Back Muscle Endurance Research Articles

Cognitive Functional Therapy for the Management of Low Back Pain in an Adolescent Male Rower: A Case Report

Case report. Contemporary low back pain models propose that the experience of and responses to pain result from a complex interaction of biopsychosocial factors. This supports the need for a management approach that addresses the biological, psychological, and social components that may be related to the pain disorder. This case report demonstrates the application of, and outcomes associated with, a cognitive functional intervention that considers neurophysiological, physical, psychosocial, cognitive, and lifestyle dimensions for the management of a rower with nonspecific chronic low back pain. An adolescent male club-level rower with nonspecific chronic low back pain was classified as having a motor control impairment with a lower lumbar compressive-loading pattern in flexion. Evaluation of this patient included ergometer rowing analysis (clinical and laboratory) before and after an 8-week intervention, and outcome measures at a 12-week follow-up. The intervention consisted of a cognitive functional approach that targeted optimization of movement behavior, providing the rower with alternative movement strategies to minimize sustained flexion loading. Reduced temporal summation of pain while ergometer rowing and reduced functional disability were observed preintervention to 12 weeks postintervention by changes in Roland-Morris Disability Questionnaire score (12/24 to 1/24) and the Patient-Specific Functional Scale (4/30 to 26/30), and associated improvements in lower-limb and back muscle endurance and changes in hip and spinopelvic kinematics during ergometer rowing. In particular, there was a greater use of available range of movement in the lumbar spine postintervention. The cognitive functional intervention for this patient resulted in reduced pain and functional disability related to ergometer rowing, which was associated with a change in lumbar kinematics and improved lower-limb and back muscle endurance. The results suggest that providing the rower with greater use of his available range of movement may enhance load distribution during the drive phase of rowing. Registered at Australian New Zealand Clinical Trials Registry (ACTRN12609000565246). Therapy, level 4.

The effects of back extension training on back muscle strength and spinal range of motion in young females.

The objective of this study was to determine the effects of a 10-week dynamic back extension training programme and its effects on back muscle strength, back muscle endurance and spinal range of motion (ROM) for healthy young females. Seventy-three young females (age: 19.32±1.80 years, height: 158.89±4.71 cm, body weight: 55.67±6.30 kg) volunteered for the study. Prior to the training period, all participants completed anthropometric measurements, back muscle strength and endurance test, lateral bending and spinal ROM measurements. After measurements, the participants were divided into two groups. The exercise group (N:35) performed the dynamic back extension exercise 3 days per week for 10 weeks. The control group (N:38) did not participate in any type of exercise. The mixed design ANOVA (group x time) was used to determine the difference in pre- and post-training values. The present findings show that there were significant differences between pre-training and post-training values for back muscle strength and spinal ROM in the exercise group. Following the dynamic strength training programme, back muscle strength and spine ROM values except flexion of the lumbar 5-sacrum 1 (L5-S1) segment of the exercise group showed a significant increase when compared with the pre test values. The control group did not show any significant changes when compared with the pre-training values. The results demonstrate that the 10-week dynamic strength training programme was effective for spinal extension ROM and back muscle strength, but there was no change in back muscle endurance. In this context, this programme could potentially be used to prevent the decrease of spinal ROM as well as provide an increase in the fitness parameters of healthy individuals.

Disability and back muscle fatigability changes following two therapeutic exercise interventions in participants with recurrent low back pain

BackgroundThe level of disability and endurance of back muscles have been investigated, but there is conflicting evidence following specific exercise interventions for participants with recurrent low back pain (LBP). The purpose of this study was to compare the level of disability and slope of median frequency (MF) of thoracic and lumbar erector spinae (ES) muscles following core stabilization exercise (CSE) and spinal flexibility exercise (SFE).Material/MethodsIn total, 46 individuals participated in this study. There were 25 participants in the CSE intervention group (average age of 47.7±8.9 years) and 21 participants in the SFE group (average age of 53.1±9.0 years). Each group participated in the specific exercise intervention program for 4 weeks while maintaining their current activity and/or exercise levels. The Oswestry Disability Index (ODI) was used to measure the level of disability changes. The fatigability of the ES back muscles was measured by the slope of MF, using a modified Sorensen test.ResultsThe disability level decreased significantly following CSE intervention (t=2.23, p<0.05). However, there was no significant difference in muscle fatigability changes in the 4-week intervention period for either group.ConclusionsThe CSE intervention reduced disability level following the 4-week intervention period. Further studies are needed to investigate the effectiveness of specific back muscle exercises in longer intervention periods for back muscle fatigability.

An aerobic walking programme versus muscle strengthening programme for chronic low back pain: a randomized controlled trial

Objective: To assess the effect of aerobic walking training as compared to active training, which includes muscle strengthening, on functional abilities among patients with chronic low back pain. Design: Randomized controlled clinical trial with blind assessors. Setting: Outpatient clinic. Subjects: Fifty-two sedentary patients, aged 18–65 years with chronic low back pain. Patients who were post surgery, post trauma, with cardiovascular problems, and with oncological disease were excluded. Intervention: Experimental ‘walking’ group: moderate intense treadmill walking; control ‘exercise’ group: specific low back exercise; both, twice a week for six weeks. Main measures: Six-minute walking test, Fear-Avoidance Belief Questionnaire, back and abdomen muscle endurance tests, Oswestry Disability Questionnaire, Low Back Pain Functional Scale (LBPFS). Results: Significant improvements were noted in all outcome measures in both groups with non-significant difference between groups. The mean distance in metres covered during 6 minutes increased by 70.7 (95% confidence interval (CI) 12.3–127.7) in the ‘walking’ group and by 43.8 (95% CI 19.6–68.0) in the ‘exercise’ group. The trunk flexor endurance test showed significant improvement in both groups, increasing by 0.6 (95% CI 0.0–1.1) in the ‘walking’ group and by 1.1 (95% CI 0.3–1.8) in the ‘exercise’ group. Conclusions: A six-week walk training programme was as effective as six weeks of specific strengthening exercises programme for the low back.

Relationship between back muscle endurance and voluntary activation

There is some evidence that the Biering-Sorensen endurance test can discriminate low back pain sufferers from healthy individuals and can predict future back pain. This test relies on the subject’s ability to voluntarily drive the back muscles. This neural drive, termed voluntary activation (VA) can be measured using the twitch interpolation technique. The aim of the current study was to investigate the relationship between back muscle endurance and VA.Twenty-one healthy volunteers (10 males) participated. Bilateral electromyographic recordings were obtained from erector spinae and rectus abdominis. Back extensor torque was recorded using a dynamometer. The protocol consisted of measurement of VA (using magnetic stimulation of the brain and assessment of the sizes of the evoked twitches) and measurement of endurance.There was a linear correlation (r2=1, P<0.01) between voluntary torque and VA. The mean (SEM) endurance time was 174.9 (12.8)s. There was no correlation between endurance and VA at either 100% MVC (r2=0.01, P=0.72) or at 50% MVC (r2=0.11, P=0.16).These findings indicate that the endurance of the back muscles, as assessed using this widely utilised test does not appear to be related to a subject’s ability to drive their back muscles voluntarily either maximally or submaximally.

Is a positive clinical outcome after exercise therapy for chronic non-specific low back pain contingent upon a corresponding improvement in the targeted aspect(s) of performance? A systematic review

The effect size for exercise therapy in the treatment of chronic non-specific low back pain (cLBP) is only modest. This review aims to analyse the specificity of the effect by examining the relationship between the changes in clinical outcome (pain, disability) and the changes in the targeted aspects of physical function (muscle strength, mobility, muscular endurance) after exercise therapy. We searched for exercise therapy trials for cLBP published up to 15 April 2010 in Medline, Embase, Cochrane Library, Cinahl, and PEDro. Two independent reviewers selected studies according to the inclusion criteria. one author extracted the data of the articles. 16 studies with a total of 1,476 participants met the inclusion criteria. There was little evidence supporting a relationship between the changes in pain or physical function and the changes in performance for the following measures: mobility (no correlation in 9 studies, weak correlation in 1 study), trunk extension strength (7 and 2, respectively), trunk flexion strength (4 and 1, respectively) and back muscle endurance (7 and 0, respectively). Changes in disability showed no correlation with changes in mobility in three studies and a weak correlation in two; for strength, the numbers were four (no correlation) and two (weak correlation), respectively. The findings do not support the notion that the treatment effects of exercise therapy in cLBP are directly attributable to changes in the musculoskeletal system. Future research aimed at increasing the effectiveness of exercise therapy in cLBP should explore the coincidental factors influencing symptom improvement.

The relationship between psychological factors and performance on the Biering-Sørensen back muscle endurance test

Many studies report an association between low back pain (LBP) and reduced back muscle endurance and consider this to indicate muscular dysfunction. However, few have investigated the potentially confounding influence of psychological factors on performance during such endurance tests. This study examined whether psychological factors were associated with "underperformance" on the Biering-Sørensen (BS) test (ie, not performing as well as one is physiologically capable of). Cross-sectional study of the baseline data of patients with chronic (>3 months) nonspecific LBP (cLBP) before participation in a clinical trial of exercise therapy. One hundred forty-eight patients with cLBP (43% men; age, 45±10 years). The time for which the modified BS isometric endurance test could be performed to exhaustion minus the time that would have been predicted based on the rate of decline in median frequency of the surface electromyographic (EMG) signal recorded bilaterally from the erector spinae at L3 and L5. Back pain and disability, psychological disturbance, catastrophizing, fear-avoidance beliefs, back beliefs, and exercise self-efficacy were measured using validated questionnaires. Patients performed the BS test to exhaustion while physiological muscle fatigability was measured from continuous surface EMG recordings. Multivariable regression analysis controlling for gender revealed that greater psychological disturbance (p=.003) and more negative back beliefs (p=.015) were unique predictors of the extent of "underperformance," accounting for 22.3% variance in expected endurance time minus actual time. It is important that the underlying nature (psychological or physiological) of performance deficits be identified during such tests because this may influence the interpretation of prospective studies reporting risk factors for LBP and dictate the particular treatment or interventional approach required to remedy the situation in individuals with LBP.

Biering-Sorensen test performance of Japanese young males: comparison with other ethnicities and relationship to electromyography, near-infrared spectroscopy and exertion ratings

Back muscle endurance is a predictor of future low back pain and is commonly assessed using the Biering-Sorensen Test (BST). Differences exist between ethnic groups that may affect the performance and interpretation of the BST and should be investigated. This study's aim was to explore objective and subjective measures of the BST in a Japanese group in comparison with previous studies in other ethnic groups. A total of 27 young male Japanese students performed the BST while measures of muscle fatigue were collected. The mean BST time (152.7 (32.5) s) was greater than the median of the reported mean times in other ethnic groups over the previous decade (128.6 s). Objective measures indicated that the Japanese subjects' lumbar muscles were as fatigued as those of previous studies, while subjective measures appear to indicate that subjects under-reported exertion. The better performance of the Japanese subjects in the BST may reflect physical, psychosocial and lifestyle differences related to ethnicity. Statement of Relevance: Ergonomics research and practice needs to be applicable to different ethnic groups. Despite the substantial body of evidence on back muscle endurance and indications of potential ethnicity related differences, this had not been previously investigated. These results help ergonomists to interpret physical ergonomics evidence in a multi-ethnic world.

An Exploration of the Relationship Between Back Muscle Endurance and Familial, Physical, Lifestyle, and Psychosocial Factors in Adolescents and Young Adults

Cross-sectional investigation. To explore the relationship between back muscle endurance (BME) and a range of familial, physical, lifestyle, and psychosocial variables in adolescents and young adults. There is evidence that low back pain interventions which focus on improved BME are effective. However, the mechanisms associated with BME performance in adolescents and young adults are largely unclear. In particular, the potential familial relationship between parents and their children remains unexplored. This study utilized a subset of participants from the Joondalup Spinal Health Study cohort. One hundred nine children (47 boys, 62 girls) and 101 parents (39 fathers, 62 mothers) completed a series of physical, lifestyle, and psychosocial assessments. The univariable relationship between each covariate and BME was explored. Those found to have an association with child BME (P<.2) were included in an initial multivariable model and sequentially removed, until all remaining covariates were statistically significant (P<.05). Mothers' BME performance was related to children's performance, accounting for 14.4% of the variance in the children's BME. Fathers' BME performance had a similar, albeit nonsignificant effect. Children's sitting trunk angle, pain sensitivity, percent trunk fat, waist girth, and body mass index were associated with their BME performance, accounting for between 5.2% and 20.9% of BME. The final multivariable model, including mother's BME, percent trunk fat, and sitting trunk angle, explained 28% of the variance in BME performance, suggesting that for successful BME intervention a range of multidimensional variables should be considered.

BACK MUSCLES' ENDURANCE IN ADOLESCENTS AND ADULTS: NORMATIVE DATA FOR A SUB-SAHARAN AFRICAN POPULATION

Purpose: Back muscles' endurance assessment provides an objective indicator of the functional capacity of the back. This study sought to establish a gender and age referenced normative data for back muscles endurance for a Sub-Saharan African population. Methods: This cross sectional study involved 1253 (623 male, 630 female) consecutive participants between the ages of 11 and 69 years without a history of symptomatic LBP within one year to the time of the study. Participants were recruited from eight secondary schools, two universities and two teaching hospitals, respectively. All participants underwent assessment of the back extensor muscles' endurance using the modified Biering-Sorensen test of muscular endurance. The mean and percentile data for endurance time were determined for six gender/age groups classified on a range of 10 years. Results: The mean endurance time (ET) of all the participants was 119 ± 53.6 secs. Men exhibited a significantly (p = 0.001) higher ET than women (125.9 ± 53.3 versus 112.6 ± 53.1 secs). Using percentile values cut-points; poor endurance (less than 25th), moderate endurance (25–75th) and good endurance (&gt; 75th percentile) were &lt; 85.0 secs, 85–163 secs, and &gt; 163 secs, respectively for male; and &lt; 69.8 secs, 69.8–148 secs and &gt; 148 secs, respectively for female. Conclusion: The normative values derived in this study would be useful in assessing impairment in back muscles' endurance in both healthy and patient populations. The results suggest that age, gender and anthropometric factors can significantly influence back muscles' endurance.

Association of Biopsychosocial Factors With Degree of Slump in Sitting Posture and Self-Report of Back Pain in Adolescents: A Cross-Sectional Study

Conflicting evidence exists regarding relationships among sitting posture, factors that influence sitting posture, and back pain. This conflicting evidence may partially be due to the presence of multiple and overlapping factors associated with both sitting posture and back pain. The purpose of this study was to determine whether the degree of slump in sitting was associated with sex and other physical, lifestyle, or psychosocial factors. Additionally, the relationship between the report of back pain made worse by sitting and the degree of slump in sitting and other physical, lifestyle, or psychosocial factors was investigated. This was a cross-sectional study. Adolescents (n=1,596) completed questionnaires to determine lifestyle and psychosocial profiles and the experience of back pain. Sagittal sitting posture, body mass index (BMI), and back muscle endurance (BME) were recorded. Standing posture subgroup categorization was determined. Multivariate analysis revealed that the most significant factor associated with the degree of slump in sitting was male sex, followed by non-neutral standing postures, lower perceived self-efficacy, lower BME, greater television use, and higher BMI. Multivariable analysis indicated poorer Child Behaviour Checklist scores were the strongest correlate of report of back pain made worse by sitting, whereas degree of slump in sitting, female sex, and BME were more weakly related. Causality cannot be determined from this cross-sectional study, and 60% of sitting posture variation was not explained by the measured variables. Slump in sitting was associated with physical correlates, as well as sex, lifestyle, and psychosocial factors, highlighting the complex, multidimensional nature of usual sitting posture in adolescents. Additionally, this study demonstrated that a greater degree of slump in sitting was only weakly associated with adolescent back pain made worse by sitting after adjustment for other physical and psychosocial factors.

Effects of Aquatic Exercise Training Using New Water-resistance Equipment on Trunk Muscles, Abdominal Circumference, and Activities of Daily Living in Elderly Women

Recently, aquatic exercise has been more widely performed as it reduces the effects of weight-bearing on the lower extremities and leg joints. Moreover, decrease in trunk muscle strength is an important factor in chronic low-back pain in obese women. The purposes of this study were to evaluate the effects of aquatic exercise training using new water-resistance equipment on abdominal circumference measurements, trunk muscles strength, and ADL (Activity of Daily Living) in older women. Subjects were divided into a resistance training group (those using the equipment) and a non-resistance training group (those without the equipment). The aquatic exercise training mostly consisted of abdominal muscle activity. All subjects underwent physical testing. In the resistance training group, abdominal circumference, abdominal muscle strength, and ADL measurement were significantly improved. Additionally, a low negative correlation was found between the degree of change in abdominal circumference and ADL scores. As it became easier to maintain posture, stand, and move, activities in everyday life improved with the increase in strength of the lower extremities and trunk muscles. These results demonstrated improvements in abdominal and back muscle endurance and suggested that, as abdominal circumference decreased, ADL improved. This aquatic exercise training using the new water-resistance equipment may be used by the elderly to improve abdominal and back muscle endurance.

Specificity of a Back Muscle Roman Chair Exercise in Healthy and Back Pain Subjects

Roman chair exercises are popular for improving back muscle endurance but do not specifically target back muscles. This study aimed to determine whether an adaptation of the Roman chair exercise would induce more fatigue in back muscles than in hip extensors. For this study, 16 healthy subjects and 18 patients with nonspecific chronic low back pain performed trunk flexion-extension cycles until exhaustion in a Roman chair with hips flexed at 40°. Surface EMG signals were recorded bilaterally on four back muscles and two hip extensors (gluteus maximus and biceps femoris). Motion analysis of the trunk segments (pelvis, lumbar, and thoracic spines) was also carried out. In both groups, EMG revealed clear evidence of muscle fatigue for the gluteus maximus, less clear evidence of fatigue for the lower back muscles, and motor unit recruitment (without fatigue) for the upper back muscles and biceps femoris. A change of muscle activation pattern was emphasized throughout the exercise bout, with some lower back muscles showing an increase followed by a decrease or leveling off of activation and with upper back muscles showing an increased activation at the end. Kinematic analyses revealed a progressive decrease (11°) in the lumbar range of motion (ROM) and a progressive increase in hip (2°) and thoracic (7°) ROM during the exercise bout. Roman chairs allow more freedom to change the kinematics of the spine during the exercise (less lumbar and more thoracic motion) to delay lower back muscle fatigue by sharing the load between the lower and upper back muscles. Even with adaptations to reduce hip extensors fatigue, this may make this exercise not as specific as wanted for fatiguing lower back muscles.

Poor Back Muscle Endurance Is Related to Pain Catastrophizing in Patients With Chronic Low Back Pain

An experimental and comparative study of chronic low back pain (CLBP) patients and healthy controls. To use a motivation-independent electromyography (EMG) based test of back muscle capacity to determine whether back muscle deconditioning is present in CLBP patients and whether it is related to pain-related psychological variables. The verification of the deconditioning syndrome in CLBP patients might be biased by the use of performance-based measures to assess physical fitness, especially in patients having fear of injury. Also, the use of lumbar-specific measures of physical fitness, such as back muscle strength and endurance, might be more sensitive to physical deconditioning than more general assessments such as aerobic capacity. A time-limited submaximal fatigue test was performed by 27 nonspecific CLBP subjects (14 men) who had not had any surgery, and 31 healthy controls (17 men) while surface EMG signals were collected from back muscles. Motivation-independent EMG indices, which are sensitive to muscle fatigue or to activation patterns, were then computed and entered as input into previously developed regression equations to predict endurance (PTend) and strength (PStrength). Between-group comparisons were completed with patients divided in subgroups based on a median split of pain intensity, fear of movement, or pain catastrophizing scores. Differences between healthy and CLBP subgroups were mainly observed when patients were divided using pain catastrophizing scores (PCS). High-PCS patients showed significantly lower PTend than low-PCS patients. Various EMG indices showed comparable results to PTend. However, some of them also pointed out that the PCS-low patients were more fatigue-resistant and showed different activation patterns comparatively to healthy subjects. These results suggest that physical deconditioning that is specific to back muscle capacity was present in a subgroup of patients while the opposite was observed in another subgroup, pain catastrophizing being related to this outcome. These findings support previous theoretical models of pain/disability.

The Relationship Between Back Muscle Endurance and Physical, Lifestyle, and Psychological Factors in Adolescents

Cross-sectional investigation. There is some evidence that interventions directed to improving back muscle endurance (BME) in adolescents are effective in reducing low back pain, with anecdotal evidence of improved performance. However, the mechanisms responsible for this improvement remain unclear. To identify the relationship between physical, lifestyle, and psychological variables and BME in a large adolescent population, while controlling for back pain and gender. One thousand four-hundred thirty-five adolescents (702 females, 733 males; mean +/- SD age, 14.0 +/- 0.2 years) completed a range of physical, lifestyle, and psychological assessments. The group mean +/- SD height and body mass were 164 +/- 8 cm and 57.1 +/- 12.6 kg, respectively. Linear regression was used to investigate the univariate association between each of the physical, lifestyle, and psychological variables and BME. Backwards stepwise multivariate linear regression was used to determine statistically significant independent correlates of BME. The final multivariate model explained 15.3% of the variance in BME and included at least 1 variable from the physical, lifestyle, and psychological domains. Adolescents who exercised less, watched more television, had a higher body mass index, sat in a more flexed trunk posture (more slumped), and had lower self-efficacy had lower BME. All the physical and lifestyle variables linked with poorer BME performance in this investigation are indicative of reduced back muscle activation and/or deconditioning. Psychological predictors may have direct and/or indirect links with BME.

Flexion-Relaxation Ratio in Sitting

A multiple-comparative study between normal and low back pain (LBP) patients before and after rehabilitation. To examine whether there is a change in flexion-relaxation phenomenon in sitting in LBP patient following a rehabilitation treatment. There is an association between LBP and seated spine posture. Previous study has reported an absence of flexion-relaxation phenomenon in LBP patients during sitting. However, it is unknown whether there is a difference in flexion-relaxation phenomenon in sitting in LBP patients before and after rehabilitation treatment. A total of 20 normal subjects and 25 chronic LBP patients who underwent a 12 weeks rehabilitation program were recruited. Surface electromyography recordings during upright sitting and flexed sitting were taken from the paraspinal muscles (L3) bilaterally from the normal subjects, and in the LBP patients before and after the rehabilitation treatment. The main outcome measures for patients include the visual analogue scale, Oswestry disability index, subjective tolerance for sitting, standing and walking, trunk muscle endurance, lifting capacity, and range of trunk motion in the sagittal plane. Flexion-relaxation phenomenon in sitting, expressed as a ratio between the average surface electromyography activity during upright and flexed sitting, was compared between normal and patients; and in LBP patients before and after rehabilitation. Flexion-relaxation ratio in sitting in normal subjects (Left: 6.83 +/- 3.79; Right: 3.45 +/- 2.2) presented a significantly higher (Left: P < 0.001; Right: P < 0.05) value than LBP patients (Left: 3.04 +/- 2.36; Right: 2.02 +/- 1.49). An increase in flexion-relaxation ratio in sitting was observed in LBP patients after rehabilitation (Left: 4.69 +/- 3.94, P < 0.05; Right: 3.58 +/- 2.97, P < 0.001), together with a significant improvement (P < 0.05) in subjective tolerance in sitting and standing, abdominal and back muscle endurance, lifting capacity, and range of motion. There were no significant changes in disability and pain scores, and subjective tolerance in walking. Flexion-relaxation ratio in sitting has demonstrated its ability to discriminate LBP patients from normal subjects, and to identify changes in pattern of muscular activity during postural control after rehabilitation.

Low back pain in adolescent female rowers: a multi-dimensional intervention study

The aim of this study was to determine whether a multi-dimensional intervention programme was effective in reducing the incidence of low back pain (LBP) and the associated levels of pain and disability in schoolgirl rowers. This non-randomised controlled trial involved an intervention (INT) group consisting of 90 schoolgirl rowers from one school and a control (CTRL) group consisting of 131 participants from three other schools. All participants in the INT group underwent a multi-dimensional programme that consisted of an individualised exercise programme based on an individual musculoskeletal screening (Week 1) and a LBP education session conducted by a physiotherapist (Week 2) and performed an off-water-conditioning programme conducted by a Physical Education teacher. All exercises were undertaken during the season. Primary outcome variables collected at Start-season, Mid-season, End-season and Post-season included the incidence of LBP and related levels of pain and disability. Secondary outcome variables from the bio-psycho-social domain were measured at Start-season and End-season in the INT group only. The INT group had a lower incidence of LBP at Mid-season and End-season and displayed significantly better results than the CTRL group for improvers and non-improvers with respect to the levels of pain and disability. The INT group following the intervention also displayed improved physical fitness levels, sat with significantly less anterior tilt of the pelvis and lumbar kyphosis when in their usual sitting posture and demonstrated positive changes in their behaviour. The multi-dimensional approach to reducing the incidence of LBP, pain and disability in schoolgirl rowers in this study was effective. Several secondary outcome variables measured in the INT group considered to be of importance in LBP significantly improved. These included physical fitness (aerobic conditioning, lower limb and back muscle endurance and sit and reach flexibility) and seated posture (usual and slump sitting).

Isometric back muscle endurance: An EMG study on the criterion validity of the Ito test

The validity of the Sorensen test as a measure for back muscle endurance is controversial due to a possible impact of hip extensor muscles. The aim of this study was to investigate the criterion validity of an alternative test (Ito test) compared to the Sorensen test. Both procedures were performed by 29 healthy subjects (11 women) for 5 s and until exhaustion (randomized order). EMG activity was measured from 3 lumbar back and 3 hip extensor muscles. Muscular involvement in test positions was calculated as percentage of maximal voluntary contraction (MVC). Muscle fatigue was determined by the normalized regression coefficient of the median frequencies of the EMG power spectrum (NMF slope). Prediction of holding time by NMF slope values was investigated using regression analysis. In the test positions, the hamstring muscles were activated to a higher MVC percentage in the Sorensen than in the Ito test, while the iliocostalis muscle was less activated. Similarly, the iliocostalis ( p = 0.006) and the multifidi muscles ( p = 0.03) significantly contributed to predict holding time in the Ito test, whereas the multifidi muscles ( p = 0.001) and the semitendinosus muscle ( p = 0.046) did so in the Sorensen test. The results of this study indicate that the Ito test might present a valuable alternative for testing back muscle endurance in LBP patients.

Identification of Modifiable Personal Factors That Predict New-onset Low Back Pain: A Prospective Study of Female Nursing Students

Prevention of occupational low back pain (LBP) in nurses is a research priority. Recent research suggests intervening before commencing nursing employment is ideal; however, identification of modifiable risk factors is required. The objective of this study was to investigate modifiable personal characteristics that predicted new-onset LBP in nursing students. This prospective study was conducted on female nursing students (n=117) without LBP at baseline to predict new-onset LBP (an episode of significant LBP during the follow-up period). At the 12-month follow-up, participants with (n=31) and without new-onset LBP (n=76) were compared across baseline social or lifestyle, psychologic (distress, back pain beliefs, coping strategies, and catastrophising), and physical (spinal postures and spinal kinematics in functional tasks, leg and back muscle endurance, spinal repositioning error, and cardiovascular fitness) characteristics. Participants response rate at follow-up was excellent (91%). After controlling for earlier LBP, age, and BMI, regression analysis showed that modifiable social or lifestyle, psychologic and physical characteristics (namely, smoking, increased physical activity, higher stress, reduced back muscle endurance, greater posterior pelvic rotation in slump sitting, and more accurate spinal repositioning in sitting) were significant and independent predictors of new-onset LBP at follow-up. Inclusion of these factors in multivariate logistic regression analysis, with significant new-onset LBP as the outcome, resulted in a substantial model R of 0.45. Modifiable personal characteristics across multiple domains are associated with new-onset LBP in female nursing students. These findings may have implications for the development of prevention and management interventions for LBP in nurses.

Specificity of a Back Muscle Exercise Machine in Healthy and Low Back Pain Subjects

To determine whether dynamic back muscle endurance exercises in a semisitting position induce more fatigue in back muscles than that in hip extensors in healthy controls as well as in patients with nonspecific chronic low back pain. Sixteen healthy volunteers and 18 volunteers with nonspecific chronic low back pain performed trunk flexion-extension cycles until exhaustion at 60% of their strength in a machine designed for back exercise in a semisitting position with knees' angle at 135 degrees . The number of cycles and perceived muscle fatigue (Borg CR-10 scale) at five areas (upper and lower back, gluteus, hamstrings, and quadriceps) were used as fatigue criteria. EMG signals were recorded bilaterally on four back muscles, two hip extensors (gluteus maximus and biceps femoris), and the vastus medialis. The slope values of the instantaneous median frequency values computed over time were retained as EMG indices of fatigue. The number of cycles was equivalent in healthy controls (n = 23 +/- 13) and patients with back pain (n = 27 +/- 16). EMG indices of fatigue disclosed evidence of muscle fatigue in all the back muscles and the vastus medialis, contrary to hip extensors. EMG revealed significantly more muscle fatigue of lower back muscles, which was further corroborated by the Borg scale assessment. No between-group difference was obtained in any EMG comparison. These results showed that this type of exercise machine can specifically train the back muscles, and this as much in subjects with nonspecific chronic low back pain as in healthy controls. This has implications for the training of back muscle endurance, especially in patients with back pain for whom poor back muscle endurance is sometimes of concern.