Reduce Muscle Fatigue Research Articles

12-week curcumin supplementation may relieve postexercise muscle fatigue in adolescent athletes.

High-intensity exercise causes oxidative stress, muscle soreness, and muscle fatigue, leading to reduced exercise performance. Curcumin possesses antioxidative and anti-inflammatory properties and thus alleviates postexercise damage. Therefore, this study evaluated the effect of curcumin on athletes' postexercise recovery. A non-randomized prospective cohort investigation was done. We recruited middle and high school athletes engaged in wrestling, soccer, and soft tennis. During the 12-week daily exercise training, the participants were assigned to receive curcumin supplementation (curcumin group) or not (control group). Body composition, exercise performance, inflammatory factors, muscle fatigue, and muscle soreness were recorded at the baseline and end of the study. We used the Mann-Whitney U test to compare the participants' demographics, such as age, height, weight, and training years. The Wilcoxon test was used to compare the differences between the groups before and after curcumin supplementation. Of 28 participants (21 men and 7 women, with a mean age of 17 years), 13 were in the curcumin group and 15 in the control group. A significant decrease in muscle fatigue and muscle soreness scores was observed in the curcumin group after 12 weeks. Moreover, a significant decrease in the 8-hydroxy-2 deoxyguanosine level and a significant increase in basic metabolic rate and fat-free mass were observed in the curcumin group. Curcumin can reduce muscle fatigue and soreness after exercise, indicating its potential to alleviate postexercise damage. It could be considered to cooperate with nutritional supplements in regular training in adolescent athletes.

Ergonomic Risk Evaluation to Minimize Musculoskeletal Disorders in SMEs Leather Shoes at Indonesia

This study was carried out at SME for the purpose of making leather shoes in the manufacturing process. Pattern, upper printing, finishing, and 16 other workstations are among the three workstations. Production operations are performed manually in a seated position that includes squatting, bending, or standing position that is repeated, and workers operate at average to rapid speeds for 7 hours each day. This signifies that the action is hazardous and may result in Musculoskeletal Disorders (MSDs). The Job Strain Index (JSI) and Muscle Fatigue Assessment (MFA) methodologies will be used in this study to identify working posture conditions. The MFA method is used to analyze the level of effort, duration of labor, and frequency of work motions in order to determine muscle tiredness in each section of the worker's body. The 14 activities were subjected to the JSI method investigation, and the high risk was achieved by printing the top right hand SI 20.25 and installing the right-hand sole 13.5. The MFA approach was used to accept high to extremely high-risk body parts, such as the back, neck, and right hand, and make recommendations for how to reduce muscle fatigue in each body part. The findings of this study can be used to improve the upper printing station's design, as well as the table design for designing and drawing patterns and the chair design for sewing activities.

Analysis of material variation in the design of knitted sportswear compression stockings to escort thermo-physiological comfort using linear regression

Compression sportswear is specialized clothing chiefly designed for the athletes muscle fatigue reduction. Compression stockings are widely used in sportswear to support muscles and control excessive body vibrations. Compression/interface pressure between the wearer and stocking’s surface is considerable in compression sportswear efficacy. However, thermo-physiological comfort is also influential while preparing summer sportswear. The research investigates the effect of fibers type and the inlay yarns number of covering filaments on compression, air permeability, water vapor permeability, and thermal resistance of sportswear compression stockings. Three different fibers, sorbtek (channelized polyester), nylon 6, and micro Nylon (polyamide-6), have been used as main yarns. Also, three distinct levels of covering yarn number of filaments have been utilized. Data have been statistically analyzed using full factorial design of experiment and regression analysis to predict fiber type and the number of covering yarn filaments for achieving desired comfort properties without compromising compression characteristics.

The effect of a pressure ventilatory support on quadriceps endurance is maintained after exercise training in severe COPD patients. A longitudinal randomized, cross over study.

Purpose: In severe chronic obstructive pulmonary disease (COPD) patients, the application of an inspiratory pressure support (IPS) during exercise increases exercise tolerance and the benefit of exercise training during pulmonary rehabilitation (PR). Moreover, it improves quadriceps endurance after a session of cycling exercise suggesting a reduced muscle fatigue. We looked for the persistence of this effect after PR and sought an association between the improved quadriceps endurance with IPS and the training load during PR. Patients and methods: We studied 20 patients with severe COPD (6 in stage 3and 14 in stage 4 of GOLD) before and after PR. As part of a PR program, patients completed 16 cycling sessions over 6 weeks with the addition of IPS during exercise. As a surrogate of muscular fatigue, quadriceps endurance was measured at 70% of maximal strength in a control condition, after a constant work rate exercise test (CWR) with IPS (TlimQ IPS) or with a sham ventilation (TlimQsham), in a random order. These tests were repeated similarly at the end of PR. Results: PR was associated with a significant increase in maximal power output, cycling endurance, quadriceps strength and endurance. Session training load (power output x duration of the session) increased by 142% during the course of the program. Before PR, CWR duration increases with IPS compared to sham ventilation (Δtime = +244s, p = 0.001). Compared to control condition, post-exercise TlimQ reduction was lower with IPS at isotime than at the end of CWR or than with sham ventilation (-9 ± 21%, -18 ± 16% and -23 ± 18%, respectively, p = 0.09, p < 0.0001 and p < 0.0001). After PR, the post-exercise decrease of TlimQ was reduced after IPS compared to sham (-9 ± 18% vs. -21 ± 17%, respectively, p = 0.004). No relationship was found between the prevention of quadriceps fatigue and the training load. Conclusion: In severe COPD patients, the beneficial effect of a ventilator support on quadriceps endurance persisted after PR with IPS. However, it was not related to the increase in training load, and could not predict the training response to non-invasive ventilation during exercise.

Multimuscle Functional-Electrical-Stimulation-Based Wrist Tremor Suppression Using Repetitive Control

Wrist motion is produced by a group of muscles acting in a coordinated way. However, existing functional electrical stimulation (FES)-based wrist tremor suppression methods just stimulate one pair of muscles, which can limit the tremor suppression performance and cause muscle fatigue. To address these problems, this article proposes a multimuscle FES-based wrist tremor suppression method by fully considering the properties of wrist motion. First, with the consideration of the mainly involved two pairs of muscles in wrist flexion and extension motion, a multimuscle wrist musculoskeletal model with a Hammerstein structure is developed, and the parameters are identified. Then, a feedback repetitive controller combined with a feedforward linearization controller is proposed for tremor suppression. A frequency-modified inverse repetitive control algorithm and a gradient-based repetitive control algorithm are put forward to regulate the FES level properly. Finally, experiments on both unimpaired subjects and intention tremor patients verify that compared to the existing single-muscle-pair FES-based methods, the proposed methods can substantially improve the performance of tremor suppression and effectively reduce the level of electrical stimulation significantly, thereby reducing muscle fatigue.

Feasibility of interleaved stimulation in peroneal stimulators: the effect of surface electrode configuration on foot kinematics

A peroneal stimulator is a neuroprosthetic device based on functional electrical stimulation (FES). It induces ankle dorsiflexion in the swing phase in patients affected by foot drop [1]. A well-known limitation of FES is the increased muscle fatigability due to the non-physiological motor unit (MU) activation. A possible approach to limit this issue is to interleave electrical pulses delivered to the muscle ( mstim ) and to the nerve ( nstim ) to distribute the stimulation among different MU groups [2], thus reducing the activation frequency of each group (interleaved stimulation). The practical applicability of this approach to peroneal stimulators requires that both mstim and nstim induce foot dorsiflexions (DFs) with minimal in-/eversion and ab-/adduction for all the knee angles within the swing phase. While for mstim knee rotations are not critical, changes in knee angle may modify the relative position between nstim electrodes and peroneal nerve, resulting in foot rotations outside the sagittal plane. Here we investigate the effect of nstim electrode positioning on induced foot rotations to identify the configuration leading to foot DF maximally similar to the voluntary ones for the entire knee ROM. We compared the electrically-induced foot movement for five nstim electrode positioning and four knee joint angles (0°, 20°, 40° and 60°, being 0° full knee extension) in ten healthy subjects. A grid of five cathodes was placed between fibular head and the tibial tuberosity (Fig. 1A) while a large anode (56 cm 2 ) was located on the patella. For each knee angle, electrical stimulation was delivered at the five stimulation sites (pulse duration: 200 µs, frequency: 20 Hz) and foot rotations were quantified with an IMU positioned under the foot. Foot in-/eversion and ab-/adduction were compared with those measured during voluntary DFs at each angle Fig. 1 B shows the ab-/adduction (Y-axes) and in-/eversion (X-axes) angles for each stimulation site (color-coded) and for the four knee angles in a representative subject. Red-dotted line delimits the acceptability area confining the angles obtained during voluntary DFs from all participants. All the points (stimulations) inside this area were regarded as producing a foot kinematic comparable to a voluntary DF. Figure c shows the number of subjects inside the acceptability area for all the stimulation configurations and knee angles. Collectively, configurations A and C included 7 out of 9 subjects, whilst for configurations D and E no subjects were inside the acceptability area for all knee angles. We identified a common nstim electrode configuration that induced, in the majority of the participants, foot (DF) with minimal eversion and inversion for the knee angles within the swing phase. This is a necessary condition to ensure the applicability of stimulation strategies based on distributed nerve/muscle stimulation (interleaved stimulation) aimed at reducing muscle fatigue in FES-based foot drop treatments.

An Occupational Shoulder Exoskeleton Reduces Muscle Activity and Fatigue During Overhead Work.

This paper assesses the effect of a passive shoulder exoskeleton prototype, Exo4Work, on muscle activity, muscle fatigue and subjective experience during simulated occupational overhead and non-overhead work. Twenty-two healthy males performed six simulated industrial tasks with and without Exo4Work exoskeleton in a randomized counterbalanced cross-over design. During these tasks electromyography, heart rate, metabolic cost, subjective parameters and performance parameters were acquired. The effect of the exoskeleton and the body side on these parameters was investigated. Anterior deltoid activity and fatigue reduced up to 16% and 41%, respectively, during isometric overhead work, and minimized hindrance of the device during non-overhead tasks. Wearing the exoskeleton increased feelings of frustration and increased discomfort in the areas where the exoskeleton and the body interfaced. The assistive effect of the exoskeleton was less prominent during dynamic tasks. This exoskeleton may reduce muscle activity and delay development of muscle fatigue in an overhead working scenario. For dynamic applications, the exoskeleton's assistive profile, which mimics the gravitational torque of the arm, is potentially sub-optimal. This evaluation paper is the first to report reduced muscle fatigue and activity when working with an occupational shoulder exoskeleton providing one third of the gravitational torque of the arm during overhead work. These results stress the potential of occupational shoulder exoskeletons in overhead working situations and may direct towards longitudinal field experiments. Additionally, this experiment may stimulate future work to further investigate the effect of different assistive profiles.

Changes in electromyographic activity of latent trigger points after a dry needling intervention: a randomised controlled trial

ObjectiveTo analyse the effects of dry needling (DN) in upper trapezius latent trigger points (LTrPs) on pressure pain threshold (PPT) and surface electromyography (sEMG). DesignRandomized, double-blind, placebo controlled clinical trial. SettingsSports Rehabilitation Laboratory, University of Castilla-La Mancha. ParticipantsForty-six participants (18–35 years old) with LTrP in the upper trapezius were divided into two groups: DN-group and Sham-DN-group. InterventionsIn the DN-group, the needle was inserted 10-times through the skin, and it was manipulated up and down using a "fast in and out" technique. In the Sham-DN-group, non-penetrating needles were used. Main outcome measuresPPT, sEMG at rest, and sEMG in isometric contraction of the LTrP of the upper trapezius muscle were evaluated at baseline, 30 min after treatment, and after 24 h, and 72 h of follow-up. ResultsThe mean change in sEMG at rest between baseline and 30 min was − 0.38 (0.38) %refRMS for the DN group and − 0.05 (0.31) %refRMS for the Sham-DN group (mean difference −0.34, 95% confidence interval (CI) of the difference: − 0.54 to − 0.13), and between baseline and 24 h was − 0.35 (0.35) %refRMS for the DN group and − 0.06 (0.58) %refRMS for the Sham-DN group (mean difference −0.29, 95% CI: −0.57 to −0.01). In addition, the DN-group showed higher values of PPT than the Sham-DN group at 72 h (5.22 (1.23) to 4.65 (1.03) kg/cm2; p < 0.05). ConclusionsA single session of DN intervention was effective in reducing the electromyographic activity, muscle fatigue and pain of the upper trapezius muscle in LTrP. Contribution of paperIn healthy volunteers dry needling is effective:•for reducing electromyography activity in latent trigger points.•for reducing muscle fatigue in latent trigger points.•in increasing pressure pain threshold in latent trigger points.

Can Photobiomodulation Therapy (PBMT) Minimize Exercise-Induced Oxidative Stress? A Systematic Review and Meta-Analysis.

Oxidative stress induced by exercise has been a research field in constant growth, due to its relationship with the processes of fatigue, decreased production of muscle strength, and its ability to cause damage to the cell. In this context, photobiomodulation therapy (PBMT) has emerged as a resource capable of improving performance, while reducing muscle fatigue and muscle damage. To analyze the effects of PBMT about exercise-induced oxidative stress and compare with placebo therapy. Data Sources: Databases such as PubMed, EMBASE, CINAHL, CENTRAL, PeDro, and Virtual Health Library, which include Lilacs, Medline, and SciELO, were searched to find published studies. Study Selection: There was no year or language restriction; randomized clinical trials with healthy subjects that compared the application (before or after exercise) of PBMT to placebo therapy were included. Study Design: Systematic review with meta-analysis. Level of Evidence: 1. Data Extraction: Data on the characteristics of the volunteers, study design, intervention parameters, exercise protocol and oxidative stress biomarkers were extracted. The risk of bias and the certainty of the evidence were assessed using the PEDro scale and the GRADE system, respectively. Results: Eight studies (n = 140 participants) were eligible for this review, with moderate to excellent methodological quality. In particular, PBMT was able to reduce damage to lipids post exercise (SMD = −0.72, CI 95% −1.42 to −0.02, I2 = 77%, p = 0.04) and proteins (SMD = −0.41, CI 95% −0.65 to −0.16, I2 = 0%, p = 0.001) until 72 h and 96 h, respectively. In addition, it increased the activity of SOD enzymes (SMD = 0.54, CI 95% 0.07 to 1.02, I2 = 42%, p = 0.02) post exercise, 48 and 96 h after irradiation. However, PBMT did not increase CAT activity (MD = 0.18 CI 95% −0.56 to 0.91, I2 = 79%, p = 0.64) post exercise. We did not find any difference in TAC or GPx biomarkers. Conclusion: Low to moderate certainty evidence shows that PBMT is a resource that can reduce oxidative damage and increase enzymatic antioxidant activity post exercise. We found evidence to support that one session of PBMT can modulate the redox metabolism.

Muscle usage and workload assessment of cardiac ablation procedure with the use of a novel catheter torque tool in a pediatric simulator.

Cardiac ablation catheters are small in diameter and pose ergonomic challenges that can affect catheter stability. Significant finger dexterity and strength are necessary to maneuver them safely. We evaluated a novel torque tool to reduce muscle activation when manipulating catheters and improve perceived workload of ablation tasks. The objective was to evaluate measurable success, user perception of workload, and muscle usage when completing a simulated ablation task with and without the use of a catheter torque tool. Cardiology attendings and fellows were fitted with surface electromyographic (EMG) sensors on 6 key muscle groups in the left hand and forearm. A standard ablation catheter was inserted into a pediatric cardiac ablation simulator and subjects navigated the catheter tip to 6 specific electrophysiologic targets, including a 1-min simulated radiofrequency ablation lesion. Time to complete the task, number of attempts required to complete the lesion, and EMG activity normalized to percentage of maximum voluntary contraction were collected throughout the task. The task was completed 4 times, twice with and twice without the torque tool, in semi-randomized order. A NASA Task Load Index survey was completed by the participant at the conclusion of each task. Time to complete the task and number of attempts to create a lesion were not altered by the tool. Subjectively, participants reported a significant decrease in physical demand, effort, and frustration, and a significant increase in performance. Muscle activation was decreased in 4 of 6 muscle groups. The catheter torque tool may improve the perceived workload of cardiac ablation procedures and reduce muscle fatigue caused by manipulating catheters. This may result in improved catheter stability and increased procedural safety.

Design Feasibility of an Energy-efficient Wrist Flexion-Extension Exoskeleton using Compliant Beams and Soft Actuators.

Passive and active exoskeletons have been used over recent decades. However, regarding many physiological systems, we see that the majority explore both active and passive elements to minimize energy consumption while retaining proper motion control. In light of this, we propose a design that combines compliant mechanisms as passive support for gravity balancing of the hand's weight and soft actuators as active support for wrist flexion-extension. Our approach offers a safe, lightweight solution that intrinsically complements and supports the wrist's degrees of freedom. We hypothesize that the proposed soft wearable device is able to increase the range of motion and reduce muscle fatigue while being energy-conservative by balancing of the passive and active subsystems. In this work, we perform a design feasibility study for such soft wrist exoskeletons, particularly focused on wrist flexion-extension rehabilitation. Through optimization, geometries for the required functionality of the compliant beam and soft actuator are obtained, and their performance as separate subsystems is evaluated by simulations and experiments. Under the appropriate inputs, we show that the system can introduce a controllable bifurcation. Through experiments, we investigate such bi-stability and explore its usefulness for rehabilitative support of wrist flexion-extension. In short, the proposed wearable can offer a viable, energy-efficient alternative to traditional rehabilitation technologies.

Long-Term Effect of Vibration Therapy for Training-Induced Muscle Fatigue in Elite Athletes.

Purpose: To evaluate the long-term effect of vibration therapy with holistic and local intervention in treating muscle fatigue in elite athletes during their intensive training season. Methods: Study participants included five male athletes from a provincial Greco-Roman wrestling team who were qualified for the finals of China’s national games. During the study, conventional therapeutic intervention was applied during the initial three weeks of the study, and an instrument intervention was adopted in the following three weeks. A surface electromyography (sEMG) was used to measure muscle fatigue of latissimus dorsi, both before and after each intervention session. Specifically, the pre-intervention measurement was conducted right after the daily training completion; and the post-intervention measurement occurred in the following morning. The data analyses were to compare the differences in the muscle fatigue data between the two modes of interventions, conventional and instrument therapy. Results: The conventional intervention showed no significant difference in the sEMG indexes before and after the intervention; while for the instrument intervention, the pre- and post- intervention sEMG indexes differed significantly (p < 0.05). Conclusion: The long-term effects of instrument vibration therapy on muscle fatigue recovery were studied based on observational data from elite athletes. The results indicate that the vibration therapy with holistic and local consideration demonstrated an effective reduction of muscle fatigue and/or fatigue accumulation in elite athletes during their intensive training season.

Effects of multimodal training program on muscle deoxygenation in women with breast cancer: Arandomized controlled trial.

Chemotherapy and/or radiation are the most often delivered treatments to cancer patients. Usually during the adjuvant treatment, patients complain about fatigue. In addition, physical exercise during adjuvant treatment of cancer seems to have beneficial effects. The aim of this investigation was to assess the effects of multimodal aerobic and strength exercises programs on muscle deoxygenation of patients with breast cancer undergoing adjuvant chemotherapy treatment. Thirty-two women with breast cancer (20 patients as the training group and 12 patients as the control group) undergoing adjuvant chemotherapy participated in the study. The training group took part in 6 weeks of supervised intermittent aerobic cycling, home-based walking, isometric and electrical muscle stimulation (EMS) exercise training programs. The Outcome measures were muscle deoxygenation (ΔHHb), Maximal Voluntary isometric Contraction (MViC) and Endurance Time (ET) before and after the training period. Compared to the control group, a significant increase in ΔHHb (P < 0.01) accompanied with an increase in ET (P < 0.01) and MViC (P < 0.01) of the quadriceps was obtained in the training group. However, no significant differences of MViC, ET and ΔHHb were observed in the control group. Multimodal aerobic and strength exercise programs enhance muscle oxygen utilization, which may partly explain the improvement in muscular strength and endurance, and the reduction of muscle fatigue in patients with breast cancer during an adjuvant chemotherapy period.

Photobiomodulation assay of muscle cells C2C12 after irradiation with LED device

Introduction: One of the ways that have been observed to reduce musculoskeletal fatigue is the use of protocols for the application of light sources (photobiomodulation) such as low-intensity laser and LED (Light Emitting Diode). Work involving photobiomodulation has shown promising results in strength performance or reduction of muscle fatigue. At the cellular level, photobiomodulation can modulate fibroblasts proliferation, the fixation and synthesis of collagen and procollagen, promote angiogenesis and improving energy metabolism in mitochondria. Compared with laser devices, LED has several advantages, such as being smaller, lighter, lower cost, and easier for operation. Objective: The present work objective is to verify if irradiation with LED device (650 nm and 860 nm) in muscle cells C2C12 modify the viability, morphology and cytoskeleton components. Methodology: C2C12 cells line (ATCC CRL - 1772) were cultured in 25 cm2 bottles at 37ºC under 5% CO2 in DMEM. The cells were irradiated with the light-emitting diodes (LED) device, Sportllux Ultra that consists of 84 LEDs, each individual LED has 8 mW of power, emitting in 660±20 nm (42 LEDs) and 850±20 nm (42 LEDs), and covering an area (A) of 120 cm2. The power density of delivered light was 5,6 mW/cm2, and the exposure time was 10 minutes, totalizing the fluence of 3,4 J/cm2. Viability assay was performed where the cells were incubated with 100 µL of Crystal Violet (CV) solution and mitochondrial activity assay was evaluated by the colorimetric MTT assay. Nucleus (DAPI) and Cytoskeleton (Rhodamine Phalloidin) fluorescence assay was performed to study the cytoskeleton based on the change in the actin filaments. Results: Our results demonstrate that the synergism of LED irradiation (660nm and 850nm) induced the proliferation of C2C12 cells. The light-emitting diode (LED) device, Sportllux Ultra has a significant effect on C2C12 cell culture. Mitochondrial activity and cell viability showed a significative increase in their activities after irradiation. The microscopy fluorescence observations showed an alignment of cytoskeletal components of C2C12 cells after irradiation. Conclusion: The application of irradiation with the Sportlux Ultra LED device stimulated an increase of energy by mitochondrial activity assay, number of cells by cell viability assay and alignment of cytoskeleton components by fluorescence assay in C2C12 line cells. Our results suggest that organizated cytoskeletal actin filaments normally contribute to cell survival and that induced major cell changes in the cytoskeleton that result in cell shape change. These results suggest that the Sport Lux Ultra LED device can help in the repair of tissue injuries and to collaborate to increase of performance in athletes in a faster way.

Store-Operated Ca2+ Entry in Skeletal Muscle Contributes to the Increase in Body Temperature during Exertional Stress.

Exertional heat stroke (HS) is a hyperthermic crisis triggered by an excessive accumulation of Ca2+ in skeletal muscle fibers. We demonstrated that exercise leads to the formation of calcium entry units (CEUs), which are intracellular junctions that reduce muscle fatigue by promoting the recovery of extracellular Ca2+ via store-operated Ca2+ entry (SOCE). Here, we tested the hypothesis that exercise-induced assembly of CEUs may increase the risk of HS when physical activity is performed in adverse environmental conditions (high temperature and humidity). Adult mice were: (a) first, divided into three experimental groups: control, trained-1 month (voluntary running in wheel cages), and acutely exercised-1 h (incremental treadmill run); and (b) then subjected to an exertional stress (ES) protocol, a treadmill run in an environmental chamber at 34 °C and 40% humidity. The internal temperature of the mice at the end of the ES was higher in both pre-exercised groups. During an ES ex-vivo protocol, extensor digitorum longus(EDL) muscles from the trained-1 month and exercised-1 h mice generated greater basal tension than in the control and were those that contained a greater number of CEUs, assessed by electron microscopy. The data collected suggest that the entry of Ca2+ from extracellular space via CEUs could contribute to exertional HS when exercise is performed in adverse environmental conditions.

Effectiveness of acute L-arginine supplementation on physical performance in strength training: a systematic review and meta-analysis

Background: The oral administration of L-arginine has been related to improved physical performance due to a likely reduction in muscle fatigue, resulting from the vasodilator effect of nitric oxide on skeletal muscle. However, there is no precise and quantitative analysis of the information in the literature. The main objective of this study was to assess the effectiveness of L-arginine supplementation on physical performance in strength training with a systematic review and meta-analysis. We hypothesized that L-arginine supplementation would improve performance capacity and the effects involved in strength training. Methods: The study period was from 2010 to 2020. The inclusion process established articles with well-designed human experiments that included only L-arginine supplementation (without any additional compounds) testing the effects of L-arginine supplementation on sports performance related to strength training; identical experimental conditions in placebo or control group; and publications in the last ten years (until December 31, 2020). Three studies were included that compared L-arginine supplementation with placebo in anaerobic performance tests. Test analysis supplementation with other supplements was removed and there was no gender, age, and ethnicity level. Results: There was no significant heterogeneity (p&gt;0.05) in the analysis of the three selected articles and the effects of L-arginine supplementation in muscular endurance; performance had a mean of 0.26 (95% CI = -0.129; 0.649; p = 0.190), peak torque with a mean of -0.002 (95% CI = -0.531; 0.527; p = 0. 99) of the third series of exercises and, furthermore, when comparing the integrated effect (resistance rate with the peak torque) there was no difference with a mean of 0.168 (95% CI = -0.145; 0.481; p = 0.292). Conclusions: Acute L-arginine supplementation provides no ergogenic effect on strength training performance.

Can Non-invasive Ventilation Modulate Cerebral, Respiratory, and Peripheral Muscle Oxygenation During High-Intensity Exercise in Patients With COPD-HF?

AimTo evaluate the effect of non-invasive positive pressure ventilation (NIPPV) on (1) metabolic, ventilatory, and hemodynamic responses; and (2) cerebral (Cox), respiratory, and peripheral oxygenation when compared with SHAM ventilation during the high-intensity exercise in patients with coexisting chronic obstructive pulmonary disease (COPD) and heart failure (HF).Methods and ResultsOn separate days, patients performed incremental cardiopulmonary exercise testing and two constant-work rate tests receiving NIPPV or controlled ventilation (SHAM) (the bilevel mode—Astral 150) in random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin (OxyHb+Mb) and deoxyhemoglobin (DeoxyHb+Mb) were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, The Netherlands). NIPPV associated with high-intensity exercise caused a significant increase in exercise tolerance, peak oxygen consumption ( in mlO2·kg−1·min−1), minute ventilation peak ( in ml/min), peak peripheral oxygen saturation (SpO2, %), and lactate/tlim (mmol/s) when compared with SHAM ventilation. In cerebral, respiratory, and peripheral muscles, NIPPV resulted in a lower drop in OxyHb+Mb (p < 0.05) and an improved deoxygenation response DeoxyHb+Mb (p < 0.05) from the half of the test (60% of Tlim) when compared with SHAM ventilation.ConclusionNon-invasive positive pressure ventilation during constant work-rate exercise led to providing the respiratory muscle unloading with greater oxygen supply to the peripheral muscles, reducing muscle fatigue, and sustaining longer exercise time in patients with COPD-HF.

Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks.

Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs). Fatigue and recovery models of muscles are essential in understanding the accumulation and the reduction in muscle fatigue for forceful exertion tasks. This study aims to explore the onset of muscle fatigue under different work/rest arrangements during manual demolition tasks and the offset of fatigue over time after the tasks were performed. An experiment, including a muscle fatigue test and a muscle fatigue recovery test, was performed. Seventeen male adults without experience in demolition hammer operation were recruited as human participants. Two demolition hammers (large and small) were adopted. The push force was either 20 or 40 N. The posture mimicked that of a demolition task on a wall. In the muscle fatigue test, the muscle strength (MS) before and after the demolition task, maximum endurance time (MET), and the Borg category-ratio-10 (CR-10) ratings of perceived exertion after the demolition task were measured. In the muscle fatigue recovery test, MS and CR-10 at times 1, 2, 3, 4, 5, and 6 min were recorded. Statistical analyses were performed to explore the influence of push force and the weight of the tool on MS, MET, and CR-10. Both muscle fatigue models and muscle fatigue recovery models were established and validated. The results showed that push force affected MET significantly (p < 0.05). The weight of the tool was significant (p < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the MS increase and the CR-10 decrease were both significant (p < 0.05) after one or more breaks. Models of MET and MS prediction were established to assess muscle fatigue recovery, respectively. The absolute (AD) and relative (RD) deviations of the MET model were 1.83 (±1.94) min and 34.80 (±31.48)%, respectively. The AD and RD of the MS model were 1.39 (±0.81) N and 1.9 (±1.2)%, respectively. These models are capable of predicting the progress and recovery of muscle fatigue, respectively, and may be adopted in work/rest arrangements for novice workers performing demolition tasks.

Impact of digital boards on hand and neck muscle activity during online teaching process.

Academicians across the globe due to Covid 19 shifted to online teaching as a mainstream method by replacing the chalk and talk method. The main objective of this study is to find the impact of different sizes of digital boards used for online teaching on muscle activity and muscle fatigue, and then results are compared with conventional writing. Initially, a questionnaire survey is conducted among 100 college professors about the issue they faced while using online teaching methods. Experimental analysis are then conducted using electromyography sensor (sEMG) among ten college professors and their muscle activity on the dominant hand and neck while writing on two commercially available digital boards namely Type 1 (small writing area) and Type 2 (large writing area). Four muscles namely Flexor carpi radialis, Extensor carpi radialis, Biceps brachii, and Sternocleidomastoid (SCM) are chosen for the study. The results are then compared with muscle activity while writing on conventional A4 sheets. Normalized root mean square (RMS) is used to assess the muscle activity and the trend line of MPF value is utilized to assess the muscle fatigue. The results show that SCM muscle has more muscle activation compared to other selected muscles followed by flexor carpi radialis. Subjective analysis is carried out using the Borg scale, which has reported that Type 2 digital board having larger working area was preferred by the participants as it reduces muscle fatigue.

Wearable Exoskeletons on the Workplaces: Knowledge, Attitudes and Perspectives of Health and Safety Managers on the implementation of exoskeleton technology in Northern Italy.

Background:Exoskeleton technology (ExT) has potential to significantly improve occupational health and safety. However, studies on stakeholders’ perspectives are lacking. To facilitate the implementation of ExT on the workplaces, a study was undertaken exploring specific knowledge, attitudes and perspectives (KAP) of Health and Safety Consultants (HSC).Methods:An online survey with quantitative and qualitative components was conducted with HSC participating to a series of qualification courses focusing on new technologies in occupational settings. Respondents rated whether they would use or recommend an exoskeleton, being assessed regarding their knowledge on ExT through a specifically designed knowledge test. Design features (n = 16) and expected benefits (n = 12) were rated and compared in terms of their importance. Regression analysis was used to identify factors significantly affecting the propensity towards the implementation of ExT.Results.A total of 59 HSC participated to the survey (participation rate, 90.8%): of them, 20 (33.9%) were somehow favorable towards the use of ExT on the workplaces. The most highly rated reason for potential use/recommendation of ExT was reducing the stress on joints and tendons (74.6%), followed by reducing muscle fatigue (71.2%). Among design features, higher ratings were identified for: comfort (4.53 ± 0.68), ease of setup (4.37 ± 0.72), portability (4.32 ± 0.97), minimization of falls risk (4.31 ± 0.93), ease of putting on/taking off the device (4.12 ± 1.16), and amount of physical energy needed for use (4.14 ± 0.92). Overall knowledge of ExT was quite low (knowledge score 43.2% ± 18.2), with high rate of false beliefs on the protective role of ExT on musculoskeletal disorders and physical efforts, positive effects on productivity. In multivariate analysis, age < 50 years and being an internal HSC were identified as significant effectors for a positive attitude towards ExT.Conclusions.This study emphasizes the opportunity to spread better knowledge of actual ExT features among potential stakeholders. Moreover, design of future exoskeleton should focus on devices comfortable, highly portable, ease to setup, with a reduced risk of falls. (www.actabiomedica.it)