The effect of increasing resistance on trunk muscle activity during extension and flexion exercises on training devices

Age-related degeneration of lumbar muscle morphology in healthy younger versus older men

AIM

The aim of this study was to evaluate age-related changes in lumbar paravertebral muscle (LPM) morphology in healthy younger and older adult men.

METHODS

T2-weighted axial MRI of the lumbar spine were obtained for 12 healthy older (67.3 ± 6.0 years) and younger (24.7 ± 3.1 years) men. Normalised muscle volume (NMV) and muscle fat infiltrate (MFI) were determined bilaterally for the psoas (PS), quadratus lumborum (QL), erector spinae (ES) and multifidus (MF). MANOVA was used to compare NMV and MFI between age groups. Follow-up ANOVA compared NMV and MFI for each muscle between age groups, with physical activity (PA) as a covariate. Stepwise regression was used to explore the association between muscle morphology.

RESULTS

NMV of the ES and QL were significantly lower in the older group (OG) (p = 0.040 and p < 0.001, respectively). MFI across all muscles was significantly greater in the OG (p < 0.001). PA did not moderate the relationship between aging and muscle degeneration. Non-dominant handgrip strength was associated with NMV (p = 0.003).

CONCLUSIONS

Age-related atrophy is muscle specific in the lumbar spine; changes in lumbar musculature is independent of PA, handgrip strength may reflect morphological changes in the postural muscles with age. This study supports establishing effective targeted exercise interventions in the lumbar musculature.

Effects of non-manipulative osteopathic management in addition to physical therapy and rehabilitation on clinical outcomes of ankylosing spondylitis patients: A preliminary randomized clinical trial

INTRODUCTION

Ankylosing Spondylitis (AS) is reported to impair quality of life, physical and functional ability of patients. Rehabilitation and physical therapy is usually proposed to improve AS patient clinical conditions. Besides, an osteopathic management has not been extensively studied in the field of inflammatory diseases. = OBJECTIVE: To investigate the effects of osteopathic approach in addition to conventional rehabilitation management on clinical and functional outcomes among patients with AS.

EQUIPMENT AND METHODS

Eighteen patients with AS were recruited to participate to a physical therapy and rehabilitation (PTR) program over an 18-week period. They were randomly allocated into two groups to complete PTR only or PTR combined with osteopathic management without manipulative techniques (OSTEO group). Thoracolumbar maximal isometric strength (for flexion, extension, lateroflexion, and axial rotation) and flexibility, functional index, pain intensity and quality of life (self-assessment questionnaires) were assessed before and after the protocol.

RESULTS

Significant improvements were observed for the OSTEO group in strength, flexibility, disease activity and pain compared to the PTR group. However the difference between groups did not reach statistical significance for all the post-intervention measures. No significant correlation was found between functional, disability data or pain intensity and disease duration for both groups.

CONCLUSION

The results suggest that osteopathic management in addition to a physical therapy and rehabilitation program may be beneficial for individuals who suffer from AS. Further investigations are required using larger sample sizes to confirm these preliminary results.

Dynamics of Changes in Isometric Strength and Muscle Imbalance in the Treatment of Women with Low back Pain

The aim of the study was to evaluate the dynamics of isometric changes in strength and muscular lumbar-pelvic imbalances in the treatment of women with low back pain. Forty-one women, nineteen in the study group (A) and twenty-two in the control group (B), participated in the study. Magnetic resonance imaging (MRI) was performed to assess the degree of degenerative changes in the lumbar spine. The diagnosis of isometric muscle strength and their imbalances was performed with the Tergumed 700 device. After six weeks of therapy in the study group (A), there was a significant improvement in the strength of all the examined muscle groups. However, in the control group (B), significant improvement occurred only in the strength of the lumbar flexor muscles and the flexor muscles on the left side. Furthermore, there was a significant intensification of the imbalance of left flexor muscle strength compared to right flexor strength in group B. Significant differences in favour of the study group (A) concerned the strength of the rotator muscles to the left, the strength of the extensor muscles of the lumbar spine, the strength of the flexors of the lumbar spine to the right, and the balance of the strength of the lumbar spine flexors to the left compared to the strength of the flexor muscles to the right. Therapy with the Tergumed 700 system leads to an increase in the muscle strength of the lumbar and pelvic complex, compensating for its imbalance, bringing beneficial effects in the treatment of low back pain.

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.

Identification of Preliminary Prognostic Indicators for Back Rehabilitation in Patients With Nonspecific Chronic Low Back Pain: A Retrospective Cohort Study

STUDY DESIGN

Retrospective Cohort.

OBJECTIVE

Our aim was to identify prognostic indicators for success after a back rehabilitation program (BR) in patients with nonspecific chronic low back pain (CLBP).

SUMMARY OF BACKGROUND DATA

Exercise therapy is recommended for patients with nonspecific CLBP. Consensus on the type of exercises is lacking, largely due to heterogeneity in the studied patient samples. The identification of subgroups through the identification of prognostic indicators is therefore needed. To our knowledge, no specific prognostic indicators for BR are described in the literature.

METHODS

We retrospectively analyzed the patient files of 49 nonspecific CLBP patients who followed a BR. Patients were selected based on predefined in- and exclusion criteria. All underwent 43 therapy sessions, two times per week. Primary outcome measure and dependent variable was the change in Oswestry Disability Questionnaire (ODI) score. Potential predictive variables were tested for association with the primary outcome and consequently entered in a logistic regression model.

RESULTS

In this study, the posthoc calculated power was 91%. Based on the change in ODI scores, 24 patients were considered as therapy success (eight points or 50% improvement on change in ODI score) and 25 as therapy failure. Univariate and multiple regression analysis revealed only one significant prognostic indicator: higher scores on the physical function subscale of the SF36 (PF-SF36) corresponded with high risk of therapy failure (odds ratio of 0.791 (95% CI =  .662-0.945); sensitivity of 0.79, and specificity of 0.68).

CONCLUSION

Potentially, the preset exercises of the BR in this study design were not appropriate for the identified subgroup. The results of this study should be replicated in a RCT design that conforms to the necessary methodological steps in the identification of prognostic indicators and clinical prediction rules (CPRs).

Trunk extension exercises: How is trunk extensor muscle recruitment related to the exercise dosage?

Trunk extension exercises are used to train endurance and strength of the trunk extensor muscles. Appropriate exercise dosage is crucial to achieve specific training effects, however literature describing the relation between the predetermined exercise intensity and the actual trunk extensors activity is scarce and inconclusive. To examine whether the actual activity of the thoracic and lumbar extensors during extensions exercises correspond with the predetermined intensity, electromyographic evaluation of the trunk extensors was performed during trunk extension exercises at various intensities expressed as percentages of 1-RM. The 1-RM was predetermined using 2 different methods: (1) through direct estimation by determining the maximum isometric force produced during semi-seated trunk extension on a Tergumed rehabilitation device, (2) through indirect estimation calculated based on the relation between the maximum number of repetitions of trunk extension from prone lying on a variable angle chair and the submaximal resistance at which the repetitions were performed as presented on the Holten-diagram. The total trunk muscle activity during extension exercises performed semi-seated on a rehabilitation device or from prone lying corresponds with the predetermined dosage using both estimation methods. The indirect estimation method more accurately predicts the actual trunk extensor activity for low load training than for high load training. However, the direct estimation method is suitable to closely predetermine the load and actual trunk extensors activity during high load exercises. A shift from a differential recruitment between the thoracic and lumbar extensors at low intensities to a more homogenous recruitment at high intensities is observed during semi-seated trunk extension exercises. During prone extension exercises both muscle groups equally contribute to the total muscle work regardless of the exercise intensity. Based on these findings suggestions regarding the appropriate choice of estimation and performance method are made.

Derivation and validation phase for the development of clinical prediction rules for rehabilitation in chronic nonspecific low back pain patients: study protocol for a randomized controlled trial

Background

There is a consensus that exercise therapy should be used as a therapeutic approach in chronic low back pain (CLBP) but little consensus has been reached about the preferential type of therapy. Due to the heterogeneity of the population no clear effect of specific therapy interventions are found. Probably a specific subgroup of the investigated population will benefit from the intervention and another subgroup will not benefit, looking at the total investigated population no significant effects can be found. Therefore there is a need for the development of clinical prediction rules (CPRs). Objectives for this trial are first, the derivation of CPRs to predict treatment response to three forms of exercise therapy for patients with nonspecific CLBP. Secondly, we aim to validate a CPR for the three forms of exercise therapy for patients with nonspecific CLBP.

Methods/Design

The study design is a randomized controlled trial. Patients with nonspecific CLBP of more than three months duration are recruited at the Antwerp University Hospital (Belgium) and Apra Rehabilitation Hospital. After examination, patients are randomly assigned to one of three intervention groups: motor control therapy, general active exercise therapy and isometric training therapy. All patients will undergo 18 treatment sessions during nine weeks. Measurements will be taken at baseline, nine weeks, six months and at one year. The primary outcome used is the Modified Oswestry Disability Questionnaire score. For each type of exercise therapy a CPR will be derived and validated. For validation, the CPR will be applied to divide each treatment group into two subgroups (matched and unmatched therapy) using the baseline measurements. We predict a better therapeutic effect for matched therapy.

Discussion

A randomized controlled trial has not previously been performed for the development of a CPR for exercise therapy in CLBP patients. Only one CPR was described in a single-arm design for motor control therapy in sub-acute non-radicular LBP patients. In this study, a sufficiently large sample will be included in both the derivation and validation phase.

Trial registration

This trial was registered with Clinicaltrials.gov on 10 February 2014, registration number: NCT02063503.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-16-4) contains supplementary material, which is available to authorized users.

Regular change in spontaneous preparative behaviour on intra-abdominal pressure and breathing during dynamic lifting

PURPOSE

Intra-abdominal pressure (IAP) and breathing behaviour are important preparative pre-lifting actions for functional stability during lifting. This study aimed to examine spontaneous changes in the peak rate of IAP development (Rate-IAP), peak IAP (Peak-IAP), the time of Rate- and Peak-IAP occurrence and respiratory volume in response to dynamic load lifting.

METHODS

Eleven healthy men performed quick dynamic deadlifting using 30, 45, 60 and 75% of the isometric maximal lifting effort (iMLE). IAP was measured using an intrarectal pressure transducer. The spontaneous respiratory volume was calculated from air flow data using pneumotachography. The lifting motion onset was determined from the hip joint motion using an electrogoniometer.

RESULTS

From 30 to 75% of the iMLE, Rate-IAP occurred early from 2 ± 28 to -179 ± 16 ms (P < 0.01), whereas Peak-IAP occurred late from 165 ± 31 to 82 ± 23 ms (P = 0.12) relative to the lifting motion onset. Rate-IAP increased from 224 ± 47 to 507 ± 69 mmHg/s (P < 0.01), whereas Peak-IAP increased from 37 ± 8 to 90 ± 11 mmHg (P < 0.01) at 30-75% of the iMLE. Rate-IAP strongly correlated with Peak-IAP at each lifting load (r = 0.94-0.97). Relative to the resting tidal volume, the inspiratory volume during pre-lifting significantly increased above 60% of the iMLE, whereas expiratory volume significantly decreased at all lifting loads.

CONCLUSIONS

Preparative pre-lifting behaviours alter IAP and breathing and are co-ordinated by the lifting load magnitude. These behaviours appear to be functionally important for dynamic lifting.

Validity and reliability of the abdominal test and evaluation systems tool (ABTEST) to accurately measure abdominal force

OBJECTIVES

Ability to generate force from the core musculature is a critical factor for sports and general activities with insufficiencies predisposing individuals to injury. This study evaluated isometric force production as a valid and reliable method of assessing abdominal force using the abdominal test and evaluation systems tool (ABTEST). Secondary analysis estimated 1-repetition maximum on commercially available abdominal machine compared to maximum force and average power on ABTEST system.

DESIGN

This study utilized test-retest reliability and comparative analysis for validity. Reliability was measured using test-retest design on ABTEST. Validity was measured via comparison to estimated 1-repetition maximum on a commercially available abdominal device.

METHODS

Participants applied isometric, abdominal force against a transducer and muscular activation was evaluated measuring normalized electromyographic activity at the rectus-abdominus, rectus-femoris, and erector-spinae.

RESULTS

Test, re-test force production on ABTEST was significantly correlated (r=0.84; p<0.001). Mean electromyographic activity for the rectus-abdominus (72.93% and 75.66%), rectus-femoris (6.59% and 6.51%), and erector-spinae (6.82% and 5.48%) were observed for trial-1 and trial-2, respectively. Significant correlations for the estimated 1-repetition maximum were found for average power (r=0.70, p=0.002) and maximum force (r=0.72, p<0.001).

CONCLUSIONS

Data indicate the ABTEST can accurately measure rectus-abdominus force isolated from hip-flexor involvement. Negligible activation of erector-spinae substantiates little subjective effort among participants in the lower back. Results suggest ABTEST is a valid and reliable method of evaluating abdominal force.

Performance based on sEMG activity is related to psychosocial components: differences between back and abdominal endurance tests

The influence of psychosocial components on back and abdominal endurance tests in patients with persistent non-specific low back pain should be investigated to ensure the correct interpretation of these measures. Three-hundred and thirty-two patients (291 men and 41 women) from 19 to 63years performed an abdominal and back muscle endurance test after completing some psychosocial questionnaires. During the endurance tests, surface electromyography signals of the internal obliques, the external obliques, the lumbar multifidus and the iliocostalis were recorded. Patients were dichotomized as underperformers and good performers, by comparing their real endurance time, to the expected time of endurance derived from the normalized median frequency slope. Independent t-tests were performed to examine the differences on the outcome of the questionnaires. In the back muscle endurance test, the underperformers had significantly lower (p<0.05) scores on some of the physical subscales of the SF-36. The underperformers group of the AE test scored significantly higher on the DRAM MZDI (p=0.018) and on the PCS scale (p=0.020) and showed also significantly lower scores on the SF-36 (p<0.05). Back muscle endurance tests are influenced by physical components, while abdominal endurance tests seem influenced by psychosocial components.

The effect of abdominal bracing in combination with low extremity movements on changes in thickness of abdominal muscles and lumbar strength for low back pain

[Purpose] The purpose of this study was to investigate the effects of abdominal bracing with low extremity movement on changes in thickness of abdominal muscles and lumbar strength. [Subjects] Sixteen patients with chronic low back pain were randomly assigned to two groups: an abdominal bracing with active straight leg raise (ABSLR) group and abdominal bracing with ankle dorsiflexion (ABDF) group. [Methods] All subjects were evaluated for their abdominal muscle strength using a MedX Lumbar Extension Machine and thickness of external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) muscles using rehabilitative ultrasound imaging. Subjects in both groups were instructed to perform Abdominal bracing (AB). Simultaneously, those in the ABSLR group performed active SLR, and those in the ABDF group performed ankle dorsiflexion. [Results] In comparison between the ABSLR and ABDF groups, significant differences in the thickness of the IO and TrA muscles were observed after the intervention in the ABSLR group. Also, lumbar strength was showed a significant increase in both groups after interventions. [Conclusion] The results of this study demonstrated that ABSLR is a more effective method than ABDF for improvement of abdominal stabilization by increasing the thicknesses of the TrA and IO.

Effect of two different exercise regimens on trunk muscle morphometry and endurance in soldiers in training

BACKGROUND

Limited evidence exists on how strength and endurance exercises commonly used to prevent low back pain affect muscle morphometry and endurance.

OBJECTIVE

The purpose of this study was to analyze the effects of 2 exercise regimens on the morphometry and endurance of key trunk musculature in a healthy population.

DESIGN

The study was designed as a randomized controlled trial.

SETTING

The study was conducted in a military training setting.

PARTICIPANTS

A random subsample (n=340; 72% men, 28% women; mean [±SD] age=21.9±4.2 years; mean [±SD] body mass index=24.8±2.8 kg/m2) from the larger Prevention of Low Back Pain in the Military trial (N=4,325) was included.

INTERVENTION

The core stabilization exercise program (CSEP) included low-load/low-repetition motor control exercises, whereas the traditional exercise program (TEP) included exercises conducted at a fast pace, with the use of high-load, high-repetition trunk strengthening exercises.

MEASUREMENTS

Baseline and follow-up examinations included ultrasound imaging of the trunk muscles and endurance tests. Linear mixed models were fitted to study the group and time effect and their interactions, accounting for the clustering effect.

RESULTS

Symmetry generally improved in the rest and contracted states, but there were no differences suggestive of muscle hypertrophy or improved ability to contract the trunk muscles between soldiers receiving the CSEP or the TEP. Total trunk endurance time decreased over the 12-week period, but endurance performance favored soldiers in the CSEP group. Endurance time was not associated with future episodes of low back pain.

LIMITATIONS

The lack of morphological changes may not be detectable in an already-active cohort, or a more intensive dose was needed.

CONCLUSIONS

Although improved symmetry was noted, neither the CSEP nor the TEP resulted in muscle hypertrophy. Longer endurance times were noted in individuals who completed the CSEP but were not strongly predictive of future low back pain episodes.

Posterior muscle chain activity during various extension exercises: an observational study

Background

Back extension exercises are often used in the rehabilitation of low back pain. However, at present it is not clear how the posterior muscles are recruited during different types of extension exercises. Therefore, the present study will evaluate the myoelectric activity of thoracic, lumbar and hip extensor muscles during different extension exercises in healthy persons. Based on these physiological observations we will make recommendations regarding the use of extensions exercises in clinical practice.

Methods

Fourteen healthy subjects performed four standardized extension exercises (dynamic trunk extension, dynamic-static trunk extension, dynamic leg extension, dynamic-static leg extension) in randomized order at an intensity of 60% of 1-RM (one repetition maximum). Surface EMG signals of Latissimus dorsi (LD), Longissimus thoracis pars thoracic (LTT) and lumborum (LTL), Iliocostalis lumborum pars thoracic (ILT) and lumborum (ILL), lumbar Multifidus (LM) and Gluteus Maximus (GM) were measured during the various exercises. Subsequently, EMG root mean square values were calculated and compared between trunk and leg extension exercises, as well as between a dynamic and dynamic-static performance using mixed model analysis. During the dynamic exercises a 2 second concentric contraction was followed by a 2 second eccentric contraction, whereas in the dynamic-static performance, a 5 second isometric interval was added in between the concentric and eccentric contraction phase.

Results

In general, the muscles of the posterior chain were recruited on a higher level during trunk extension (mean ± SD, 56.6 ± 30.8%MVC) compared to leg extension (47.4 ± 30.3%MVC) (p ≤ 0.001). No significant differences were found in mean muscle activity between dynamic and dynamic-static performances (p = 0.053). The thoracic muscles (LTT and ILT) were recruited more during trunk extension (64.9 ± 27.1%MVC) than during leg extension (54.2 ± 22.1%MVC) (p = 0.045) without significant differences in activity between both muscles (p = 0.138). There was no significant differences in thoracic muscle usage between the dynamic or dynamic-static performance of the extension exercises (p = 0.574).

Lumbar muscle activity (LTT, ILL, LM) was higher during trunk extension (70.6 ± 22.2%MVC) compared to leg extension (61.7 ± 27.0%MVC) (p = 0.047). No differences in myoelectric activity between the lumbar muscles could be demonstrated during the extension exercises (p = 0.574). During each exercise the LD (19.2 ± 13.9%MVC) and GM (28.2 ± 14.6%MVC) were recruited significantly less than the thoracic and lumbar muscles.

Conclusion

The recruitment of the posterior muscle chain during different types of extension exercises was influenced by the moving body part, but not by the type of contraction. All muscle groups were activated at a higher degree during trunk extension compared to leg extension. Based on the recruitment level of the different muscles, all exercises can be used to improve the endurance capacity of thoracic muscles, however for improvement of lumbar muscle endurance leg extension exercises seem to be more appropriate. To train the endurance capacity of the LD and GM extension exercises are not appropriate.

Magnetic resonance imaging and electromyography to measure lumbar back muscle activity

STUDY DESIGN

Mixed model analysis of muscle functional magnetic resonance imaging (MRI) and electromyography (EMG) changes in lumbar muscles during trunk extension exercise at varying intensities.

OBJECTIVE

To gain insight within the relationship between muscle functional MRI and activity of the lumbar back muscles, which is related to exercise intensity.

SUMMARY OF BACKGROUND DATA

It is known that muscle activity during exercise induces a force-sensitive T2 increase; however, it is not known how sensitive this T2 change is. In addition, the association between MRI and EMG measurement was investigated.

METHODS

Multifidus and erector spinae muscle activity was investigated during a trunk extension exercise at 5 increasing loads (from 40% to 80% of 1 repetition maximum), with both MRI and EMG. Data were analyzed using mixed model analysis.

RESULTS

Our results indicate a linear relationship between MRI and exercise intensity; for both muscles an increase of 10% exercise intensity corresponds with an increase of the T2 value with 1.18 (0.89, 1.47) ms. Also for EMG there is a linear relationship with exercise intensity; an increase of 10% exercise intensity corresponds with an increase of 6.98 (5.33, 8.62) microV. Furthermore, a linear association between MRI and EMG is acceptable. For the multifidus, an increase of 1 muV (EMG) corresponds with an increase of 0.168 (0.117, 0.219) ms (MRI). For the erector spinae, an increase of 1 microV corresponds with an increase of 0.078 (0.042, 0.114) ms.

CONCLUSION

Both muscle functional MRI and EMG have specific (dis-) advantages and therefore have to be seen as complementary techniques. Nevertheless, our results support the validity of each method and indicate that MRI and EMG can be used independently to quantify lumbar muscle activity.

The myth of core stability

The principle of core stability has gained wide acceptance in training for the prevention of injury and as a treatment modality for rehabilitation of various musculoskeletal conditions in particular of the lower back. There has been surprisingly little criticism of this approach up to date. This article re-examines the original findings and the principles of core stability/spinal stabilisation approaches and how well they fare within the wider knowledge of motor control, prevention of injury and rehabilitation of neuromuscular and musculoskeletal systems following injury.