Right Rectus Abdominis Research Articles

Perceived Muscle Soreness Does Not Modulate Corticospinal Excitability

Soreness due to exercise-induced muscle damage temporarily impairs motor performance. Transcranial magnetic stimulation (TMS) is often used to assess subtle changes in corticospinal excitability (CSE) and motor system input-output properties and demonstrates sensitivity to chronic pain. Nevertheless, the acute effects of muscle soreness on TMS-based measures of corticospinal excitability require further investigation. PURPOSE: To examine the relationship between perceived muscle soreness and CSE of postural and lower-extremity muscles. METHODS: 12 healthy adults (3 W, age: 27.2 ± 5.4 yr, ht: 175.6 ± 11.0 cm, wt: 72.6 ± 13.4 kg) completed three visits with maximal anaerobic lower extremity exercise. At the start of each visit, participants confirmed they abstained from any physical activity 24 hr prior, and rated their overall residual muscle soreness using a 100 mm visual analog scale. Visits were ranked based on muscle soreness with the highest and lowest soreness visits retained for analysis. To assess CSE, electromyographic motor-evoked potentials (MEPs) were recorded from the right rectus abdominis (RA) and vastus lateralis (VL). Active motor thresholds (AMT) were determined for each muscle during 15% of maximal voluntary isometric force using a biphasic stimulator and 96 mm curved double coil. To determine CSE, ten TMS pulses were applied to each M1 hotspot at 120% AMT with the resultant MEPs averaged based on peak-to-peak amplitude from 15-65 ms post-stimulus. Paired-samples t-test were used to assess mean differences in soreness, AMT, and MEP amplitudes. RESULTS: As expected, muscle soreness differed between visits (mean difference: 25.3 mm, t = 5.08, p < 0.01). Similar motor-thresholds were observed for the RA (mean difference: 0.3%, t = 0.26, p = 0.80) and VL (mean difference: 0.5%, t = 0.45, p = 0.66). MEP amplitudes were also similar for the RA (mean difference: 0.13 mV, t = 1.74, p = 0.12) and VL (mean difference: 0.01 mV, t = 0.30, p = 0.77). CONCLUSION: Day-to-day variation in CSE during lower extremity and axial contractions is not explained by differences in muscle soreness. Future work should examine CSE at multiple timepoints after acute exercise and use various submaximal intensities to further clarify whether CSE is responsive to muscle soreness.

Congenital absence of the deep inferior epigastric system: a case report

Preoperative computerised tomographic angiography (CTA) in free flap breast reconstruction outlines the deep inferior epigastric perforator (DIEP). It can identify a single or twin system, measure vessel calibre, and identify iatrogenic/congenital anatomical variations. Evidence of the effect of previous abdominal incisions on this vessel system remain inconclusive. We present the case of a congenital absence of the system identified from routine preoperative CTA. A 61-year-old female presented for immediate unilateral breast reconstruction following mastectomy for ductal carcinoma in situ. She previously had a right-sided Kocher’s incision performed for an open cholecystectomy and a gridiron incision. Coincidentally, preoperative CTA demonstrated congenital absence of the left DIEP system, and marked atrophy of the upper right rectus abdominis (RA). As a result, the superior gluteal artery perforator (SGAP) flap was planned. Intraoperatively, a 1.318-kg SGAP was raised on three perforators and coupled to the internal mammary vessels. In the postoperative period, there were no complications. Preoperative CTA demonstrated multiple hazards in raising a DIEP flap, CTA permitted surgical planning, improving patient safety and surgical efficiency. Preoperative CTA identifies vessel abnormalities resulting from abdominal scarring. The rate of congenital anomalies is unknown. This incidental discovery highlights the role CTA has in reducing operative time, facilitating a successful free tissue transfer, therefore improving patient safety.Level of Evidence: Level V, diagnostic study.

Differential control of abdominal muscles during multi-directional support-surface translations in man

The current study aimed to understand how deep and superficial abdominal muscles are coordinated with respect to activation onset times and amplitudes in response to unpredictable support-surface translations delivered in multiple directions. Electromyographic (EMG) data were recorded intra-muscularly using fine-wire electrodes inserted into the right rectus abdominis (RA), obliquus externus (OE), obliquus internus (OI) and transversus abdominis (TrA) muscles. Twelve young healthy male subjects were instructed to maintain their standing balance during 40 support surface translations (peak acceleration 1.3 m s(-2); total displacement 0.6 m) that were counter-balanced between four different directions (forward, backward, leftward, rightward). Differences between abdominal muscles in EMG onset times were found for specific translation directions. The more superficial RA (backward translations) and OE (forward and leftward translations) muscles had significantly earlier EMG onsets compared to TrA. EMG onset latencies were dependent on translation direction in RA, OE and OI, but independent of direction in TrA. EMG amplitudes in RA and OE were dependent on translation direction within the first 100 ms of activity, whereas responses from the two deeper muscles (TrA and OI) were independent of translation direction during this interval. The current results provide new insights into how abdominal muscles contribute to postural reactions during human stance. Response patterns of deep and superficial abdominal muscles during support surface translations are unlike those previously described during upper-body perturbations or voluntary arm movements, indicating that the neural mechanisms controlling individual abdominal muscles are task-specific to different postural demands.

들기/내리기 빈도와 회복시간 변화에 따른 몸통 근육의 피로도 분석

The purpose of this study was to investigate the relationship between the cumulative fatigue of trunk muscles and the period of recovery time during repetitive lifting and lowering task with two different frequencies(4 times/min and 6 times/min). Eight healthy males with no prior history of LBD(low back disorders) volunteered for this study. Subjects had 2, 3, 4, and 5 minutes recovery time respectively while they were preforming the lifting and lowering task at 15% level of MVC. EMG signals from six trunk muscles were collected and the fatigue level was analyzed quantitatively. In results, the fatigue levels of LES(left elector spinae), RLD(right lattissimus dorsi), LLD(left lattissimus dorsi), RRA(right rectus abdominis) and LRA(left rectus abdominis) were recovered when 3 minutes recovery time was given at 4 times/min frequency. However, the fatgue level of RES(right elector spinae) was recovered when 4 minutes recovery was given. On the other hand, when 6 times/min frequency was used, the RLD, LLD, RRA and LRA were recovered at 5 minutes of recovery time. But for RES and LES, it took longer than 5 minutes to be recovered. This results can be applied to design the adequate length of recovery time to control the cumulative fatigue of trunk muscles in industry with repetitive lifting and lowering task.

Quantifying Muscle Patterns and Spine Load during Various Forms of the Push-Up

This study was conducted to quantify the normalized amplitudes of the abdominal wall and back extensor musculature during a variety of push-up styles. We also sought to quantify their impact on spinal loading by calculating spinal compression and torque generation in the L4-5 area. Ten university-age participants, nine males and one female, in good to excellent condition, volunteered to participate in this study. All participants were requested to perform a maximum of 12 different push-up exercises, three trials per exercise. Surface electromyographic data (EMG) were collected bilaterally on rectus abdominis, external oblique, internal oblique, latissimus dorsi, and erector spinae muscles, and unilaterally (right side) on pectoralis major, triceps brachii, biceps brachii, and anterior deltoid muscles. Spine kinetics were obtained using an anatomically detailed model of the torso/spine. This study revealed that more dynamic push-ups (i.e., ballistic, with hand movement) required more muscle activation and higher spine load, whereas placing labile balls under the hands only resulted in modest increases in spine load. Right rectus abdominis (RA) activation was significantly higher than left RA activation during the left hand forward push-up and vice versa for the right hand forward push-up (P < 0.001). External oblique (EO) demonstrated the same switch in dominance during staggered hand push-ups (P < 0.01). The one-arm push-up resulted in the highest spine compression. Skilled participants showed greater synchronicity with peak muscle activation (plyometric type of contractions) during ballistic push-ups. These data will help guide exercise selection for individuals with differing training objectives and injury history.

Differential activity of regions of transversus abdominis during trunk rotation

The role of the abdominal muscles in trunk rotation is not comprehensively understood. This study investigated the electromyographic (EMG) activity of anatomically distinct regions of the abdominal muscles during trunk rotation in six subjects with no history of spinal pain. Fine-wire electrodes were inserted into the right abdominal wall; upper region of transversus abdominis (TrA), middle region of TrA, obliquus internus abdominis (OI) and obliquus externus abdominis (OE), and lower region of TrA and OI. Surface electrodes were placed over right rectus abdominis (RA). Subjects performed trunk rotation to the left and right in sitting by rotating their pelvis relative to a fixed thorax. EMG activity was recorded in relaxed supine and sitting, and during an isometric hold at end range. TrA was consistently active during trunk rotation, with the recruitment patterns of the upper fascicles opposite to that of the middle and lower fascicles. During left rotation, there was greater activity of the lower and middle regions of contralateral TrA and the lower region of contralateral OI. The upper region of ipsilateral TrA and OE were predominately active during right rotation. In contrast, there was no difference in activity of RA and middle OI between directions (although middle OI was different between directions for all but one subject). This study indicates that TrA is active during trunk rotation, but this activity varies between muscle regions. These normative data will assist in understanding the role of TrA in lumbopelvic control and movement, and the effect of spinal pain on abdominal muscle recruitment.

LOWER TRUNK MUSCLE ACTIVITY DURING THE TENNIS SERVE

971 The purpose of this study was to examine the activation patterns of the left and right rectus abdominis (RA), external oblique (EO), internal oblique(IO), and lumbar erector spinae (ES) muscles during three different types of tennis serve - flat, topspin, and slice - using surface electromyographic(EMG) techniques. Five male collegiate tennis players served as the subjects. Each subject performed 10 trials for each serve type and the average values of two selected trials for each serve type were used for analysis. Average EMG values were computed for different phases of a tennis serve. Means were compared across serve type using an ANOVA for repeated measures (p ≤.05). The results showed no major difference in muscle activation pattern across serve type and that bilateral differences in muscle activation were more pronounced in the RA and EO than in the IO and ES. In general, the left muscle activity was more pronounced than the right over a greater duration during the serve. In the acceleration phase (from end of windup to ball impact), bilateral difference was found only in RAs. This suggests that the obliques are responsible for the trunk flexion and RAs help to maintain the side-bent posture during this phase. The abdominal muscles seemed to be more active in the topspin than the other two types of serve during the upward swing of the racket. A high degree of abdominal/low back and bilateral co-contraction was observed during certain phases of the serve. The co-contractions and the hyperlordotic posture may place considerable stress on the lumbar intervertebral joints and cause lumbar spine injury.