Increase Muscle Performance Research Articles

UCHL1 Negatively Regulates Key Factors and Signals Involved in Skeletal Muscle Myogenesis

Ubiquitin C-terminal hydrolase L1 (UCHL1), a deubiquitinating enzyme that was originally discovered in neurons, is also expressed in skeletal muscle, but its functions remain to be fully understood. Skeletal muscle injury is prevalent in trauma and surgical procedures, and skeletal muscle ischemia-reperfusion (IR) injury is a common and significant public health problem. Myogenesis is a critical process involved in embryonic development, growth, and regeneration following skeletal muscle injury. In this study we report that UCHL1 negatively affects some key factors that are involved in myogenesis and mitophagy, both during muscle development as well as during the regeneration process following IR injury; we hypothesize that UCHL1 is a negative regulator of myogenesis. First, we observed that UCHL1 knockdown in C2C12 myoblasts resulted in increased differentiation and myotube formation. Furthermore, western blot showed that UCHL1 KD consistently upregulated myogenin and MyoD protein levels, key proteins involved in myogenesis, at multiple time points throughout differentiation of the myotubes. Consistent with this in vitro result, skeletal muscle specific knockout (smKO) of UCHL1 increased muscle fiber size in both 1- and 2-month-old mice (p=1.77x10−17, p=6.51x10−13). Additionally, 1- and 2- month-old UCHL1 smKO mice also exhibited increased protein levels of various myosin heavy chain isoforms. To induce IR injury, a tourniquet was placed on the hindlimb for 90 minutes and then removed, allowing for reperfusion for 3-12 days with the contralateral hindlimb serving as a control. Following skeletal muscle IR injury, myogenin and MyoD protein expression was upregulated in injured muscle from UCHL1 smKO mice. Functionally, UCHL1 smKO mice had increased muscle performance after injury compared to control mice when subjected to in situ contractile testing. Interestingly, several mitophagy markers including Parkin and DRP1 were upregulated in IR injured muscle from UCHL1 smKO mice compared to WT mice (p=0.0003, p=0.029). This data suggests that skeletal muscle UCHL1 may function as a negative regulator of myogenesis, both during growth, and repair following injury, possibly by decreasing mitochondrial activity. This work was funded by NIH grant R01HL147105. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Perception of fatigue in elite athlete in West Java.

An elite athlete is someone who trains and competes in a high-level sport and has greater physical performance and physical endurance. In the training process, elite athletes use high resistance strength training strategies causing fatigue in athletes. On the positive side, fatigue is considered as a stimulus for muscle adaptation and increased muscle performance; on the negative side, it can lead to overreaching to overtraining. Monitoring and training time of athletes is needed to ensure athletes are consistent with training and minimize the risk of maladaptation of training to injury. Monitoring with the self-report method can be done as a marker of the athlete’s fatigue symptoms. This study aims to describe the perceptions of elite athletes towards fatigue. This research design uses descriptive method with cross-sectional design. The subjects involved in this study were the elite athletes of West Java KONI who did the training for PON XX 2021. In this case, the subjects were 215 elite athletes with 36 martial arts, 51 teams, 9 ratings, 34 games, 85 measured. Three RPE Scale with the highest frequency, namely the 13 scale “somewhat hard” (n = 64 29.8%), the 17 “very hard” (n = 47 21.9%), followed by a 12 “between light and somewhat hard” (n = 24 11.2%). There are athletes who choose scale of 6 “no exertion at all” (n = 6 2.8%) and for scale of 20 “maximum exertion” (n = 2 0.9%). Also, there are three RPE Scale with the lowest frequency, namely the 20 “maximum exertion” scale (n = 2 0.9%), followed by scale 19 “extremely hard” (n = 2 0.9%) with the same score and scale 18 (n = 3 1.4%). In this study, the perception of fatigue of elite athletes in West Java using the RPE scale of 20 scales is 13 “somewhat hard” and 17 “very hard”. There is no significant difference between gender, sport, duration, and age in selecting this scale.

Postactivation performance enhancement in the vertical jump using loads above or below the optimum-power load for a jump squat.

Postactivation performance enhancement (PAPE) is an acute response of increased muscle performance following a conditioning activity (CA), generally prescribed based on the percentage of a one-repetition maximum. However, it is unknown how the PAPE response is affected when the CA is performed near the optimum power zone. The purpose of this study was to examine PAPE using loads that were 20% above or below the optimum-power load (OPL). Fifteen recreationally trained subjects, with at least one-year resistance training experience participated in this study. First, the OPL for the JS was determined. Then, subjects performed two protocols in a counterbalanced order: 20% above (+20%OPL) or below (-20%OPL). To examine PAPE on performance, the vertical jump was performed prior to and seven times following each jump squat protocol, with a 2-min rest interval between trials. The two-way ANOVA revealed main effects for condition (F=4.978; P<0.001) for jump height and jump power (F=2.589; P=0.017), but post-hoc comparisons did not show differences. Between baseline and the best trial following each jump squat protocol, two-way ANOVA did not reveal main effects (F=3.048; P=0.103) or interactions (F=0.304; P=0.590). Paired t-tests did not show significant differences between conditions for relative changes in jump height (P=0.543) or jump power (P=0.233). This study revealed similar results between 20% above or below the OPL on subsequent vertical jump performance.

Blood flow restriction training activates the muscle metaboreflex during low-intensity sustained exercise.

Blood flow restriction training (BFRT) employs partial vascular occlusion of exercising muscle and has been shown to increase muscle performance while using reduced workload and training time. Numerous studies have demonstrated that BFRT increases muscle hypertrophy, mitochondrial function, and beneficial vascular adaptations. However, changes in cardiovascular hemodynamics during the exercise protocol remain unknown, as most studies measured blood pressure before the onset and after the cessation of exercise. With reduced perfusion to the exercising muscle during BFRT, the resultant accumulation of metabolites within the ischemic muscle could potentially trigger a large reflex increase in blood pressure, termed the muscle metaboreflex. At low workloads, this pressor response occurs primarily via increases in cardiac output. However, when increases in cardiac output are limited (e.g., heart failure or during severe exercise), the reflex shifts to peripheral vasoconstriction as the primary mechanism to increase blood pressure, potentially increasing the risk of a cardiovascular event. Using our chronically instrumented conscious canine model, we utilized a 60% reduction in femoral blood pressure applied to the hindlimbs during steady-state treadmill exercise (3.2 km/h) to reproduce the ischemic environment observed during BFRT. We observed significant increases in heart rate (+19 ± 3 beats/min), stroke volume (+2.52 ± 1.2 mL), cardiac output (+1.21 ± 0.2 L/min), mean arterial pressure (+18.2 ± 2.4 mmHg), stroke work (+1.93 ± 0.2 L/mmHg), and nonischemic vascular conductance (+3.62 ± 1.7 mL/mmHg), indicating activation of the muscle metaboreflex.NEW & NOTEWORTHY Blood flow restriction training (BFRT) increases muscle mass, strength, and endurance. There has been minimal consideration of the reflex cardiovascular responses that could be elicited during BFRT sessions. We showed that during low-intensity exercise BFRT may trigger large reflex increases in blood pressure and sympathetic activity due to muscle metaboreflex activation. Thus, we urge caution when employing BFRT, especially in patients in whom exaggerated cardiovascular responses may occur that could cause sudden, adverse cardiovascular events.

Creatine supplementation combined with blood flow restriction training enhances muscle thickness and performance: a randomized, placebo-controlled, and double-blind study.

This study aimed to compare the effects of an 8-week creatine (CR) or placebo (PL) supplementation on muscle strength, thickness, endurance, and body composition employing different training paradigms with blood flow restriction (BFR) vs. traditional resistance training (TRAD). Seventeen healthy males were randomized between the PL (n=9) and CR (n=8) groups. Participants were trained unilaterally utilizing a within-between subject bicep curl exercise where each arm was allocated to TRAD or BFR for 8 weeks. Muscular strength, thickness, endurance, and body composition were evaluated. Creatine supplementation promoted increases in muscle thickness in TRAD and BFR compared with their placebo counterparts, however, without a significant difference between treatments (p=0.349). TRAD training increased maximum strength (1 repetition maximum (1RM)) compared with BFR after 8 weeks of training (p=0.021). Repetitions to failure at 30% of 1RM were increased in the BFR-CR group compared with the TRAD-CR group (p=0.004). Repetitions to failure at 70% 1RM were increased from weeks 0-4 (p<0.05) and 4-8 (p<0.05) in all groups. Creatine supplementation exerted a hypertrophic effect when utilized with TRAD and BFR paradigms and increased muscle performance at 30% 1RM when utilized in conjunction with BFR. Therefore, creatine supplementation seems to amplify muscle adaptation following a BFR program. Registered in the Brazilian Registry of Clinical Trials (ReBEC), under the registration number: RBR-3vh8zgj.

Supplementation with Nitric Oxide Precursors for Strength Performance: A Review of the Current Literature.

Nitric-oxide-stimulating dietary supplements are widely available and marketed to strength athletes and weightlifters seeking to increase muscle performance and augment training adaptations. These supplements contain ingredients classified as nitric oxide (NO) precursors (i.e., "NO boosters"). Endogenous NO is generated via a nitric oxide synthase (NOS)-dependent pathway and a NOS-independent pathway that rely on precursors including L-arginine and nitrates, with L-citrulline serving as an effective precursor of L-arginine. Nitric oxide plays a critical role in endothelial function, promoting relaxation of vascular smooth muscle and subsequent dilation which may favorably impact blood flow and augment mechanisms contributing to skeletal muscle performance, hypertrophy, and strength adaptations. The aim of this review is to describe the NO production pathways and summarize the current literature on the effects of supplementation with NO precursors for strength and power performance. The information will allow for an informed decision when considering the use of L-arginine, L-citrulline, and nitrates to improve muscular function by increasing NO bioavailability.

Muscle Amino Acid and Adenine Nucleotide Metabolism during Exercise and in Liver Cirrhosis: Speculations on How to Reduce the Harmful Effects of Ammonia.

Studies from the last decades indicate that increased levels of ammonia contribute to muscle wasting in critically ill patients. The aim of the article is to examine the effects of two different causes of hyperammonemia—increased ATP degradation in muscles during strenuous exercise and impaired ammonia detoxification to urea due to liver cirrhosis. During exercise, glycolysis, citric acid cycle (CAC) activity, and ATP synthesis in muscles increase. In cirrhosis, due to insulin resistance and mitochondrial dysfunction, glycolysis, CAC activity, and ATP synthesis in muscles are impaired. Both during exercise and in liver cirrhosis, there is increased ammonia detoxification to glutamine (Glu + NH3 + ATP → Gln + ADP + Pi), increased drain of ketoglutarate (α-KG) from CAC for glutamate synthesis by α-KG-linked aminotransferases, glutamate, aspartate, and α-KG deficiency, increased oxidation of branched-chain amino acids (BCAA; valine, leucine, and isoleucine), and protein-energy wasting in muscles. It is concluded that ammonia can contribute to muscle wasting regardless of the cause of its increased levels and that similar strategies can be designed to increase muscle performance in athletes and reduce muscle loss in patients with hyperammonemia. The pros and cons of glutamate, α-KG, aspartate, BCAA, and branched-chain keto acid supplementation are discussed.

Вплив залишкової дії водорозчинного С60-фулерену на скорочення muscle soleus та muscle gastrocnemius щурів за розвитку втоми

A comparison of biomechanical and biochemical markers of muscle soleus and muscle gastrocnemius fatigue in rats for two days after 5 days of using antioxidant C60 fullerene (daily dose was 1 mg·kg-1) was performed. It was shown that its long-term use to increase muscle strength response against the background of muscle fatigue by 60-65 and 35-40% in slow and fast muscle, respectively. The residual effect of water-soluble C60 fullerene on slow muscle remains significant (20-25%) even after 2 days after discontinuation of the drug. At the same time, its residual effect on fast muscle on the 2nd day remains at a minimum level, which does not significantly increase muscle performance. Prolonged usage of water-soluble C60 fullerene helps to reduce oxidative processes by 30-40% in fast and by 21-25% in slow muscles by maintaining a balance between prooxidants and antioxidant defense system. A comparative analysis of oxidative stress markers and indicators of the state of antioxidant defense systems in fast and slow muscles showed that the residual therapeutic effect of water-soluble C60 fullerene after long-term use is 30-40% higher in muscle soleus than in muscle gastrocnemius. The obtained results demonstrate the long-term kinetics of water-soluble C60 fullerene excretion from the body, which contributes to long-term (at least two days) compensatory activation of the endogenous antioxidant system in response to muscle stimulation, which should be considered when developing new therapeutic drugs based on it.

Plant-Based Diet: Is It as Good as an Animal-Based Diet When It Comes to Protein?

Protein is a macronutrient that is responsible for multiple functions in the human body and is made up of twenty amino acids. Nine amino acids are not synthesized in the human body and require dietary ingestion to prevent deficiency. These essential amino acids are easily obtained through animal-based proteins but can be in limited quantities through plant-based protein sources. With the obesity epidemic rising, great attention has turned to plant-based protein diets and their health and environmental implications. The differences in plant and animal protein sources have been explored for their effects on general health, sarcopenia, and muscle performance. This review discusses the benefits and drawbacks of a plant-based diet, as well as some of the latest literature on muscle protein synthesis between animal- and plant-based dietary intakes of protein. High meat consumption is associated with increased saturated fat intake and lower dietary fiber intake. As a result, meat consumption is correlated with obesity, heart disease, metabolic syndrome, and gastrointestinal cancers. However, animal-based diets contain higher amounts of leucine and other essential amino acids which are associated with increased anabolic potential and muscle protein synthesis. Yet, multiple studies show conflicting results on the true benefits of animal-based diets, suggesting total protein intake may be the best predictor for preserving lean muscle mass and increasing muscle performance. While many studies support animal protein sources superior to plant-based diets on intracellular anabolic signaling, other studies show conflicting results regarding the true benefit of animal-based protein diets on overall performance and effect on sarcopenia. The health benefits seem to favor plant-based protein sources; however, further research is needed to examine the effects of protein from plant- and animal-based diets on muscle mass and protein synthesis.

Time-Response of Photobiomodulation Therapy by Light-Emitting Diodes on Muscle Torque and Fatigue Resistance in Young Men: Randomized, Double-Blind, Crossover and Placebo-Controlled Study.

Background: Photobiomodulation therapy (PBMT) by lasers or light-emitting diodes (LEDs) has been used in the last two decades to increase muscle performance in humans. The main findings of PBMT on muscle performance are increment in torque and number of muscle contractions, and fatigue resistance in high-intensity exercises. Although there are suggested light energies to be followed, the literature has also pointed out to a possible time-response of PBMT to increase exercise performance and recovery in humans. Objective: To investigate the possible time-response of PBMT by LEDs to increase muscle performance in young men regarding peak torque (PT), rate of torque development (RTD), fatigue resistance, and subjective perception of effort in maximal voluntary isometric contractions (MVIC) of elbow flexion. Methods: This randomized, double-blind, placebo-controlled, crossover trial with two arms enrolled 34 healthy and physically active young men, but 30 (21.10 ± 2.25 years old) completed all procedures. All volunteers were allocated into two equal arms (groups): PBMT (60 J; 1152 mW; 52 sec; and 166.75 cm2) applied on biceps brachii by a flexible array of LEDs, and placebo treatment. Each arm (n = 15) investigated the time-response (5 min, 1 h, 3 h, and 6 h) of PBMT in a randomized, double-blind, and crossover manner on the PT, RTD, fatigue resistance, and subjective perception of effort. Results: There were no significant results (p > 0.05) for all comparisons within and between groups regarding PT, RTD, fatigue resistance, and subjective perception of effort in MVIC of the elbow flexion in all time-response tested (5 min, 1 h, 3 h, and 6 h) before or after fatigue test. Only RTD did not decay significantly after fatigue test at all time-responses for PBMT group. Conclusions: PBMT was not effective to increase muscle performance and decrease fatigue to demonstrate the possible time-response in humans.

Caffeine Increases Muscle Performance During a Bench Press Training Session.

Previous investigations have established the ergogenic effect of caffeine on maximal muscle strength, power output and strength-endurance. However, these investigations used testing protocols that do not replicate the structure of a regular strength training session. Thus, the aim of this study was to investigate the effect of acute caffeine ingestion on muscle performance during a simulated velocity-based training workout. In a double-blind, randomized and counterbalanced experiment, 12 participants performed two experimental trials after ingesting 3 mg/kg/b.m. of caffeine or a placebo. The trials consisted of 4 sets of 8 repetitions of the bench press exercise at 70% of their one-repetition maximum performed at maximal velocity. Bar velocity was recorded with a rotatory encoder and force, power output and work were calculated. Regarding the whole workout, caffeine increased mean bar velocity (+7.8%; p=0.002), peak bar velocity (+8.7%; p=0.006), mean force (+1.5%; p=0.002), mean power output (+10.1%; p=0.003) and peak power output (+8.2%; p=0.004) when compared to the placebo. The total work performed in the caffeine trial was superior to the placebo trial (7.01±2.36 vs 6.55±2.20 kJ, p=0.001). These results suggest that the acute intake of 3 mg/kg/b.m. of caffeine before a velocity-based strength workout increased muscle performance and the total work performed across the whole training session. Thus, caffeine can be considered as an effective strategy to enhance muscle performance during the bench press training sessions.

Effects of Photobiomodulation Therapy and Restriction of Wrist Extensor Blood Flow on Grip: Randomized Clinical Trial.

Objective: To evaluate the influence of two different photobiomodulation therapy (PBMT) protocols (red 660 nm vs. infrared 830 nm) combined with a blood flow restriction (BFR) training protocol in wrist extensor muscles on handgrip, wrist extension force, and electromyographic behavior [root mean square (RMS)]. Background: PBMT has been widely used to increase muscle performance and recovery in recent clinical trials. However, there is no evidence whether PBMT (red and/or infrared) can promote better results when combined with BFR, a known method to induce better strength gains. Methods: This study was a randomized controlled trial including 58 volunteers allocated into four groups: (1) control (conventional strengthening), (2) BFR (strengthening with BFR), (3) 660 nm (BFR strengthening with 660 nm PBMT-35 mW; 0.05 cm2; 2.10 J, total energy 18.9 J), and (4) 830 nm (BFR strengthening with 830 nm PBMT-32 mW; 0.101 cm2; 1.92 J, total energy 17.2 J). Data were analyzed by using a mixed-effects model, with a 5% significance index. Results: A statistically significant increase was obtained for handgrip strength for the 660 nm group [27.36 ± 2.61 kilogram force (kgF)] compared with the 830 nm group (23.04 ± 3.06 kgF) (p = 0.010) and for wrist extensor strength in the 660 nm (7.77 ± 0.58 kgF) and BFR (7.54 ± 0.92 kgF) groups compared with the control group (5.33 ± 0.61 kgF) (p = 0.001 and p = 0.004, respectively). The RMS value for the 660 nm group was significantly higher than control (p < 0.0001), BFR (p < 0.0001), and the 830 nm group (p = 0.0009). Conclusions: The association of PBMT (660 nm) and BFR was effective for increasing handgrip strength of the wrist extensors, associated with an increase in RMS.

Influence of Histidine Administration on Ammonia and Amino Acid Metabolism: A Review.

Histidine (HIS) is an essential amino acid investigated for therapy of various diseases, used for tissue protection in transplantation and cardiac surgery, and as a supplement to increase muscle performance. The data presented in the review show that HIS administration may increase ammonia and affect the level of several amino acids. The most common are increased levels of alanine, glutamine, and glutamate and decreased levels of glycine and branched-chain amino acids (BCAA, valine, leucine, and isoleucine). The suggested pathogenic mechanisms include increased flux of HIS through HIS degradation pathway (increases in ammonia and glutamate), increased ammonia detoxification to glutamine and exchange of the BCAA with glutamine via L-transporter system in muscles (increase in glutamine and decrease in BCAA), and tetrahydrofolate depletion (decrease in glycine). Increased alanine concentration is explained by enhanced synthesis in extrahepatic tissues and impaired transamination in the liver. Increased ammonia and glutamine and decreased BCAA levels in HIS-treated subjects indicate that HIS supplementation is inappropriate in patients with liver injury. The studies investigating the possibilities to elevate carnosine (beta-alanyl-L-histidine) content in muscles show positive effects of beta-alanine and inconsistent effects of HIS supplementation. Several studies demonstrate HIS depletion due to enhanced availability of methionine, glutamine, or beta-alanine.

Milk protein consumption improves muscle performance and total antioxidant status in young soccer athletes: a randomized controlled trial

BACKGROUND Muscle performance and antioxidant balance are closely related to an athlete achievement. Milk proteins (whey and casein) contain essential and non-essential amino acids, which benefit muscle performance through increased antioxidant levels. This study was aimed to evaluate the effects of milk protein on muscle performance and total antioxidant status (TAS) in soccer athletes.&#x0D; METHODS A randomized controlled trial was conducted on 20 males 16- to 18-year-old athletes at the Central Java Soccer Club in January 2018. For 28 days, the treatment group received 24 g/d of milk protein and the control group received 24 g/d of maltodextrin. Muscle performance was measured through a 20-m sprint, shuttle run, Illinois run, standing broad jump, sit-ups, push-ups, sit-and-reach test, and one-repetition maximum (1RM) leg extension. TAS was analyzed using the 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method.&#x0D; RESULTS The treatment group had a decreased shuttle run time (-0.16 [0.11] versus 0.08 [0.14] sec), greater increase in sit-ups (6.80 [2.57] versus 1.10 [2.84] times/60 sec), greater increase in push-ups (2.40 [1.78] versus 0.30 [1.77] times/60 sec), and greater increase in 1RM leg extension (32.00 [13.78] versus 3.50 [13.75] kg). After adjustments for age, energy intake, carbohydrates, and pre-interventional performance, these parameters remained significantly improved after the intervention of milk protein. The TAS increase was greater in the treatment group than in the control group (0.36 [0.32] versus -0.12 [0.20] mmol/l) before and after adjustment for age, vitamin C, iron, selenium intake, and TAS pre-treatment.&#x0D; CONCLUSIONS Milk protein supplementation for 28 days increased muscle performance and TAS.

Alleviation of Simvastatin-Induced Myopathy in Rats by the Standardized Extract of Ginkgo Biloba (EGb761): Insights into the Mechanisms of Action

Statins are the most widely prescribed cholesterol-lowering drugs to reduce the risk of cardiovascular diseases. Statin-induced myopathy is the major side effect of this class of drugs. Here, we studied whether standardized leaf extracts of ginkgo biloba (EGb761) would improve simvastatin (SIM)-induced muscle changes. Sixty Wistar rats were allotted into six groups: control group, vehicle group receiving 0.5% carboxymethyl cellulose (CMC) for 30 days, SIM group receiving 80 mg/kg/day SIM in 0.5% CMC orally for 30 days, SIM withdrawal group treated with SIM for 16 days and sacrificed 14 days later, and EGb761-100 and EGb761-200 groups posttreated with either 100 or 200 mg/kg/day EGb761 orally. Muscle performance on the rotarod, serum creatine kinase (CK), coenzyme Q₁₀ (CoQ₁₀), serum and muscle nitrite, muscle malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) activities were estimated. Additionally, muscle samples were processed for histopathological evaluation. We found that SIM decreased muscle performance on the rotarod, serum CoQ₁₀, as well as muscle SOD and CAT activities while it increased serum CK, serum and muscle nitrite, as well as muscle MDA levels. SIM also induced sarcoplasmic vacuolation, splitting of myofibers, disorganization of sarcomeres, and disintegration of myofilaments. In contrast, posttreatment with EGb761 increased muscle performance, serum CoQ₁₀, as well as muscle SOD and CAT activities while it reduced serum CK as well as serum and muscle nitrite levels in a dose-dependent manner. Additionally, EGb761 reversed SIM-induced histopathological changes with better results obtained by its higher dose. Interestingly, SIM withdrawal increased muscle performance on the rotarod, reduce serum CK and CoQ₁₀, and reduced serum and muscle nitrite while it reversed SIM-induced histopathological changes. However, SIM withdrawal was not effective enough to restore their normal values. Additionally, SIM withdrawal did not improve SIM-induce muscle MDA, SOD, or CAT activities during the period studied. Our results suggest that EGb761 posttreatment reversed SIM-induces muscle changes possibly through its antioxidant effects, elevation of CoQ₁₀ levels, and antagonizing mitochondrial damage.

Early pathological signs in young dysf−/− mice are improved by halofuginone

Dysferlinopathies are a non-lethal group of late-onset muscular dystrophies. Here, we evaluated the fusion ability of primary myoblasts from young dysf−/− mice and the muscle histopathology prior to, and during early stages of disease onset. The ability of primary myoblasts of 5-week-old dysf−/− mice to form large myotubes was delayed compared to their wild-type counterparts, as evaluated by scanning electron microscopy. However, their fusion activity, as reflected by the presence of actin filaments connecting several cells, was enhanced by the antifibrotic drug halofuginone. Early dystrophic signs were already apparent in 4-week-old dysf−/− mice; their collagen level was double that in wild-type mice and continued to rise until 5 months of age. Continuous treatment with halofuginone from 4 weeks to 5 months of age reduced muscle fibrosis in a phosphorylated-Smad3 inhibition-related manner. Halofuginone also enhanced myofiber hypertrophy, reduced the percentage of centrally nucleated myofibers, and increased muscle performance. Together, the data suggest an inhibitory effect of halofuginone on the muscle histopathology at very early stages of dysferlinopathy, and enhancement of muscle performance. These results offer new opportunities for early pharmaceutical treatment in dysferlinopathies with favorable outcomes at later stages of life.

Muscle Activation Response Using a Constant Resistance Sled Trainer Within Different Tasks

The XPO Trainer used in this inquiry is a novel device which provides low rolling resistance at low speeds with an immediate and automatic proportional gain in resistance with increased speed. Resistance exercise (RE) has been shown to induce many positive benefits to the body and mind, including hypertrophy of muscles, increased muscle performance, cardiovascular benefits, decrease risk of mortality, and decrease the risk of functional limitations.PURPOSEExamine the impact of pushing a constant resistance on gait and neuromuscular activation at low and high speeds in young, seemingly healthy adults.METHODSThe study consisted of 21 healthy adult males and females (age: 25.07±3.46 years, weight: 148.2±25.96 lbs, height: 66.57±4.14 inches). Each participant wore surface electromyography electrodes on their dominant leg for their quadriceps (QUAD), hamstring (HAM), anterior tibialis (TA), and gastrocnemius (GA). First, the maximal voluntary isometric contractions were gathered for each muscle. Then, participants performed 3 trials of 4 conditions: walking, walking and pushing, running, and running and pushing. After the data was normalized as a percentage (0–100%) for the gait tasks and the muscle activation amplitude, a repeated measures ANOVA was performed with the SPSS 24 system.RESULTSThe QUAD muscle exhibited a significantly higher muscle activation (P≤0.05) between walk (45.39±24.43) and walk push (74.40±56.73) tasks. Additionally, there is a significantly higher muscle activation (p≤0.05) between GA (81.85±37.84) and QUAD (46.06±23.93) during the walking task. A significant difference (p≤.05) was found between GA (0.33±0.17) and HAM (0.47±0.17) muscle activation timing during walking activity. During the walking activity, maximal muscle activation occurred in the GA muscle earlier than the HAM muscle. Additionally, there was a significant difference (p≤.05) in timing of the TA (0.43±0.17) vs QUAD (0.55±0.18), as well as the GA (0.41±0.10) vs the QUAD(0.55±0.18). TA and GA activation occurred significantly earlier than the QUAD activation during the walk and push task.CONCLUSIONWith the constant resistance sled being a novel device, it is important to understand how it affects the activation and response of muscles during different activities. Based on the results, patients can benefit from utilizing the sled in combination of walking and running to either promote a higher or lower muscle activation. With patients with weak QUADs or in need of QUAD strength training, a walking task is advocated. Additionally, if the goal of the intervention is to focus on endurance of the TA and GA, two of the main muscles used in postural balance, walking with the sled is recommended. Knowing all of these effects on muscle activation utilizing a constant resistance sled trainer will allow for more effective exercise training.

Periodized versus Non-periodized Stretch Training on Gymnasts Flexibility and Performance.

Static stretching (SS) can increase joint range of motion (ROM), due to neural, morphological, and physio-psychological factors. Periodized training programs (PD) (e. g., strength, power) are adopted to induce greater adaptations while avoiding overtraining. However, the effectiveness of periodized stretch training adaptations are unknown. Therefore, the objective of this study was to compare the effects of periodized and non-periodized (NP) stretching programs on flexibility, hamstrings stiffness and muscle performance. Sixteen gymnasts were allocated to either periodized or non-periodized SS training and tested pre- and post-8 weeks for countermovement jump height, hip flexors, hip extensors and dorsiflexors ROM, hamstrings stiffness and hamstrings and quadriceps peak torque. Both stretch training groups significantly and similarly increased hip extensor (33.2%), hip flexor (25.2%), and dorsiflexor (23.8%) ROM, hamstrings peak torque (7.9%) and jump height (8.1%) from pre - to post- training. Both groups decreased hamstrings stiffness across the last ten angles (32.1%). PD elicited consistently large magnitude flexibility effect size changes compared to small and moderate magnitude changes for the non-periodized. Therefore, 8-week PD and NP SS programs can decrease young gymnasts' muscle-tendon stiffness and increase muscle performance. However, effect sizes indicate that PD stretch training was more advantageous to increasing flexibility and improving performance.

Taurine enhances skeletal muscle mitochondrial function in a rat model of resistance training

Taurine (β-amino sulfonic acid; TAU) is the most abundant amino acid in the human body. Recently, the positive effects of TAU on cellular mitochondria has been considered as an interesting mechanism for its beneficial effects. On the other hand, skeletal muscle disorders are debilitating complications, which could affect patients’ quality of life. Moreover, increasing muscle performance and stamina without violating standard rules are of particular interest in athletes. The current study was designed to evaluate the effect of resistance training (RT) with and without TAU supplementation on skeletal muscle function. Rats underwent RT training for eight weeks. Concurrently, animals received TAU (100, 500, and 1000 mg/kg/day, gavage). It was found that TAU treatment significantly decreased animals weight gain and enhanced the weight carrying capacity in RT rats. Mitochondrial indices, including dehydrogenases activity, ATP level, and membrane potential were significantly increased upon TAU treatment. These data indicate the positive effects of TAU on skeletal muscle function and provide insight into its potential mechanism of action. Therefore, TAU could be feasibly used to enhance muscle function and stamina. Moreover, TAU could be considered as a potential preventive/therapeutic agent against muscle disorders linked to mitochondrial impairment and disrupted cellular energy metabolism.

The Effectiveness of Photobiomodulation Therapy Versus Cryotherapy for Skeletal Muscle Recovery: A Critically Appraised Topic.

Clinical Scenario: Cryotherapy is one of the most commonly used modalities for postexercise muscle recovery despite inconsistencies in the literature validating its effectiveness. With the need to find a more effective modality, photobiomodulation therapy (PBMT) has gained popularity because of recent research demonstrating its ability to accelerate the muscle recovery process. Focused Clinical Question: Is PBMT more effective than cryotherapy at reducing recovery time and decreasing delayed onset muscle soreness after strenuous exercise? Summary of Key Findings: Three moderate- to high-quality double-blinded, randomized, placebo-controlled trials and 2 low- to moderate-quality translational studies performed on rats were included in this critically appraised topic. All 5 studies supported the use of PBMT over cryotherapy as a treatment for postexercise muscle recovery following exercise. PBMT was superior in reducing creatine kinase, inflammation markers, and blood lactate compared with cryotherapy, following strenuous/high intensity aerobic or strength muscular exercise. PBMT was also shown to improve postexercise muscle performance and function more than cryotherapy. Clinical Bottom Line: There is moderate evidence to suggest the use of PBMT over cryotherapy postexercise to enhance muscle recovery in trained and untrained athletes. Shorter recovery times and increased muscle performance can be seen 24 to 96hours following PBMT application. Strength of Recommendation: Based on consistent findings from all 5 studies, there is grade B evidence to support the use of PBMT over cryotherapy for more effective postexercise recovery of skeletal muscle performance.