were obtained in spatiotemporal parameters between pulling a trolley and control. Carrying a backpack resulted in larger kinematics gait alterations than pulling the trolley compared to control. In conclusion, pulling a school trolley (15%BW) was more similar to not carrying a bag than carrying a backpack of the same load during level walking.

Comparison of Electromyographic Activity of the Superior and Inferior Portions of the Gluteus Maximus Muscle During Common Therapeutic Exercises.

Study Design Controlled laboratory study, repeated-measures design. Background Previous studies have reported that the superior and inferior portions of the gluteus maximus have different functional roles. Knowledge of how the different portions of the gluteus maximus are activated during therapeutic exercise may lead to more specific exercise prescription. Objective To compare muscle activation of the superior and inferior portions of the gluteus maximus during commonly used therapeutic exercises. Methods Twenty healthy persons participated. Electromyographic (EMG) signals were obtained from the superior and inferior portions of the gluteus maximus using fine-wire electrodes. Normalized EMG signal amplitudes were compared between the superior and inferior gluteus maximus across 11 exercises using a 2-way repeated-measures analysis of variance. Results The superior portion of the gluteus maximus had significantly greater relative EMG activity than the inferior portion of the gluteus maximus during exercises that incorporated elements of hip abduction and/or external rotation (5 of 11 exercises evaluated). There was no significant difference in activation between the superior and inferior portions of the gluteus maximus during the remaining 6 exercises. Conclusion The results of the present study demonstrate preferential activation of the superior portion of the gluteus maximus during exercises that incorporate elements of hip abduction and/or external rotation. In contrast, exercises that primarily involve hip extension target both portions of the gluteus maximus to a similar extent. J Orthop Sports Phys Ther 2016;46(9):794-799. Epub 5 Aug 2016. doi:10.2519/jospt.2016.6493.

Postural Cueing to Increase Lumbar Lordosis Increases Lumbar Multifidus Activation During Trunk Stabilization Exercises: Electromyographic Assessment Using Intramuscular Electrodes.

STUDY DESIGN: Controlled laboratory study, repeated-measures design. BACKGROUND: Diminished multifidus activation and cross-sectional area are frequent findings in persons with low back pain. Increasing lumbar lordosis has been shown to increase activation of the multifidus with a minimal increase in activation of the long global extensors during unsupported sitting. OBJECTIVES: To examine the influence of postural cueing to increase lumbar lordosis on lumbar extensor activation during trunk stabilization exercises. METHODS: Thirteen asymptomatic participants (9 male, 4 female) were instructed to perform 6 trunk stabilization exercises using a neutral position and increasing lumbar lordosis. Electrical activity of the deep multifidus and longissimus thoracis was recorded using fine-wire intramuscular electrodes. The mean root-mean-square of the electromyography (EMG) signal obtained during each exercise was normalized to a maximum voluntary isometric contraction (MVIC). A 2-way, repeated-measures analysis of variance (posture by exercise) was performed for each muscle. RESULTS: When averaged across the 6 exercises, postural cueing to increase lumbar lordosis resulted in greater multifidus EMG activity compared to performing the exercises in a neutral posture (35.3% ± 15.1% versus 29.5% ± 11.2% MVIC). No significant increase in longissimus thoracis EMG activity was observed when exercising with cueing to increase lumbar lordosis. CONCLUSION: This study suggests that postural cueing to increase lumbar lordosis during trunk stabilization exercises may better promote multifidus activation than traditional stabilization exercises alone. Future studies are needed to determine whether increasing lumbar lordosis improves multifidus activation in persons with low back pain.

Construct validity of center of rotation in differentiating of lumbar segmental instability patients.

PURPOSE: Lumbar Segmental Instability (LSI) is a subgroup of nonspecific Low Back Pain (NSLBP) without any accepted diagnostic tool as a gold standard. Some authors emphasize on quality measure such as centre of rotation (COR) but construct validity of this measure had not been approved. Therefore the purpose of the present study was to evaluate Concurrent and Convergent validity of COR in differentiating LSI. METHODS: A total of 66 volunteered males participated in three groups named control, NSLBP and LSI groups based on clinical examination. Patients were diagnosed as LSI according to screening criteria adopted by Hicks et al. Study variables included CORs of lumbar segments in sagittal plane. Three x-rays were taken in neutral, flexion and extension positions. The variables were calculated using CARA software. The ANOVA and Tukey test were utilized in statistic analysis. RESULTS: ANOVA results demonstrated mean differences between three groups for COR of L4 motion segment in y axis (p= 0/008) and L5 motion segment in y axis (p= 0/005) were significant. Tukey test showed significant difference for COR of L4 motion segment in y axis between LSI and healthy groups (p= 0/038) and between LSI and NSLBP groups (p= 0/009). For COR of L5 motion segment in y axis, tukey test demonstrated mean difference between LSI and healthy groups (p= 0/028) and between LSI and NSLBP groups (p= 0/007) were significant. Tukey test did't show any significant difference between NSLBP and healthy groups for COR of L4 (p= 0/852) and L5 (p= 0/871) motion segments in y-axis. CONCLUSIONS: The COR has ability to differentiate patients with signs and symptoms of LSI from other NSLBP and healthy subjects based on the present study results. However, more researches are needed to develop and support results of this study.

Intensive, progressive exercise improves quality of life following lumbar microdiskectomy: a randomized controlled trial.

OBJECTIVE: The purpose of the study was to examine changes in quality of life measures in patients who have undergone an intensive exercise program following a single level microdiskectomy. DESIGN: Randomized controlled trial with blinded examiners. SETTING: The study was conducted in outpatient physical therapy clinics. SUBJECTS: Ninety-eight participants (53 male, 45 female) who had undergone a single-level lumbar microdiskectomy allocated to receive exercise and education or education only. INTERVENTIONS: A 12-week periodized exercise program of lumbar extensor strength and endurance training, and mat and upright therapeutic exercises was administered. OUTCOME MEASURES: Quality of life was tested with the Short Form 36 (SF-36). Measurements were taken 4-6 weeks postsurgery and following completion of the 12-week intervention program. Since some participants selected physical therapy apart from the study, analyses were performed for both an as-randomized (two-group) design and an as-treated (three-group) design. RESULTS: In the two-group analyses, exercise and education resulted in a greater increase in SF-36 scales, role physical (17.8 vs. 12.1) and bodily pain (13.4 vs. 8.4), and the physical component summary (13.2 vs. 8.9). In the three-group analyses, post-hoc comparisons showed exercise and education resulted in a greater increase in the SF-36 scales, physical function (10.4 vs. 5.6) and bodily pain (13.7 vs. 8.2), and the physical component summary (13.7 vs. 8.9) when compared with usual physical therapy. CONCLUSIONS: An intensive, progressive exercise program combined with education increases quality of life in patients who have recently undergone lumbar microdiskectomy.

Spectral analysis of EMG using intramuscular electrodes reveals non-linear fatigability characteristics in persons with chronic low back pain.

Greater fatigability across lumbar extensors has been reported in persons with chronic low back pain (LBP), however, extensor atrophy tends to be local to the site of pain. Therefore, specific ultrasound guided local and remote intramuscular electromyographic recordings were undertaken during an isometric horizontal trunk hold in two carefully matched cohorts; persons with and without LBP. The test was performed to self-determined maximal hold time, and the control group held the horizontal position longer (P < 0.001). A power spectral analysis was performed to calculate the normalized median frequency (NMF) slope for both the first and last 30s of the fatigue test due to the group difference in hold times. There were no significant group differences in NMF slope at the first 30s of testing (P = 0.650). The NMF slope for the first and last 30s was not different in healthy subjects (P = 0.688), but was different in persons with LBP, illustrated by shallowing of the slope at the last 30s of the test (P = 0.008). A between muscle comparison in the LBP group showed greater non-linear behavior in the deep multifidus (painful region) in contrast to T10 longissimus thoracis (nonpainful region) (P = 0.013). Possible explanations for these findings are discussed.

Which exercises target the gluteal muscles while minimizing activation of the tensor fascia lata? Electromyographic assessment using fine-wire electrodes.

STUDY DESIGN: Controlled laboratory study, repeated-measures design. OBJECTIVES: To compare hip abductor muscle activity during selected exercises using fine-wire electromyography, and to determine which exercises are best for activating the gluteus medius and the superior portion of the gluteus maximus, while minimizing activity of the tensor fascia lata (TFL). BACKGROUND: Abnormal hip kinematics (ie, excessive hip adduction and internal rotation) has been linked to certain musculoskeletal disorders. The TFL is a hip abductor, but it also internally rotates the hip. As such, it may be important to select exercises that activate the gluteal hip abductors while minimizing activation of the TFL. METHODS: Twenty healthy persons participated. Electromyographic signals were obtained from the gluteus medius, superior gluteus maximus, and TFL muscles using fine-wire electrodes as subjects performed 11 different exercises. Normalized electromyographic signal amplitude was compared among muscles for each exercise, using multiple 1-way repeated-measures analyses of variance. A descriptive gluteal-to-TFL muscle activation index was used to identify preferred exercises for recruiting the gluteal muscles while minimizing TFL activity. RESULTS: Both gluteal muscles were significantly (P<.05) more active than the TFL in unilateral and bilateral bridging, quadruped hip extension (knee flexed and extending), the clam, sidestepping, and squatting. The gluteal-to-TFL muscle activation index ranged from 18 to 115 and was highest for the clam (115), sidestep (64), unilateral bridge (59), and both quadruped exercises (50). CONCLUSION: If the goal of rehabilitation is to preferentially activate the gluteal muscles while minimizing TFL activation, then the clam, sidestep, unilateral bridge, and both quadruped hip extension exercises would appear to be the most appropriate.

Multifidus atrophy is localized and bilateral in active persons with chronic unilateral low back pain.

OBJECTIVE: To compare the lumbar multifidi muscle volume devoid of fat local to the site of pain in persons with and without chronic unilateral lower lumbar pain. DESIGN: Prospective cross-sectional design. SETTING: University biokinesiology laboratory. PARTICIPANTS: Active individuals (n=14) with chronic unilateral lower lumbar pain (>1 y) were matched for age, height, weight, and activity level with healthy individuals (n=14). Individuals with back pain had minimal disability (Oswestry Disability Index [mean ± SD], 14.9%±6.3%) at the time of testing. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Multifidus and erector spinae muscle volumes at the L5-S1 levels, multifidus muscle volumes at the L4 and S2-3 levels. RESULTS: Average multifidus volume was diminished by 18.1% between groups (P=.026) only at the L5-S1 levels. There was no difference between painful and pain-free sides. There were no volume differences between groups above L5, below S1, or in erector spinae at the L5-S1 levels. CONCLUSIONS: The results of this study indicate that despite a low level of disability and an activity level similar to that of matched control subjects, considerable localized, bilateral multifidus atrophy is present. Such impaired size of the multifidus will likely reduce its capacity to control intersegmental motion, thus increasing the susceptibility to further injury. Unlike acute unilateral low back pain (LBP), muscle size is reduced bilaterally in persons with chronic unilateral LBP.

Secondary mediation and regression analyses of the PTClinResNet database: determining causal relationships among the International Classification of Functioning, Disability and Health levels for four physical therapy intervention trials.

BACKGROUND: Each of the 4 randomized clinical trials (RCTs) hosted by the Physical Therapy Clinical Research Network (PTClinResNet) targeted a different disability group (low back disorder in the Muscle-Specific Strength Training Effectiveness After Lumbar Microdiskectomy [MUSSEL] trial, chronic spinal cord injury in the Strengthening and Optimal Movements for Painful Shoulders in Chronic Spinal Cord Injury [STOMPS] trial, adult stroke in the Strength Training Effectiveness Post-Stroke [STEPS] trial, and pediatric cerebral palsy in the Pediatric Endurance and Limb Strengthening [PEDALS] trial for children with spastic diplegic cerebral palsy) and tested the effectiveness of a muscle-specific or functional activity-based intervention on primary outcomes that captured pain (STOMPS, MUSSEL) or locomotor function (STEPS, PEDALS). OBJECTIVE: The focus of these secondary analyses was to determine causal relationships among outcomes across levels of the International Classification of Functioning, Disability and Health (ICF) framework for the 4 RCTs. METHOD AND DESIGN: With the database from PTClinResNet, we used 2 separate secondary statistical approaches-mediation analysis for the MUSSEL and STOMPS trials and regression analysis for the STEPS and PEDALS trials-to test relationships among muscle performance, primary outcomes (pain related and locomotor related), activity and participation measures, and overall quality of life. RESULTS: Predictive models were stronger for the 2 studies with pain-related primary outcomes. Change in muscle performance mediated or predicted reductions in pain for the MUSSEL and STOMPS trials and, to some extent, walking speed for the STEPS trial. Changes in primary outcome variables were significantly related to changes in activity and participation variables for all 4 trials. Improvement in activity and participation outcomes mediated or predicted increases in overall quality of life for the 3 trials with adult populations. LIMITATIONS: Variables included in the statistical models were limited to those measured in the 4 RCTs. It is possible that other variables also mediated or predicted the changes in outcomes. The relatively small sample size in the PEDALS trial limited statistical power for those analyses. CONCLUSIONS: Evaluating the mediators or predictors of change between each ICF level and for 2 fundamentally different outcome variables (pain versus walking) provided insights into the complexities inherent across 4 prevalent disability groups.

The Low Back Activity Confidence Scale (LoBACS): preliminary validity and reliability.

BACKGROUND: Low back pain affects a substantial number of adults each year and is persistent or recurrent for many. Self-efficacy is an important predictor of functional recovery. OBJECTIVE: The purpose of this investigation was to assess the preliminary reliability and validity of the Low Back Activity Confidence Scale (LoBACS) for individuals with histories of low back pain or lumbar surgery. DESIGN: Two overlapping samples of patients who had undergone a microdiskectomy participated: a test-retest sample of 21 individuals and a validity sample of 53 individuals. METHODS: Low Back Activity Confidence Scale items pertaining to self-efficacy for functional activities (FnSE subscale), self-regulation of back health (Self-RegSE subscale), and regular exercise (ExSE subscale) were generated from existing literature and clinical observations. The test-retest sample completed the LoBACS twice, approximately 10 days apart. The validity sample completed the LoBACS and measures of functional performance, self-reported leisure and occupational physical activity, pain, fear beliefs, disability, and quality of life. RESULTS: The FnSE, Self-RegSE, and ExSE subscale scores and LoBACS total score had excellent to acceptable test-retest reliability (intraclass correlation coefficients of .924, .634, .710, and .850, respectively) and internal consistency (Cronbach α coefficients of .924, .804, .941, and .911, respectively). The LoBACS subscales were correlated in expected directions with physical performance, physical activity, pain, fear beliefs, disability, and quality of life, providing initial evidence of concurrent validity. CONCLUSIONS: The findings provide preliminary content and concurrent validity and interrater and internal consistency reliability for the LoBACS measure of self-efficacy for individuals with histories of low back pain and lumbar microdiskectomy.