Left Muscle Research Articles

Muscle structure assessment using synchrotron radiation X-ray micro-computed tomography in murine with cerebral ischemia.

Muscles are crucial for balance and walking, activities which depend specifically on the lower extremity muscles. Therefore, the evaluation of stroke induced atrophy and paralysis is essential; however, determining the extent of damage in the days after its occurrence remains challenging. In this study, we evaluated ischemic stroke-induced soleus muscle damage in gerbils using synchrotron radiation X-ray micro-computed tomography (SR-µCT), comparing a control group (n = 3), animals 7 days after stroke (7 d, n = 3), and animals 14 days after stroke (14 d, n = 3). The left muscle was paralyzed, whereas the right muscle was not. Subsequently, we quantified the assessment by segmenting the soleus muscle based on the extracellular space/matrix and fiber region to determine the degree of damage. The muscle fiber-to-extracellular space/matrix ratio were significantly damaged due to paralysis on the left side (control vs. 14 d, P = 0.040). Muscle area was significantly different at 14 d between the left and right sides (P = 0.010). Additionally, the left local fascicle surface area, thickness, global pennation angle, and local fascicle angle were significantly different between the control and 14 d groups (P = 0.002, P = 0.007, P = 0.005, and P = 0.014 respectively). These findings underscore the potential of post-stroke animal studies in improving rehabilitation treatment for the central nervous system by assessing the degree of muscle recovery.

Electromyographic Analysis of Upper- and Lower-extremity Muscles in Adults during Agro-healing Activities

This study investigated the activity of upper- and lower-extremity muscles for 15 agricultural tasks of agro-healing. For the development of an agro-healing program using farm resource types, 15 selected agro-healing activities (namely, digging, raking, fertilizing, planting transplants, tying plants to stakes, watering, harvesting, washing, cutting, cooking, collecting natural objects, decorating natural objects, interacting with dogs, walking dogs, and feeding fish) were extracted and performed in a total of 21 adults (average age: 42.29 ± 14.76 years) at D Care Farm in Cheongju, Korea, from June to July 2022. Before these activities, informed consent was obtained from participants and muscle activity of the upper and lower extremities was measured. Muscle activation during activity performance was measured using electromyography (EMG), and the rating of perceived exertion for each activity was investigated. Bipolar surface EMG electrodes were attached at 16 locations on the left and right upper-extremity muscles (anterior deltoid, biceps brachialis, brachioradialis, and flexor carpi ulnaris) and lower-extremity muscles (vastus lateralis, vastus medialis, biceps femoris, and gastrocnemius). The results indicated that the activity of the lower-extremity muscles was higher than that of the upper-extremity muscles during 15 agricultural activities. During plant-mediated activity and animal-assisted activities, the rate of right muscle use was higher than that of left muscle use among the upper-extremity muscles, whereas the rate of right and left muscle use showed a similar tendency among the lower-extremity muscles. During plant-mediated activities, agricultural activities involving the use of heavy tools highly activated the right forearm muscle (flexor carpi ulnaris), whereas holding and interacting with animals highly activated the left forearm muscles (biceps brachialis, brachioradialis, and flexor carpi ulnaris). It is expected that the EMG data obtained in this study can be used as basic biomechanical data when designing an agro-healing program to improve physical function.

PERINEURAL INJECTION THERAPY AS INTERVENTIONAL PAIN MANAGEMENT IN POST HERPETIC NEURALGIA : A CASE REPORT

Introduction: Post Herpetic Neuralgia is a neurological complication of herpes zoster resulting in neuropathic pain syndrome that worsens as a direct result of peripheral nerve damage that occurs during an attack of herpes zoster. It manifests as significant dermatomal pain or abnormal sensations and impacting various aspects of quality of life. Physically, patients may experience fatigue, anorexia, weight loss, insomnia, reduced mobility, and physical inactivity. Psychologically, it can lead to depression, anxiety, emotional burden, difficulty in concentration, and fear. Perineural Injection Therapy (PIT), developed by John Lyftogt, offers a treatment option for chronic neuropathic pain. Case Report: A 65-year-old male, currently unemployed for the past two years and previously worked as a tire repairman, came to the Husada Asih Clinic, with sharp, not radiating, and continuous left facial pain (VAS 9-10). He received treatment comprising Transcutaneous Electrical Nerve Stimulation (TENS) and Low Laser Light Therapy (LLLT) on the left face, combined with PIT injections using 5% dextrose at the left side of the face, targeting dermatomes left N V.1, V.2, V.3, and C3 , with repetition after three weeks. After the third injection, the pain at his left head was reduced (VAS 6). Pain at his left jaw and left neck reduced and became intermittently (VAS 5). Barthel Index : 20/20 (Independent). Discussion: The immediate clinical improvement in PIT administration is attributed to the sensorineural effects of dextrose. Clinically, pain decreases immediately or within 1-2 days after therapy. In this case, three series PIT resulted in significant pain relief, reduced burning sensation, improved left muscle motor function, full mouth opening, eased in eating and speaking, and the ability to resume social activities and work. Conclusion: Perineural injection therapy (PIT), previously developed by John Lyftogt, involves a series of subcutaneous injections using 5% dextrose in sterile water (D5W) near the affected nerve. This regenerative therapy offers pain control for PHN patients by targeting skin nerves as potential pain generators. PIT proves to be a valuable rehabilitation tool for managing PHN.

Evaluation of functional interaction masseter and sternocleidomastoid muscles affected by TMJ dysfunction.

Aim: To evaluate the functional connection and the bioelectrical state of the m.masseter and m. sternocleidomastoid using functional tests before and after treatment. Materials and Methods: The sample consisted of 21 individuals with temporomandibular joint dysfunction. Examinations were carried out before and after treatment using repositioning splint therapy and in seated/standing positions. Results: M. masseter - p=0.072 before treatment and p=0.821 after treatment. Symmetry is also maintained after treatment. After treatment, a significant difference is noted at the level of significance p<0.001 for the right chewing muscle. In seated and standing positions before treatment did not reveal a statistically significant difference (p=0.07, p=0.143) and after (p=0.272, p=0.623).M. sternocleidomastoid- p<0.001 when comparing right and left sides. After treatment, there was no difference between the right and left sides (p=0.169). No statistical difference was found when assessing indicators separately for the right and left muscles in seated and standing positions (p=0.304, p=0.611, p=0.089, p=0.869). When comparing the bioelectric potentials of the right muscle before, after treatment, a statistically significant difference was found p=0.001. Conclusions: Biostatistical analysis of the indicators of bioelectrical activity of m. masseter and sternocleidomastoid indicates no changes in muscle microvolt indicators with changes in body position in patients. However, repositioning splint therapy is associated with reduced muscle tone in initially more spasmodic muscles. It is worth noting that the symmetry of interaction between muscles improves.

Enhancing Physicochemical Characteristics of Donkey Meat through High‐Voltage Electrostatic Stimulation during Acid Excretion

To investigate the impact of high‐voltage electrostatic stimulation on the quality of donkey meat, ten 30‐month‐old Dezhou donkeys (each weighing 250 ± 50 kg) were selected. Following slaughter, longissimus dorsi (LD) samples from both left and right carcasses were collected. The control group refrigerated the right muscle in a 0–4°C refrigerator for normal acid excretion. Meanwhile, the high‐voltage electrostatic group subjected the left muscle to high‐voltage electrostatic stimulation (30000 V) for 60 s before refrigerating it in the same conditions for acid excretion. The study showed that at the 1st, 6th, and 24th h of acid excretion, the high‐voltage electrostatic group exhibited significantly lower pH levels than the control group (P&lt;0.05). Furthermore, a∗ values in the high‐voltage electrostatic group showed an increasing trend relative to the control group at the 6th and 24th h of acid excretion (P = 0.0751, P = 0.0860). With increasing acid excretion time, both treatment groups displayed increased PV and TBARS values. At 48 and 72 h, the PV values in the high‐voltage electrostatic group were significantly lower than those in the control group (P &lt; 0.05). As acid excretion time increased, T‐AOC, SOD, and GSH‐Px in both groups decreased. However, the high‐voltage electrostatic group consistently exhibited higher antioxidant enzyme activity than the control group at all time points. SOD and GSH‐Px activity in the high‐voltage electrostatic group showed an increasing trend at 48 h of acid excretion (P = 0.0838, P = 0.0860). At 72nd h of acid excretion, the shear force of donkey meat in the high‐voltage electrostatic group was significantly lower than that in the ordinary treatment group (P &lt; 0.05). With increasing acid excretion time, the MFI of both treatment groups gradually increased. In particular, at the 1st and 48th h of acid excretion, the MFI of the high‐voltage electrostatic group was significantly higher than that of the ordinary treatment group (P &lt; 0.05). Following high‐voltage electrostatic stimulation, ultrastructure images of donkey meat at 6 and 72 h revealed numerous contractions and stretching bands. Therefore, this stimulation significantly improved the tenderness of donkey meat, reduced the oxidation rate of donkey meat, and improved the quality of donkey meat.

Is There a Relationship between Psychological Status and Posture in Chronic Low Back Pain?

Context: Chronic non-specific low back pain (CNLBP) is a major public health. Numerous studies have evaluated the contribution of post urology in the assessment and the rehabilitation of this pathology. Nevertheless, the relationship between post urology and muscle assessment is still a subject of controversy and no clear cause and effect relationship between the two could be established. Aim: The aim of our work was to investigate the relationship between post urological and muscular assessments in patients with CNLBP. Methods: It’s about an observational, descriptive, and cross-sectional study. The muscle assessment included Quadriceps Femoris flexibility using the heel-to-buttock distance and Hamstrings flexibility using the popliteal angle. Isometric muscle strength of the extensor and flexor muscles of the trunk was assessed by the Biering-Sorensen test and the Shirado test, respectively. The evaluation of static postural control was performed by the SATEL® force platform in two conditions (opened eyes/closed mouth) and (closed eyes/closed mouth). The selected parameters were S (mm2), XY (mm), X (mm), Y (mm), support (%), and Romberg Quotient (RQ). The chi-square test or Fisher's exact test was used to assess differences between categorical variables, and means were compared using Pearson's or Spearman's correlation tests depending on the distribution of the variables. Comparison between qualitative and quantitative variables was done by ANOVA test for normally distributed variables and Mann-Whitney or Kruskall-Wallis tests for non-normally distributed data. Results: Forty patients were included. The study of muscle flexibility according to force platform parameters showed that left Hamstring stiffness was significantly correlated with XY (p=.037) and with instability in the sagittal plane (p=.036). On the other hand, the stiffness of the anterior rectus muscles (right and/or left) was significantly correlated with XY (p=0.019 for the right muscle and 0.011 for the left muscle) and with postural instability in the frontal plane (p=.015 for the right muscle and .026 for the left muscle). We also founded a significant association between the increase in Romberg quotient and right Hamstring stiffness (p=.003). Conclusions: Our study as well as literature findings suggest that the Quadriceps Femoris and the Hamstrings play have a significant role in core stability of patients with chronic non-specific back pain. However, the origin of the population is also an important factor in the postural evaluation. A larger number of patients and a control group would have made it possible to establish a cause- effect relationship between Quadriceps Femoris, Hamstrings and static postural control abnormalities.

Effects of a passive shoulder exoskeleton on muscle activity among Danish slaughterhouse workers

AimTo evaluate the effect of a shoulder exoskeleton on muscle activity and to compare the effect with a lifting glove among slaughterhouse workers in occupational settings. Materials and methodsWe conducted a crossover study of 26 workers measured during two work days with and without the use of a passive shoulder exoskeleton and a lifting glove at a Danish slaughterhouse. Electromyography sensors were placed bilateral on 5 shoulder muscles. The 10th, 50th, and 90th percentiles of muscle activity normalized by maximal voluntary contractions were measured and analyzed using mixed effect models. ResultsFor the 50th percentiles of the agonist muscles, the exoskeleton reduced muscle activity bilaterally for deltoid anterior with up to 29.47%, deltoid middle with 10.22%, and upper trapezius with 22.21%. The lifting glove only reduced muscle activity for right deltoid anterior (36.59%) and upper trapezius (7.11%), but generally increased left muscle activity with up to 15.58%. DiscussionThe exoskeleton showed larger reductions in muscle activity compared to the lifting glove.

Fall risk in older adults hospitalized with tumours: Contributing factors and prediction model.

Rates vary widely across hospitals globally and typically range from 3 to 11 falls per 1000 bed days and as 7-11 in Affiliated Hospital of Nantong University. This study determined to explore contributing factors and poor prognosis of fall in elderly tumour patients in China. A cross-sectional study. 161 older adults were invited to participate in this study and completed a self-reported questionnaire, took blood tests, and received the exam of musculoskeletal ultrasound. Among 161 patients, falls occurred in 41 cases, accounting for 24.8%. 51.6% of older adults suffered from intermediate-to-high risk of falls. Fall history, reduced self-care ability, sleep disturbance, hearing impairment, hyperkyphosis, chronic disease, platelet count, and the thickness of left muscle rectus femoris (LF-MLT), and left cross-sectional area (LF-CSA) were all contributing factors of fall, and higher risk of fall indicating lower quality of life. A fall prediction model was established in this study based on above contributing factors with good prediction efficiency (AUC = 0.920). The patient volunteers participated in this study and provided valuable data for the final analysis and the acquisition of conclusion.

Up- and Downregulated Genes after Long-Term Muscle Atrophy Induced by Denervation in Mice Detected Using RNA-Seq.

Skeletal muscle atrophy occurs rapidly as a result of inactivity. Although there are many reports on changes in gene expression during the early phase of muscle atrophy, the patterns of up-and downregulated gene expression after long-term and equilibrated muscle atrophy are poorly understood. In this study, we comprehensively examined the changes in gene expression in long-term denervated mouse muscles using RNA-Seq. The murine right sciatic nerve was denervated, and the mice were housed for five weeks. The cross-sectional areas of the hind limb muscles were measured using an X-ray CT system 35 days after denervation. After 28 d of denervation, the cross-sectional area of the muscle decreased to approximately 65% of that of the intact left muscle and reached a plateau. Gene expression in the soleus and extensor digitorum longus (EDL) muscles on the 36th day was analyzed using RNA-Seq and validated using RT-qPCR. RNA-Seq analysis revealed that three genes-Adora1, E230016M11Rik, and Gm10718-were upregulated and one gene-Gm20515-was downregulated in the soleus muscle; additionally, four genes-Adora1, E230016M11Rik, Pigh, and Gm15557-were upregulated and one gene-Fzd7-was downregulated in the EDL muscle (FDR < 0.05). Among these genes, E230016M11Rik, one of the long non-coding RNAs, was significantly upregulated in both the muscles. These findings indicate that E230016M11Rik could be a candidate gene for the maintenance of atrophied skeletal muscle size and an atrophic state.

The Effect of Pyridostigmine as an Antidote for Botulinum Type A: An Experimental Study on Rabbits

Background: Botulinum toxin (BoNT) or Botox injections are popular non-surgical and non-invasive option to optimize and change an individual’s facial appearance and achieve rejuvenation. Pyridostigmine is an acetylcholinesterase inhibitor important in clinical practice. This study evaluated the toxic effect of BoNT to demonstrate the efficacy of anticholinesterase inhibitor pyridostigmine. Methods: We conducted an experimental interventional study to evaluate the antidote effect of pyridostigmine against BoNT. Forty rabbits (skeletally mature males, body weight 1000–2000 g) were included in the study. The rabbits were injected with Clostridium botulinum type A neurotoxin complex (BoNT or Botox), which was reconstituted with 0.9% sterile sodium chloride to a concentration of 100 U/2.5 mL. Animals were divided randomly into four groups (10 in each) as follows: Group 1 (control group), group 2 (pyridostigmine-treated group), group 3 (BoNT only group), and group 4 (BoNT + pyridostigmine treated group). Results: In the control group, there was statistical difference between the rabbits’ weight (P=0.03). The left muscle was significantly heavier than the right (P=0.025). In the pyridostigmine only group, the rabbits’ weight had a high statistical difference during four weeks of the study (P=0.002). In the BoNT injection group, weight had high statistically significant difference four weeks of the study (P=0.033), which was more in first week (1.55±0.2 kg) and then subsequently decreased in the fourth week (1.345±0.13 kg). The mean weight of the rabbits’ right quadriceps muscle was 6.573±1.3 g, which was significantly lower than the mean weight of the rabbits’ left quadriceps muscle (8.09±1.2 g, P=0.0001). Conclusions: To the best of our knowledge, this is the first study conducted in Iraq to investigate the antidote effect of pyridostigmine against BoNT injections. Pyridostigmine and saline caused increased weight of rabbits in comparison to rabbits that received BoNT injections. Pyridostigmine can act as strong antidote against Botox toxicity.

Role of Rotated Head Postures on Volunteer Kinematics and Muscle Activity in Braking Scenarios Performed on a Driving Simulator

Occupants exposed to low or moderate crash events can already suffer from whiplash-associated disorders leading to severe and long-lasting symptoms. However, the underlying injury mechanisms and the role of muscle activity are not fully clear. Potential increases in injury risk of non-nominal postures, i.e., rotated head, cannot be evaluated in detail due to the lack of experimental data. Examining changes in neck muscle activity to hold and stabilize the head in a rotated position during pre-crash scenarios might provide a deeper understanding of muscle reflex contributions and injury mechanisms. In this study, the influence of two different head postures (nominal vs. rotation of the head by about 63 ± 9° to the right) on neck muscle activity and head kinematics was investigated in simulated braking experiments inside a driving simulator. The braking scenario was implemented by visualization of the virtual scene using head-mounted displays and a combined translational-rotational platform motion. Kinematics of seventeen healthy subjects was tracked using 3D motion capturing. Surface electromyography were used to quantify muscle activity of left and right sternocleidomastoideus (SCM) and trapezius (TRP) muscles. The results show clear evidence that rotated head postures affect the static as well as the dynamic behavior of muscle activity during the virtual braking event. With head turned to the right, the contralateral left muscles yielded higher base activation and delayed muscle onset times. In contrast, right muscles had much lower activations and showed no relevant changes in muscle activation between nominal and rotated head position. The observed delayed muscle onset times and increased asymmetrical muscle activation patterns in the rotated head position are assumed to affect injury mechanisms. This could explain the prevalence of rotated head postures during a crash reported by patients suffering from WAD. The results can be used for validating the active behavior of human body models in braking simulations with nominal and rotated head postures, and to gain a deeper understanding of neck injury mechanisms.

Sedentary Behaviour Impairs Skeletal Muscle Repair Modulating the Inflammatory Response.

This study investigated whether sedentary behaviour modulates skeletal-muscle repair and tissue inflammatory response after cardiotoxin (CTX)-induced injury. Singly caged rats spent 8 weeks either as a sedentary group (SED, n = 15) or as a control group (EX, n = 15)—caged with running wheels for voluntary running. All rats had each tibial anterior muscle infused either with CTX (CTX; right muscle) or saline solution (Sham; left muscle) and were sacrificed (n = 5 per group) on the 1st, 7th, and 15th day post-injection (dpi). Histological and immunohistochemical analyses were used to calculate myotube percentage and fibrosis accretion, and quantify the number of neutrophils and M1 and M2 macrophage subtypes. The SED group showed an increased number of both neutrophils and M1 macrophages (7th and 15th dpi) compared to the EX group (p < 0.01). The EX group showed an increased number of M2 macrophages on the 1st dpi. On the 7th dpi, the SED group showed a lower myotube percentage compared to the EX group (p < 0.01) and on the 15th dpi showed only 54% of normal undamaged fibres compared to 90% from the EX group (p < 0.01). The SED group showed increased fibrosis on both the 7th and 15th dpi. Our results show that sedentary behaviour affects the inflammatory response, enhancing and prolonging the Th1 phase, and delays and impairs the SMR process.

Physiological Implications Of Petit Allegro As A Pre-activity Warm Up

PURPOSE: The purpose of this study was to examine if 30 seconds of petit allegro as sautés induced physiological changes that aid in preparing dancers for activity. METHODS: Ten females (age = 20.9 ± 2.18 years) participated. Subjects sat at rest for five minutes (Pre). At rest, glucose and lactate levels were collected via finger pricking. Subjects completed 30 seconds of petit allegro. Glucose and lactate data were immediately collected during recovery. Throughout the entire trial, VO2 and VCO2 data were collected. Muscle oxygenation of the left and right gastrocnemii were monitored and analyzed as the average of three different time periods (0-5 min post, 5-10 min post, 10-15 min post). RESULTS: Repeated measures ANOVA (RM ANOVA) for time indicated that there was a significant increase in lactate (F = 14.1935, p = 0.0003) with significant increases between Pre and Post 5 minutes (p = 0.0008, pre 1.93 ± 1.46 mmol vs 3.91 ± 1.64 mmol) and between Pre and Post 10 (p = 0.0112, pre 1.93 ± 1.46 mmol vs 3.81 ± 1.52 mmol). RM ANOVA for time indicated a significant difference in VO2 (F = 13.3375, p = 0.0003). Significant increases were found between Pre and During (p < 0.001, 0.228 ± 0.053 L O2*min-1 vs 0.511 ± 0.187 L O2*min-1) as well as between Pre and Post (p = 0.002, 0.228 ± 0.053 L O2*min-1 vs 0.460 ± 0.106 L O2*min-1). RM ANOVA for RER indicated a significant main effect of time (F = 18.5607, p = 0.001). Significant increased were found between Pre and Post (p < 0.001, 0.843 ± 0.046 vs 1.147 ± 0.154). RM ANOVA revealed a significant main effect of time for minute ventilation (F = 10.0896, p = 0.0065). No individual time points were significantly different (p > 0.05). No significant differences were noted for time for blood glucose (F = 0.7383, p = 0.4918). Differences by time for left muscle oxygenation (F = 3.1185, p = 0.0239), with pre being significantly different from post (0-5 min) (p = 0.0170, pre: 67.29 ± 14.22 , post (0-5 min): 48.35 ± 24.61), and post (0-5 min) being different from post (5-10 min) (p = 0.0100, post 1 48.35 ± 24.61, post (5-10 min) 68.91 ± 9.54) and post (10-15 min) (p = 0.0220, post 1 48.35 ± 24.61, post (10-15 min) 73.20 ± 12.79). No differences were noted for right muscle oxygenation (F = 2.009, p = 0.1093). CONCLUSION: Petit allegro elicits some desirable characteristics of warm-up such as increased VO2 and minute ventilation.

Effects of a combined progressive resistance training and functional electrical stimulation-evoked cycling exercise on lower limb muscle strength of individuals with incomplete spinal cord injury: A randomized controlled study.

This study was conducted to investigate the effects of combined progressive resistance training (PRT) and functional electrical stimulation-evoked leg cycling exercise (FES-LCE) on isometric peak torque and muscle volume in individuals with incomplete spinal cord injury. In the single-blind, randomized controlled trial performed between April 2015 and August 2016, 28 participants were randomized between two exercise interventions (FES-LCE+PRT and FES-LCE alone), and training was conducted over 12 weeks. The isometric muscle peak torque and muscle volume for both lower limbs were measured at the baseline and after 6 and 12 weeks. Linear mixed-model analysis of variance was performed to test the effects of FES-LCE+PRT versus FES-LCE on each outcome measure over time via an intention-to-treat analysis. Twenty-three participants (18 males, 5 females; mean age: 33.4±9.7 years; range 21 to 50 years) completed study (10 in the FES-LCE+PRT group, and 13 in the FES-LCE group). The 12-week pre-and posttraining change for left hamstrings' muscle peak torque in the FES-LCE+PRT group (mean difference=4.5±7.9 Nm, 45% change, p<0.05) was consistently higher than that in the FES-LCE group (mean difference=2.4±10.3 Nm, 4% change; p<0.018). The improvement in the right quadriceps muscle's peak torque of the FES-LCE+PRT group (mean difference=19±7.6 Nm, 31% change, p<0.05) was more significant compared to the FES-LCE group. The left muscle volume showed a remarkable increase after 12 weeks in the FES-LCE+PRT group (mean difference=0.3±9.3 L, 7% change, p<0.05). The combination of PRT and FES-LCE was better in improving lower limb muscle strength and volume in chronic incomplete individuals with spinal cord injury.

Thermovision as a Tool for Athletes to Verify the Symmetry of Work of Individual Muscle Segments.

In the presented research, we characterised the temperature profiles and the degree of preparation for exercise of individual muscle groups of athletes We hypothesise that by means of thermal imaging studies, the effectiveness of the warm-up can be monitored to determine whether the effort of individual muscles is equal and symmetrical, which can help to avoid a potential injury. In the study, thermographic imaging was performed on a group of athletes exercising on a rowing ergometer involving almost 80% of the muscle parts of the human body for intense and symmetrical exercise. Thermovision studies have confirmed, based on the increased temperature of the muscle areas, that the rowing ergometer involves many muscle groups in training. Moreover, based on the shape of the temperature function obtained from individual body regions of interest, it was shown that conventional exercise on a rowing ergometer causes almost symmetrical work of the right and left sides of the body. Obtained temperature changes in most of the studied muscle areas showed minimum temperature reached the beginning of training—mostly phases 1 and 2. During the subsequent phases, the temperature increase was monitored, stopping at resting temperature. Significantly, temperature variations did not exceed 0.5 °C in all post-training phases. Statistical analyses did not show any significant differences in the symmetry of right and left muscle areas corresponding to the muscle location temperature. Thermal imaging may be an innovative wholly non-invasive and safe method, because checking induces adaptation processes, which may become indicators of an athlete’s efficiency. The imaging can be continuously repeated, and automatic comparison of average temperature or temperature difference may provide some clues that protect athletes from overtraining or serious injuries.

Torso dynamics during follow through in baseball batting

ABSTRACT The purpose of this study was to clarify the relationship between the bat swing speed immediately after the ball impact and the dynamics of the torso during the follow through in baseball batting. The batting motion and ground reaction forces acting on each foot for 29 collegiate baseball players were recorded using a motion capture system and two force plates. The biomechanical variables of the torso joint (i.e., the virtual joint that divides the torso between upper and lower) were calculated. For right-handed batters, the torque power of the right rotation in the torso joint was negative. Additionally, the bat head speed immediately after the ball impact was significantly correlated with the negative (i.e., right) peak rotation torque of the torso joint (r = −.635, p < 0.001) and the negative peak power in the right rotation torque of the torso joint (r = −.590, p = 0.001). These results suggest that the left external abdominal oblique muscle is in eccentric contraction during the follow through in baseball batting. Moreover, the results imply that the higher the bat head speed immediately after the ball impact, the higher the possibility to strain the abdominal oblique muscle.

Malignant solitary fibrous tumor of the pleura

BackgroundSolitary fibrous tumors of the pleura are rare diseases of the thoracic cavity. They frequently grow unnoticed until they exert compressive effects on adjacent organs. Treatment of solitary fibrous tumors of the pleura is surgical resection. Post-operative surveillance is recommended to identify early recurrent disease.Case presentationWe present a rare case of a 76-year-old female patient with no previous pulmonary history who presented with progressive dyspnea, fatigue, and involuntary weight loss. On chest X-ray and computed chest tomography scan, she was found to have a 16.7 cm × 12.8 cm × 10.1 cm bulky mass occupying the left hemithorax with associated compressive atelectasis of the lung. She underwent a computed tomography guided biopsy that revealed the mass to be a solitary fibrous tumor. The patient underwent left muscle sparing lateral thoracotomy with complete resection of the tumor. Post procedure, the left lung fully expanded. 18 months post-resection, she developed a 3.3 cm × 1.7 cm tumor along the left internal thoracic artery lymph node chain which was histologically identical to the resected tumor. The patient is currently being treated with bevacizumab and temozolomide.ConclusionSolitary fibrous tumors are very rare pleural tumors. Surgical resection is the treatment of choice followed by close post-operative surveillance.

Botulinum toxin injection in masseter muscle evokes musculoskeletal impairment of the masticatory system

The masticatory system is a finely coordinated machine, where minimal deregulation induces alterations of the whole system. Botulinum toxin type A (BoNTA) injection in masseter muscle is widely used as a clinical/aesthetic procedure. However, the non‐desirable effects of masseter muscle paralysis in neighbor masticatory muscles or mandibular bone are unknown. In the current work, we aimed to evaluate musculoskeletal loss at the masticatory system after BoNTA‐injection in masseter muscle of adult mice.Unilateral paralysis of masseter muscles was induced in male BalbC mice (8 weeks‐old) by single‐injection of BoNTA (0.2U/10 µL) in the right muscle and saline solution in the left muscle. Masticatory muscles (masseter, temporalis, lateral‐ and medial‐pterygoid) and mandibles were dissected after 2‐7‐14d for molecular measurements (qPCR), histology, or morphology (microcomputed tomography). All procedures were approved by the IACUC‐Universidad de Chile (# 20381‐ODO‐UCH). T‐test or Wilcoxon‐test were used for statistical comparisons between BoNTA‐ and Control‐side (n=3‐10, p&lt;0,05).The expression of molecular markers of atrophy (Atrogin1, Murf1) and regeneration (myogenin) significantly increased in the BoNTA‐side, as early as 2‐7d, in the intervened masseter but also in the ipsilateral temporalis and medial pterygoid muscles. There was a time‐dependent reduction in masseter fibers diameter from 2d to 14d. Masseter, temporalis, and medial pterygoid’s volumes significantly reduced in the BoNTA‐injected side at 14d. Interestingly, the volume of lateral pterygoid increased in the BoNTA side, with no change in atrophy/regeneration markers. Microstructural analysis of mandibular condyles demonstrated a progressive bone loss in the BoNTA‐injected side, starting as early as 7d and worsening 14d after the intervention.In conclusion, BoNTA injection in the masseter muscle impairs the whole masticatory system, inducing atrophy of masseter but also the ipsilateral temporalis and medial pterygoid, and even early‐bone loss of the mandibular condyle at the injected side. Then, clinical uses of BoNTA in masticatory muscles should be avoided or carried out under strict morpho‐functional monitoring.

Non-local muscle fatigue is mediated at spinal and supraspinal levels.

The objective was to measure the corticospinal excitability and motoneuron responsiveness of the right and left Biceps Brachii (BB), and left Abductor Digiti Minimi (ADM) muscles in response to submaximal isotonic fatiguing contractions performed by the right BB muscle. With the familiarization session, ten young moderately active male subjects came to the lab on seven occasions. Three sets of 3min seated elbow curls at 25% of one-repetition maximum (1RM) separated by a 1-min rest performed by the right BB muscle were used as the fatiguing protocol. The motor evoked potential (MEP), cervicomedullary motor evoked potential (CMEP), and compound muscle action potential (Mmax) of the right BB muscle (baseline and after each set of the fatiguing task), the left BB and ADM muscles (baseline, post-fatigue, post-10, and post-20min) were measured. MEP and CMEP were then normalized to Mmax for statistical analysis. The results showed that in the right BB muscle, there was a significant reduction in the MEP after performing the fatiguing task (p= 0.03), while no significant effect of time was seen in the CMEP (p= 0.07). In the left BB muscle, the MEP significantly decreased from pre-fatigue to post-fatigue (p= 0.01) and post-10 (p= 0.001), while there was a significant decline in the CMEP post-fatigue (p= 0.03). In the left ADM muscle, MEP significantly decreased post-fatigue (p= 0.03) and no changes were seen in the CMEP (p= 0.12). These results not only confirm the incidence of non-local muscle fatigue (NLMF) in response to performing submaximal isotonic fatiguing contractions but also as a new finding, imply that both spinal and supraspinal modulations account for the NLMF response.

Histomorphological and functional contralateral symmetry in the gastrocnemius muscles of the laboratory rat.

It is usual in anatomical and physiological research to assess the effects of some intervention on extremities (e.g., training programmes or injury recovery protocols) using one muscle for the intervention and its contralateral as control. However, the existence of laterality (left‐handedness or right‐handedness) in athletes of different specialities is widely recognized. In rats, gastrocnemius is one of the muscles most widely used because of its importance in locomotion and high relative limb mass. Since we have not found studies reporting laterality assessment on the morphology and function in rat gastrocnemius, our study aimed to evaluate the fibre histochemical, morphometrical and muscle force contractile properties between right and left gastrocnemius of the laboratory rat. Fibre‐type proportion, fibre morphometrical measurements, muscle capillarization and muscle force properties were analysed in the right and left gastrocnemius of six male rats. No statistically significant differences (p = 0.265) were found in gastrocnemius to body weight ratio (‰) between right (6.55 ± 0.40) and left (6.49 ± 0.40) muscles. The muscles analysed showed a great degree of heterogeneity in fibre type distribution, having three clearly distinguished regions named red, mixed and white. In the three regions, there were no statistical differences in fibre type proportions between right and left gastrocnemius, as is indicated by the p‐values (from 0.203 to 0.941) obtained after running t‐Student paired tests for each fibre type. When analysing fibre cross‐sectional area, individual fibre capillarization and fibre circularity, no significant differences between right and left gastrocnemius in any of these morphometrical parameters were found in any muscle region or fibre type. Most of the p‐values (70%) resulting from running t‐Student paired tests were higher than 0.400, and the lowest p‐value was 0.115. Seemingly, global capillary and fibre densities were not statistically different between right and left sides in all muscle regions with p‐values ranging from 0.337 to 0.812. Force parameters normalized to gastrocnemius mass (mN g−1) did not show any significant difference between right (PF = 74.0 ± 13.4, TF = 219.4 ± 13.0) and left (PF = 70.9 ± 10.7, TF = 213.0 ± 18.0) muscles with p = 0.623 (PF) and p = 0.514 (TF). Twitch time parameters (ms) also lacked significant differences between the two sides (CT: 43.4 ± 8.6 vs. 45.0 ± 14.3, p = 0.639; HRT: 77.6 ± 15.0 vs. 82.3 ± 25.3, p = 0.475). Finally, both muscles also showed similar (p = 0.718) fatigue properties. We did find an absence of laterality at the morphological and functional levels, which raises the possibility of using right and left gastrocnemius muscles interchangeably for experimental designs where one muscle is used to analyse data after a physiological intervention and its contralateral muscle plays the control role, thus allowing unbiased paired comparisons to derive accurate conclusions.