Timing of Activation of the Erector Spinae and Hamstrings During a Trunk Flexion and Extension Task (original) (raw)
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Journal of Electromyography and Kinesiology, 2009
Background: Movements in the lumbar spine, including flexion and extension are governed by a complex neuromuscular system involving both active and passive units. Several biomechanical and clinical studies have shown the myoelectric activity reduction of the lumbar extensor muscles (flexion-relaxation phenomenon) during lumbar flexion from the upright standing posture. The relationship between flexibility and EMG activity pattern of the erector spinae during dynamic trunk flexion-extension task has not yet been completely discovered.
Journal of sports science & medicine, 2006
The flexion-relaxation phenomenon consisting of an erector spinae silent period occurring with trunk flexion can place considerable stress upon tissues. Since individuals often flex their trunks while unstable, the purpose of the study was to examine the effect of an unstable base on the flexion-relaxation response. Fourteen participants flexed at the hips and back while standing on a stable floor or an unstable dyna-disc. Hip and trunk flexion were repeated four times each with one-minute rest. Electromyographic (EMG) electrodes were placed over the right lumbo-sacral erector spinae (LSES), upper lumbar erector spinae (ULES), lower abdominals (LA), biceps femoris and soleus. In addition to the flexion-relaxation phenomenon of the ES, a quiescence of biceps femoris and a burst of LA EMG activity was observed with the majority of stable trials. There was no effect of instability on the flexion-relaxation phenomenon of the ULES or LSES. The incidence of a biceps femoris silent period ...
Posterior muscle chain activity during various extension exercises: an observational study
BMC Musculoskeletal Disorders, 2013
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.
Muscle Activation Is Enhanced With Multi- and Uni-Articular Bilateral Versus Unilateral Contractions
Canadian Journal of Applied Physiology, 2003
Ten resistance trained (RT) and 6 non-resistance trained (NRT) subjects were used to determine differences in quadriceps activation between isometric single and double knee extensions and squat contractions. Greater inactivation, as measured by the interpolated twitch technique, was recorded with single (RT: 16.5%, NRT: 17.6%) than double leg extensions (RT: 8.4%, NRT: 13.4%) or squats (RT: 4.03%, NRT: 1.7%). There was no significant difference between the maximum voluntary contraction (MVC) force of the dominant leg during single and double leg extensions. However, in NRT subjects, the contralateral or nondominant leg during double leg extensions exhibited significantly less force than the dominant leg (715.9 vs 566.9 N). This deficit may be due to a lesser reliance on the non-dominant limb. The contractions of multiple lower body muscle groups enhanced the activation of the dominant quadriceps. Greater levels of activation may be necessary to cope with the stabilization necessary for bilateral and multi-articular contractions. Dix sujet entraînés à la force (RT) et six sujets non entraînés (NRT) participent à une étude sur l'analyse de l'activation du quadriceps au cours d'extensions isométriques unilatérales 38 The authors are with the School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland. Muscle Activation • 39 et bilatérales du genou et au cours d'un développé des membres inférieurs. Le degré d'inactivation, mesuré par la méthode de la secousse interpolée, est plus important au cours des actions unilatérales (RT: 16,5 %, NRT: 17,6 %) qu'au cours des actions bilatérales (RT: 8,4 %, NRT: 13,4 %) et des développés (RT: 4,03 %, NRT: 1,7 %). Il n'y a pas de différence significative entre la force d'une contraction maximale volontaire (MVC) de la jambe dominante au cours de mouvements unilatéraux et bilatéraux. Chez les sujets du groupe NRT, la jambe controlatérale ou non dominante est significativement moins forte que la jambe dominante (715,9 N vs 566,9 N) au cours d'actions bilatérales. Cette différence peut être attribuable à une moins grande sollicitation de la jambe non dominante. Les contractions de plusieurs groupes musculaires du bas du corps améliorent l'activation du quadriceps. Pour produire des mouvements stables par des actions bilatérales et pluriarticulaires, il faudrait probablement plus d'activation.
There were significant shoulder ROM increases following lower body SS (P < 0.010, ∆ % = 8.2 %) and DS (P < 0.019, ∆ % = 9 %). There was a significant hip flexor ROM (P < 0.016, ∆ % = 5.2 %) increase following upper body SS. There were no significant main effects or interactions for dynamic ROM or muscle force and activation variables. Conclusion The lack of stretch-induced force and fatigue changes suggests that rather than a mechanical or neural drive mechanism, an enhanced stretch tolerance was likely the significant factor in the improved ROM.
Scandinavian Journal of Medicine & Science in Sports, 2014
The present study examined the activity levels of the thoracic and lumbar extensor muscles during different extension exercise modalities in healthy individuals. Therefore, 14 subjects performed four different types of extension exercises in prone position: dynamic trunk extension, dynamic-static trunk extension, dynamic leg extension, and dynamic-static leg extension. Pre-and post-exercise muscle functional magnetic resonance imaging scans from the latissimus dorsi, the thoracic and lumbar parts of the longissimus, iliocostalis, and multifidus were performed. Differences in water relaxation values (T2-relaxation) before and after exercise were calculated (T2-shift) as a measure of muscle activity and compared between extension modalities. Linear mixed-model analysis revealed higher lumbar extensor activity during trunk extension compared with leg extension (T2shift of 5.01 ms and 3.55 ms, respectively) and during the dynamic-static exercise performance compared with the dynamic exercise performance (T2-shift of 4.77 ms and 3.55 ms, respectively). No significant differences in the thoracic extensor activity between the exercises could be demonstrated. During all extension exercises, the latissimus dorsi was the least activated compared with the paraspinal muscles. While all extension exercises are equivalent effective to train the thoracic muscles, trunk extension exercises performed in a dynamic-static way are the most appropriate to enhance lumbar muscle strength.
Altered muscle recruitment during extension from trunk flexion in low back pain developers
Background: A functionally induced, transient low back pain model consisting of exposure to prolonged standing has been used to elucidate baseline neuromuscular differences between previously asymptomatic individuals classified as pain developers and non-pain developers based on their pain response during a standing exposure. Previous findings have included differences in frontal plane lumbopelvic control and altered movement strategies that are present prior to pain development. Control strategies during sagittal plane movement have not been previously investigated in this sample. The purpose of this research was to investigate neuromuscular control differences during the extension phase from trunk flexion between pain developers and non-pain developers. Methods: Continuous electromyography and kinematic data were collected during standing trunk flexion and extension on 43 participants (22 male) with an age range of 18–33 years, prior to entering into the prolonged standing exposure. Participants were classified as pain developer/non-pain developer by their pain response (≥10 mm increase on a 100 mm visual analog scale) during standing. Relative timing and sequencing data between muscle pairs were calculated through cross-correlation analyses, and evaluated by group and gender. Findings: Pain developers demonstrated a 'top-down' muscle recruitment strategy with lumbar extensors activated prior to gluteus maximus, while non-pain developers demonstrated a typical 'bottom-up' muscle recruitment strategy with gluteus maximus activated prior to lumbar extensors. Interpretation: Individuals predisposed to low back pain development during standing exhibited altered neuro-muscular strategies prior to pain development. These findings may help to characterize biomechanical movement profiles that could be important for early identification of people at risk for low back pain.
Effects of Static, Stationary, and Traveling Trunk Exercises on Muscle Activation
A new fitness trend incorporates stability exercises that challenges trunk muscles and introduces crawling as an exercise, but has yet to be investigated for muscle activity. Purpose: To compare the effects of static (STA), stationary (STN), and traveling (TRV) trunk exercises on muscle activation of the rectus abdominis, rectus femoris, external oblique, and erector spinae using surface electromyography (EMG). Methods: Seventeen recreationally active women (mean age ± SD = 22.4 ± 2.4 years, body mass 62.9 ± 6.9 kg, height 165.1 ± 5.8 cm) and twenty-three men (23.6 ±3.9 years, 83.2 ±17.1 kg, 177.1 ± 9.1 cm) volunteered to participate in this study. Subjects performed maximal voluntary contractions for normalization of each muscle's EMG activity. They then performed the three exercises in random order for thirty seconds each with a two-minute rest in between. Results: For the rectus abdominis, STA was significantly lower than STN (P = 0.003) and TRV (P = 0.001). For the external oblique, STA was significantly lower than STN (P = 0.001) and TRV (P = 0.001) and STN was significantly greater than TRV (P = 0.009). For the erector spinae and rectus femoris, STA was significantly lower than STN (P = 0.001) and TRV (P = 0.001) Conclusions: There was greater muscle activation in all muscles tested in the stationary and traveling exercises versus the static. Strength and conditioning coaches and allied health professionals could potentially use stationary and traveling forms of trunk stabilization exercises as a viable strategy to increase muscle activation.
Evaluation of the Flexion Relaxation Phenomenon of the Trunk Muscles in Sitting
Spine, 2006
Study Design. A normative, single-group study was conducted. Objective. To investigate the flexion relaxation phenomenon in the thoraco-lumbopelvic muscles among a pain-free population when moving from an upright to a slump sitting posture. Summary of Background Data. The presence of the flexion relaxation phenomenon (FRP) of the back muscles is well documented at end-range spinal flexion when standing. This phenomenon is commonly found disrupted in low back subjects. However, whether FRP occurs in sitting remains controversial. Methods. The sample consisted of 24 healthy painfree adults. Surface electromyography was used to measure activity in the superficial lumbar multifidus (SLM), the thoracic erector spinae (TES), and the transverse fibers of the internal oblique (IO) muscles while subjects moved from an erect to a slump sitting posture. An electromagnetic motion-tracking device simultaneously measured thoracolumbar kinematics during this task. Results. There was a significant decrease in both the SLM and the IO activity when moving from an erect to a slump sitting posture (P ϭ 0.001 and P ϭ 0.004, respectively), indicating the presence of FRP. TES activity was highly variable. While 13 subjects exhibited an increase in activity (P ϭ 0.001), 11 demonstrated a decrease in activity (P ϭ 0.001), indicating the presence of FRP. FRP occurred in the mid-range of spinal flexion for the SLM, IO and TES when present. Conclusion. The findings show that the SLM and the IO are facilitated in neutral lordotic sitting postures and exhibit FRP at mid range flexion while moving from upright sitting to slump sitting. These findings show that FRP in sitting differs from that in standing. Variable motor patterns (activation or FRP) of the TES were observed. These findings suggest that sustaining mid to end-range flexed sitting spinal postures result in relaxation of the spinal stabilizing muscles.