Different ways to balance the spine in sitting: Muscle activity in specific postures differs between individuals with and without a history of back pain in sitting

BackgroundPrevious research explored muscle activity in four distinct sitting postures with fine-wire electromyography, and found that lumbar multifidus muscle activity increased incrementally between sitting with flat thoracolumbar and lumbar regions, long thoracolumbar lordosis, or short lordosis confined to the lumbar region. This study used similar methods to explore whether people with a history of low back pain provoked by prolonged sitting used different patterns of trunk muscle activity in specific postures.MethodsFine-wire electromyography electrodes were inserted into the right lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis and transversus abdominis muscles. Superficial abdominal muscle activity was recorded with surface or fine-wire electrodes. Electromyography amplitude was compared between postures for the back pain group and observations were contrasted with the changes previously reported for pain-free controls. For comparison between groups normalised and non-normalised electromyography amplitudes were compared.FindingsIndividuals with a history of back pain demonstrated greater activity of the longissimus thoracis muscle in the long lordosis compared with the flat posture [mean difference (95% CI): 46.6 (17.5–75.7)%, normalised to sitting posture peak activity], but pain-free participants did not [mean difference: 7.7 (minus 12–27.6)%]. Pain-free participants modulated lumbar multifidus activity with changes in lumbar curve, but people with a history of pain in prolonged sitting did not change multifidus activity between the long and short lordotic postures.InterpretationIn clinical ergonomic interventions that modify spinal curves and sagittal balance in sitting, the muscle activity used in those postures may differ between people with and without a history of back pain.     

Can we reduce the effort of maintaining a neutral sitting posture? A pilot study

Neutral sitting postures encouraging lumbar lordosis have been recommended in the management of sitting-related low back pain (LBP). However, prolonged lordotic sitting postures can be associated with increased fatigue and discomfort. This pilot study investigated whether changing the type of chair used in sitting can reduce the effort of maintaining a neutral sitting posture. The muscle activation of six trunk muscles was recorded using surface electromyography in 12 painfree participants. Participants were facilitated into a neutral sitting posture for 1 min on both a standard backless office chair and a dynamic, forward-inclined chair (Back App). Lumbar multifidus activity was significantly lower on the Back App chair (p = 0.013). None of the other five trunk muscles measured demonstrated a significant difference in activity between the chairs. There was no significant difference (p = 0.108) in the perceived effort of maintaining the neutral sitting posture on the two chairs. This study suggests that the lumbar multifidus activation required to maintain a neutral sitting posture can be reduced by considering the type of chair used. The mechanism through which the Back App chair reduces lumbar multifidus activation is unclear, but the greatest difference between chairs is the degree of hip flexion. The ability to maintain a neutral lumbar posture with less lumbar multifidus activation is potentially advantageous during prolonged sitting. Further investigations of the effects of chair design on longer duration sitting, and among LBP subjects, are warranted.     

Relevance of adding a triangular dynamic cushion on a traditional chair: A 3D-analysis of seated schoolchildren

BackgroundLow back pain is highly prevalent in the general population and is even reported as early as at primary school. A poor sitting position has been suggested as an etiologic factor. This study analysed, in primary schoolchildren, the influence of a triangular dynamic cushion that aims to help children maintain their physiological lumbar lordosis and to induce movement to reduce the static effect of the sitting position.MethodsThirty 8-year-old children took part in this study. A 3D analysis combined with electromyography was used to evaluate the biomechanics and the related muscle activation in two sitting positions (with and without a triangular cushion on a horizontal stool) during a 15-minute working task. In addition, the force of the feet on the ground was assessed with a force plate.FindingsThe cushion improved the trunk–thighs angle, lumbar lordosis, anterior pelvis tilt, and feet support on the ground (p < 0.0001). In addition, sitting on the cushion appeared to be more dynamic (p < 0.05) and induced a decrease of the lumbar paravertebral muscle activity (p < 0.01).InterpretationSitting on a dynamic triangular cushion tends to favour the “ideal” siting position usually described in the literature and to decrease the level of paravertebral muscle recruitment. Seeing that sitting position is a risk factor to develop low back pain, the cushion could be a solution to prevent it.     

Effect of low back pain on the muscles controlling the sitting posture

[Purpose] The purpose of the current study was to reveal the association between posture control and muscle activity by measuring the trunk and hip joint muscle activities in the upright and slump sitting positions in both the healthy participants and patients with recurrent lower back pain. [Participants and Methods] We recruited eleven patients of recurrent lower back pain and ten healthy participants. During the maintenance of the two types of posture, upright and slump, we collected the surface electromyography data. We assessed the following muscles: rectus abdominis, external oblique, thoracic erector spinae, lumbar erector spinae, internal oblique, lumbar multifidus, iliacus, serratus anterior, rectus femoris, tensor fascia latae, and gluteus maximus. We studied the differences in spinal–pelvic curvature and muscle activity between the upright and slump positions in each group. [Results] In the healthy group, comparison of the muscle activity in upright and slump positions for both the trunk (external oblique, internal oblique, lumbar erector spinae, and lumbar multifidus), and the hip muscles (iliacus and gluteus maximus) showed a significant decrease in activity in the slump position. In the group with recurrent lower back pain, although the external oblique, lumbar erector spinae and lumbar multifidus showed reduced activity in slump position, these values were smaller when compared to those in the healthy group. [Conclusion] This study aimed to clarify the relationship between posture (upright and slump) and the activity of the trunk and hip joint muscles in the healthy participants and the patients with recurrent lower back pain. The results indicated that postural changes caused by recurrent lower back pain significantly affected the activity of the muscles involved in controlling the posture.Key words: Sitting posture, Muscle control, Low back pain     

Back posture and low back muscle activity in female computer workers: A field study

BackgroundFew studies have investigated sitting posture and low back muscle activity in occupational settings. This study aims to determine back posture and its influence on low back muscle activity in computer workers, and to investigate whether the work situation is associated with exacerbation of low back pain.MethodsTwenty-one female computer workers participated. Surface electromyographic activity was recorded from lumbar multifidus, longissimus, and iliocostalis throughout the workday. Simultaneous inclinometer recordings from pelvis, upper trunk, and left thigh were used to determine back posture and identify periods with sitting, standing, and walking. Low back pain intensity was recorded by visual analogue scale every hour throughout the work and leisure periods.FindingsAll subjects adopted a markedly flexed back posture while seated at work. Surface electromyographic activity was very low for all muscles during sitting (group median <1.4% of root-mean-square-detected response at maximal voluntary contraction). Back posture moderately influenced electromyographic activity, accounting for 19% (sitting) to 38% (standing) of intra-individual variation in muscle activity. Subjects reporting aggravating low back pain (n = 10) during the workday were not distinguished by duration of sitting, sitting posture, or low back muscle activity. Low back pain was markedly reduced from the last hour of work to the first hour of leisure, accompanied by an increase in low back muscle activity.InterpretationLow back muscle activity was very low during seated posture, presumably due to the flexion–relaxation phenomenon. Sustained stretch of passive lumbar structures in combination with essentially silent muscles may exacerbate low back pain in sedentary workers.     

Reliability of ultrasound measurement of the lateral abdominal and lumbar multifidus muscles in individuals with chronic low back pain: A cross-sectional test-retest study

ObjectivesUltrasound (US) imaging has been suggested to evaluate the morphology and function of trunk muscles; however, little is known about the reliability of the US measures in patients with chronic low back pain (CLBP). This study aimed to evaluate intrarater reliability of US imaging of the lateral abdominal and lumbar multifidus muscles in individuals with nonspecific CLBP.MethodsIn this cross-sectional study, intrarater within-day and between-day reliability of US measurements of the transversus abdominis, internal oblique, external oblique and lumbar multifidus (at the L3-L4, L4-L5, and L5-S1 levels) muscles were obtained on both sides. The resting and contracted thickness and contraction ratio of each muscle were measured in 21 individuals with nonspecific CLBP.ResultsAll US measurements of the lateral abdominal and lumbar multifidus muscles demonstrated good to excellent within-day (Intraclass correlation coefficients (ICCs: 0.80–0.98) and between-day (ICCs: 0.80–0.97) reliability. The standard error of the measurement (SEMs) and minimal detectable change (MDCs) of the lateral abdominal muscles on both sides ranged 0.5–1.6 mm and 0.4–4.4 mm, respectively. The SEMs and MDCs of the LM muscles on both sides ranged 1.1–2.7 mm and 2.86–7.49 mm, respectively.ConclusionThe findings indicate that US imaging has good to high intrarater within- and between-day reliability for assessing absolute thickness and contraction ratio of the trunk muscles on both right and left sides in patients with nonspecific CLBP. The vertical alignment of the US transducer is a reliable method for assessing the lateral abdominal muscles.     

Kinematic characteristics of arm and trunk when drinking from a glass in children with and without cerebral palsy

BackgroundChildren with cerebral palsy (CP) often have difficulty with activities that require the upper extremities secondary to deficits in strength and range of motion, spasticity, and poor timing and coordination of movement. This study aimed to identify and compare timing and coordination of the trunk and upper extremity in children with and without CP during a functional task.MethodsEighteen children, N = 9 with CP and N = 9 with typical development were enrolled. Participants were seated in a standard chair and instructed to drink from a glass placed at a distance of 75% of available arm length. The task was divided into 3 Phases: 1) reaching to the glass, 2) transporting the glass to the mouth, and 3) returning the glass to the table. The spatiotemporal and angular variables were analyzed with 3D kinematics of movement using a 4-camera Qualysis Motion System.FindingsChildren with CP demonstrated poor upper extremity timing and coordination. Despite significant trunk displacement used as a compensation in Phase 1, children with CP demonstrated a significantly lower mean velocity and velocity peak during Phases 2 and 3; and demonstrated less straight motion which required more time and movement units in all phases.InterpretationChildren with CP demonstrated poor upper extremity timing and coordination when drinking (even when they successfully completed the task) measured by more trunk displacement, slower, less straight movements, and more movement units. Current rehabilitation strategies could consider training speed and use functional tasks that require different strategies across multiple phases.     

Association of low back pain with muscle stiffness and muscle mass of the lumbar back muscles,and sagittal spinal alignment in young and middle-aged medical workers

BackgroundMuscle stiffness of the lumbar back muscles in low back pain (LBP) patients has not been clearly elucidated because quantitative assessment of the stiffness of individual muscles was conventionally difficult. This study aimed to examine the association of LBP with muscle stiffness assessed using ultrasonic shear wave elastography (SWE) and muscle mass of the lumbar back muscle, and spinal alignment in young and middle-aged medical workers.MethodsThe study comprised 23 asymptomatic medical workers [control (CTR) group] and 9 medical workers with LBP (LBP group). Muscle stiffness and mass of the lumbar back muscles (lumbar erector spinae, multifidus, and quadratus lumborum) in the prone position were measured using ultrasonic SWE. Sagittal spinal alignment in the standing and prone positions was measured using a Spinal Mouse. The association with LBP was investigated by multiple logistic regression analysis with a forward selection method. The analysis was conducted using the shear elastic modulus and muscle thickness of the lumbar back muscles, and spinal alignment, age, body height, body weight, and sex as independent variables.FindingsMultiple logistic regression analysis showed that muscle stiffness of the lumbar multifidus muscle and body height were significant and independent determinants of LBP, but that muscle mass and spinal alignment were not. Muscle stiffness of the lumbar multifidus muscle in the LBP group was significantly higher than that in the CTR group.InterpretationThe results of this study suggest that LBP is associated with muscle stiffness of the lumbar multifidus muscle in young and middle-aged medical workers.     

Intraclass correlation coefficient of trunk muscle thicknesses in different positions measured using ultrasonography

[Purpose] This study aimed to clarify the required number of measurements to calculate trunk muscle thickness at each position. [Participants and Methods] The participants were 30 elderly males aged >65 years. The right lumbar multifidus (L2), lumbar multifidus (L5), erector spinae, transversus abdominis, internal oblique, and external oblique muscle thicknesses were measured on longitudinal images obtained using ultrasonography in the lying, sitting, and standing positions. Two measurement values for each muscle thickness was used to calculate the intraclass correlation coefficient (1.1–1.5). [Results] The intraclass correlation coefficients of the abdominal muscle thickness measurements with “great reliabilities” were as follows: 1.3–1.5 for the external oblique muscle and 1.2–1.5 for the internal oblique and transversus abdominis muscles in the lying position; 1.3–1.5 for the external oblique and transversus abdominis muscles and 1.2–1.5 for the internal oblique muscle in the sitting position; the intraclass correlation coefficient in the standing position was 1.5 for the external oblique muscle 1.1–1.5 for the internal oblique muscle and 1.3–1.5 for the transversus abdominis muscle. In all the positions, the intraclass correlation coefficient of the measurements of the back-muscle thicknesses ranged from 1.1 to 1.5 for the right lumbar multifidus (L2), lumbar multifidus (L5), and erector spinae. [Conclusion] Depending on the posture, the abdominal muscles require multiple measurements, whereas the back muscles only require a single measurement.Key words: Intraclass correlation coefficient, Trunk muscle thicknesses, Ultrasonography     

Application of Ultrasonography in the Assessment of Abdominal and Lumbar Trunk Muscle Activity in Participants With and Without Low Back Pain: A Systematic Review

ObjectiveThe purpose of this study was to systematically review the literature regarding which condition (task, position, or contraction type), changes in muscle thickness could be interpreted as muscle activity of trunk muscles.MethodsStudies that assessed the correlation between changes in muscle thickness measured with ultrasonography (US) and electromyography (EMG) activity were included. Only the data related to abdominal and lumbar trunk muscles in participants with or without low back pain were extracted. The PubMed, ScienceDirect, Ovid MEDLINE, Scopus, Springer, and Cumulative Index to Nursing and Allied Health Literature databases were searched from inception to August 2018. Two independent raters appraised the quality of the included studies using the Critical Appraisal Skills Program checklist.ResultsFourteen studies were included. The results revealed significant correlations between US and EMG measures for the lumbar multifidus and erector spinae muscle during most contraction levels and postures. For transverse abdominis and internal oblique, US and EMG measures were correlated during low load abdominal drawing or bracing. The correlations were influenced by trunk position for higher intensities of contraction. For the external oblique muscle, correlation was observed only during trunk rotation.ConclusionChanges in muscle thickness should not be interpreted as muscle activity for all tasks, positions, and contraction types. Only during prime movement tasks performed with isometric contraction could muscle thickness change be considered as muscle activity. Also, upright postures influenced the relationship between changes in muscle thickness and muscle activity for abdominal muscles.     

In healthy subjects,the sitting position can be used to validate the postural effects induced by wearing a lumbar lordosis brace

Aim of the studyTo assess the validity of the sitting position when testing lumbar braces for the maintenance of lordosis.Patients and methodsTwelve young adult subjects participated in the experiment, in which they were seated on force platform. The four experimental conditions (with or without a brace and with or without enforced lordosis) were chosen in order to distinguish between the roles played by lordosis and the brace, respectively. The trajectories of the centre of pressure (CP) were analyzed and compared, in order to assess postural orientation and stabilisation processes.ResultsAlthough no effect was seen in terms of orientation, our data showed that use of a lumbar brace led to a notable reduction in CP displacement along the mediolateral and anteroposterior axes. Lordosis barely affected postural performance and only an increase in the mean CP velocity was observed. Lastly, an analysis of variance failed to reveal an interaction between the “lordosis” and “brace” factors.ConclusionA lumbar brace (in the absence or presence of lordosis) helps subjects to improve their sitting performance. In contrast to previous studies based on the standing posture, the fact that significant differences were found as a function of brace wear emphasises the discriminant power of the sitting position. This task should therefore be applied more widely in the development of more appropriate, validated equipment for lower back pain sufferers.     

Recruitment of the deep cervical flexor muscles during a postural-correction exercise performed in sitting

Specific strategies to optimally facilitate postural muscles to retrain postural form are advocated in the clinical management of neck pain. The purpose of this study was to compare the activation of selected cervical, thoracic and lumbar muscles during independent and facilitated postural correction in sitting in 10 subjects with chronic neck pain. Deep cervical flexor (DCF) muscle activity was recorded with custom electrodes inserted via the nose and fixed by suction to the posterior mucosa of the oropharynx. Surface electrodes were placed over the thoracic erector spinae and lumbar multifidus muscles. Root-mean-square EMG amplitude was measured for each muscle across two conditions. In the first condition, subjects were instructed to spontaneously "sit up straight" from a slumped posture without any other guidance from the therapist. In the second condition the therapist provided specific manual and verbal facilitation to assist the patient to correct to an upright pelvic position with a neutral spinal lumbo-pelvic position. Activation of the DCF and lumbar multifidus muscles (P<0.05) were significantly greater when the therapist facilitated postural correction compared to independent sitting correction. Specific postural-correction strategies result in better facilitation of key postural muscles compared to non-specific postural advice. The results of this study highlight the need for clinical skill and precision in postural training of patients with neck pain.     

Effects of lumbar lordosis increment on gait deteriorations in ambulant boys with Duchenne Muscular Dystrophy: A cross-sectional study

BackgroundIncrement of lumbar lordosis, a frequent spinal finding in Duchenne Muscular Dystrophy (DMD), is a compensatory mechanism secondary to muscle weakness. However, excessive lumbar lordosis may change the position of the center of mass, and lead to balance and walking difficulties.ObjectiveTo study the relationship between factors that may influence ambulatory function in boys with DMD and to investigate the effects of lumbar lordosis increment on gait and balance perturbations.MethodsTwenty-one ambulant patients with DMD and 10 healthy boys were included. Lumbar lordosis and thoracic kyphosis angles, dynamic and static balance tests, ambulatory function, muscle strength, and disease severity were assessed. Usage of steroids and orthotic devices were recorded. Scoliosis was assessed on radiographs. Receiver operator characteristic curves were formed and area under curve (AUC) measurements were performed to assess the ability of the tests to discriminate ambulatory status and optimal cut-off values were established according to the Youden index.ResultsThe amount of lumbar lordosis correlated strongly and negatively with quality of ambulation (r = −0.710) and moderately with performance on balance tests. The strength of both upper limbs and lower limbs muscles were not associated with any of the variables. According to the AUC analysis, patients with a lumbar lordosis higher than 36° had worse scores on gait and dynamic balance tests.ConclusionAmbulation and dynamic balance are negatively affected by the increment of lumbar lordosis with a cut-off point of 36°in boys with DMD.     

Electromyographic analysis of muscle activation of the trunk and lower limbs during human gait and hippotherapy using different ride mount materials

ObjectiveActivation of the trunk and lower limb muscles, namely the multifidus, rectus abdominis, rectus femoris, and tibialis anterior, was analyzed using surface electromyographyin 40 young, healthy, and sedentary individuals.MethodsData were collected from sneaker-clad subjects with independent gait and during hippotherapy using saddles and blankets, with the feet in and out of the stirrups.ResultsSurface electromyography results demonstrated a statistically significantly greater activation of the rectus femoris comparison to tibialis anterior muscle during hippotherapy. No statistically significant differences were observed when comparing variables related to the mount materials used in hippotherapy and human gait.ConclusionIn this study, similarities were observed between activation of the trunk and lower limb muscles during hippotherapy and human gait. In addition, the mount materials and practices used in hippotherapy did not influence muscle activity.     

Neuromuscular activation analysis of the trunk muscles during hippotherapy sessions

IntroductionHippotherapy allows the development of affective, sensory, motor, and cognitive areas, besides providing the practitioner with several movements and stimuli necessary for therapeutic progress. However, there is a limited amount of scientific evidence regarding the suitability of the mount material, mount type, and hippotherapy session duration, as well as regarding the activation of specific muscle groups during the practice and its applicability to activities of daily living.ObjectiveThis study aimed to study the neuromuscular activation behavior of the iliocostalis, longissimus, multifidus, and upper trapezius muscles of children during four hippotherapy session time points using a functional task. It also compared two different mount materials for riding.MethodologyA total of 30 children were randomly assigned to one of three groups: Saddle Hippotherapy Group, Blanket Hippotherapy Group, and Control Group. Data were collected with an electromyograph in a functional task that comprised trunk movements to pick up an object. Assessments took place at four times during the session.ResultsThere was a significant increase in the neuromuscular activation of the iliocostalis, longissimus, and multifidus muscles after a 30-min session. The trapezius muscle showed increased neuromuscular activation after only 10 min. It continued to increase (but without a statistical difference) after and 20 and 30 min.ConclusionHippotherapy promoted neuromuscular activation of the trunk muscles in children, assessed through a functional task, and was influenced by both session time and mount material. Specifically, the greater neuromuscular performance occurred when an exercise was performed using saddle and stirrup and lasted 30 min.     

Influence of trunk control and lower extremity impairments on gait capacity in children with cerebral palsy

Abstract

Purpose: We investigated the combined impact of trunk control and lower extremities impairments on predicting gait capacity in children with cerebral palsy (CP) and evaluated relationships between trunk control and lower extremities impairments.

Methods: Data of 52 children with CP [29 boys, mean age 11 years 9 months (±4 years 6 months)] were included in this observational study. Gait capacity was measured by the “modified Time Up and Go test”. Experienced therapists performed the “Modified Ashworth Scale”, “Manual Muscle Test”, the “Selective Control Assessment of the Lower Extremity”, and the “Trunk Control Measurement Scale”. We calculated Spearman correlations coefficients (ρ) and performed regression analyses.

Results: Trunk control was the strongest predictor (β?=?–0.624, p?<?0.001) when explaining the variance of gait capacity and remained in the model together with spasticity (R²?=?0.67). Muscle strength and selectivity correlated moderately to strongly with the trunk control and gait capacity (–0.68?≤?ρ?≤?–0.78), but correlations for the spasticity were low (ρ<–0.3).

Conclusions: The interconnection between trunk control, leg muscle strength and selectivity for gait capacity in children with CP was shown. It indicates the significance of these impairments in gait assessment and, potentially, rehabilitation.

• Implications for Rehabilitation

• Trunk control was the strongest predictor for gait capacity in a regression model with lower extremity spasticity, muscle strength and selectivity and age as independent variables.

• Lower extremity muscle strength, selectivity, and trunk control explained a similar amount of gait capacity variance which is higher than that explained by lower extremity spasticity.

• Lower extremity muscle strength and selectivity correlated strongly with trunk control.

• Therefore, we cautiously suggest that a combined trunk control and lower extremity training might be promising for improving gait capacity in children with CP (Gross Motor Function Classification System level I–III), which needed to be tested in future intervention-studies.

     

Lumbar posture biomechanics and its influence on the functional anatomy of the erector spinae and multifidus

Abstract

Background:

Lumbar posture has a significant impact on the functional biomechanics of the erector spinae and multifidus muscles, which has implications for the loads placed on the tissues of the lumbar spine.

Objectives:

The objective of this review is to discuss the effects of lumbar posture on the functional biomechanics of the different divisions of the erector spinae and the multifidus muscle and its importance when developing clinical interventions.

Methods:

This review used the search engines PubMed, EBSCO, CINAHL and SCOPUS to identify studies investigating erector spinae and multifidus muscle architecture and the influence of lumbar posture on the biomechanical properties of these muscles and the resulting impact on spinal loading.

Results:

Changes in lumbar curvature alter muscle fascicle obliquity, lever arm distances, the length–tension relationships and muscle volume of the different divisions of erector spinae and multifidus, which impact on the spine's ability to resist moments and shear forces.

Conclusion:

Changes in lumbar posture influence the functional biomechanics of the different divisions of erector spinae and the multifidus muscles. Therapists should develop low back interventions that avoid end range of lumbar postures and optimise the functional biomechanics of the erector spinae and multifidus muscles and minimise loading on the lumbar spine.     

Is it possible to stabilize the trunk using rhythmic stabilization in the upper limb? A cross-sectional study of asymptomatic individuals

Objective: The study aim was to evaluate the immediate effect of rhythmic stabilization on local and distant muscles involved in a functional reach. Method: Prospective, observational cross-sectional study. Eight right-handed and non-impaired individuals (4 females and 4 males) aged 18–24 years (21.5 ± 1.58 years) were evaluated. Bilateral electromyographic recording of the biceps brachii, triceps brachii, multifidus lumbar, and rectus abdominis muscles was performed during three different tasks. Task 1 involved functional reach, while Task 2 involved rhythmic stabilization followed by a functional reach. Task 3 was similar to Task 2, but with 3 repetitions before a functional reach. Results: The results showed no difference between the tasks or sides. However, an interaction was observed between each side and muscles, with greater activation of the right multifidus lumbar muscle. Conclusion: Rhythmic stabilization during the task of reaching promotes an increase of multifidus activity ipsilateral to its application. Thus, this particular technique of proprioceptive neuromuscular facilitation can be useful for improving stability of the trunk and can be used in clinical practice for this purpose. Level of Evidence: 5.     

Selective Activation of Lumbar Paraspinal Muscles during Various Exercises in the Prone Position as Measured by EMG

[Purpose] This study compared the effects of three exercises performed in a prone position on the selective activation of the lumbar erector spinae (LES) and lumbar multifidus (LM) muscles in healthy males to investigate the effective method for selective activation of the LM. [Subjects] Twenty-two healthy males were recruited. Surface EMG data were collected from the right LES and LM muscles during three exercises: 1) trunk extension, 2) hip extension, and 3) the arm lift. [Results] The ratio of LM to LES EMG activity during hip extension was higher than those during trunk extension and the arm lift. [Conclusion] Hip extension in a prone position may be effective for selective activation of the lumbar multifidus muscles in healthy males.Key words: Lumbar erector spinae, Lumbar multifidus, Selective activation