Systematic review of the synergist muscle ablation model for compensatory hypertrophy / Revisão sistemática do modelo de ablação dos músculos sinérgicos na hipertrofia compensatória

Summary Objective: The aim was to evaluate the effectiveness of the experimental synergists muscle ablation model to promote muscle hypertrophy, determine the period of greatest hypertrophy and its influence on muscle fiber types and determine differences in bilateral and unilateral removal to reduce the number of animals used in this model. Method: Following the application of the eligibility criteria for the mechanical overload of the plantar muscle in rats, nineteen papers were included in the review. Results: The results reveal a greatest hypertrophy occurring between days 12 and 15, and based on the findings, synergist muscle ablation is an efficient model for achieving rapid hypertrophy and the contralateral limb can be used as there was no difference between unilateral and bilateral surgery, which reduces the number of animals used in this model. Conclusion: This model differs from other overload models (exercise and training) regarding the characteristics involved in the hypertrophy process (acute) and result in a chronic muscle adaptation with selective regulation and modification of fast-twitch fibers in skeletal muscle. This is an efficient and rapid model for compensatory hypertrophy.

Resumo Objetivo: Avaliar a eficácia do modelo experimental de ablação dos sinergistas para promover a hipertrofia muscular, determinar o período de maior hipertrofia, sua influência sobre os tipos de fibras musculares e determinar diferenças na remoção unilateral ou bilateral para reduzir o número de animais utilizados nesse modelo. Método: Após a aplicação dos critérios de elegibilidade para sobrecarga mecânica do músculo plantar em ratos, 19 artigos foram incluídos na revisão. Resultados: Ocorre maior hipertrofia entre os dias 12 e 15, o que torna o modelo eficiente para alcançar a hipertrofia rapidamente. O membro contralateral também pode ser usado, pois não houve diferença entre a cirurgia unilateral e bilateral, o que reduz o número de animais usados no experimento. Conclusão: O modelo difere de outros modelos de sobrecarga (exercício e treinamento) em razão das características envolvidas no processo de sobrecarga imposta (aguda), resultando em uma adaptação crônica muscular com modificação de fibras de contração rápida do músculo esquelético. É um modelo rápido e eficiente para se estudar hipertrofia compensatória.

Age- and athletic event-related differences in trunk muscularity in junior athletes: A comparison with the results for the senior athletes / 体力科学

<p>The purpose of this study was to examine the age- and athletic event-related differences in trunk muscularity among junior and senior athletes. The cross-sectional areas (CSAs) of the rectus abdominis, lateral abdominal muscle group, psoas major and erector spinae were determined on magnetic resonance imaging for 188 junior athletes aged 12-18 years and 164 senior athletes aged ≥ 19 years in six different athletic events (male: archery, table tennis, Nordic combined, basketball, and wrestling; female: archery, table tennis, and gymnastics). To examine the age-related differences for each athletic event and sex, the subjects were classified into the following age groups: 12-15 years, 16-18 years and senior (≥ 19 years). The main results were as follows. 1) The magnitude relationships of trunk muscle CSA/height² differed among the age groups by athletic event and muscle. 2) The values of CSA/height² of the lateral abdominal muscle group and erector spinae were significantly larger in female gymnasts aged 12-15 years than in female athletes from the other athletic events. These results respectively indicated that 1) each trunk muscle has the potential to specifically develop according to the athletic events and 2) selective hypertrophy of the trunk muscles can be induced by training reflecting athletic event-specific characteristics in female junior high school athletes.</p>

Comparison of Ultrasonography and Magnetic Resonance Imaging in Measurement of Lumbar Muscles / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to compare magnetic resonance imaging (MRI) and ultrasonography measurement of peri-lumbar muscle atrophy which is thought to be a cause of low back pain. MATERIALS AND METHODS: Eighty-two patients (44 males, 38 females) who visited Wonkang University Hospital from March, 2015 to August, 2015 complaining of lumbar back pain and underwent lumbar MRI were enrolled in this study. Cross section area (CSAMRI) and muscle thickness (MTMRI) of psoas major (PS) and lumbar extensor (LM) located on both sides of L4/5 and L3/4 was measured by MRI, and sono measurement of thickness of the same muscle (MTUS) at the same level of that MRI measurement were analyzed. RESULTS: In correlation analysis of PS CSAMRI and PS MTUS is the correlation coefficient of L4/5 was 0.136 (p=0.64), L3/4 right (Rt) was 0.070 (p=0.81), and L3/4 left (Lt) was 0.288 (p=0.32). PS CSAMRI at L4/5 Rt showed that correlation coefficient of PS MTUS showed a positive correlation to 0.559 (p=0.04). In analysis of the PS MTMRI and PS MTUS, the correlation coefficient of L4/5 Rt was measured by a 0.316 (p=0.27), L4/5 Lt was 0.022 (p=0.94), L3/4 Rt was 0.236 (p=0.41), and L3/4 Lt did not show a significant result with 0.287 (p=0.31). In the results of correlation analysis of the LM MTMRI and LM MTUS, the correlation coefficient of L4/5 Rt was 0.207 (p=0.49), L4/5 Lt was 0.051 (p=0.86), and L3/4 was Rt 0.048 (p=0.87), L3/4 Lt did not show a significant value with 0.154 (p=0.61). CONCLUSION: This study proved that muscle volume obtained from ultrasono is effective for evaluation of cross-sectional area of lumbar muscle.

Efeito de diferentes doses de nandrolona associado ao treinamento de força sobre o perfil fenotípico e área de secção transversa do músculo de ratos / Effect of different doses of nandrolone associated with resistance training on muscle phenotypic profi le and cross-sectional area of rats

O presente estudo avaliou a influência de diferentes doses de decanoato de nandrolona (DN) associado ao Treinamento de Força (TF) sobre o fenótipo de fibras e área de secção transversa (AST) do músculo extensor longo dos dedos (EDL) em ratos "Wistar". Os animais foram divididos em sete grupos: controle (GC) e grupos de acordo com a concentração de DN (0,1, 1, 2, 5, 10 e 20 mg/kg) administrada intramuscular 3 vezes/semana. O TF consistiu de saltos em meio líquido (carga 50-70% do peso corporal) 3x/semana, durante cinco semanas. A associação do TF e DN promoveu ação modulatória sobre os tipos de fibras. Houve hipertrofia das fibras de contração rápida (tipo II) em comparação com as fibras de contração lenta (tipo I). Em conclusão, apesar da associação do TF com DN aumentar a AST muscular e alterar o fenótipo das fibras, não houve efeito gradual das doses mais altas.

The aim of the present study was to evaluate the influence of different doses of nandrolone decanoate (ND) associated with Strength Training (ST) on the phenotype of fibers and cross-sectional area (CSA) of the extensor digitorum longus (EDL) in Wistar rats. The animals were divided into seven groups: control (CG) and the groups according to the dose of ND administered (0,1, 1, 2, 5, 10 e 20 mg/kg). The ST consisted of water jumping with loads of 50-70% of their body mass, three times per week during five weeks. The association of ST with ND promoted a modulatory role on the muscle fiber types. There was a hypertrophy of fast twitch fibers (type II) as compared with slow twitch (type I). In conclusion, although the association of ST with ND increased muscle CSA and modified fiber phenotype, there was no additional effect of higher doses.

Exercise profile during cycling, and fitness and health level among middle and older adults with a cycling habit / 体力科学

This study evaluated the exercise profile (heart rate, cycling speed and pedal cadence) during 25-30 km cycling and fitness and health level for adults (11 males: 69.6 ± 4.7 yrs; 6 females: 66.3 ± 4.9 yrs) with a recreational cycling habit (27.6 ± 14.8 km/week). Exercise intensity at a constant speed on a flat road during male and female cycling was 71.2 ± 11.5 and 66.8 ± 11.4% heart rate reserved (HRR), respectively. Exercise intensity over 60% HRR occupied 72% of cycling time. Peak intensity during male and female cycling was 89.2 ± 8.9 and 93.1 ± 6.1% HRR, respectively. VO2max and CS (chair stand)-30 test for male and female were 40.3 ± 4.3 and 37.7 ± 2.4 ml/kg/min, and 30.8 ± 3.1 and 30.1 ± 3.2 times, respectively. The muscle cross-sectional area of thigh extensor and flexor measured by MRI were 55.4 ± 6.5 and 58.3 ± 13.3 cm² for male, and 45.5 ± 6.4 and 50.2 ± 5.7 cm² for female, respectively. Blood profile for HDL-C (cholesterol), LDL-C and HbA1c (JDS) for male and female were 65.9 ± 8.2 and 67.9 ± 10.6 mg/dl, 112.3 ± 32.0 and 130.6 ± 12.3 mg/dl, and 4.8 ± 0.4 and 4.7 ± 0.1%, respectively. Fitness level and blood profile results were superior to those of the same aged adults. We concluded that the exercise intensity of cycling by middle and older adults with a recreational cycling habit is high and their fitness and health level are higher than average adults.

Quantitative Correlations of Trunk Muscles in Young and Middle-aged Men with Chronic Low Back Pain by Magnetic Resonance Imaging

OBJECTIVE: To evaluate the correlation of the cross-sectional areas (CSA) of paraspinal (multifidus and erector spinae) and psoas muscles and chronic low back pain by MRI (magnetic resonance image) in young and middle-aged patients. METHOD: Medical records of eighty subjects (50 young-aged and 30 middle-aged men) with low back pain were retrospectively reviewed. Their MR images were scanned and analysed by means of pixel to find the lumbar paraspinal and psoas muscle CSA and evaluated the correlation of the types of disc and age. RESULTS: There were significant increases of body mass index (BMI) in middle-aged patients compared with young- aged, and no difference in the disc types. Paraspinal muscle atrophy was increased in young patients with HIVD (herniated intervertebral disc), but not in middle-aged patients although they had HIVD. CONCLUSION: The paraspinal and psoas muscle atrophy could be assessed by MRI of lumbar spine in young patient with chronic low back pain. It may helpful for further evaluation and planning the treatment of low back pain.

Correlation between Cross-sectional Areas of Paraspinal Muscles and Isometric Lumbar Extension Strength

OBJECTIVE: To evaluate the correlation of the cross-sectional areas (CSA) of paraspinal muscles (back extensors and psoas muscles) and full range-of-motion isometric lumbar extension strength in the individuals with low back pain. METHOD: Twenty four subjects (14 men and 10 women) with low back pain completed a maximum isometric lumbar extension strength test at seven angles through a 72degrees range of motion (0, 12, 24, 36, 48, 60, 72 degrees of lumbar flexion). CSA of back extensors and psoas muscles were measured from standardized transaxial view by CT scanner. RESULTS: CSA of lumbar extensor and psoas were correlated with isometric lumbar extension strength from full flexion to extension in the low back pain patients. The greater the lumbar flexion angle, the greater the coefficient of determination (R2). The correlation coefficients of psoas muscles were greater than those of lumbar extensors. CONCLUSION: Both back extensors and psoas muscles do their important role during isometric lumbar extension. Isometric lumbar extension strength of full lumbar flexion is well correlated with CSA of paraspinal muscles.

Relationship Between Reduction of Hip Joint and Thigh Muscle and Walking Ability in Elderly People / 体力科学

The purpose of this study was to investigate the hypothesis that the reduction in walking ability is due to muscle atrophy in the lower limb muscles with aging using equational structure modeling as well as investigate the influence of muscle on walking ability. The subjects consisted of 127 persons (57 males and 70 females) aged 20-84 year, who were grouped into 6 age brackets of 20-39, 40-49, 50-59, 60-69, 70-74, and 75 or older. Using MRI, muscle cross-sectional area was measured on psoas major and thigh muscle (divided into extensor and flexor) . For walking patterns, each subject walked along a 7-m walking passage at normal speed for VTR-recording of the motion. The resulting pictures were used to analyze stride length, trunk inclination and walking speeds. Walking speeds showed a statistically significant decrease in value from the 50's age group in males and the 60's age group in females when compared with the 20-39 age bracket (p<0.05) . In males, a significant co-relationship was observed only between the muscle cross-sectional area of thigh extensor and walking speed (p<0.01) while in females, a significant co-relationship was found between the muscle cross-sectional area of psoas major (p<0.001) /thigh muscle extensor (p<0.01) and walking speed. These results indicate that the muscle atrophy with aging in psoas major and thigh muscle extensor is a factor responsible for the decrease in walking speed. Meanwhile, a difference in sex was observed between the muscle cross-sectional area of psoas major and walking speed. It was considered that the muscle atrophy rate of the female's psoas major being higher than the male's influenced this. Furthermore, it was suggested possibility that the decline of walking ability is due to decreased muscle mass of the lower limbs with aging.

A cross-sectional study of the size and strength of the thigh muscles in sedentary 259 japanese adults / 体力科学

Thigh muscle cross-sectional area (CSA) and maximum voluntary isometric strength of knee extensor and flexor muscles were measured in 97 men (2065 years) and 162 women (2069 years) in sedentary Japanese adults. Each subject was assigned to one of five age groups (3<SUP>rd</SUP> 4<SUP>th</SUP> 5<SUP>th</SUP> 6<SUP>th</SUP> and 7<SUP>th</SUP> decade) . Thigh muscle CSA was estimated by our developmental measuring system using an ultrasonographic device, which was connected to a PC for graphical processing. Muscle CSA for the 7<SUP>th</SUP> decade in men was significantly smaller than that for the 3<SUP>rd</SUP> decade. For women, muscle CSA were no significant from the 3<SUP>rd</SUP> to the 7<SUP>th</SUP> decade. The isometric knee extensor strength showed a significant decline with age from the 7<SUP>th</SUP> decade in men, whereas there was no significant change with age in women. Isometric strength of knee flexors in men showed a gradual decline from the 5<SUB>th</SUB> decade. The aging-associated reduction of muscle strength per muscle CSA in the extensors and flexors started from the 6<SUB>th</SUB> decade in men. It was concluded that the size and strength of the thigh muscles begin to decrease simultaneously by approximately the 6<SUB>th</SUB> decade in men, whereas there are no change until the 7<SUP>th</SUP> decade in women.

The difference between effects of "power-up type" and "bulk-up type" strength training exercises. With special reference to muscle cross-sectional area, muscular strength, anaerobic power and anaerobic endurance / 体力科学

In this study, the difference between the effects of “power-up type” and “bulk-up type” strength training exercise was investigated by analyzing parameters such as structural and functional adaptations in the neuromuscular system. Eleven subjects were divided into power-up and bulk-up groups. The power-up group comprised five male subjects who performed 5 sets at 90% of one repetition maximum (1 RM) with a 3-min rest between sets (repetition method) . The bulk-up group comprised six male subjects who performed 9sets at 80-60-50%, 70-50-40%, and 60-50-40% of 1 RM with rest intervals between sets of either 30 s or 3 min (interval method) . Both groups performed isotonic knee extension exercise twice a week for 8 weeks. The power-up group showed a lower rate of improvement than the bulk-up group in terms of cross-sectional area (CSA) of the quadriceps femoris at levels 30%, 50% and 70% from the top of the femur, and also in average isokinetic strength (Isok. ave. ; 180 deg/s, 50 consecutive repetitions) . However, the power-up group showed a greater rate of improvement in 1 RM, maximal isometric strength (Isom. max), and maximal isokinetic strength (Isok. max ; 60, 180, 300 deg/s) . Furthermore, the rate of reduction in strength over 50 consecutive isokinetic repetitions decreased in the bulk-up group. On the other hand, the power-up group showed no significant changes in the above throughout the entire training program. These results indicate that the characteristics of the two types of training exercise are as follows : (1) power-up exercise is effective mainly for improving muscular strength and anaerobic power, and (2) bulk-up exercise is effective mainly for improving hypertrophy and anaerobic endurance. These findings support the idea that “power-up type” and “bulk-up type” strength training exercises should be applied appropriately according to the training aim.

Effect of high-speed resistance training on muscle cross-sectional area and speed of movement / 体力科学

A conducted to determine 1) the effect of high-velocity movement in resistance training with a constant load on the velocity of movement after training and 2) the differences in the effect on muscle hypertrophy according to training velocity. Fourteen of the total subjects (male; n=10, female ; n=7) were placed in the experimental group and agreed to participate in 8 weeks of training sessions (4 times a week) . Five of the 17 subjects were in control a group before the training session. Subjects performed elbow extension and flexion exercise using 50% of one repetition maximum (% 1 RM) load. The exercise session consisted of 6 sets of 10 repetitions and 30s of rest was taken between the sets. The subjects in the experimental group trained their arms using two different protocols ; one was high-velocity movement performed as rapidly as possible (Type R), the other was low-velocity movement performed at a constant and slow velocity (Type S) . Isokinetic torque in elbow flexion was measured at angular velocities of 60, 180, 300 deg/s, respectively, during elbow flexion performed under different constant loads of 0, 30, 50% 1 RM, and the muscle cross-sectional area (CSA) of the elbow flexor was determined before and after training. It was found that Type R did not increased isokinetic torque at 300 deg/s significantly after training. However, the increase in angular velocity of elbow flexion in Type R exercise tended to be higher than in Type S exercise. The increase in CSA [Type S; 11.2%, Type R ; 14.2%] was significantly higher in Type R exercise (p<0.05) . These results suggest that high-velocity movement with a constant load in resistance training might increase the angular velocity of movement in the same mode, but might not produce a change in isokinetic strength, which involves a different mode of muscle contraction. Muscle hypertrophy would be induced to a greater extent by high-velocity movement than by low-velocity movement in resistance training with a constant load.

Effect of moderate endurace training(60%Vo2max) on morphological characteristics and muscule strength in human thigh muscles / 体力科学

In this study, the effect of moderate endurance training on muscle morphological properties of human thigh muscles and isokinetic strength was examined. Five sedentary females carried out a training program of 30 min./day, 3 times a week for a ten-week period. The load requirement was set to 60% of maximal aerobic capacity (Vo<SUB>2</SUB>max) of the subjects. In the determination of muscle cross-sectional areas (CSAs) by MRI, longitudinal sections were first imaged, and ten axial images along the length of femur were taken before and after the endurance training. Muscle CSA and mus-cle volume of knee extensors (KE), flexors (KF), and adductors (AD) were calculated, using the ten axial images. Vo<SUB>2</SUB>max was significantly increased after endurance training (14.6%, p<0.01) . Muscle CSA in KE was significantly increased at the ten levels of femur length. There were also significant increases at seven levels of femur length after endurance training in KF (p<0.05, and 0.01) . Percentage increase of msucle CSA in KE and KF were 10.9 to 16.5% and 7.7 to 15.8%, respectively. Although the muscle volume of KE, KF, and AD was significantly increased, no change in fat volume was observed after endurance training. Isokinetic knee extension and flexion peak torque and peak torque per unit of muscle CSA at three angular velocities (30, 180, and 300 deg/sec) didn't show significant changes. These results suggest that muscle hypertrophy induced by moderate endurance training has no effect on muscle strength.

EFFECT OF MODERATE ENDURANCE TRAINING (60% Vo<SUB>2</SUB>max) ON MORPHOLOGICAL CHARACTERISTICS AND MUSCLE STRENGTH IN HUMAN THIGH MUSCLES / 体力科学

In this study, the effect of moderate endurance training on muscle morphological properties of human thigh muscles and isokinetic strength was examined. Five sedentary females carried out a training program of 30 min./day, 3 times a week for a ten-week period. The load requirement was set to 60% of maximal aerobic capacity (Vo<SUB>2</SUB>max) of the subjects. In the determination of muscle cross-sectional areas (CSAs) by MRI, longitudinal sections were first imaged, and ten axial images along the length of femur were taken before and after the endurance training. Muscle CSA and mus-cle volume of knee extensors (KE), flexors (KF), and adductors (AD) were calculated, using the ten axial images. Vo<SUB>2</SUB>max was significantly increased after endurance training (14.6%, p<0.01) . Muscle CSA in KE was significantly increased at the ten levels of femur length. There were also significant increases at seven levels of femur length after endurance training in KF (p<0.05, and 0.01) . Percentage increase of msucle CSA in KE and KF were 10.9 to 16.5% and 7.7 to 15.8%, respectively. Although the muscle volume of KE, KF, and AD was significantly increased, no change in fat volume was observed after endurance training. Isokinetic knee extension and flexion peak torque and peak torque per unit of muscle CSA at three angular velocities (30, 180, and 300 deg/sec) didn't show significant changes. These results suggest that muscle hypertrophy induced by moderate endurance training has no effect on muscle strength.

The effects of isometric strength training on muscle area and strength in the prepubescent age / 体力科学

The purpose of the present study was to determine the effect of isometric strength training in prepubescent boys and girls on muscle strength and cross-sectional area of upper arm muscle. Subjects were ninety-nine healthy elementary school children from the 1 st, 3 rd and 5th grades and who were assigned to either training (TG, n=52) or control (CG, n=47) groups. The TG participated in a strength training program for 12 weeks which consisted of three maximaly sustained isometric contractions of elbow flexion for ten sec, twice a day, three days per week, whereas the CG did not participate in a special training program during this period. The cross-sectional areas of whole tissue, muscle, fat, and bone of the upper arm were measured by ultrasonic methods. Maximum isometric and isokinetic muscle strength of elbow flexion and extension were measured by means of a Cybex II. The hand-wrist X-ray photograph was used to estimate the skeletal age (TW 2 method) . Means (SDs) of skeletal age (yrs) were 6.27 (0.98), 8.48 (0.89), and 10.77 (1.22) for 1 st, 3 rd, and 5 th graders, respectively. After the 12-week training period, the cross-sectional area of the whole tissue increased significantly in both TG (8.9%, 2.52 cm<SUP>2</SUP>) and CG (7.3%, 2.11 cm<SUP>2</SUP>) . This interment in the TG was due to the significant increases in both muscle and bone areas, while that in CG was due to the significant increase only in fat area. Mean increase in muscle area in the TG was 10.3% (1.29 cm<SUP>2</SUP>) with this increase notable in 5th graders (12.5% for males and 12.7% for females) . The increment in cross-sectional area of muscle with training significantly correlated with the skeletal age (r=0.36, p<0.01) . Maximum isometric strength in the TG increased by 5.7% (0.3kg) in flexion and 17.5% (1.2 kg) in extension and in the CG, -0.3 kg (-1.0%) in flexion and 5.7% (0.3 kg) in extension. The increases in the strength of elbow extension were statistically significant in 1st (p<0.01), 3rd (p<0.05), and 5th (p<0.05) grade males. On the other hand, maximum isokinetic strength did not change with training. Muscle strength per cross-sectional area did not show a significant increase except in the training group of 5th grade boys. It was suggested that the effects of strength training on muscle area and strength for prepubescents were similar in its direction to but different in its magnitude from those found in adults.