Muscle activity of the upper and lower rectus abdominis during exercises performed on and off a Swiss ball

This study sought to examine any differences in upper rectus abdominis (URA) and lower rectus abdominis (LRA) muscle activity during four abdominal exercises, the curl-up, Swiss ball curl-up, Swiss ball jackknife and Swiss ball rollout. Fourteen healthy adults (7 males, 7 females, mean age±S.D.=21.8±3.8 years) performed abdominal exercises in a randomised order following maximal voluntary isometric contraction. Muscle activity of the URA and LRA was assessed using surface electromyography. Results indicated that activity of the URA was significantly greater than muscle activity of the LRA for the curl-up, Swiss ball curl-up and Swiss ball rollout. LRA muscle activity was greater than URA during the jacknife exercise. Muscle activity during the curl-up was significantly lower than muscle activity during the other exercises. To conclude, muscle activity was greater when exercises were performed on a Swiss ball in comparison to a stable surface and LRA muscle activity was maximized during the Swiss ball jacknife.     

Comparison of the gluteus medius and rectus femoris muscle activities during natural sit-to-stand and sit-to-stand with hip abduction in young and older adults

[Purpose] The purpose of this study was to compare the relative levels of activation of the gluteus medius (Gmed) and rectus femoris (RF) muscles during natural (N) sit-to-stand (STS) and STS with hip abduction (ABD) in young and elderly females. [Subjects] We recruited 15 healthy young females and 15 healthy elderly females. [Methods] The activities of the dominant lower extremity gluteus medius (Gmed) and rectus femoris (RF) muscles were measured using a wireless electromyography (EMG) system for natural STS and STS with hip abduction. [Result] In the elderly subjects, the Gmed increased significantly and RF decreased significantly when STS was performed with hip ABD compared with when it was performed naturally. The Gmed in the elderly subjects was significantly increased during natural STS compared with in the young subjects. [Conclusion] These results indicate that the Gmed was recruited to compensate for weakened RF muscle function in the elderly adults.Key words: Gluteus medius, Sit-to-stand, Hip abduction     

EMG comparison of quadriceps femoris activity during knee extension and straight leg raises.

Both knee extension and straight leg raises have been used to rehabilitate atrophied quadriceps musculature following knee immobilization. A comparison of the tension developed during these two exercises was made in each of the three surface quadriceps muscles (quadriceps femoris, vastus lateralis, vastus medialis) at three different levels of activity (20%, 50%, and 80% of 1RM). Integrated EMG (m Volt-seconds) was used to measure tension developed during a seven second contraction. Tension developed was significantly greater during a seven second contraction. Tension developed was significantly greater during knee extension than during straight leg raises at each exercise intensity. For both exercises and at all three exercise levels, the vastus lateralis was the most active; the vastus medialis was the least active. The difference between knee extension and straight leg raises became greater with increasing levels of activity. Therefore, unless contraindicated by chondromalacia of lack of knee flexibility, knee extensions should be used for post-surgical knee rehabilitation. The greater tension development would lead to a more rapid return of strength, and therefore quicker rehabilitation.     

Muscle thickness and echo intensity measurements of the rectus femoris muscle of healthy subjects: Intra and interrater reliability of transducer tilt during ultrasound

This study aimed to assess the intra and interrater reliability of transducer tilt during the ultrasound (US) measurements of the muscle thickness and the echo intensity of the rectus femoris muscle (RF). Fourteen healthy male subjects (20.8 ± 0.8 years) participated in this study. The transducer tilt was measured using a digital angle gauge (°) during US. Two experimenters took two images to measure the muscle thickness (mm) and the echo intensity (a.u.: arbitrary unit). The intra and interclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were also calculated. These measurements were immediately repeated. The ICC for the intrarater reliability for the transducer tilt, muscle thickness, and echo intensity were 0.96 (SEM: 0.9°, MDC: 2.6°), 0.99 (SEM: 0.4 mm, MDC: 0.1 mm), and 0.97 (SEM: 0.6 a.u., MDC: 1.7 a.u.), respectively. The ICC for the interrater reliability for the transducer tilt, muscle thickness, and echo intensity were 0.40 (SEM: 4.0°, MDC: 11.1°), 0.96 (SEM: 0.7 mm, MDC: 2.0 mm), and 0.95 (SEM: 0.9 a.u., MDC: 2.4 a.u.), respectively. The intrarater reliability of the transducer tilt was reliable, but the interrater reliability was questionable. Meanwhile, both the intra- and interrater reliability of the muscle thickness and the echo intensity were reliable.     

Motor time of the rectus femoris during passive movements

Motor time (MT) of 10 normal subjects were examined in three conditions: 1) during passive flexion of the knee (PFLX), 2) during passive extension (PEXT), and without passive movement (STAT). Compared to STAT, MTs of PFLX and PEXT were significantly long. MT tended to be shorter, though insignificant statistically, in PFLX than in PEXT. In conclusion, passive movements are influential in changing the physical state of the muscle including both series-elastic and contractile components.     

Relationship between muscle echo intensity on ultrasound and isokinetic strength of the three superficial quadriceps femoris muscles in healthy young adults

[Purpose] The purpose of this study was to clarify the relationship between muscle echo intensity measured with ultrasound and the isokinetic strength of each of the three superficial quadriceps femoris muscles in healthy young adults. [Participants and Methods] We measured the echo intensity of the three superficial muscles of the quadriceps femoris in 25 healthy adults (10 males and 15 females; mean age, 22.3 years) using ultrasound. Moreover, we obtained the maximum force during isokinetic knee extension at 60°/s using an isokinetic dynamometer. [Results] In males and females, a significant negative correlation between echo intensity and muscle strength was found in the VM (r=−0.65 and r=−0.63, respectively). [Conclusion] In both males and females, only the muscle echo intensity of the vastus medialis was found to have a negative correlation with the maximum force during isokinetic knee extension at 60°/s. Our data lay the foundation for simplifying and rationally performing the measurement of muscle echo intensity of the quadriceps femoris. And it would therefore be sufficient to only measure the VM to clarify a relationship between EI and maximum isokinetic force in the quadriceps.Key words: Echo intensity, Isokinetic strength, Quadriceps femoris muscle     

Short vs. long length of rectus femoris during eccentric exercise in relation to muscle damage in healthy males

BACKGROUND: We investigated the effects of short vs. long length of rectus femoris during eccentric exercise of similar range of motion on selected muscle damage indicators. METHODS: Using an isokinetic dynamometer at 1.05 rad/s, 12 healthy male [mean (standard deviation), 21 (2) years] volunteers randomly underwent two exercise sessions, one on each leg, 14 days apart. During each session, subjects had to accomplish 12 sets of 10 maximal voluntary efforts in seated and prone positions to achieve short and long length of rectus femoris, respectively. Muscle damage indicators [serum creatine kinase activity, delayed onset muscle soreness, range of motion, eccentric peak torque, concentric peak torque and isometric peak torque] were assessed pre-exercise and 24, 48, 72 as well as 96 h post-exercise. FINDINGS: Compared to baseline data, creatine kinase, delayed onset muscle soreness, and range of motion disclosed significant changes at all time points after both exercise sessions (P<0.05). However, these muscle damage indicators demonstrated greater changes following exercise at short compared to long length of rectus femoris (P<0.05). Torque assessments also revealed that nine out of 12 and only two out of 12 measurements decreased significantly following short and long length eccentric exercise of rectus femoris, respectively (P<0.05). Short length eccentric exercise resulted in greater torque declines compared to long length during concentric and isometric evaluations (P<0.05). No such differences were observed when torque changes were evaluated eccentrically. INTERPRETATION: Short length of rectus femoris eccentric exercise induces greater muscle damage and peak torque declines than the corresponding long length in healthy adults.     

Reliability of the rectus femoris muscle cross-sectional area measurements by ultrasonography

The skeletal muscle system can adapt to an external stimulus from either physiological or pathological conditions. This plasticity is measured by imaging techniques such as magnetic resonance imaging or ultrasound. The anatomical cross-sectional area of a muscle is one of the muscle architecture parameters that relates to the maximum muscle strength. The aim of this study was to determine the reliability of anatomical cross-sectional area rectus femoris measurements, obtained by ultrasound, with two different protocols. Acquisition of four anatomical cross-sectional area images of the right rectus femoris in two distinct regions (15 cm above the patella and 50% of the thigh length) was performed in 2 days, from a group of 15 young healthy subjects. The cross-sectional area of each image was measured five times. The reliability of the anatomical cross-sectional area measures was determined by the coefficient of variation (CV), intraclass correlation coefficient (ICC) and typical error of measurement (TEM). In each protocol, there were no significant differences between the means of anatomical cross-sectional area in measurements, images and days (P>0·05). The CVs were 8·53% and 8·9%, the ICCs 0·88 and 0·87 and the TEMs 65·59 and 94·25 between the 2 days in the regions of 15 cm and 50% of the thigh length, respectively. The average values of the cross-sectional area at 50% of the thigh length were significantly higher than those for at 15 cm above the patella (P<0·001). The measurement of rectus femoris anatomical cross-sectional area by ultrasound proved reliable.     

Relationship between joint motion and acceleration during single-leg standing in healthy male adults

[Purpose] The purpose of this study was to clarify the relationship between acceleration and joint movement by synchronizing accelerometers and a three-dimensional motion analysis system, and to show the utility of an accelerometer as a postural control assessment tool. [Subjects and Methods] Head, lumbar, shank accelerations and various joint angles during single-leg standing were measured of 20 healthy males. Root mean squares of acceleration and joint angle were calculated. Fast Fourier transform analysis was performed for head, lumbar, and shank accelerations, and the median frequencies were calculated. Then, principal component analysis was performed for the median frequency of each acceleration. Stepwise multiple regression analysis was also used to examine the relationship between joint angle and acceleration. [Results] The score of the first principal component was highest for shank acceleration, while that of the second principal component was highest for lumbar and head accelerations. In multiple regression analysis, hip flexion/extension and adduction/abduction were identified as variables associated with head acceleration. [Conclusion] We were able to confirm the aggregation of acceleration into two components, which we interpreted as postural control strategies using primarily the ankle and hip joints. Furthermore, though multiple regression analysis, we were able to clarify the joint movement indicated by acceleration of each segment.Key words: Postural control, Acceleration, Ankle sprain     

10例双蒂横行腹直肌皮瓣转移乳房再造术的护理

总结了10例双蒂横行腹直肌皮瓣(双蒂TRAM)转移乳房再造术的护理经验.术前加强有针对性的心理护理,保护供区部位皮肤;术后给予正确的体位护理及充分合理的营养支持,采用红外线照射等方法,保护转移肌皮瓣;密切观察引流液的颜色、性质和量,保持引流管的通畅,认真观察有无肌皮辩坏死和皮瓣感染的发生.本组发生肌皮瓣感染2例,皮下积液1例,经积极治疗和护理,皮瓣愈合良好.术后患者再造乳房塑形良好,按计划进行化疗.     

Kinematic analysis during toe-gripping strength exertion: angular changes in the ankle joint and leg muscle activities

[Purposes] To investigate angular changes in the ankle joint and leg muscle activities during toe-gripping, and to examine the relationship between these changes and toe-gripping strength. [Subjects] Eleven healthy young women were selected. [Methods] We measured the toe-gripping strength, angular changes in the ankle joint, and leg muscle activities of all patients during toe-gripping. [Results] The mean change in the ankle angle in dorsiflexion from a neutral position was 3°, and a positive correlation was observed between this angle and toe-gripping strength (r = 0.61). Thus, toe-gripping strength increased with the angle of dorsiflexion. Regarding the leg muscle activities, activities of the tibialis anterior muscle and medial head of the gastrocnemius muscle demonstrated positive correlations with toe-gripping strength (r = 0.75 and r = 0.72, respectively). [Conclusion] These findings suggest that the ankle dorsiflexes in order to exert great toe-gripping strength, and the crural muscles contract simultaneously because of ankle fixation.Key words: Toe-gripping strength, Angle of the ankle joint, Kinematic analyses     

Relationship between Muscle Fiber Conduction Velocity and the Force-time Curve during Muscle Twitches

[Purpose] The aim of this study was to clarify the relationship between the muscle fiber conduction velocity (MFCV) obtained during muscle twitches from evoked potentials and the dynamic characteristics of muscular tension (muscle dynamic characteristics) by manipulating deep temperature. [Subjects] Subjects were 10 healthy adult men. Their mean age was 23.0 ± 3.9 years. [Methods] Measurement items were MFCV of the right tibialis anterior muscle and the force-time curve of right ankle dorsiflexion (muscle twitch). Measurements were made under conditions of ordinary (room) temperature, hot and cold. The rate of change in maximum torque was calculated from the force-time curve. [Results] In all subjects, MFCV increased significantly with heating and decreased significantly with cooling. A strong correlation was seen between MFCV and deep temperature. A strong correlation was also seen between MFCV and the rate of change in maximum torque. Stronger correlations were seen in the present results than in previous studies that conducted investigations using voluntary contractions. [Conclusion] The present results were not affected by psychological or other such factors, and are valuable as data with high physiological reliability. In conclusion, this study was able to clarify the relationship between MFCV from evoked potentials and muscle dynamic characteristics.Key words: Muscle fiber conduction velocity, Dynamic characteristics of muscular tension, Muscle twitches     

高频超声对腹直肌及其周围疾病的诊断价值

目的探讨腹直肌及其周围病变的声像图特点及高频超声检查特异性。方法研究对象为38例经临床确诊的腹直肌及其周围病变患者,其中男17例,女21例,年龄28d至65岁,平均(38.2±1.6)岁,采用高频探头对腹直肌及其周围进行纵、横、斜切扫查,将资料分为损伤性病变、感染性病变、肿瘤性及肿瘤样病变三大类,分析各类疾病的声像图特点及超声检查特异性。结果高频超声对腹直肌及其周围病变的敏感性为97.4%(37/38),特异性73.7%(28/38),其中损伤性病变、感染性病变、肿瘤性及肿瘤样病变特异性分别为75.0%(9/12)、90.0%(9/10)、62.5%(10/16)。结论高频超声对腹直肌及其周围感染性病变及损伤性病变具有较高的特异性,对肿瘤性及肿瘤样病变特异性较低,可作为首选的影像学检查方法。     

Avulsion fracture of the straight and reflected heads of rectus femoris.

We present a rare case of avulsion fracture of the reflected head of rectus femoris. This occurred in a 13-year-old male footballer. Diagnosis was made with pelvic radiology and treatment was bed rest and analgesia.     

Influence of angular velocity on vastus lateralis and rectus femoris oxygenation dynamics during knee extension exercises

The purpose of this study was to investigate whether changes in angular velocity would alter vastus lateralis (VL) and rectus femoris (RF) oxygenation status during maximal isokinetic knee extension exercises. Eleven recreationally active male participants randomly performed ten maximal knee extensions at 30, 60, 120 and 240° s(-1). Tissue oxygenation index (TOI) and total haemoglobin concentration ([tHb]) were acquired from the VL and RF muscles by means of near-infrared spectroscopy (NIRS). Breath-by-breath pulmonary oxygen consumption (VO(2p)) was recorded throughout the tests. Peak torque and VO(2p) significantly decreased as a function of velocity (P<0·05). Interestingly, RF and VL TOI significantly increased as a function of velocity (P<0·05), whereas [tHb] significantly decreased as a function of velocity (P<0·05). A greater number of muscle fibre recruited at slow velocity, where the torque and VO(2p) were the highest, might explain the lower VL and RF TOI observed herein. Furthermore, the increase in local blood flow (suggested by [tHb] changes) during isokinetic knee extension exercises performed at slow angular velocity might have been induced by a higher intramuscular pressure during the contraction phases as well as a greater microcirculatory vasodilatation during relaxation phases. Implementing slow-velocity isokinetic exercises in rehabilitation or other training programmes could delay the short-term anoxia generated by such exercises and result in muscle metabolism enhancement.     

In vivo measurement of human rectus femoris architecture by ultrasonography: validity and applicability

The architectural feature of the rectus femoris (RF) has been scarcely investigated despite its substantial contribution to knee extension torque and large plasticity in the muscularity. This study aimed to examine the reproducibility and validity of ultrasound measurements of RF architecture and interrelationships among the architectural parameters. After confirming the measurement accuracy of an examiner (measurement errors <1%), in vivo and cadaveric measurements of fascicle lengths and pennation angles of RF were performed. Day‐to‐day reproducibility of measurements was investigated in vivo including muscle thickness measurement. Validity of measurements was investigated by comparing the values between direct and ultrasound measurements for the cadaver. The intraclass correlation coefficients were 0·984, 0·960 and 0·932, and root mean square difference between measured values on 2 days was 0·8 mm, 3·1 mm and 1·4° for muscle thickness, fascicle length and pennation angle, respectively. The validity of measurements was similar or better than those of previous reports on other muscles. We also confirmed a positive correlation between the muscle thickness and the pennation angle as has been shown in other muscles. The current results warrant the use of B‐mode ultrasonography for examining the architectural characteristics of RF in vivo.     

Association between Muscle Synergy and Stability during Prolonged Walking

[Purpose] The purpose of this study was to examine whether changes in muscle synergy could affect gait stability or muscle activity by comparing muscle activity before and after prolonged walking. [Subjects and Methods] Twelve healthy male subjects walked on a treadmill for 10 min as a warm-up. Data were recorded from the participants during the first and last 1 min during 90 min of walking at 4.5 km/h. Electromyographic (EMG) activity was recorded for 7 leg muscles, and patterns of coordination were determined by principal component analysis (PCA). The patterns of activity within the anatomic muscle groups were additionally determined by repeating PCA. iEMG was calculated using the mean EMG for each cycle step during the 1 min walking periods. The largest Lyapunov exponent was calculated to quantify each subject’s inherent local dynamic stability. [Results] The patterns for each of the 7 muscles showed no change between the start and end periods. However, the end period showed a higher co-activation of the triceps surae, lower iEMG of the medial gastrocnemius, and a smaller largest Lyapunov exponent of the mediolateral and anteroposterior directions than those observed during the start period. [Conclusion] The increase in triceps surae co-activation may be associated with gait stability.Key words: Muscle synergy, Muscle activity, Gait stability     

Effects of closed chain exercises for the lumbar region performed with local vibration applied to an unstable support surface on the thickness and length of the transverse abdominis

[Purpose] This study examined the effects of closed chain exercises performed with local vibration applied to an unstable support surface on the thickness and length of the transverse abdominis. [Subjects] The subjects were 64 healthy university students who were randomly assigned to a bridge exercise with sling and vibration group (BESVG, n=30) and a bridge exercise with sling group (BESG, n=34). [Methods] The bridge exercise was repeated four times per set and a total of 18 sets were performed: 9 sets in a supine position and 9 sets in a prone position. In both the BESVG and the BESG groups, the thickness and length of the transverse abdominis (TrA) were measured using ultrasonography with the abdomen “drawn-in” and the pressure of a biofeedback unit maintained at 40 mmHg, both before and after the intervention. [Results] In intra-group comparisons, the BESVG showed significant increases in the thickness of the TrA and significant decreases in the length of the TrA. The BESG showed significant increases in the thickness of the TrA. The BESVG showed significant increases in the thickness of the TrA and significant decreases in the length of the TrA compared to BESG. [Conclusion] Closed chain exercises for the lumbar region performed with local vibration applied to slings, which are unstable support surfaces, are an effective intervention for altering the thickness and length of the TrA.Key words: Closed chain exercise, Vibration, Transverse abdominis     

Hip Muscle Activity during Isometric Contraction of Hip Abduction

[Purpose] This study aimed to determine the effect of varying hip flexion angle on hip muscle activity during isometric contraction in abduction. [Subjects] Twenty-seven healthy men (mean age=21.5 years, SD=1.2) participated in this study. [Methods] Surface electromyography (EMG) was recorded of the upper portion of the gluteus maximus (UGM), lower portion of the gluteus maximus (LGM), tensor fasciae latae (TFL), and gluteus medius (GMed) during isometric contraction under two measurement conditions: hip flexion angle (0, 20, 40, 60, and 80 degrees) and abduction of the hip joint at 20, 40, 60, and 80% maximum strength. Integrated EMG (IEMG) were calculated and normalized to the value of maximum voluntary contraction (MVC). [Results] Results indicated that the IEMG of both the UGM and LGM increased significantly with increases in hip flexion angle, whereas the IEMG of the TFL decreased significantly. The maximum activities of the UGM and the LGM were 85.7 ± 80.8%MVC and 38.2 ± 32.9%MVC at 80 degrees of hip flexion, respectively, and that of the TFL was 71.0 ± 39.0%MVC at 40 degrees of hip flexion. [Conclusion] The IEMG of the GMed did not change with increases in hip flexion angle. Hip flexion angle affected the activity of the GM and TFL during isometric contraction in abduction.Key words: Hip abductor, Electromyography, Muscle activity     

Effect of botulinum toxin injection on length and lengthening velocity of rectus femoris during gait in hemiparetic patients

Background

In hemiparetic patients, rectus femoris spasticity is one of the main causes of reduced knee flexion in swing phase, known as stiff knee gait. Botulinum toxin is often used to reduce rectus femoris spasticity and to increase knee flexion during swing phase. However, the mechanisms behind these improvements remain poorly understood. The aim of this study was (1) to quantify maximal rectus femoris length and lengthening velocity during gait in ten adult hemiparetic subjects with rectus femoris spasticity and stiff knee gait and to compare these parameters with those of ten healthy subjects and (2) to study the effect of botulinum toxin injection in the rectus femoris muscle on the same parameters.

Methods

10 patients with stiff knee gait and rectus femoris spasticity underwent 3D gait analysis before and one month after botulinum toxin injection of the rectus femoris (200 U Botox®, Allergan Inc., Markham, Ontario, CANADA). Rectus femoris length and lengthening velocity were quantified using a musculoskeletal model (SIMM®, MusculoGraphics, Inc., Santa Rosa, California, USA).

Findings

Maximal length and lengthening velocity of the rectus femoris were significantly reduced on the paretic side. There was a significant increase in muscle length as well as lengthening velocity during gait following botulinum toxin injection.

Interpretation

This study showed that botulinum toxin injection in the spastic rectus femoris of hemiparetic patients improves muscle kinematics during gait. However maximal rectus femoris length did not reach normal values following injection, suggesting that other mechanisms are likely involved.