Trunk Muscle Activity Research Articles

The effects of curl-up exercise in terms of posture and muscle contraction direction on muscle activity and thickness of trunk muscles

The curl-up exercise is widely used in clinical practice for strengthening abdominal muscles, but has been applied without a systematic method. The purpose of this study was to determine the most effective method considering the angle and muscle contraction direction during the curl-up exercise. Fourteen healthy males performed the curl-up exercise according to contraction direction (concentric and eccentric) and angle (30∘, 60∘, and 90∘). The muscle activity of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and iliopsoas (IP) was measured using electromyography (EMG), and the muscle thickness of transversus abdominis (TrA) was measured using ultrasonography. The activities of the abdominal muscles (RA, EO, and IO) decreased with increasing angles (30∘, 60∘, and 90∘) (p< 0.05). There was no significant difference between eccentric and concentric contractions. The thickness ratio of TrA was the largest at an eccentric curl-up at 30∘, and the smallest at a concentric curl-up at 30∘ (p< 0.05). The most effective angle for curl-up was 30∘. Although there is no difference in the direction of muscle contraction, eccentric curl-up at 30∘ could be considered the most effective posture for abdominal strengthening considering the importance of TrA.

Electromyographic activity of head and trunk muscles in newborns

Abstract Introduction: The electric activity of muscles can be assessed using electromyography to determine their function and help identify possible delays in motor development. Objective: Determine the amplitude of the electromyographic activity of the head and trunk flexor and extensor muscles of term and preterm newborns. Method: This is a longitudinal pilot study where 20 preterm and 20 term newborns admitted to the Prof. Fernando Figueira Institute of Comprehensive Medicine were assessed. All the newborns were evaluated between 24 and 72 hours after delivery, with the premature children assessed a second time when term equivalent age was reached at 40 weeks. Data were recorded using a surface electromyograph and the electrodes were attached to the muscle bellies of the sternocleidomastoid, upper portion of the trapezius, rectus abdominis and erector spinae muscles. Results: Comparison of the electromyographic activity between the preterm newborns showed significantly higher values in all the muscles when the group reached term equivalent age. Additionally, the electromyographic activity of the term group was greater than that obtained by the preterm newborns. Conclusion: With advancing age and maturation of the physiological systems, including the muscle system, preterm newborns tend to exhibit a similar muscle activation behavior to that of the term infants, resulting in better motor development.

Kinesiology of kayaking in case of physical disablity with a special focus on footrest

During kayaking, the whole body works in a perfect harmony. While the trunk is doing a rotation, flexion­extension helps to the upper limb to create a special cyclic paddle. The purpose of this study was to gain whether there were any significant differences between disabled and non-disabled kayakers with special focus on the use of footrest. Methods: Thirteen (n=13) elite physical disabled athletes, eleven (n=11) elite non-disabled athletes and nine (n=9) athletes whose movements were artificially limited to imitate disabled conditions were measured. Results: Upper limb muscle activities were significantly different in the disabled group. In the disabled group, knee and trunk motions and muscle activities were also significantly different compared to the non-disabled group. Significant differences were found in performance, force and footrest use. Conclusions: Our results proved our assumption that motions and muscle activities of disabled and non-disabled athletes were significantly different.

Immediate changes in trunk muscle activation patterns during a lifting task following an abdominal drawing-in exercise in subjects with recurrent low back pain.

The abdominal drawing-in exercise could help improve delayed transversus abdominis (TrA) activation during limb movement in subjects with recurrent low back pain (rLBP). However, little is known about whether the same effect is observed during lifting tasks in subjects with rLBP. This study aimed to clarify whether a single session of abdominal drawing-in exercise could correct the altered trunk muscle activation patterns during a lifting task in subjects with rLBP. Fifteen subjects with rLBP performed lifting tasks before and immediately after three sets of 10 repetitions of isolated TrA voluntary contractions. The time of onset and activation amplitude during the lifting tasks were measured by surface electromyography (EMG) and compared between the trials before and immediately after exercise. During lifting, the onset of internal abdominal oblique/TrA (IO/TrA) and multifidus activation occurred earlier, the EMG amplitude of IO/TrA increased, and the EMG amplitude of erector spinae and multifidus decreased, compared with the pre-exercise data. These results suggest a possibility that the abdominal drawing-in exercise might be effective in improving the muscle recruitment pattern in people with rLBP.

Effects of a Pilates protocol in individuals with non-specific low back pain compared with healthy individuals: Clinical and electromyographic analysis

BackgroundElectromyography may be useful for assessing and understanding trunk muscle activation, and Pilates is commonly used as a treatment for low back pain. The objective of this study was to verify electromyography of trunk muscles after a Pilates protocol in individuals with non-specific low back pain and in healthy individuals. MethodsVolunteers were divided into two groups: non-specific low back pain (n = 19) and clinically healthy (n = 16) groups. Clinical assessments, classification of patients into subgroups, electromyography evaluations of the right lumbar extensor and right transverse abdominal/internal oblique muscle of the abdomen were performed before and after an 8-week Pilates protocol. FindingsComparisons were made before and after the protocol and with the control group. There was significant improvement in pain, flexibility, resistance and strength of trunk muscles. In addition, after the Pilates, there was a decrease in the time elapsed between the onset and peak of lumbar muscle activation during the evaluation of trunk extension in the low back pain group, coming closer to the time of the abdominal muscle, as it also occurred in the control group. InterpretationPilates caused clinical improvement and balanced trunk muscle activation in the low back group, becoming similar to that of the control group. Furthermore, the effects of the proposed protocol were the same between the groups. Thus, Pilates may be indicated for management of non-specific low back pain.

Subject-specific regression equations to estimate lower spinal loads during symmetric and asymmetric static lifting

Workplace safety assessment, personalized treatment design and back pain prevention programs require accurate subject-specific estimation of spinal loads. Since no noninvasive method can directly estimate spinal loads, easy-to-use regression equations that are constructed based on the results of complex musculoskeletal models appear as viable alternatives. Thus, we aim to develop subject-specific regression equations of L4-L5 and L5-S1 shear and compression forces during various symmetric/asymmetric tasks using a nonlinear personalized finite element musculoskeletal trunk model. Kinematics and electromyography (EMG) activities of 19 young healthy subjects were collected during 64 different symmetric/asymmetric tasks. To investigate the reliability and accuracy of the musculoskeletal model and regression equations, we compared estimated trunk muscle activities and L4-L5 intradiscal pressures (IDPs) respectively with our own electromyography data (EMGs) and reported in vivo pressure measurements. Although in general, six independent rotation components (three trunk T11 rotations and three pelvic S1 rotations) are required to determine kinematics along the spine, only two surrogate variables (trunk flexion and its asymmetric angles) satisfactorily predicted all six rotation components (R2 > 0.94). Regression equations, developed based on subject-specific inputs, predicted spinal loads in satisfactory agreement with IDP measurements (R2 = 0.85). Predicted muscle activities in the personalized musculoskeletal models were in moderate to weak agreements with our measured EMGs in 19 participants. Based on dominance analysis, trunk flexion and its asymmetry angle, hand-load weight, hand-load lever arm, and body weight were the most important variables while the effects of body height and sex on spinal loads remained small.

Comparison of Trunk Muscle Activity During Modified Side-Bridge Exercises and Traditional Side Bridge Exercise.

The modified side-bridge exercise is designed for some special situations in which it is impossible to tolerate the compressive load on the side supported during the side bridge, such as in the older people with a hip or knee replacement and even in athletes with shoulder pain. To examine the effects of 3 modified side-bridge exercises on the spinal stability muscles compared with traditional side-bridge (TSB) exercises for healthy men. The effects of different exercises on the muscle activities of the external oblique (EO), internal oblique (IO), and quadratus lumborum (QL) during TSB exercise, both legs lift on side lying (BLLS), torso lift on a 45° bench while side lying (TLBS), and wall side bridge (WSB) were analyzed with the 1-way repeated-measures analysis of variance. This study was conducted in a university hospital laboratory. A total of 20 healthy men were recruited for this study. The participants performed TSB, BLLS, TLBS, and WSB in a random order. Surface electromyography measured the muscle activity of the EO, IO, and QL. A 1-way repeated-measures analysis of variance assessed the statistical significance of the EO, IO, and QL muscle activity. When there was a significant difference, a Bonferroni adjustment was performed. BLLS and TLBS showed similar effects to TSB in the EO, IO, and QL muscle activity, whereas WSB showed significantly less QL muscle activity than TSB (P < .05). Moreover, TLBS was significantly greater in the muscle activity of QL and EO than WSB (P < .05). BLLS and TLBS may be effective rehabilitation techniques to activate EO, IO, and QL in patients who are unable to perform TSB as spine stability exercises.

Trunk and hip muscle activity during the Balance-Dexterity task in persons with and without recurrent low back pain

Coordination of the trunk and hips is crucial for successful dynamic balance in many activities of daily living. Persons with recurrent low back pain (rLBP), both while symptomatic and during periods of symptom remission, exhibit dysfunctional muscle activation patterns and coordination of these joints. In a novel dynamic balance task where persons in remission from rLBP exhibit dissociated trunk motion, it is unknown how trunk and hip musculature are coordinated. Activation of hip and trunk muscles were acquired from nineteen persons with and without rLBP during the Balance-Dexterity Task, which involves balancing on one limb while compressing an unstable spring with the other. There were no between-group differences in activation amplitude for any muscle groups tested. In back-healthy control participants, hip and trunk muscle activation amplitudes increased proportionally in response to the added instability of the spring (R = 0.837, p < 0.001). Increases in muscle activation amplitudes in the group in remission from rLBP were not proportional (R = 0.113, p = 0.655). Instead, hip muscle activation in this group was associated with task performance, i.e. dexterous control of the spring (R = 0.676, p = 0.002). These findings highlight atypical coordination of hip and trunk musculature potentially related to task demands in persons with rLBP even during remission from pain.

Abdominal draw-in maneuver changes neuromuscular responses to sudden release from trunk loading in patients with non-specific chronic low back pain

BackgroundAbdominal draw-in maneuver (ADIM) has been recommended to achieve appropriate trunk muscle response for patients with non-specific chronic low back pain (CLBP). However, it has remained unclear whether the intervention with ADIM could change the trunk muscle response to sudden release from loading, which is considered to contribute mechanical circumstances to low back pain. The purpose of the present study was to investigate the effects of the intervention with ADIM on electromyography (EMG) activities of trunk muscles following sudden release from loading. MethodsSeventeen subjects with non-specific CLBP participated. Subjects resisted trunk flexion or extension loading in semi-seated position, and then the loading was suddenly released. EMG recordings of 6 trunk muscles were acquired using a wireless surface EMG system. Onset and offset times were calculated from the EMG data. The intervention with ADIM was provided for 4 weeks. The onset and offset times were compared between pre- and post-intervention with ADIM. ResultsAt the post-intervention, the onset of trunk flexors following release from trunk flexion loading became significantly earlier than pre-intervention (P = 0.028). The offset of flexors following release from trunk extension loading of post-intervention was significantly earlier than that of pre-intervention (P = 0.001). ConclusionsWe showed that the intervention with ADIM changed the EMG activity of trunk flexors in response to sudden release from loading. These results suggest a possibility that ADIM might be effective to improve the neuromuscular control of trunk flexors for the treatment of young patients with non-specific CLBP.

Are there differences in lifting technique between those with and without low back pain? A systematic review.

Background and aims To systemically review the literature to compare freestyle lifting technique, by muscle activity and kinematics, between people with and without low back pain (LBP). Methods Five databases were searched along with manual searches of retrieved articles by a single reviewer. Studies were included if they compared a freestyle lifting activity between participants with and without LBP. Data were extracted by two reviewers, and studies were appraised using the CASP tool for case-control studies. Results Nine studies were eligible. Heterogeneity did not allow for meta-analysis. Most studies (n = 8 studies) reported that people with LBP lift differently to pain-free controls. Specifically, people with LBP lift more slowly (n = 6 studies), use their legs more than their back especially when initiating lifting (n = 3 studies), and jerk less during lifting (n = 1 studies). Furthermore, the four larger studies involving people with more severe LBP also showed that people with LBP lift with less spinal range of motion and greater trunk muscle activity for a longer period. Conclusions People with LBP move slower, stiffer, and with a deeper knee bend than pain-free people during freestyle lifting tasks. Interestingly, such a lifting style mirrors how people, with and without LBP, are often told how to lift during manual handling training. The cross-sectional nature of the comparisons does not allow for causation to be determined. Implications The changes described may show embodiment of cautious movement, and the drive to protect the back. There may be value in exploring whether adopting a lifting style closer to that of pain-free people could help reduce LBP.

The effects of familiarization with loading, weight and size of loading on neuromuscular responses during sudden upper limb loading in chronic low back pain patients.

Changes in the motor control of the spine were found in patients with chronic low back pain (CLBP). Sudden loading of the spine is supposed to be the cause of about 12% of lower back injuries. However, some aspects of this problem, such as alterations in the sensory-motor control of the spine, remain questionable. To investigate the effects of familiarization with loading, weight and size of loading on neuromuscular responses during sudden upper limb loading in CLBP patients. In this quasi-experimental study surface electromyography of the erector spinae (ES) and transverses abdominis/internal oblique (TrA/IO) and external oblique (EOA) muscles were recorded in 7 men and 13 women with CLBP and 20 asymptomatic subjects (10 men and 10 women) aged 18-45 years from the general community familiarization. Moreover, investigating control of the posture measurements of the center of pressure (COP) and vertical ground reaction force (GRF) or Fz were recorded using a force plate. Data were analyzed using paired t-test and independent t-test with the significance level of 0.05. Data analyses were performed using SPSS version 18. Some electromyography and force plate variables were significantly different for different conditions in each group and between the asymptomatic and low back pain groups (p⩽ 0.05). Several motor control changes were observed in the CLBP patients. These patients showed decreased trunk muscle activity as well as too early and too delayed responses compared to asymptomatic subjects.

Arm crank ergometer "spin" training improves seated balance and aerobic capacity in people with spinal cord injury.

There is some evidence that upper-body training modalities can improve not only aerobic capacity but also seated balance in people with spinal cord injury (SCI), even in those classified with motor-complete paralysis above T6. Here, we evaluated the effect of arm crank ergometry (ACE) "spin" training on trunk muscle recruitment and its effects on seated balance and aerobic capacity. Eight individuals with high-level complete and 6 with either a low-level complete or a motor-incomplete SCI participated in this study. Participants completed 5weeks of a group ACE "spin" training protocol which featured modulations in cadence and resistance as well as back-supported and unsupported bouts. Surface electromyography was used to confirm trunk muscle recruitment during unsupported ACE. Changes in aerobic capacity (peak oxygen consumption) and seated balance control (center of pressure parameters) were assessed at pre- and post-intervention. Unsupported ACE was effective for eliciting trunk muscle activity (P<.05). Following training, peak oxygen consumption significantly improved by an average of 16% (P=.005). Static sitting balance significantly improved from pre- to post-intervention, but only when tested with eyes closed as measured by a reduction in area (P=.047) and velocity of center of pressure (P=.013). No significant changes were observed in static sitting balance with eyes open or in dynamic sitting balance. Group ACE "spin" classes may benefit not only aerobic fitness but also static seated balance control in people with SCI.

Crossed activation of thoracic trunk motoneurons by medullary reticulospinal neurons.

Activation of contralateral muscles by supraspinal neurons, or crossed activation, is critical for bilateral coordination. Studies in mammals have focused on the neural circuits that mediate cross activation of limb muscles, but the neural circuits involved in crossed activation of trunk muscles are still poorly understood. In this study, we characterized functional connections between reticulospinal (RS) neurons in the medial and lateral regions of the medullary reticular formation (medMRF and latMRF) and contralateral trunk motoneurons (MNs) in the thoracic cord (T7 and T10 segments). To do this, we combined electrical microstimulation of the medMRF and latMRF and calcium imaging from single cells in an ex vivo brain stem-spinal cord preparation of neonatal mice. Our findings substantiate two spatially distinct RS pathways to contralateral trunk MNs. Both pathways originate in the latMRF and are midline crossing, one at the level of the spinal cord via excitatory descending commissural interneurons (reticulo-commissural pathway) and the other at the level of the brain stem (crossed RS pathway). Activation of these RS pathways may enable different patterns of bilateral trunk coordination. Possible implications for recovery of trunk function after stroke or spinal cord injury are discussed.NEW & NOTEWORTHY We identify two spatially distinct reticulospinal pathways for crossed activation of trunk motoneurons. Both pathways cross the midline, one at the level of the brain stem and the other at the level of the spinal cord via excitatory commissural interneurons. Jointly, these pathways provide new opportunities for repair interventions aimed at recovering trunk functions after stroke or spinal cord injury.

Investigating differences in trunk muscle activity in non-specific chronic low back pain subgroups and no-low back pain controls during functional tasks: a case-control study

BackgroundTrunk muscle dysfunction is often regarded as a key feature of non-specific chronic low back pain (NSCLBP) despite being poorly understood and variable with increases, decreases and no change in muscle activity reported. Differences in thoraco-lumbar kinematics have been observed in motor control impairment NSCLBP subgroups (Flexion Pattern, Active Extension Pattern) during static postures and dynamic activities. However, potential differences in muscle activity during functional tasks has not been established in these subgroups to date.MethodsA case-control study design recruited 50 NSCLBP subjects (27 Flexion Pattern, 23 Active Extension Pattern) and 28 healthy individuals. Surface electromyography determined muscle activity during functional tasks: reaching upwards, step-down, step-up, lifting and replacing a box, stand-to-sit, sit-to-stand, bending to retrieve (and returning from retrieving) a pen from the floor. Normalised (% sub-maximal voluntary contraction) mean amplitude electromyography of bilateral musculature (transversus abdominis/internal oblique, external oblique, superficial lumbar multifidus and longissimus thoracis) was analysed using Kruskal-Wallis and post-hoc Mann-Whitney U tests.ResultsTransversus abdominis/internal oblique activity was significantly increased in the Flexion Pattern group compared to controls during stand-to-sit (p = 0.009) on the left side only. External oblique activity was significantly greater in the Active Extension Pattern group compared to controls during box lift (p = 0.016) on the right side only. Significantly greater activity was identified in the right Superficial lumbar multifidus during step up (p = 0.029), reach up (p = 0.013) and box replace (p = 0.007) in the Active Extension Pattern group compared to controls. However left-sided superficial lumbar multifidus activity was significantly greater in the Flexion Pattern group (compared to controls) only during stand-to-sit (p = 0.009). No significant differences were observed in longissimus thoracis activity bilaterally during any task. No significant differences between NSCLBP subgroups were observed.ConclusionsMuscle activity in these NSCLBP subgroups appears to be highly variable during functional tasks with no clear pattern of activity identified. The findings reflect inconsistencies and variability in trunk muscle activity previously observed in these NSCLBP subgroups. Further work evaluating ratios of muscle activity and changes in muscle activity throughout task duration is warranted.

Effects of Ankle Joint Motion on Pelvis-Hip Biomechanics and Muscle Activity Patterns of Healthy Individuals in Knee Immobilization Gait.

The purpose of the study was to investigate the pelvis-hip biomechanics and trunk and lower limb muscle activity patterns between healthy people walking in two gaits and evaluate the effects of ankle joint motion on these two gaits. The two gaits included walking with combined knee and ankle immobilization and with individual knee immobilization. Ten healthy participants were recruited and asked to walk along a 10 m walk away at their comfortable speeds in the two gaits. Kinematic data, ground reaction force, and electromyography waveforms of trunk and lower limb muscles on the right side were collected synchronously. Compared to individual knee immobilization gait, people walking in the combined knee and ankle immobilization gait increased the range and average angle of the anterior pelvic tilt during the first double support and the single support phase, respectively. The combined knee and ankle immobilization gait also increased the range of hip abduction during the second double support phase. These kinematic alternations caused changes in trunk and lower limb muscle activity patterns. The ankle immobilization increased the range of gluteus maximus activation in the first double support phase, the range of rectus abdominis activation, the average amplitude of rectus femoris activation in the single support phase, and the range of rectus femoris activation in swing phase and decreased the range of and tibialis anterior activation in the first double support phase. The ankle immobilization also increased the average values of proximodistal component in AKI gait during the single support phase. This study revealed significant differences in pelvis-hip biomechanics and trunk and lower limb muscle activity patterns between the two gaits.

Trunk Muscle Activation in Reaching Movement in Individuals with Spinal Cord Injuries Involving Functional Banding: EMG Analysis

AbstractFunctional banding (BF) theoretically enhances or inhibits muscle activity in accordance with the direction and tension generated. In the literature a few articles were published, and, in the vast majority, using healthy subjects (without neurological injury) and electromyographic (EMG) analysis to check the muscles electrical activity. Studies conducted with individuals with spinal cord injury were not found. Type of Study: Serie of Cases. It was evaluated as dependent variables: muscle activity measured by EMG surface of the lower trapezius muscles, lumbar erectors and Iliocostalis bilaterally, and the distance of the functional reaching movement. Five individuals with spinal cord injuries with movements and sufficient mobility of the upper limbs to perform the reaching movement and 4 without injury. The reaching test with electromyographic evaluation was performed in three moments: Reaching without BF, reaching with BF and again reaching without BF. In qualitative analysis there seems to have been influenced by the bandage on temporal aspects of muscle activation. Quantitatively, there was no statistical difference in the RMS values and in the results of the reaching tests. The bandage seems to influence in the temporal parameters of muscle activation, being required a larger sample to show quantitative differences in muscle activation and the reaching tests performance. Keywords: Athletic Tape. Electromyography. Career Mobility. Resumo A bandagem funcional (BF) teoricamente aumenta ou inibe atividade muscular de acordo com o direcionamento e tensao gerada. Na literatura foram publicados poucos artigos, e, na grande maioria, utilizando sujeitos saudaveis (sem lesao neurologica) e analise eletromiografica (EMG) para verificar a atividade eletrica dos musculos. Estudos feitos com individuos com lesao medular nao foram encontrados. Tipo de Estudo: Serie de casos. Foi avaliado como variaveis dependentes: atividade muscular medida por EMG de superficie dos musculos trapezio inferior, eretores lombares e iliocostais bilateralmente, e distância do alcance funcional. Cinco individuos com lesao medular com movimentos e mobilidade suficiente de membros superiores para realizar o alcance e 4 sem lesao. O teste de alcance com avaliacao eletromiografica foi realizado em tres momentos: Alcance sem BF, alcance com BF e novamente alcance sem BF. Em analise qualitativa parece ter havido influencia da bandagem sobre aspectos temporais da ativacao muscular. Quantitativamente nao houve diferenca estatistica nos valores de RMS e nos resultados dos testes de alcance. A bandagem parece influenciar em parâmetros temporais da ativacao muscular, sendo necessaria uma amostra maior para visualizar diferencas quantitativas na ativacao muscular e no desempenho dos testes de alcance. Palasvras-chave: Fita Atletica. Eletromiografia. Mobilidade Ocupacional.

Change in Pelvic Motion Caused by Visual Biofeedback Influences Trunk and Hip Muscle Activities During Side-Lying Hip Abduction in Asymptomatic Individuals

Background: Ipsilateral pelvic elevation has been reported as a common compensatory movement during side-lying hip abduction. It has been reported that pelvic elevation inhibits sufficient contraction of gluteus medius. However, few studies have identified the effects of controlled pelvic elevation on the trunk and hip muscles. Objective: To examine the effects of controlled pelvic elevation using visual biofeedback on the muscle activity of the trunk and hip muscles. Design: Crossover study. Methods: Twelve healthy males performed side-lying hip abduction exercises with and without visual biofeedback for pelvic elevation. Electromyography (EMG) activities of the gluteus medius, quadratus lumborum, and multifidus were analyzed using a wireless EMG system while the ipsilateral pelvic elevation angle was measured using a motion sensor during side-lying hip abduction exercises. Results: EMG activities of the gluteus medius (p = .002), quadratus lumborum (p = .022), and multifidus (p = .020) were significantly increased and ipsilateral pelvic elevation was significantly decreased (p = .001) during side-lying hip abduction with visual biofeedback compared to without visual biofeedback. Conclusions: The results of this study suggest that the application of biofeedback for pelvic motion could improve the trunk and hip muscle activation pattern and decrease compensatory pelvic motion during side-lying hip abduction exercise.

Comparison of trunk muscle activity according to hip abduction angle during plank exercise

Comparison of trunk muscle activity according to hip abduction angle during plank exercise

Trunk Muscle Activation During Balance Task. A Case Control Study Related To Age-CLBP Differences

Trunk Muscle Activation During Balance Task. A Case Control Study Related To Age-CLBP Differences

Chronic low back pain influences trunk neuromuscular control during unstable sitting among persons with lower-limb loss

BackgroundPersons with unilateral lower-limb loss are at increased risk for developing chronic low back pain. Aberrant trunk and pelvis motor behavior secondary to lower-limb loss potentially alters trunk postural control and increases demands on the trunk musculature for stability. However, it is unclear whether trunk postural control is associated with the presence or chronicity of low back pain within this population. Research questionIs there a potential role of impaired trunk postural control among persons with lower limb loss and chronic low back pain? MethodsTwo groups of males with unilateral lower-limb loss (n = 18 with chronic low back pain; n = 13 without pain) performed an unstable sitting task. Trunk postural control was characterized using traditional and non-linear measures derived from center-of-pressure time series, as well as trunk kinematics and the ratio of lumbar to thoracic erector spinae muscle activations. ResultsTraditional and non-linear center-of-pressure measures and trunk muscle activation ratios were similar between groups, while participants with chronic low back pain demonstrated greater trunk motion and reduced local dynamic stability. SignificanceOur results suggest that persons with both lower-limb loss and chronic low back pain exhibit impaired trunk postural control compared to those with limb loss but without pain. Aberrant trunk motor behavior may be a response to altered functional requirements of walking with a prosthesis. An inability to adequately control the trunk could lead to spinal instability and pain in the presence of repetitive exposure to aberrant motor behavior of these proximal structures during everyday activities.