Neuromuscular Efficiency Research Articles

Massage prior to exercise delays the onset of the physical working capacity at the fatigue threshold (PWCFT).

Functional massage (FM) is a soft tissue technique that incorporates non-end range joint movement with tissue compression to treat musculotendinous pain and dysfunction. FM has been associated with promoting neural excitability and neuromuscular efficiency. In clinical practice, FM may be used at the beginning of a treatment session to prepare fibers of the target muscle and surrounding soft tissues for functional activity. The Physical Working Capacity at the Fatigue Threshold (PWC<inf>FT</inf>) uses surface electromyography (EMG) to demarcate between non-fatiguing and fatiguing exercise. To our knowledge, no studies have examined the efficacy of FM when performed prior to an exercise session. The purpose of this study was to determine whether pre-performance FM delays the onset of neuromuscular fatigue. We hypothesized that FM would increase maximal power output as well as PWC<inf>FT</inf> compared to the control condition. Thirteen healthy college-aged men (mean±SEM: age, 24.1±0.5 years; weight, 83.0±3.2 kg; and height, 1.80±0.02 m) ranging from 22 to 28 years-old volunteered for the present study. On two occasions separated by at least 7 days, participants visited the laboratory to perform single-leg knee-extensor ergometer exercise after either receiving 7 min of FM (experimental condition) or no FM (control condition). The results indicated that the onset of neuromuscular fatigue was significantly delayed for the absolute and relative PWC<inf>FT</inf> (~80%) values compared to the control condition. There was no significant mean difference between FM and control for maximal power output. The findings of the present study indicated that FM was effective in delaying neuromuscular fatigue as assessed by PWC<inf>FT</inf>. These findings may be applicable to both athletic and clinical settings as FM prior to exercise may help to prime a target muscle before training.

Acute effects of the short-foot exercise in runners with medial tibial stress syndrome: A quasi-experimental study

ObjectivesAnalyze whether there are immediate changes in peak soleus activation and peak hindfoot eversion after short-foot exercise (SFE) in runners with medial tibial stress syndrome (MTSS). Secondarily, establish differences in peak soleus activation and peak hindfoot eversion between asymptomatic individuals and those presenting MTSS. DesignQuasi-experimental study. SettingUniversity Laboratory. ParticipantsThirty-two runners participated: 16 with MTSS and 16 in the no-pain group (NPG). Main outcome measuresSoleus activation was measured using electromyography, and hindfoot eversion via 3D kinematic analysis. Participants performed SFE, and running data were collected at 9,12 and 15 km/h pre- and post-intervention. ResultsSFE reduced peak soleus activation at 9 (p = 0.017) and 15 km/h (p = 0.019) for the MTSS group and at 15 km/h (p < 0.001) for the NPG, suggesting improved neuromuscular efficiency and potentially reduced tibial stress. SFE did not significantly affect peak hindfoot eversion. Significant correlations were found between ankle dorsiflexion range of motion and muscle activation (r = 0.585 to 0.849, p < 0.05). These findings suggest SFE could improve neuromuscular efficiency and reduce tibial stress, and highlights ankle flexibility's role in muscle activation. ConclusionsSFE significantly reduces soleus activation, potentially improving neuromuscular efficiency and decreasing tibial stress.

The effects of low vs. high rating of perceived exertion clamp exercise on performance, neuromuscular, and muscle oxygen saturation responses in females.

This study examined the time course of changes in force, relative to critical force (CF), electromyographic amplitude (EMG AMP), neuromuscular efficiency (NE), and muscle oxygen saturation (SmO2), as well as time to task failure (TTF) and performance fatigability (PF) during isometric handgrip holds to failure (HTF) anchored to the rating of perceived exertion (RPE) at 3 and 7. Ten females completed pre-test maximal voluntary isometric contractions (MVICs), submaximal HTF at four percentages of MVIC, an HTF at RPE = 3 and 7, and post-test MVICs. Analyses included paired samples t-tests, repeated measures ANOVAs and planned comparisons. TTF was not different between RPE 3 (540.4 ± 262.1s) and 7 (592.2 ± 299.6s), but PF for RPE 7 (42.1 ± 19.1%) was greater than RPE 3 (33.5 ± 15.4%) (p < 0.05). There were RPE-dependent decreases in force, EMG AMP, and NE across three discernable phases during the HTF (p < 0.01), but there were no significant changes in SmO2 across time. Although there were overall similar patterns across time for force, neuromuscular, and muscle metabolic responses between the RPE holds, the greater PF at RPE 7 than RPE 3 may be explained by the longer sustained time above CF at RPE 7, resulting in greater accumulation of intramuscular metabolites and afferent feedback. Throughout each trial, it is possible that force was adjusted to avoid the sensory tolerance limit, and the task was ended when force could no longer be reduced to maintain the assigned RPE, resulting in a similar TTF for RPE 7 and RPE 3.

The Impact of Short-Term Nitric Oxide Supplementation on Muscular Power and Neuromuscular Adaptation in Strength Athletes

Nitric oxide (NO) plays a crucial role in various physiological processes, particularly in enhancing blood flow and modulating neuromuscular function. This study investigates the impact of short-term NO supplementation on muscular power and neuromuscular adaptation in strength athletes, with a focus on biomechanical and neurological regulation. Thirty experienced strength athletes were randomly assigned to either a NO supplementation group or a placebo group for 14 days. The primary outcomes measured were peak power output across three key resistance exercises (back squat, bench press, and deadlift) and neuromuscular adaptation, assessed through electromyography (EMG) and motor unit recruitment patterns. The results demonstrated a significant increase in peak power output in the NO group compared to the placebo group, with average improvements of 8.5%, 7.2%, and 9.1% in the back squat, bench press, and deadlift, respectively. Additionally, the NO group showed enhanced neuromuscular efficiency, evidenced by increased EMG amplitude and improved motor unit recruitment patterns. A positive correlation was observed between corticospinal excitability and peak power output, suggesting that NO supplementation enhances neural drive, contributing to better performance outcomes. These findings indicate that short-term NO supplementation can effectively improve muscular power and neuromuscular adaptation, making it a valuable strategy for strength athletes aiming to optimize their training and performance.

Effectiveness of High-Intensity Circuit Training on Physical Fitness Among Athletes: A Systematic Review of Randomized-Controlled and Non-Controlled Trials

Background and Aim of the Study: The continuous evolution of sports and athletics necessitates innovative training strategies to optimize athletes’ performance and physical fitness. High-Intensity Circuit Training (HICT) has emerged as a time-efficient method that combines high-intensity exercises with minimal rest, targeting various muscle groups to enhance physical fitness components. Therefore, this systematic review aims to evaluate the effectiveness of HICT on physical fitness components among athletes to provide a clear, evidence-based understanding of HICT’s benefits and limitations. Material and Methods: A comprehensive search strategy was employed, retrieving articles published before September 24, 2023, from databases including the Cochrane Central Register of Controlled Trials, PubMed, and Google Scholar. The selection process followed the PRISMA guidelines, focusing on studies that assessed the impact of HICT on athletes’ physical fitness. The quality of included studies was assessed using the PEDro scale, and data synthesis was conducted to summarize findings on various physical fitness components. Results: The review included 13 studies, highlighting HICT’s positive effects on muscle strength, endurance, flexibility, balance, power, body composition, and cardiovascular endurance. Improvements were noted in neuromuscular efficiency, muscle power, coordination, and cardiovascular fitness, which are crucial for athletic performance. However, the review also identified variability in training adaptations and the need for sport-specific exercises to maximize the benefits of HICT for speed and power enhancements. Conclusions: HICT is a versatile and effective training modality that can significantly improve various aspects of athletes’ physical fitness. Incorporating targeted, sport-specific exercises into HICT programs could further optimize performance enhancements. Despite promising findings, the review acknowledges methodological heterogeneity among studies and calls for further research to refine HICT protocols for athletes.

The science of ladder drills and plyometrics: Enhancing neuromuscular efficiency in athletes

The objectives of this study are to determine whether there is any interaction between agility and athletic performance skills and plyometric training, ladder drill, and agility training; how different these effects are from one another; and how different the effects of low and high agility are from one another. The experimental methodology employed in this work uses a factorial analysis in 2x2. A population of 40 athletes, aged 15 to 17, were selected for the research sample using ordinal pairing. Devices that measure agility using the Illinois Agility Test. The following are the study's findings: The post-test indicates a significant value of p &lt; 0.05, indicating that the plyometric training technique, ladder drill, affects athletic performance skills (p &gt; 0.05). Because the significance value indicates p of 0.006 &lt; 0.05, there is a significant difference between the effects of low and high agility on athletic performance skills (p &lt; 0.05). There is a significant (p &gt; 0.05) interaction between agility (high and low), ladder drill training techniques, and plyometric training methods of athletic performance skills (p &lt; 0.05). The findings indicate that following training, there is a relationship between agility and athletic performance abilities. According to the study, there is a connection between agility (high and low) and athletic performance skills, and agility has a major impact on athletic performance. Training techniques such as plyometric training and ladder drills are also related to agility. Applying the ladder drill and plyometric training techniques affects athletes' performance abilities. It has been demonstrated that doing plyometric and ladder drills may enhance one's athlete's performance ability.

A Holistic Focus of Attention Increases Torque Production and Electromyography Activity in an Isokinetic Elbow Flexion

Recent research suggests that both a holistic focus of attention (i.e., focusing on the general feeling of a movement) and an external focus of attention improve motor performance relative to an internal focus of attention. The purpose of this study was to determine how a holistic, internal, and external focus impacts torque production and electromyography (EMG) activity in the biceps brachii during an isokinetic elbow flexion task. Twenty-four young adults completed five repetitions of an isokinetic elbow flexion task in internal, external, and holistic focus conditions. Peak torque, integrated torque, peak EMG amplitude, integrated EMG, and neuromuscular efficiency were averaged across trials in each condition. Peak torque, integrated torque, peak EMG amplitude, and integrated EMG were all significantly higher with a holistic focus than an internal or external focus. Internal and external focus conditions did not differ from each other in any variable. No differences due to focus were observed for neuromuscular efficiency. The present results suggest that using a holistic focus of attention can be a useful strategy for motor tasks requiring peak force production. However, it does not appear that this benefit is related to increased neuromuscular efficiency, as we hypothesized.

Sleep restriction reduces voluntary isometric quadriceps strength through reduced neuromuscular efficiency, not impaired contractile performance.

To determine how SR affects quadriceps contractile function and recruitment. Eighteen healthy subjects (9M, 9F, age 23.8 ± 2.8y) underwent isometric (maximal and submaximal), isokinetic (300-60°·s-1), and interpolated twitch (ITT) assessment of knee extensors following 3d of adequate sleep (SA; 7-9h·night-1), 3d of SR (5h·night-1), and 7d of washout (WO; 7-9h·night-1). Compared to SA (227.9 ± 76.6Nm) and WO (228.19 ± 62.9Nm), MVIC was lesser following SR (209.9 ± 73.9Nm; p = 0.006) and this effect was greater for males (-9.8 v. -4.8%). There was no significant effect of sleep or sleep x speed interaction on peak isokinetic torque. Peak twitch torque was greater in the potentiated state, but no significant effect of sleep was noted. Males displayed greater potentiation of peak twitch torque (12 v. 7.5%) and rate of torque development (16.7 v. 8.2%) than females but this was not affected by sleep condition. ITT-assessed voluntary activation did not vary among sleep conditions (SA: 81.8 ± 13.1% v. SR: 84.4 ± 12.6% v. WO 84.9 ± 12.6%; p = 0.093). SR induced a leftward shift in Torque-EMG relationship at high torque output in both sexes. Compared to SA, females displayed greater y-intercept and lesser slope with SR and WO and males displayed lesser y-intercept and greater slope with SR and WO. Three nights of SR decreases voluntary isometric knee extensor strength, but not twitch contractile properties. Sex-specific differences in neuromuscular efficiency may explain the greater MVIC reduction in males following SR.

Loading or Unloading? This Is the Question! A Multi-Season Study in Professional Football Players.

This study examined the impact of training load periodization on neuromuscular readiness in elite football players using the Locomotor Efficiency Index (LEI) as a measure of performance optimization. Throughout the 2021/22 and 2022/23 seasons, 106 elite male players (age: 19.5 ± 3.9 years) from an Italian professional football club were monitored using Global Positioning Systems (GPS) external load data. The LEI was derived from a machine learning model, specifically random forest regression, which compared predicted and actual PlayerLoad™ values to evaluate neuromuscular efficiency. Players were categorized by weekly LEI into three readiness states: bad, normal, and good. Analysis focused on the variation in weekly LEI relative to weekly load percentage variation (large decrease, moderate decrease, no variation, moderate increase, large increase), which included total distance, high-speed distance (above 25.2 km/h), and mechanical load, defined as the sum of accelerations and decelerations. Statistical analysis showed significant differences only with variations in total distance and mechanical load. Specifically, reducing weekly loads improved LEI in players in lower readiness states, while maintaining or slightly increasing loads promoted optimal readiness. This approach enables coaches to tailor training prescriptions more effectively, optimizing workload and recovery to sustain player performance throughout a demanding season.

Are performance and perceived fatigability dependent on the anchor scheme of fatiguing isometric tasks in men?

Ratings of perceived exertion (RPE) can be used to regulate exercise intensity. This study examined the effect of anchor scheme on performance fatigability and neuromuscular responses following fatiguing forearm flexion tasks. Twelve men (age 20.9±2.2 years; height 179.8±5.3 cm; body mass 80.2±9.9 kg) performed sustained, isometric forearm flexion tasks to failure anchored to RPE=6 (RPEFT) and the torque (TRQFT) that corresponded to RPE=6. Pre-test and post-test maximal voluntary isometric contractions (MVIC) were performed to quantify changes in the amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals. Neuromuscular efficiency (NME) was calculated by dividing normalized torque by normalized EMG AMP. A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated measures ANOVAs were used to compare mean differences for performance fatigability and normalized neuromuscular parameters. The RPEFT had a greater TTF than the TRQFT (P<0.001). MVIC and NME decreased from pre-test to post-test following the RPEFT and TRQFT (P<0.05) with no differences between anchor schemes. Following the TRQFT, normalized EMG MPF decreased from pre-test to post-test (P=0.004). Following the RPEFT, normalized MMG MPF increased from pre-test to post-test (P=0.021). There were no changes in normalized EMG AMP or MMG AMP (P>0.05). These findings indicated anchor scheme-specific neuromuscular responses and TTF, despite no difference in performance fatigability. Furthermore, performance fatigability was likely due to peripheral fatigue (based on normalized EMG MPF and NME) following the TRQFT, but peripheral and central fatigue (based on normalized MMG MPF and NME) following the RPEFT.

The Effects of Anchoring a Fatiguing Forearm Flexion Task to a High vs. Low Rating of Perceived Exertion on Torque and Neuromuscular Responses.

Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Schmidt, RJ, and Johnson, GO. The effects of anchoring a fatiguing forearm flexion task to a high versus low rating of perceived exertion on torque and neuromuscular responses. J Strength Cond Res 38(5): e219-e225, 2024-This study examined the torque and neuromuscular responses following sustained, isometric, forearm flexion tasks anchored to 2 ratings of perceived exertion (RPE). Nine men (mean ± SD: age = 21.0 ± 2.4 years; height = 179.5 ± 5.1 cm; body mass = 79.6 ± 11.4 kg) completed maximal voluntary isometric contractions (MVIC) before and after sustained, isometric, forearm flexion tasks to failure anchored to RPE = 2 and RPE = 8. The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) signal were recorded from the biceps brachii. Normalized torque was divided by normalized EMG AMP to calculate neuromuscular efficiency (NME). A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated-measures analysis of variances was used to compare mean differences for MVIC and normalized neuromuscular parameters. There was no significant difference in TTF between RPE = 2 and RPE = 8 (p = 0.713). The MVIC decreased from pretest to posttest at RPE = 2 (p = 0.009) and RPE = 8 (p = 0.003), and posttest MVIC at RPE = 8 was less than that at RPE = 2 (p < 0.001). In addition, NME decreased from pretest to posttest (p = 0.008). There was no change in normalized EMG AMP or EMG MPF (p > 0.05). The current findings indicated that torque responses were intensity specific, but TTF and neuromuscular responses were not. Furthermore, normalized EMG AMP and EMG MPF remained unchanged but NME decreased, likely due to peripheral fatigue and excitation-contraction coupling failure. Thus, this study provides information regarding the neuromuscular responses and mechanisms of fatigue associated with tasks anchored to RPE, which adds to the foundational understanding of the relationship between resistance exercise and the perception of fatigue.

Effect of Menstrual Cycle on Neuromuscular Efficiency and Muscular Strength in Runners

PURPOSE: The aim of this study was to examine the influence of the menstrual cycle (MC) stages on neuromuscular efficiency and muscular strength in female runners. METHODS: Three runners (females) underwent testing using a BIODEX isokinetic dynamometer concurrently with a BioPac EMG, during which peak torque, peak torque/body weight, time to peak torque, mean amplitude, median amplitude, minimum amplitude, maximum amplitude, frequency, and the p-p value were collected throughout the test. During the test, the performance variables were assessed on the quadriceps (rectus femoris) muscle and collected at speeds of 60 degrees/second and 180 degrees/second. STATISTICAL ANALYSIS: A paired-sample t-test was used to determine the correlation between neuromuscular efficiency and peak torque of the quadriceps during extension in the two MC phases. A paired-sample t-test was also used to determine the difference in neuromuscular efficiency between the MC phases, as well as peak torque between the MC phases. RESULTS: Muscular strength testing did not reveal statistical significance between neuromuscular efficiency and peak torque of the quadriceps during MC phases. Furthermore, there was no statistical significance between the differences in peak torque of the MC phases. Maximum amplitude at 60 degrees/second on the left leg between the MC phases revealed statistical significance (p = 0.026). EMG wave frequency at 60 degrees/second on the right leg between the MC phases revealed statistical significance (p = 0.007). CONCLUSION: Results show a significant difference in maximum amplitude and wave frequency at 60 degrees/second during knee extension between the MC phases.

Positive end-expiratory pressure limits inspiratory effort through modulation of the effort-to-drive ratio: an experimental crossover study

BackgroundHow assisted spontaneous breathing should be used during acute respiratory distress syndrome is questioned. Recent evidence suggests that high positive end-expiratory pressure (PEEP) may limit the risk of patient self-inflicted lung injury (P-SILI). The aim of this study was to assess the effects of PEEP on esophageal pressure swings, inspiratory drive, and the neuromuscular efficiency of ventilation. We hypothesized that high PEEP would reduce esophageal pressure swings, regardless of inspiratory drive changes, by modulating the effort-to-drive ratio (EDR). This was tested retrospectively in an experimental animal crossover study. Anesthetized pigs (n = 15) were subjected to mild to moderate lung injury and different PEEP levels were applied, changing PEEP from 0 to 15 cmH2O and back to 0 cmH2O in steps of 3 cmH2O. Airway pressure, esophageal pressure (Pes), and electric activity of the diaphragm (Edi) were collected. The EDR was calculated as the tidal change in Pes divided by the tidal change in Edi. Statistical differences were tested using the Wilcoxon signed-rank test.ResultsInspiratory esophageal pressure swings decreased from − 4.2 ± 3.1 cmH2O to − 1.9 ± 1.5 cmH2O (p < 0.01), and the mean EDR fell from − 1.12 ± 1.05 cmH2O/µV to − 0.24 ± 0.20 (p < 0.01) as PEEP was increased from 0 to 15 cmH2O. The EDR was significantly correlated to the PEEP level (rs = 0.35, p < 0.01).ConclusionsHigher PEEP limits inspiratory effort by modulating the EDR of the respiratory system. These findings indicate that PEEP may be used in titration of the spontaneous impact on ventilation and in P-SILI risk reduction, potentially facilitating safe assisted spontaneous breathing. Similarly, ventilation may be shifted from highly spontaneous to predominantly controlled ventilation using PEEP. These findings need to be confirmed in clinical settings.

The predictive value of neurally adjusted ventilatory assist indexes for the prognosis of patients with severe cerebral hemorrhage

ObjectiveThis study assessed the predictive value of electrical activity of the diaphragm (EAdi) and the EAdi-derived monitoring index in the prognosis of patients with severe cerebral hemorrhage. MethodsNinety patients with severe cerebral hemorrhage were admitted to the Neurosurgery Intensive Care Unit of Yijishan Hospital from April 2019 to June 2021 and were divided into the good prognosis group (Glasgow Outcome Scale [GOS] ≥ 4) and poor prognosis group (GOS ≤ 3). The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to evaluate prediction accuracy.ResultsEAdi, neuro-ventilatory efficiency (NVE), and neuro-muscular efficiency (NME) in patients with good prognosis were significantly higher than those in patients with poor prognosis (4.707 µV vs 2.80 µV, P < 0.001; 141.85 ml/µV vs 66.01 ml/µV, P = 0.000; 2.57 cm H2O/µV vs 1.37 cm H2O/µV, P = 0.000). The area under the ROC curve for the EAdi score was 0.719, with sensitivity of 69.70% and specificity of 68.42% when EAdi was 3.6 µV. The AUC for NVE score was 0.793, with sensitivity of 75.76% and specificity of 75.44% when the NVE value was 95.32 ml/µV. The AUC for NME score was 0.792, with sensitivity of 69.70% and specificity of 78.95% when the NME value was 2.06 H2O/µV. The 6-month survival time of patients with higher EAdi, NVE, and NME was significantly longer than that of patients with lower EAdi, NVE, and NMEConclusionEAdi, NVE, and NME can be used as indices for predicting the prognosis of patients with severe cerebral hemorrhage.Trial registration No.ChiCTR1900022861. Registered April 28, 2019, http://www.chictr.org.cn.

Effects of a Sustained, Isometric Forearm Flexion Task to Failure on Torque and Neuromuscular Responses at 3 Elbow Joint Angles

Abstract Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Anders, JPV, Schmidt, RJ, and Johnson, GO. The effects of a sustained, isometric forearm flexion task to failure on torque and neuromuscular responses at 3 elbow joint angles. J Strength Cond Res 38(1): e25–e33, 2024—This study examined the effects of a sustained, isometric forearm flexion task anchored to torque to task failure on maximal voluntary isometric contraction (MVIC) and neuromuscular responses at 3 elbow joint angles. Eleven women (mean ± SD: age = 20.8 ± 2.7 years, height = 169.3 ± 7.4 cm, body mass = 67.7 ± 6.9 kg) performed two 3s forearm flexion MVICs at elbow joint angles (JAs) of 75°, 100°, and 125° before and after a sustained, isometric forearm flexion task to failure at a fatiguing joint angle of 100° anchored to a torque value that corresponded to a rating of perceived exertion of 8 (RPE = 8). The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii. Repeated-measures ANOVAs were used to compare mean differences for MVIC and neuromuscular parameters. Collapsed across JAs, MVIC (p &lt; 0.001) and EMG MPF (p = 0.006) pretest values were greater than posttest values. Collapsed across time, EMG MPF at JA75 was greater than JA100 (p &lt; 0.001) and JA125 (p &lt; 0.001), and JA100 was greater (p = 0.007) than JA125. For EMG AMP, there was a fatigue-induced decrease at JA75 (p = 0.003). For neuromuscular efficiency (NME = normalized torque/normalized EMG AMP), there were decreases from pretest to posttest at JA100 (p = 0.002) and JA125 (p = 0.008). There were no significant interactions or main effects for MMG AMP and MMG MPF. From these findings, it was hypothesized that the decline in MVICs at JA75, JA100, and JA125 was due to fatigue-induced metabolic perturbations that resulted in JA-specific neuromuscular responses. Thus, neuromuscular parameters may provide insight into the JA-specific mechanisms of fatigue.

Effect of Lactobacillus plantarum PS128 on neuromuscular efficiency after a half-marathon

Introduction:Lactobacillus plantarum PS128 (PS128) could be considered an antioxidant supplement to reduce muscle fatigue and improve exercise capacity recovery after vigorous exercise.Purpose: The purpose of this study is to investigate the effect of PS128 on muscle fatigue and electromyography (EMG) activity after a half-marathon (HM).Methods: The experimental design used a repeated-measures design with a double-blind approach. The participants either took two capsules of PS128 for 4 weeks as the PS128 group (PSG, n = 8) or took two capsules of a placebo for 4 weeks as the placebo group (PLG, n = 8) to ensure counterbalancing. The time points of the maximal voluntary isometric contraction (MVIC) and EMG activity test were set before probiotics were taken (baseline), 48 h before HM (Pre), and immediately at 0 h, 3 h, 24 h, 48 h, 72 h, and 96 h after HM.Results: EMG activity included median power frequency (MDF), integrated EMG (iEMG), and neuromuscular efficiency (peak torque/iEMG). The MVICs of knee extensors, analyzed by using an isokinetic dynamometer, showed a decrease from the Pre to 0 h (p = 0.0001), 3 h (p &amp;lt; 0.0001), 24 h (p &amp;lt; 0.0001), 48 h (p &amp;lt; 0.0001), 72 h (p = 0.0002), and 96 h (p = 0.0408) time points in the PLG. Sidak’s multiple comparisons tests showed that the PLG was significantly lower than the PSG at 0 h (p = 0.0173), 3 h (p &amp;lt; 0.0001), 24 h (p &amp;lt; 0.0001), 48 h (p &amp;lt; 0.0001), 72 h (p &amp;lt; 0.0001), and 96 h (p = 0.0004) time points. The MDF of vastus medialis oblique (VMO) in the PLG was significantly decreased 24 h after HM and significantly lower than that in the PSG at all times points after HM. The iEMG of VMO in the PLG was significantly decreased 48 h after HM and significantly lower than that in the PSG at 0 h, 3 h, 24 h, 48 h, and 72 h after HM.Conclusion: The PS128 supplementation may prevent the decrease in MDF, iEMG, and peak torque after vigorous exercise. Recreational runners may consider implementing a probiotic supplementation regimen as a potential strategy to mitigate muscle fatigue following HM.

Resistance Training in Post-COVID Recovery: Rationale and Current Evidence.

During hospitalisation with COVID-19, individuals may experience prolonged periods of immobilisation. Combined with the inflammatory effects of the virus, this may lead to a significant reduction in both muscle mass and strength. Data from several long-term studies suggest that these symptoms may not fully resolve within one year. Owing to its effectiveness at inducing muscle fibre hypertrophy and improving neuromuscular efficiency, resistance training is of great interest in the rehabilitation of this population. This narrative review aims to identify the rationale and potential efficacy of resistance training for restoring physical function following infection with SARS-CoV-2, as well as evidence of its use in clinical practice. The studies included in this narrative review consisted mostly of multi-component rehabilitation trials. Of these, widespread improvements in muscle strength were reported using intensities of up to 80% of participants' 1-repetition-maximum. Evidence thus far indicates that resistance training may be safe and effective in patients following COVID-19, although its individual contribution is difficult to discern. Future exercise intervention studies investigating the efficacy of resistance training as a sole modality are needed.

Fatiguing Joint Angle Does Not Influence Torque and Neuromuscular Responses Following Sustained, Isometric Forearm Flexion Tasks Anchored to Perceptual Intensity in Men.

This study examined the effects of joint angle (JA) on maximal voluntary isometric contraction (MVIC) and neuromuscular responses following fatiguing tasks anchored to RPE. Nine men (mean ± SD: age = 20.7 ± 1.2 yrs) performed forearm flexion MVICs at elbow JAs of 75° and 125° before and after sustained, isometric forearm flexion tasks to failure at fatiguing joint angles (FJA) of 75° and 125° anchored to RPE = 8. The amplitude and frequency of the electromyographic and mechanomyographic signals were recorded. Neuromuscular efficiency was calculated by dividing normalized torque by normalized electromyographic amplitude. A dependent t-test was used to assess the mean difference for time to task failure (TTF) between FJA. Repeated measure ANOVAs were used to assess mean differences for pre-test to post-test MVIC and neuromuscular responses. There was no significant difference between FJA for TTF (p = 0.223). The MVIC (collapsed across FJA and MVIC JA) decreased from pre-test to post-test (51.1 ± 5.0 vs. 45.3 ± 5.6 Nm, p < 0.001). Normalized neuromuscular parameters remained unchanged (p > 0.05). The FJA resulted in similar torque and neuromuscular responses, and the decreases in MVIC were not tracked by changes in the neuromuscular parameters. Thus, the neuromuscular parameters were not sensitive to fatigue, and pre-test to post-test measures may be compared between different FJA.

Enhancing Functional Ability in Chronic Nonspecific Lower Back Pain: The Impact of EMG-Guided Trunk Stabilization Exercises.

Nonspecific lower back pain (NSLBP) is described as pain that is not caused by an identifiable, well-known disease, such as infection, tumor, osteoporosis, fracture, structural deformity, inflammatory condition, radicular syndrome, or cauda equina syndrome. The aim of this study was to determine the effect of EMG-guided trunk stabilization exercises on functional disability associated with LBP. A single-blinded pre- and post-test experimental comparative design was used for this study. Fifty individuals with chronic NSLBP were screened for inclusion criteria. Of these, forty were randomly grouped into the EMG group receiving trunk-stability exercises with electromyography biofeedback and non-EMG group receiving trunk-stabilization exercises without EMG biofeedback. Participants performed five trunk-stability exercises 3 days a week for 4 weeks. The intensity of pain, range of motion, functional disability, and balance were measured at baseline and after 4 weeks. Both techniques indicated a significant effect on chronic NSLBP; however, trunk-stability exercises combined with EMG biofeedback produced better results in alleviating the intensity of pain, increasing the range of motion, and improving functional disabilities and static balance. The present study confirms that trunk-stability exercises with EMG biofeedback can be practiced safely, contributes to a greater boost in neuromuscular efficiency in the lumbar flexors and extensors, and is effective in modifying functional disability for patients with NSLBP.

Exploring forearm muscle coordination and training applications of various grip positions during maximal isometric finger dead-hangs in rock climbers.

Maximal isometric finger dead-hangs are used in rock climbing to strengthen finger flexors. Although various grip positions are often used when performing finger dead-hangs, little is known regarding how these grip positions can affect forearm muscle activity. Understanding how forearm muscles are recruited during dead-hangs could help foreseeing the potential for training of different grip positions. The aim of the present study was to explore the training applications of the various grip positions by comparing the activity of forearm muscles during maximal dead-hangs in rock climbers. Twenty-five climbers performed maximal dead-hangs in three climbing-specific grip positions: CRIMP, SLOPE, and SLOPER. We recorded the maximal loads used and the sEMG of the flexor digitorum profundus (FDP), the flexor digitorum superficialis (FDS), the flexor carpi radialis (FCR), and the extensor digitorum communis (EDC). Individual and global (sum of all muscles) root mean square (RMS) and neuromuscular efficiency (NME) values were computed. Repeated measures analysis were performed to assess grip differences (p<0.05). SLOPER showed the largest maximal load values among the three grip positions (p<0.001, d≥2.772). Greater global (p≤0.044, d≥0.268), FDS (p≤0.005, d≥0.277), and FCR (p<0.001, d≥1.049) activity was observed for the SLOPER compared to CRIMP and SLOPE, while EDC (p≤0.005, d≥0.505) showed lower activity in the SLOPER compared to the other two grip positions. SLOPER presented the highest global (p<0.001, d≥0.629), FDP (p<0.001, d ≥ 0.777), FDS (only CRIMP vs SLOPER: p < 0.001, d = 0.140), and EDC NME (p < 0.001, d ≥ 1.194). The CRIMP showed greater FDS activity (p = 0.001, d = 0.386) and lower NME (p = 0.003, d = 0.125) compared to SLOPE. These results revealed that, under maximum intensity conditions, SLOPER could stimulate the FDS and FCR better than the other grip positions at the expense of using greater loads. Similarly, maximum CRIMP dead-hang could better stimulate the FDS than the SLOPE, even when using similar loads.