Relationship between limb and trunk muscle hypertrophy following high-intensity resistance training and blood flow-restricted low-intensity resistance training

We examined the relationship between training-induced limb and trunk muscle hypertrophy in high-intensity resistance training (HIT) or blood flow-restricted low-intensity resistance training (LI-BFR) programmes. Thirty young men were divided into three groups: HIT (n = 10), LI-BFR (n = 10) and non-training control (CON, n = 10). The HIT and LI-BFR groups performed 75% and 30%, respectively, of one-repetition maximal (1-RM) bench press exercise, 3 days per week for 6 weeks. During the training sessions, the LI-BFR group wore elastic cuffs around the most proximal region of both arms. Muscle cross-sectional area (CSA) and 1-RM bench press strength were measured before and 3 days after the final training session. Total training volumes (lifting weight × number of repetitions) for all of the sessions were similar between the two training groups. The training led to a significant increase (P < 0·05) in bench press 1-RM in the two training groups, but not in the CON group. Triceps brachii and pectoralis major muscle CSA increased 8·8% and 15·8% (P < 0·01), respectively, in the HIT group and 4·9% (P < 0·05) and 8·3% (P < 0·01), respectively, in the LI-BFR group, but not in the CON group (-1·1% and 0·0%, respectively). There was significant correlation (r = 0·70, P < 0·05) between increases in triceps brachii and pectoralis major muscle CSA in the HIT group; however, the correlation was lower and non-significant in the LI-BFR group (r = 0·54). Our results suggest that limb and trunk muscle hypertrophy occurs simultaneously during HIT but not during LI-BFR, possibly owing to individual differences in activation of the arm and chest muscles during the training sessions.     

Effects of short‐term detraining following blood flow restricted low‐intensity training on muscle size and strength

We investigated the effects of 3 weeks of detraining on muscle cross‐sectional area (CSA) and one‐repetition maximum strength (1‐RM) in young men who had previously participated in 6 weeks (3 days week^?1) of bench press training [blood flow restricted low‐intensity (LI‐BFR; n = 10, 20% 1‐RM) or high‐intensity (HI; n = 7, 75% 1‐RM)]. Bench press 1‐RM and muscle CSA of triceps brachii (TB) and pectoralis major (PM) were evaluated before (pre) and after training period (post) as well as after detraining period (detraining). Bench press 1‐RM was higher at both post and detraining than at pre for LI‐BFR (P<0·01) and the HI (P<0·01). TB and PM muscle CSA were higher at both post and detraining than at pre for the HI group (P<0·01), while the LI‐BFR group only increased (P<0·01) at post. Relative dynamic strength (1‐RM divided by TB muscle CSA) was higher at both post and detraining than at pre for the HI group (P<0·01), while the LI‐BFR group only increased (P<0·01) at detraining. In conclusion, increased muscle strength following 6 weeks of training with LI‐BFR as well as HI was well preserved at 3 weeks of detraining. HI‐induced muscle strength appears to be dependent upon both neural adaptations and muscle hypertrophy with training and detraining. On the other hand, LI‐BFR‐induced muscle strength appears to be related primarily to muscle hypertrophy with training and to neural adaptations with detraining.     

Effects of periodic and continued resistance training on muscle CSA and strength in previously untrained men

To determine muscle adaptations to retraining after short-term detraining, we examined the effects of continuous and interrupted resistance training on muscle size and strength in previously untrained men. Fifteen young men were divided into continuous training (CTr) or retraining (RTr) groups and performed high-intensity bench press training. The CTr group trained continuously for 15 weeks, while the RTr group trained for 6 weeks, stopped for a 3-week detraining period and resumed training at week 10. After the initial training phase, increases (P<0·01) in one repetition maximum (1-RM) and magnetic resonance imaging-measured triceps brachii and pectorals major muscle cross-sectional areas (CSAs) were similar in both groups. Muscle CSA and 1-RM increased (P<0·05) continuously for the CTr group, but the muscle adaptations were lower (P<0·05) after the last 6-week training period than after the initial phase. In the RTr group, there were no significant decreases in muscle CSA and 1-RM after the 3-week detraining period, and increases in muscle CSA after retraining were similar to those observed after initial training. Ultimately, improvements in 1-RM and muscle CSA in both groups were similar after the 15-week training period. Our results suggest that compared with continuous 15-week training, 3-week detraining does not inhibit muscle adaptations.     

Relationships between contraction properties of knee extensor muscles and fasting IGF‐1 and adipocytokines in physically active postmenopausal women

The aim of this cross‐sectional study was to find possible relationships between insulin‐like growth factor‐1 (IGF‐1), adipocytokines (leptin and adiponectin) and twitch contraction (TC) characteristics of the knee extensor (KE) muscles in healthy physically active postmenopausal women (n = 28, 64–78 years old). We hypothesized that IGF‐1 is related at least to isometric TC peak torque (Pt) as the highest value of isometric torque production and maximal voluntary contraction (MVC) torque, and there will not be any relationships between TC characteristics and leptin and adiponectin. During the measurement of MVC torque and twitch contractile properties of KE muscles, the subjects sat in a custom‐made dynamometric chair with the knee and hip angles equal to 90° and 100°, respectively. To assess the contractile properties of the KE muscles, electrically evoked isometric twitch was elicited by percutaneous electrical nerve stimulation. Serum leptin, adiponectin, IGF‐1, insulin‐like growth factor–binding protein‐3 (IGFBP‐3) and insulin were determined. There were a very few significant relationships between the measured muscle contractile parameters and fasting blood hormones. TC Pt correlated significantly with IGFBP‐3 (r = 0·652, P = 0·001) and insulin (r = 0·495, P = 0·007). In conclusion, this study suggests that only TC peak torque correlated positively with serum fasting IGFBP‐3 and insulin concentration. Adipocytokines leptin and adiponectin not correlated significantly with measured strength parameters in physically active postmenopausal women.     

Circulatory response to single circuit weight and walking training sessions of similar energy cost in middle‐aged overweight females

The aim of this study was to compare circulatory responses to circuit weight (CWT) and aerobic walking training sessions of similar energy cost in middle‐aged overweight females. Thirty‐three middle‐aged pre‐menopausal females participated in the experiment. They were divided into overweight (n=18, 36·2 ± 6·3 years, 166·3 ± 8·0 cm, 83·5 ± 9·7 kg, BMI 30·2 ± 3·1 kg m^–2) and non‐overweight control (n=15, 34·1 ± 6·3 years, 165·0 ± 5·6 cm, 61·6 ± 5·0 kg, BMI 22·7 ± 1·5 kg m^–2) groups. Individual physical working capacity (PWC) was measured using the cycle ergometer test (calculated at the level of predicted HR_max (205 – ½ age). A CWT session consisted of leg extension, bench press, sit‐ups and leg press exercises. The subjects performed four circuits at the maximal possible speed, using a work‐to‐rest ratio of 60 s. Blood pressure (BP) was measured during every rest period between the exercises, and the heart rate (HR) was recorded continuously during the whole CWT programme. During the walking training session, the subjects walked as fast as possible on the indoor track. The total energy cost of the walking training session was the same as during the CWT session, approximately 270 kcal, and was controlled by a CALTRAC accelerometer. HR and BP were measured every 5 min during the walking training session. The PWC index was significantly (P<0·05) higher in the overweight group in comparison with the control females (215·4 ± 76·1 and 187·9 ± 42·4 W, respectively). The resting BP was normal in both groups (<140/90 mmHg). HR was between 120 and 140 beats min^–1 during CWT and walking sessions. There were no differences in BP during both training sessions in overweight and control subjects. It was concluded that both CWT and walking training sessions were acceptable forms of physical activity to increase cardiovascular fitness in middle‐aged overweight and normal body weight females.     

Changes in water content in response to an acute bout of eccentric loading in a patellar tendon with a history of tendinopathy: A case report

Objective: This case-based report assessed resting water content and exercise-driven water exchange within a tendon with a history of tendinopathy and compared the response to that of a healthy uninvolved tendon. Design: Case Report. Setting: University imaging center. Participant: The participant was a 27-year-old female basketball player 39 months following knee trauma. Patellar tendinopathy developed 12 months after the injury episode and was treated with eccentric exercises. Eighteen months from the beginning of the first eccentric training bout, the participant reported full resolution of symptoms and returned to her pre-injury sport participation without symptoms. Intervention: Eccentric decline squat exercise. Main Outcome Measures: Tendon water content obtained from magnetic resonance imaging (MRI). Results: MRI acquired 39 months post-injury demonstrated increased resting water content of the involved tendon (involved: 91.1% vs. uninvolved: 84.6%). Immediately after the eccentric squat maneuver, water content decreased on both involved and uninvolved tendons (involved: 89.5% vs. uninvolved: 83.3%). Conclusions: Elevated resting water content of the involved tendon found in this report may be indicative of reduced tendon stiffness. A similar amount of water content reduction was observed on both sides following mechanical loading, suggesting that the involved tendon may respond to the eccentric exercise similarly to the uninvolved tendon. Future investigations are needed to study the relationships among tendon water exchanges, mechanical properties, patient symptoms, and tissue injuries.     

单侧下背痛患者脊柱核心肌群的磁共振成像变化

目的:探讨单侧下背痛患者脊柱核心肌群的变化,为指导制定下背痛运动治疗方案提供一定的研究依据.方法:178例单侧下背痛患者根据病程长短分为急性期组(n=76)和慢性期组(n=102),采用Onis软件和Image J软件分析受试者腰部MRI图像,比较痛侧和非痛侧腰大肌(PM)、腰方肌(QL)、多裂肌(MF)和竖脊肌(ES)的肌肉横截面积(CSA)、肌肉平均信号强度(MSI)和脂肪浸润(FI)比例.结果:急性期组中,痛侧PM和ES的CSA较非痛侧肌肉小(P＜0.05),MSI和FI比例较非痛侧肌肉高(P＜0.05);慢性期组中,痛侧MF和ES的CSA较非痛侧肌肉小(P＜0.05),MSI和FI比例较非痛侧肌肉高(P＜0.05);急性期组痛侧ES的CSA较慢性期组痛侧肌肉大(P＜0.05),MSI和FI比例较慢性期组痛侧肌肉低(P＜0.05).结论:急性期组和慢性期组患者存在痛侧竖脊肌的肌肉萎缩和脂肪浸润,慢性期组患者痛侧多裂肌萎缩明显.通过MRI研究LBP患者腰椎核心肌群情况,可为出现异常变化的肌肉设计针对性训练动作和方法提供依据,有助于尽快恢复脊柱力学,改善功能障碍.     

Effects of combined aerobic and resistance training in patients with heart failure: A meta‐analysis of randomized,controlled trials

Cardiac rehabilitation programs consisting of core features of exercise training for patients with heart failure have demonstrated a wide range of physical and psychological benefits. In study, a meta‐analysis of combined aerobic and resistance training was conducted on various outcomes in patients with heart failure. Database searches included EMBASE, PubMed, Medline, Cochrane Library, Web of Science, OVID, and CINAHL. Only randomized, controlled trials were included. Review Manager 5.3 software was used to perform the meta‐analysis. In total, 12 studies and 516 patients were included. The results demonstrated that combined aerobic and resistance training is effective in promoting exercise capacity, muscle strength, and 6 min walk distance. Furthermore, combined training significantly improves the quality of life of patients with heart failure. However, there was no significant difference found for outcomes of depression and sleep. Future studies with rigorous methodological designs and long‐term follow ups are recommended to evaluate the sustainable benefits of combined aerobic and resistance intervention programs.     

Fine‐tuning the Diagnosis of Fetal Scalp Cysts

Objective. The purpose of this series is to emphasize the importance of an exhaustive and appropriately conducted sonographic examination in the correct diagnosis of fetal cystic scalp lesions and the place of magnetic resonance imaging (MRI) in the diagnostic sequence. Methods. Transabdominal and transvaginal 2‐ and 3‐dimensional sonography with color and power Doppler imaging as well as 3‐dimensional rendering techniques such as inversion and Doppler angiography were used. In 1 case, an MRI study was performed. Results. In 1 case, the MRI missed and the different sonographic techniques correctly made the diagnosis of a meningocele. In the second case, sonography was sufficient to establish the diagnosis of an epidermal cyst. Conclusions. These 2 cases show the value of going the distance with the newly available high‐frequency sonography. Ultimately, the correct diagnoses were made with the tools offered by sonography without the need for any other imaging modality.     

Diagnostic accuracy of magnetic resonance imaging for an acute pulmonary embolism: results of the ‘IRM‐EP’ study

Summary. Background: Magnetic resonance imaging (MRI) has not been validated as an alternative diagnostic test to computed tomography angiography (CTA) in patients with suspicion of a pulmonary embolism (PE). Objectives: To evaluate performance of current MRI technology in diagnosing PE, in reference to a 64‐detector CTA. Patients/methods: Prospective investigation including 300 patients with a suspected PE, referred for CTA after assessment of clinical probability and D‐dimer testing. MRI protocol included unenhanced, perfusion and angiographic sequences. MRI results were interpreted by two independent readers, to evaluate inter‐reader agreement. Sensitivity and specificity were evaluated globally and according to PE location and to clinical probability category. Results: Of 300 enrolled patients, 274 were analyzed and 103 (37.5%) had a PE diagnosed by CTA. For patients with conclusive MRI results (72% for reader 1, 70% for reader 2), sensitivity and specificity were 84.5% (95% confidence interval [CI], 74.9–91.4%) and 99.1% (95% CI, 95.1–100.0%), respectively, for reader 1, and 78.7% (95% CI, 68.2–87.1%) and 100% (95% CI, 96.7–100.0%) for reader 2. After exclusion of inconclusive MRI results for both readers, inter‐reader agreement was excellent (kappa value: 0.93, 95% CI: 0.88–0.99). Sensitivity was better for proximal (97.7–100%) than for segmental (68.0–91.7%) and sub‐segmental (21.4–33.3%) PE (P < 0.0001). Sensitivity was similar for both readers within each clinical probability category. Conclusions: Current MRI technology demonstrates high specificity and high sensitivity for proximal PE, but still limited sensitivity for distal PE and 30% of inconclusive results. Although a positive result can aid in clinical decision making, MRI cannot be used as a stand‐alone test to exclude PE.     

Increasing circulating levels of Tenascin C in response to the Wingate anaerobic test

Aim

Tenascin C (TNC) is a large extracellular matrix glycoprotein. It is involved in development and upregulated both during tissue repair and in several pathological conditions, including cardiovascular disease. Extracellular matrix proteins play a role in promoting exercise responses, leading to adaptation, regeneration, and repair. The main goal of this study was to investigate whether a short anaerobic effort leads to increased levels of TNC in serum.

Methods

Thirty-nine healthy men performed a Wingate test followed by a muscle biopsy. Myoblasts were isolated from the muscle biopsies and differentiated to myotubes ex vivo. TNC RNA was quantified in the biopsies, myotubes and myoblasts using RNA sequencing. Blood samples were drawn before and 5 min after the Wingate test. Serum TNC levels were measured using enzyme-linked immunosorbent assay.

Results

After the Wingate test, serum TNC increased on average by 23% [15–33], median [interquartile range]; P_Wilcoxon < 0.0001. This increase is correlated with peak power output and power drop, but not with VO_2max. TNC RNA expression is higher in myoblasts and myotubes compared to skeletal muscle tissue.

Conclusion

TNC is secreted systemically as a response to the Wingate anaerobic test in healthy males. The response was positively correlated with peak power and power drop, but not with VO_2max which implicates a relation to mechanical strain and/or blood flow. With higher expression in undifferentiated myoblast cells than muscle tissue, it is likely that TNC plays a role in muscle tissue remodelling in humans. Our findings open for research on how TNC contributes to exercise adaptation.     

Inter‐ and intramuscular differences in training‐induced hypertrophy of the quadriceps femoris: association with muscle activation during the first training session

The purpose of this study was to examine whether inter‐ and intramuscular differences in hypertrophy induced by resistance training correspond to differences in muscle activation during the first training session. Eleven young men completed 12 weeks of training intervention for knee extension. Before and after the intervention, T1‐weighted magnetic resonance (MR) images were recorded to determine the volume and anatomical cross‐sectional area (CSA) along the length of the individual muscles of the quadriceps femoris. The T2‐weighted MR images were also acquired before and immediately after the first training session. The T2 was calculated for each pixel within the quadriceps femoris, from which the muscle activation was evaluated as %activated volume and area. The results showed that the %activated volume after the first training session was significantly higher in the vastus intermedius than the vastus medialis. However, the relative change in muscle volume after the training intervention was significantly greater in the rectus femoris than the vasti muscles (vastus lateralis, intermedius and medialis). Within the rectus femoris, both the %activated area and relative increase in CSA were significantly greater in the distal region than the proximal region. In contrast, the %activated area and relative increase in CSA of the vasti were nearly uniform along each muscle. These results suggest that the muscle activation during the first training session is associated with the intramuscular difference in hypertrophy induced by training intervention, but not with the intermuscular difference.     

Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training

One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion.     

Pharmacokinetic and in vivo evaluation of a self‐assembled gadolinium(III)‐iron(II) contrast agent with high relaxivity

A high‐molecular weight tetrametallic supramolecular complex [(Ln‐DTPA‐phen)₃Fe]^? (Ln = Gd, Eu, La) has been obtained upon self‐assembly around one iron(II) ion of three 1,10‐phenantroline‐based molecules substituted in 5′‐position with the polyaminocarboxylate diethylenetriamine‐N,N,N′,N′,N′‐pentaacetate, DTPA‐phen^4?. The ICP‐MS measurements indicated that the lanthanide:iron ratio is 3:1. Photoluminescence spectra of [Eu‐DTPA‐phen]^? and of [(Eu‐DTPA‐phen)₃Fe]^? are nearly identical, implying that the first coordination sphere of the lanthanide(III) ion has not been changed upon coordination of phenantroline unit to iron(II) ion. NMRD measurements revealed that at 20 MHz and 310 K the relaxivity of the [(Gd‐DTPA‐phen)₃Fe]^? is equal to 9.5 ± 0.3 s^?1 mM^?1 of Gd (28.5 s^?1 per millimole per liter of complex) which is significantly higher than that for Gd‐DTPA (3.9 s^?1 mM^?1). The pharmacokinetic parameters of [(Gd‐DTPA‐phen)₃Fe]^? in rats indicate that the elimination of [(Gd‐DTPA‐phen)₃Fe]^? is significantly slower than that of Gd‐DTPA and is correlated with a reduced volume of distribution. The low volume of distribution and the longer elimination time (T_e1/2) suggest that the agent is confined to the blood compartment, so it could have an important potential as a blood pool contrast agent. The biodistribution profile of [(Gd‐DTPA‐phen)₃Fe]^? 2 h after injection indicates significantly higher concentrations of [(Gd‐DTPA‐phen)₃Fe]^? as compared with Gd‐DTPA in kidney, liver, lungs, heart and spleen. The images obtained on rats by MR angiography show the enhancement of the abdominal blood vessels. The signal intensity reaches a maximum of 55% at 7 min post‐contrast and remains around 25% after 90 min. MRI‐histomorphological correlation studies of [Gd‐DTPA‐phen]^? and [(Gd‐DTPA‐phen)₃Fe]^? showed that both agents displayed potent contrast enhancement in organs including the liver. The necrosis avidity tests indicated that, in contrast to the [Gd‐DTPA‐phen]^? precursor complex, the supramolecular complex [(Gd‐DTPA‐phen)₃Fe]^? exhibits necrosis avidity. Copyright © 2006 John Wiley & Sons, Ltd.