Peak torque angle, acceleration time and time to peak torque as additional parameters extracted from isokinetic test in professional soccer players: a cross-sectional study.

This study investigated additional and traditional variables from isokinetic test of thigh muscles in soccer players across different field positions. One hundred and eighty-nine athletes performed maximal concentric isokinetic knee contractions on dominant (DL) and non-dominant limb (NDL) at 60º/s and 240º/s. The additional outcomes peak torque angle (AngPT), acceleration time (AcT) and time to peak torque (TPT) and traditional outcomes Peak torque (PT), total work (TW) and power (Pw) were extracted from the exam. Goalkeepers (GK), side backs (SB), central backs (CB), central defender midfielders (CDM), central attacking midfielders (CAM) and forwards (FW) were considered. Comparisons between limbs and positions demonstrated that SB extensors of the DL presented TPT lower (p = 0.006) and AngPT higher (p = 0.011) than NDL at 60°/s. CDM extensors of the DL showed lower TPT at 60°/s (p = 0.003) and 240°/s (p = 0.024). CAM flexors of the DL showed lower TPT (p = 0.026) and AcT (p = 0.021) at 240°/s than NDL. CB, CDM and CAM extensors of the NDL showed higher PT, TW and Pw than DL (p < 0.05). In conclusion, there are muscle imbalances between limbs in SB, CDM and CAM and across different field positions.

Rate of torque development of paretic lower limb is an excellent predictor of walking speed in chronic stroke individuals.

BACKGROUND: Walking speed discriminates levels of functionality in stroke survivors, but its relationship with neuromuscular parameters remains unclear. We aimed to (1) verify relationships between walking speed, peak torque, and rate of torque development in individuals with chronic stroke and (2) investigate whether adjusting the predictive model for assistive device use and lower limb motor function improves its accuracy. METHODS: Twenty-nine stroke survivors (time post-stroke ≥6 months) were assessed for walking speed, motor function, torque of knee extensors, and rate of torque development. Hierarchical multiple regression was conducted to infer the contribution of assistive device use and lower limb motor function in the proportion of variance in walking speed explained by neuromuscular parameters. Adequacy of regression models was verified using Shapiro-Wilk test and visual inspection of histograms. FINDINGS: Rate of torque development measures presented higher coefficients of determination (R2 = 0.399-0.457) than peak torque (R2 = 0.333). However, no differences were observed between correlation coefficients (P > 0.05). When adjusted for assistive device use and lower limb motor function, coefficients of determination of all neuromuscular parameters were improved (P < 0.05). Regression models showed good adequacy. INTERPRETATION: Peak torque and rate of torque development from knee extensors are adequate predictors of walking speed in stroke survivors. Adjusting predictive models for assistive device use and lower limb motor function increases predictive capacity. These findings may have repercussions for assessing chronic stroke individuals and developing treatment strategies.

Can Skin Temperature Be Altered After Different Magnitudes of Eccentric Exercise-Induced Muscle Damage?

Purpose: This study aimed to assess skin temperature (Tsk) changes after different magnitudes of exercise-induced muscle damage (EIMD) of the elbow flexor muscles and investigate whether Tsk is related to indirect markers of EIMD. Methods: Thirty healthy active men were randomly allocated to the mild (MiDG) (n = 15) or moderate (MoDG) (n = 15) muscle damage group. Muscle damage in elbow flexor muscles was induced by 10 (for MiDG) or 30 (for MoDG) maximal eccentric isokinetic contractions at 60 degrees/s. Tsk, maximal voluntary isometric contraction (MVIC), delayed-onset muscle soreness (DOMS), plasma creatine kinase (CK) activity, range of motion (ROM), and pressure pain threshold (PPT) were measured before and up to 72 hr after EIMD. Results: Tsk increased only immediately after EIMD (p < .05; f = 1.44) in the MoDG (4.2%) and MiDG (4.6%), returning to near baseline values 30 min after EIMD and remaining so thereafter. In addition, there was no intergroup difference (p > .05) at any of the times analyzed, or correlation between Tsk and most indirect markers of EIMD. Conclusions: In conclusion, Tsk should not be considered an indirect marker of mild or moderate muscle damage in active men, since alterations in this variable last less than 30 min after damaging exercise and showed no correlation with most indirect markers of EIMD.

Low-Load Blood-Flow Restriction Exercise to Failure and Nonfailure and Myoelectric Activity: A Meta-Analysis.

OBJECTIVE: To compare the short- and long-term effects of low-load resistance training with blood-flow restriction (LL-BFR) versus low- (LL-RT) or high- (HL-RT) load resistance training with free blood flow on myoelectric activity and investigate the differences between failure (exercise performed to volitional failure) and nonfailure (exercise not performed to volitional failure) protocols. DATA SOURCES: We identified sources by searching the MEDLINE, PubMed, CINAHL, Web of Science, CENTRAL, Scopus, SPORTDiscus, and PEDro electronic databases. STUDY SELECTION: We screened the titles and abstracts of 1048 articles using our inclusion criteria. A total of 39 articles were selected for further analysis. DATA EXTRACTION: Two reviewers independently assessed the methodologic quality of each study and extracted the data. A meta-analytic approach was used to compute standardized mean differences (SMDs) ± 95% CIs. Subgroup analyses were conducted for both failure and nonfailure protocols. DATA SYNTHESIS: The search identified 39 articles that met the inclusion criteria. Regarding the short-term effects, LL-BFR increased muscle excitability compared with LL-RT during nonfailure protocols (SMD = 0.61; 95% CI = 0.34, 0.88), whereas HL-RT increased muscle excitability compared with LL-BFR during failure (SMD = -0.61; 95% CI = -1.01, -0.21) and nonfailure (SMD = -1.13; 95% CI = -1.94, -0.33) protocols. Concerning the long-term effects, LL-BFR increased muscle excitability compared with LL-RT during exercises performed to failure (SMD = 1.09; 95% CI = 0.39, 1.79). CONCLUSIONS: Greater short-term muscle excitability levels were observed in LL-BFR than in LL-RT during nonfailure protocols. Conversely, greater muscle excitability was present during HL-RT than LL-BFR, regardless of volitional failure. Furthermore, LL-BFR performed to failure increased muscle excitability in the long term compared with LL-RT.

Use of rating of perceived exertion during anterior cruciate ligament reconstruction and knee osteoarthritis rehabilitation: a scoping review protocol.

INTRODUCTION: Anterior cruciate ligament (ACL) tear and knee osteoarthritis (KOA) are the most prevalent musculoskeletal disorders of the knee. Rehabilitation with progressive resistance training is recommended for both disorders. Rating of perceived exertion (RPE) is widely used to prescribe, monitor, and control exercise load. However, the lack of detailed methodological description and variability in the use of RPE may hinder its validity. This scoping review summarises methodological aspects of the use of RPE in resistance exercises during ACL reconstruction and KOA rehabilitation. We also aim to identify possible methodological issues related to the use of RPE and provide recommendations for future studies. METHODS AND ANALYSIS: This scoping review protocol was developed following the Joanna Briggs Institute and Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement extension for Scoping Reviews. The search will be conducted in Medline/PubMed, Embase, CINAHL, PEDro, Central and SPORTDiscus databases. The terms "anterior cruciate ligament rehabilitation", "knee osteoarthritis" and "resistance exercise" and their synonymous will be used isolated and combined (boolean operators AND/OR/NOT). Two reviewers will independently conduct title and abstract screening and evaluate full texts of potentially eligible articles. Data related to study design, sample, intervention characteristics and RPE outcomes will be extracted, summarised and qualitatively analysed. ETHICS AND DISSEMINATION: The proposed scoping review does not require ethical approval since it will synthesise information from publicly available studies. Regarding dissemination activities, results will be submitted for publication in a scientific journal and presented at conferences in the field.

Blood Flow Restriction Training: To Adjust or Not Adjust the Cuff Pressure Over an Intervention Period?

Blood flow restriction (BFR) training combines exercise and partial reduction of muscular blood flow using a pressured cuff. BFR training has been used to increase strength and muscle mass in healthy and clinical populations. A major methodological concern of BFR training is blood flow restriction pressure (BFRP) delivered during an exercise bout. Although some studies increase BFRP throughout a training intervention, it is unclear whether BFRP adjustments are pivotal to maintain an adequate BFR during a training period. While neuromuscular adaptations induced by BFR are widely studied, cardiovascular changes throughout training intervention with BFR and their possible relationship with BFRP are less understood. This study aimed to discuss the need for BFRP adjustment based on cardiovascular outcomes and provide directions for future researches. We conducted a literature review and analyzed 29 studies investigating cardiovascular adaptations following BFR training. Participants in the studies were healthy, middle-aged adults, older adults and clinical patients. Cuff pressure, when adjusted, was increased during the training period. However, cardiovascular outcomes did not provide a plausible rationale for cuff pressure increase. In contrast, avoiding increments in cuff pressure may minimize discomfort, pain and risks associated with BFR interventions, particularly in clinical populations. Given that cardiovascular adaptations induced by BFR training are conflicting, it is challenging to indicate whether increases or decreases in BFRP are needed. Based on the available evidence, we suggest that future studies investigate if maintaining or decreasing cuff pressure makes BFR training safer and/or more comfortable with similar physiological adaptation.

Repetition Failure Occurs Earlier During Low-Load Resistance Exercise With High But Not Low Blood Flow Restriction Pressures: A Systematic Review and Meta-analysis.

ABSTRACT: Cerqueira, MS, Lira, M, Mendonça Barboza, JA, Burr, JF, Wanderley e Lima, TB, Maciel, DG, and De Brito Vieira, WH. Repetition failure occurs earlier during low-load resistance exercise with high but not low blood flow restriction pressures: a systematic review and meta-analysis. J Strength Cond Res XX(X): 000-000, 2021-High-load and low-load resistance training (LL-RT) performed to failure are considered effective for improving muscle mass and strength. Alternatively, LL-RT with blood flow restriction (LL-BFR) may accelerate repetition failure and has been suggested to be more time efficient than LL-RT. This study explores the evidence for the effects of LL-BFR vs. LL-RT on repetition failure. A systematic literature search was conducted in the PubMed, CINAHL, Web of Science, CENTRAL, Scopus, SPORTDiscus, and PEDro databases. Meta-analyses of mean differences and 95% confidence intervals (CIs) were performed using a random-effects model. Subgroup analyses were conducted for both the high and low blood flow restriction pressures. The search identified n = 10 articles that met the inclusion criteria. The meta-analysis comprised a total of 218 healthy subjects. Low-load resistance training with blood flow restriction with high pressures (≥50% arterial occlusion pressure [AOP]) precipitate repetition failure in ∼14.5 fewer repetitions (95% CI -19.53 to -9.38) compared with LL-RT, whereas the use of low pressures (<50% AOP) stimulated repetition failure with ∼1.4 fewer repetitions (95% CI -3.11 to 0.37); however, this difference was not statistically significant. Repetition failure has been demonstrated to be an important normalizing variable when comparing the hypertrophic and strength effects resulting from resistance training and occurs earlier during low-load resistance exercise with high but not low blood flow restriction pressures.

Effects of transcranial direct current stimulation associated or combined with exercise on musculoskeletal pain: systematic review / Efeitos da estimulação transcraniana por corrente contínua associada ou combinada ao exercício na dor musculoesquelética: revisão sistemática

ABSTRACT BACKGROUND AND OBJECTIVES: Aerobic/resistance exercises and transcranial direct current stimulation (tDCS) can produce analgesic effects in patients with musculoskeletal pain, however, the summed effect of these two therapeutic resources remains unclear. The present study aimed to verify the effects of tDCS associated or combined with aerobic/resistance exercise on musculoskeletal pain. CONTENTS: The search was carried out in the databases: Pubmed, LILACS, Scielo. The intervention considered was tDCS associated or combined with exercises and the comparison was exercise without tDCS or with sham tDCS. Randomized controlled trials enrolling patients with musculoskeletal pain were included. There were no restrictions on the language and year of publication and the methodological quality was verified with PEDro Scale. Three trials were included with a total of 110 participants. The methodological quality was high, with an average of 9 points on the PEDro Scale. The studies used tDCS in the primary motor cortex with an intensity of 1 or 2 mA, for 20 minutes. The participants included were aged between 18 and 75 years and had the following diseases: fibromyalgia, osteoarthritis or chronic low back pain. CONCLUSION: Overall, tDCS did not overcome the sham tDCS to enhance the effects of exercise in reducing musculoskeletal pain.

RESUMO JUSTIFICATIVA E OBJETIVOS: Os exercícios aeróbios/resistidos e a estimulação transcraniana por corrente contínua (ETCC) podem produzir efeitos analgésicos em pacientes com dores de origem musculoesquelética, porém, o efeito somado destes dois recursos terapêuticos ainda não está claro. O objetivo do presente estudo foi verificar os efeitos da ETCC associada ou combinada ao exercício aeróbio/resistido na dor musculoesquelética. CONTEÚDO: A busca foi realizada nas bases de dados Pubmed, LILACS e Scielo. A intervenção considerada foi ETCC associada ou combinada a exercícios e a comparação foi exercício sem ETCC ou com ETCC simulada. Foram incluídos ensaios clínicos randomizados envolvendo pacientes com dor musculoesquelética aguda ou crônica. Não houve restrições quanto ao idioma e ano de publicação e a qualidade metodológica dos estudos foi verificada por meio da escala PEDro. Três ensaios foram incluídos com um total de 110 participantes. A qualidade metodológica foi alta, com uma média de 9 pontos na escala PEDro. Os estudos utilizaram a ETCC no córtex motor primário com intensidade de 1 ou 2 mA, por 20min. Os participantes tinham idade entre 18 e 75 anos e eram portadores de fibromialgia, osteoartrite ou lombalgia crônica. CONCLUSÃO: A ETCC não superou a ETCC simulada para potencializar os efeitos do exercício na redução de dor musculoesquelética.

Effect of Pain Education, Cryotherapy, and Transcutaneous Electrical Nerve Stimulation on the Pain, Functional Capacity, and Quality of Life in Patients With Nonspecific Chronic Low Back Pain: A Single-Blind Randomized Controlled Trial.

OBJECTIVE: The aim of the study was to analyze the effects of pain education and the combined use of cryotherapy and transcutaneous electrical nerve stimulation on the pain sensation, functional capacity, and quality of life of patients with nonspecific chronic low back pain. DESIGN: This is a randomized controlled and blind clinical trial including patients with nonspecific chronic low back pain in the following 4 groups: control group, cryotherapy group, burst transcutaneous electrical nerve stimulation group, and cryotherapy combined with burst transcutaneous electrical nerve stimulation group. They were evaluated at baseline and after the protocol was concluded using the following: Roland-Morris questionnaire and sit-to-stand test; quality-of-life questionnaire; and pain. The protocol consisted of 10 sessions with pain education associated the combination of the electrophysical agents. RESULTS: There were no statistical differences between groups after the intervention protocol. In the within analysis, all groups presented an improvement in visual analog scale scores, Roland-Morris questionnaire, sit-to-stand test, and pain domain of quality-of-life questionnaire. CONCLUSIONS: This study showed that with pain education, there was no difference between cryotherapy and transcutaneous electrical nerve stimulation alone, combined, or placebo mode in improving pain, functional capacity, and quality of life in patients with nonspecific chronic low back pain.

Perceived Barriers to Blood Flow Restriction Training.

Blood flow restriction (BFR) training is increasing in popularity in the fitness and rehabilitation settings due to its role in optimizing muscle mass and strength as well as cardiovascular capacity, function, and a host of other benefits. However, despite the interest in this area of research, there are likely some perceived barriers that practitioners must overcome to effectively implement this modality into practice. These barriers include determining BFR training pressures, access to appropriate BFR training technologies for relevant demographics based on the current evidence, a comprehensive and systematic approach to medical screening for safe practice and strategies to mitigate excessive perceptual demands of BFR training to foster long-term compliance. This manuscript attempts to discuss each of these barriers and provides evidence-based strategies and direction to guide clinical practice and future research.

Acute effects of whole-body vibration on spinal excitability level and ankle plantar flexion spasticity in post-stroke individuals: A randomized controlled trial.

INTRODUCTION: This study aimed to evaluate the acute effects (up to 30 min) of whole-body vibration (WBV) on spinal excitability level and ankle plantar flexion spasticity in chronic stroke subjects. METHODS: Twenty-one subjects (age 30-70 years old) with chronic stroke and ankle plantar flexion spasticity were randomly assigned to the vibration group (VG, n = 11) or the control group (CG, n = 10). Subjects in the VG underwent 10 minutes of WBV with a frequency of 35 Hz and amplitude of 2 mm. Subjects in the CG remained on the platform for 10 min without receiving vibratory stimulus. The spinal excitability level was estimated by the Hmax/Mmax ratio extracted from the H-reflex with simple stimulus examination. The value of the second/first wave ratio (H2/H1 ratio) at the peak of the first facilitation was also considered through the recovery curve with double stimulation. Spasticity was estimated by the Modified Ashworth Scale (MAS) and global perception of change. All outcomes were assessed before and at 10, 20, and 30 min after the WBV, except for MAS, which was evaluated only 10 min after WBV. RESULTS: No between-group differences were found in either the spinal excitability level or plantar flexor spasticity at the three evaluated moments after WBV. CONCLUSION: These results suggest that WBV does not reduce spinal excitability level or spasticity of the plantar flexor muscles in chronic stroke patients in the first 30 min after vibratory stimulus.

Effects of blood flow restriction without additional exercise on strength reductions and muscular atrophy following immobilization: A systematic review.

Purpose: To investigate whether blood flow restriction (BFR) without concomitant exercise mitigated strength reduction and atrophy of thigh muscles in subjects under immobilization for lower limbs. Methods: The following databases were searched: PubMed, CINAHL, PEDro, Web of Science, Central, and Scopus. Results: The search identified 3 eligible studies, and the total sample in the identified studies consisted of 38 participants. Isokinetic and isometric torque of the knee flexors and extensors was examined in 2 studies. Cross-sectional area of thigh muscles was evaluated in 1 study, and thigh girth was measured in 2 studies. The BFR protocol was 5 sets of 5 min of occlusion and 3 min of free flow, twice daily for approximately 2 weeks. As a whole, the included studies indicate that BFR without exercise is able to minimize strength reduction and muscular atrophy after immobilization. It is crucial to emphasize, however, that the included studies showed a high risk of bias, especially regarding allocation concealment, blinding of outcome assessment, intention-to-treat analyses, and group similarity at baseline. Conclusion: Although potentially useful, the high risk of bias presented by original studies limits the indication of BFR without concomitant exercise as an effective countermeasure against strength reduction and atrophy mediated by immobilization.

Skin temperature of middle distance runners after a maximum effort test

The purposeof this study was to analyze skin temperature(Tsk)responses after a short-term maximum effort test in middle-distance runners.Aquasi-experimental study was conducted with ten men (age 23.5±5.10 years)who trained 5 days per week, 2 to 3 hours per day,and were submitted to thermographic evaluationbefore and after Cooper's 12-minute run test (CRT). The mean temperature of the anterior-superior,posterior-superior,anterior-inferior,and posterior-inferiorregionswas compared between the sides(i.e., left and right)before and after CRT.The paired t-testshowed asignificantdecrease in Tskafter CRT in thefollowingregions:right pectoralis major (-3.4%), left pectoralis major (-3.4%),and abdomen (-5%) in the anterior-superior view (p<0.01); and in the upper right trunk (-1.9%),upper lefttrunk(-1.9%) and lower back (-2.9%) in the posterior-superior view (p<0.05). In the lower limbs,asignificantincreaseintemperature of the left knee (1.6%),and right (3.6%) and left ankles (2.9%) in the anteriorview (p<0.05),as well as in theright (4.3%) and left ankles (3.7%) in the posteriorview (p<0.05)wereobserved. There was no difference in temperature between the right and left sides. In conclusion, the Tskchange of middle-distance runners wassymmetricalbetween sides,decreasing in upper limbs and trunk and increasing in lower limbs after a short-term maximum effort test.

Effects of blood flow restriction exercise with very low load and low volume in patients with knee osteoarthritis: protocol for a randomized trial.

BACKGROUND: Knee osteoarthritis (OA) is characterized by chronic pain, physical dysfunction, and reduced quality of life. Low-load resistance exercises with blood flow restriction (BFR) have presented results similar to those of high-intensity resistance exercise (HIRE) without BFR provided that the exercise volume in both is paired. However, it is unclear whether BFR exercise with reduced load and volume generates clinical improvements similar to those of HIRE. The aim of the proposed study is to evaluate the effects of BFR resistance exercise with very low load and low volume against HIRE in patients with knee OA for the outcomes of knee pain, muscle performance, physical function, disease severity, quality of life, perceived exertion during the exercises, adherence, and patient satisfaction with treatment. METHODS: This two-arm, prospectively registered, randomized controlled trial with blinded assessors and volunteers will involve 40 patients with knee OA. Two weekly treatment sessions will be provided for 12 weeks. Patients will perform very low-load (10% of 1-RM) and low-volume BFR exercise or HIRE (60% of 1-RM) for strengthening thigh muscles. The primary outcome will be the knee pain measured after 12 weeks of treatment. The secondary outcomes include knee pain 6 months after randomization, physical function, disease severity, quality of life, muscle performance, knee pain and perceived exertion during exercise, adherence, and patient satisfaction with treatment. DISCUSSION: If the improvements in the outcomes are similar in the two groups, BFR exercise with reduced load and volume may be an interesting alternative in the treatment of knee OA, especially when exercises with high loads generate joint pain. TRIAL REGISTRATION: Registro Brasileiro de Ensaios Clínicos (REBEC), RBR-6pcrfm . Registered on July 10, 2018.

Rate of force development to evaluate the neuromuscular fatigue and recovery after an intermittent isometric handgrip task with different blood flow restriction conditions

Aim: To investigate the neuromuscular fatigue and recovery after an intermittent isometric handgrip exercise (IIHE) executed until failure with different blood flow restriction (BFR) conditions (free flow, partial and total vascular restriction). Methods: Thirteen healthy men carried out an IIHE at 45% of maximum voluntary isometric force (MVIF) until failure with total restriction (TR), partial restriction (PR) or free flow (FF). The rate of force development (RFD) was extracted from the MIVF over the time intervals of 0-30, 0-50, 0-100, and 0-200ms and normalized by MVIF [relative RFD (RFDr)]. Results: The RFDr decreased significantly (p<0.01) after the IIHE in all BFR conditions and time intervals studied, remaining lower for five minutes. The medians of the RFDr in FF condition were significantly lower (p=0.01) at 30ms (1.56 %MVIF·s-1) and 50ms (1.70 %MVIF·s-1) when compared to TR at 30ms (2.34 %MVIF·s-1) and 50ms (2.63 %MVIF·s-1) in minute 1 post failure. Conclusions: These results show that, regardless of the blood flow restriction level, there is no RFD recovery five minutes after an exhaustive IIHE. When the task was executed with FF, the reduction of the RFD was greater when compared with the TR condition.(AU)

Whole body vibration to attenuate reduction of explosive force in chronic kidney disease patients: a randomized controlled trial.

To investigate whether whole body vibration (WBV) training increases the explosive force of the knee extensors in chronic kidney disease (CKD) patients. Fourteen CKD patients undergoing hemodialysis were randomly allocated in WBV training or Sham group. Explosive force parameters (contractile impulse [CImp] and relative rate of force development [RFDr]) obtained in early (30 and 50 msec) and late phases (100 and 200 msec) of the knee extensors force/time curve. CImp and RFDr obtained at the early phase of force/time curve reduced after the intervention period, with a smaller decline for WBV (CImp at 50 msec [~-15% and -51%, P=0.038], RFDr at 30 msec [~-22% and -52%, P=0.044] and RFDr at 50 msec [~-11% and -54%; P=0.008]). In the late phase there was a lower decline for WBV group compared to Sham group, respectively: CImp: 100 msec (~-8% and -55%, P=0.025), 200 msec (~-3% and -46%, P= 0.025); RFDr 100 msec (~0.01% and -56%, P=0.033), 200 msec (~-5% and -36%, P=0.004). Three months of WBV training may attenuate the explosive force reduction in CKD patients.