The impact of neuromuscular electrical stimulation on recovery after intensive, muscle damaging, maximal speed training in professional team sports players

Acute Recovery after a Fatigue Protocol Using a Recovery Sports Legging: An Experimental Study

Enhancing recovery is a fundamental component of high-performance sports training since it enables practitioners to potentiate physical performance and minimise the risk of injuries. Using a new sports legging embedded with an intelligent system for electrostimulation, localised heating and compression (completely embodied into the textile structures), we aimed to analyse acute recovery following a fatigue protocol. Surface electromyography- and torque-related variables were recorded on eight recreational athletes. A fatigue protocol conducted in an isokinetic dynamometer allowed us to examine isometric torque and consequent post-exercise acute recovery after using the sports legging. Regarding peak torque, no differences were found between post-fatigue and post-recovery assessments in any variable; however, pre-fatigue registered a 16% greater peak torque when compared with post-fatigue for localised heating and compression recovery methods. Our data are supported by recent meta-analyses indicating that individual recovery methods, such as localised heating, electrostimulation and compression, are not effective to recover from a fatiguing exercise. In fact, none of the recovery methods available through the sports legging tested was effective in acutely recovering the torque values produced isometrically.

Localization of the gracilis muscle motor points - key considerations for botulinum neurotoxin injection and electrical stimulation

INTRODUCTION

Muscle motor points are considered the best sites for electrode positioning in electrical stimulation and, by some researchers, for botulinum neurotoxin injections. The aim of this study is to locate the motor points in the gracilis muscle to improve muscle function maintenance and treatment of spasticity.

MATERIAL AND METHODS

Ninety-three gracilis muscles (49 right, 44 left), fixed in 10% formalin solution, were subjected to the research. All nerve branches running towards the muscle were precisely traced to each motor point. Specific measurements were collected.

RESULTS

The gracilis muscle presents multiple motor points (median of 12), all of which were localized on the deep (lateral) side of the muscle belly. Generally, motor points of this muscle were spread between 15% and 40% of the reference line length.

CONCLUSION

Our findings may help clinicians identify appropriate locations for electrode placement during electrical stimulation of the gracilis muscle; they also deepen our understanding of the correlation between motor points and motor end plates and improve the application of botulinum neurotoxin injections.

Comparison of Different Recovery Strategies After High-Intensity Functional Training: A Crossover Randomized Controlled Trial

We aimed to determine whether voluntary exercise or surface neuromuscular electrical stimulation (NMES) could enhance recovery after a high-intensity functional training (HIFT) session compared with total rest. The study followed a crossover design. Fifteen male recreational CrossFit athletes (29 ± 8 years) performed a HIFT session and were randomized to recover for 15 min with either low-intensity leg pedaling (“Exercise”), NMES to the lower limbs (“NMES”), or total rest (“Control”). Perceptual [rating of perceived exertion (RPE) and delayed-onset muscle soreness (DOMS) of the lower-limb muscles], physiological (heart rate, blood lactate and muscle oxygen saturation) and performance (jump ability) indicators of recovery were assessed at baseline and at different time points during recovery up to 24 h post-exercise. A significant interaction effect was found for RPE (p = 0.035), and although post hoc analyses revealed no significant differences across conditions, there was a quasi-significant (p = 0.061) trend toward a lower RPE with NMES compared with Control immediately after the 15-min recovery. No significant interaction effect was found for the remainder of outcomes (all p > 0.05). Except for a trend toward an improved perceived recovery with NMES compared with Control, low-intensity exercise, NMES, and total rest seem to promote a comparable recovery after a HIFT session.

Effects of electrode size and placement on comfort and efficiency during low-intensity neuromuscular electrical stimulation of quadriceps, hamstrings and gluteal muscles

Background

Neuromuscular electrical stimulation (NMES) may prevent muscle atrophy, accelerate rehabilitation and enhance blood circulation. Yet, one major drawback is that patient compliance is impeded by the discomfort experienced. It is well-known that the size and placement of electrodes affect the comfort and effect during high-intensity NMES. However, during low-intensity NMES the effects of electrode size/placement are mostly unknown. Therefore, the purpose of this study was to investigate how electrode size and pragmatic placement affect comfort and effect of low-intensity NMES in the thigh and gluteal muscles.

Methods

On 15 healthy participants, NMES-intensity (mA) was increased until visible muscle contraction, applied with three electrode sizes (2 × 2 cm, 5 × 5 cm, 5 × 9 cm), in three different configurations on quadriceps and hamstrings (short-transverse (ST), long-transverse (LT), longitudinal (L)) and two configurations on gluteus maximus (short-longitudinal (SL) and long-longitudinal (LL)). Current–density (mA/cm²) required for contraction was calculated for each electrode size. Comfort was assessed with a numerical rating scale (NRS, 0–10). Significance was set to p < 0.05 and values were expressed as median (inter-quartile range).

Results

On quadriceps the LT-placement exhibited significantly better comfort and lower current intensity than the ST- and L-placements. On hamstrings the L-placement resulted in the best comfort together with the lowest intensity. On gluteus maximus the LL-placement demonstrated better comfort and required less intensity than SL-placement. On all muscles, the 5 × 5 cm and 5 × 9 cm electrodes were significantly more comfortable and required less current–density for contraction than the 2 × 2 cm electrode.

Conclusion

During low-intensity NMES-treatment, an optimized electrode size and practical placement on each individual muscle of quadriceps, hamstrings and gluteals is crucial for comfort and intensity needed for muscle contraction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-022-00403-7.

Physical therapy interventions for the treatment of delayed onset muscle soreness (DOMS): Systematic review and meta-analysis

OBJECTIVE

To evaluate the impact of interventions on pain associated with DOMS.

DATA SOURCES

PubMed, EMBASE, PEDro, Cochrane, and Scielo databases were searched, from the oldest records until May/2020. Search terms used included combinations of keywords related to "DOMS" and "intervention therapy".

ELIGIBILITY CRITERIA

Healthy participants (no restrictions were applied, e.g., age, sex, and exercise level). To be included, studies should be: 1) Randomized clinical trial; 2) Having induced muscle damage and subsequently measuring the level of pain; 3) To have applied therapeutic interventions (nonpharmacological or nutritional) and compare with a control group that received no intervention; and 4) The first application of the intervention had to occur immediately after muscle damage had been induced.

RESULTS

One hundred and twenty-one studies were included. The results revealed that the contrast techniques (p = 0,002 I² = 60 %), cryotherapy (p = 0,002 I² = 100 %), phototherapy (p = 0,0001 I² = 95 %), vibration (p = 0,004 I² = 96 %), ultrasound (p = 0,02 I² = 97 %), massage (p < 0,00001 I² = 94 %), active exercise (p = 0,0004 I² = 93 %) and compression (p = 0,002 I² = 93 %) have a better positive effect than the control in the management of DOMS.

CONCLUSION

Low quality evidence suggests that contrast, cryotherapy, phototherapy, vibration, ultrasound, massage, and active exercise have beneficial effects in the management of DOMS-related pain.

Decreased excitability of motor axons contributes substantially to contraction fatigability during neuromuscular electrical stimulation

The present study was designed to (i) determine the time course of changes in motor axon excitability during and after neuromuscular electrical stimulation (NMES); and (ii) characterize the relationship between contraction fatigability, NMES frequency, and changes at the axon, neuromuscular junction, and muscle. Eight neurologically intact participants attended 3 sessions. NMES was delivered over the common peroneal nerve at 20, 40, or 60 Hz for 8 min (0.3 s “on”, 0.7 s “off”). Threshold tracking was used to measure changes in axonal excitability. Supramaximal stimuli were used to assess neuromuscular transmission and force-generating capacity of the tibialis anterior muscle. Torque decreased by 49% and 62% during 8 min of 40 and 60 Hz NMES, respectively. Maximal twitch torque decreased only during 60 Hz NMES. Motor axon excitability decreased by 14%, 27%, and 35% during 20, 40, and 60 Hz NMES, respectively. Excitability recovered to baseline immediately (20 Hz) and at 2 min (40 Hz) and 4 min (60 Hz) following NMES. Overall, decreases in axonal excitability best predicted how torque declined over 8 min of NMES. During NMES, motor axons become less excitable and motor units “drop out” of the contraction, contributing substantially to contraction fatigability and its dependence on NMES frequency.

Novelty: The excitability of motor axons decreased during NMES in a frequency-dependent manner. As excitability decreased, axons failed to reach threshold and motor units dropped out of the contraction. Overall, decreased excitability best predicted how torque declined and thus is a key contributor to fatigability during NMES.

Changes in Salivary Levels of Creatine Kinase, Lactate Dehydrogenase, and Aspartate Aminotransferase after Playing Rugby Sevens: The Influence of Gender

Rugby sevens is characterised by continuous exertion and great physical contact per unit of time, leading to muscle damage. It is important to identify markers that can quantify muscle damage in order to improve recovery strategies. The objective of this study was to evaluate the release dynamics of muscle damage markers creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) in saliva samples when playing rugby sevens, analysing the influence of gender, during the rugby sevens university championship of Spain. The total sample included 27 athletes, divided into two teams of 14 men and 13 women between 18 and 31 years of age. CK, LDH, and AST were quantified from salivary samples collected from each athlete before and after three rugby sevens matches. The modified Borg scale of perceived exertion was also used after each match. When the results were analysed globally, there were no differences in CK and LDH before and after any match, but AST did show differences after two days of completing all matches. In terms of gender, the three enzymes showed different responses in men and women. Regarding the Borg scale, there were only significant differences between men and women after completing all mataches, with a greater perceived exertion in women. Based on our results, it can be stated that that serial matches of rugby sevens can cause changes of different magnitude in AST, CK and LDH activities in saliva, with AST showing the most significant variations and these changes are more pronounced in men than in women.

Current methods for stress marker detection in saliva

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Introduction of relevant biomarkers in stress conditions.

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Reference ranges of biomarkers in normal conditions.

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Saliva as easy-accessible specimen.

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Review of analytical methods for biomarker determination in saliva.

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Possibilities for design of point-of-care devices.

Stress and stress-related diseases are leading to drastic consequences in private and professional life. Therefore, the need for stress prevention strategies is of personal and economic interest. Especially during the recent period related to covid-19 outbreak and lock-down, an ongoing discussion of increasing stress etiology is reported. Biomarker analysis may help to assist diagnosis and classification of stress-related diseases and therefore support therapeutical decisions. Due to its non-invasive sampling, the analysis of saliva has become highly attractive compared to the detection methods in other specimen. This review article summarizes the status of research, innovative approaches, and trends. Scientific literature published since 2011 was excerpted with concentration on the detection of up to seven promising marker substances. Most often reported cortisol represents the currently best evaluated stress marker, while norepinephrine (noradrenaline) or its metabolite 3-methoxy-4-hydroxyphenylglycol is also a quite commonly considered stress marker. Other complementary stress marker candidates are testosterone, dehydroepiandrosterone (DHEA) and its sulfonated analogue DHEA-S, alpha-amylase, secretory immunoglobulin A, and chromogranin A. Several working groups are researching in the field of stress marker detection to develop reliable, fast, and affordable methods. Analytical methods reported mainly focused on immunological and electrochemical as well as chromatographic methods hyphenated to mass spectrometric detection to yield the required detection limits.

Is Low-Frequency Electrical Stimulation a Tool for Recovery after a Water Rescue? A Cross-Over Study with Lifeguards

This study aimed to evaluate the degree to which transcutaneous electrical stimulation (ES) enhanced recovery following a simulated water rescue. Twenty-six lifeguards participated in this study. The rescue consisted of swimming 100 m with fins and rescue-tube: 50 m swim approach and 50 m tow-in a simulated victim. Blood lactate clearance, rated perceived effort (RPE), and muscle contractile properties were evaluated at baseline, after the water rescue, and after ES or passive-recovery control condition (PR) protocol. Tensiomiography, RPE, and blood lactate basal levels indicated equivalence between both groups. There was no change in tensiomiography from pre to post-recovery and no difference between recovery protocols. Overall-RPE, legs-RPE and arms-RPE after ES (mean ± SD; 2.7 ± 1.53, 2.65 ± 1.66, and 2.30 ± 1.84, respectively) were moderately lower than after PR (3.57 ± 2.4, 3.71 ± 2.43, and 3.29 ± 1.79, respectively) (p = 0.016, p = 0.010, p = 0.028, respectively). There was a significantly lower blood lactate level after recovery in ES than in PR (mean ± SD; 4.77 ± 1.86 mmol·L^-1 vs. 6.27 ± 3.69 mmol·L^-1; p = 0.045). Low-frequency ES immediately after a water rescue is an effective recovery strategy to clear out blood lactate concentration.

Effects of Foam Rolling as a Recovery Tool in Professional Soccer Players

Rey, E, Padrón-Cabo, A, Costa, PB, and Barcala-Furelos, R. Effects of foam rolling as a recovery tool in professional soccer players. J Strength Cond Res 33(8): 2194-2201, 2019-Foam rolling (FR) is a common strategy used after training and competition by players. However, no previous studies have assessed the effectiveness of FR as a recovery tool in sports populations. The aim of this study was to examine the effectiveness of FR (20 minutes of FR exercises on quadriceps, hamstrings, adductors, gluteals, and gastrocnemius) and passive recovery (20 minutes sit on a bench) interventions performed immediately after a training session on Total Quality Recovery (TQR), perceived muscle soreness, jump performance, agility, sprint, and flexibility 24 hours after the training. During 2 experimental sessions, 18 professional soccer players (age 26.6 ± 3.3 years; height: 180.2 ± 4.5 cm; body mass: 75.8 ± 4.7 kg) participated in a randomized fully controlled trial design. The first session was designed to collect the pretest values of each variable. After baseline measurements, the players performed a standardized soccer training. At the end of training unit, all the players were randomly assigned to the FR recovery group and the passive recovery group. A second experimental session was conducted to obtain the posttest values. Results from the between-group analyses showed that FR had a large effect on the recovery in agility (effect sizes [ES] = 1.06), TQR (ES = 1.08), and perceived muscle soreness (ES = 1.02) in comparison with the passive recovery group at 24 hours after training. Thus, it is recommended that soccer coaches and physical trainers working with high-level players use a structured recovery session lasting from 15 to 20 minutes based on FR exercises that could be implemented at the end of a training session to enhance recovery between training loads.

Effects of External Counterpulsation on Postexercise Recovery in Elite Rugby League Players

PURPOSE

External counterpulsation (ECP) has previously been used to treat cardiac patients via compression of the lower extremities during diastole to increase venous return and coronary perfusion. However, the effects of ECP on exercise performance and markers of recovery in elite athletes are largely unknown.

METHODS

On 2 separate occasions, 48 h apart, 7 elite National Rugby League players performed an identical 60-min field-based conditioning session followed by a 30-min period of either regular ECP treatment or placebo. Power measures during repeated cycle bouts and countermovement jump height and contraction time derivatives were measured at rest and 5 h postexercise. Saliva samples and venous blood samples were taken at rest, postexercise, and 5 h postexercise to assess stress, inflammation, and muscle damage.

RESULTS

After ECP treatment, cycling peak power output (P = .028; 11%) and accumulated peak power (P = .027; 14%) increased compared with the placebo condition. Postexercise plasma interleukin 1 receptor antagonist only increased after ECP (P = .024; 84%), and concentrations of plasma interleukin 1 receptor antagonist tended to be higher (P = .093; 76%) 5 h postexercise. Furthermore, testosterone-to-cortisol ratio was increased above baseline and placebo 5 h postexercise (P = .017-.029; 24-77%). The ratio of postexercise salivary α-amylase to immunoglobulin A decreased after treatment (P = .013; 50%) compared with the placebo control.

CONCLUSIONS

Exercise performance and hormonal indicators of stress were improved and inflammation markers were reduced following acute ECP.

Evidence-based post-exercise recovery strategies in rugby: a narrative review

In the sport of rugby, athletes need a multitude of sport-specific skills along with endurance, power, and speed to optimize performance. Further, it is not unusual for athletes to play several competitive matches with insufficient recovery time. Rugby requires repeated bouts of high-intensity actions intermixed with brief periods of low-to-moderate active recovery or passive rest. Specifically, a match is characterized by repeated explosive activities, such as jumps, shuffles, and rapid changes of direction. To facilitate adequate recovery, it is necessary to understand the type of fatigue induced and, if possible, its underlying mechanisms. Common approaches to recovery may include nutritional strategies as well as active (active recovery) and passive recovery (water immersions, stretching, and massage) methods. However, limited research exists to support the effectiveness of each strategy as it related to recovery from the sport of rugby. Therefore, the main aim of the current brief review is to present the relevant literature that pertains to recovery strategies in rugby.

Training Load and Fatigue Marker Associations with Injury and Illness: A Systematic Review of Longitudinal Studies

Background

Coaches, sport scientists, clinicians and medical personnel face a constant challenge to prescribe sufficient training load to produce training adaption while minimising fatigue, performance inhibition and risk of injury/illness.

Objective

The aim of this review was to investigate the relationship between injury and illness and longitudinal training load and fatigue markers in sporting populations.

Methods

Systematic searches of the Web of Science and PubMed online databases to August 2015 were conducted for articles reporting relationships between training load/fatigue measures and injury/illness in athlete populations.

Results

From the initial 5943 articles identified, 2863 duplicates were removed, followed by a further 2833 articles from title and abstract selection. Manual searching of the reference lists of the remaining 247 articles, together with use of the Google Scholar ‘cited by’ tool, yielded 205 extra articles deemed worthy of assessment. Sixty-eight studies were subsequently selected for inclusion in this study, of which 45 investigated injury only, 17 investigated illness only, and 6 investigated both injury and illness. This systematic review highlighted a number of key findings, including disparity within the literature regarding the use of various terminologies such as training load, fatigue, injury and illness. Athletes are at an increased risk of injury/illness at key stages in their training and competition, including periods of training load intensification and periods of accumulated training loads.

Conclusions

Further investigation of individual athlete characteristics is required due to their impact on internal training load and, therefore, susceptibility to injury/illness.

Dietetic-nutritional, physical and physiological recovery methods post-competition in team sports

To a proper recovery, is absolutely necessary to know that athletes with enhanced recovery after maximal exercise are likely to perform better in sports. Recovery strategies are commonly used in team sports despite limited scientific evidence to support their effectiveness in facilitating optimal recovery and the players spend a much greater proportion of their time recovering than they do in training. According to authors, some studies investigated the effect of recovery strategies on physical performance in team sports, lack of experimental studies about the real origin of the fatigue, certify the need for further study this phenomenon. Thus, developing effective methods for helping athletes to recover is deemed essential. Therefore, the aim of this review is provide information for his practical application, based on scientific evidence about recovery in team sports.

Effectiveness evaluation of whole-body electromyostimulation as a postexercise recovery method

BACKGROUND

Whole-body electromyostimulation (WB-EMS) devices are now being used in health and sports training, although there are few studies investigating their benefits. The objective of this research was to evaluate the effectiveness of WB-EMS as a postexercise recovery method and compare it with other methods like active and passive recovery.

METHODS

The study included nine trained men (age =21±1 years, height =1.77±0.4 m, mass =62±7 kg). Three trials were performed in three different sessions, 1 week apart. Each trial, the participants completed the same exercise protocol and a different recovery method each time. A repeated measures design was used to check the basal reestablishing on several physiological variables (lactate, heart rate, percentage of tissue hemoglobin saturation, temperature, and neuromuscular fatigue) and to evaluate the quality of recovery. The non-parametric Wilcoxon and Friedman ANOVA tests were used to examine the differences between recovery methods.

RESULTS

The results showed no differences between methods in the physiological and psychological variables analyzed. Although, the blood lactate concentration showed borderline statistical significance between methods (P=0.050). Likewise, WB-EMS failed to recover baseline blood lactate concentration (P=0.021) and percentage of tissue hemoglobin saturation (P=0.023), in contrast to the other two methods.

CONCLUSIONS

These findings suggest that WB-EMS is not a good recovery method because the power of reestablishing of several physiological and psychological parameters is not superior to other recovery methods like active and passive recovery.

miR-146a-5p acts as a negative regulator of TGF-β signaling in skeletal muscle after acute contusion

Growing evidence suggests the importance of microRNAs (miRNAs) in stress signaling pathways. Transforming growth factor-β (TGF-β) is a potent cytokine that promotes the development of skeletal muscle fibrosis after acute contusion. However, how miRNAs are involved in TGF-β signaling and confer the robustness of TGF-β-induced fibrotic response remains to be fully elucidated. Here, we demonstrated that miR-146a-5p (miR-146) levels were reduced in a fibrotic mouse model after acute muscle contusion. It was also found that TGF-β treatment decreased the expression of miR-146 in vitro in a dose- and time-dependent manner. In addition, overexpression of Smad3 and Samd4, two key players in TGF-β signaling, suppressed the expression of miR-146 in muscle cells. Overexpression of miR-146 inhibited the expressions of fibrosis markers both in vitro and in vivo. Moreover, increase in the expression of miR-146 in muscle cells was able to attenuate the effect of TGF-β on the expressions of fibrosis markers. Mechanistic analysis revealed that Smad4 is a direct target of miR-146 in muscle cells. Furthermore, the anti-fibrotic effect of miR-146 could be blocked by overexpression of Smad4 in vivo. These results suggest that Smad4 is down-regulated by miR-146 in skeletal muscle. Taken together, our results indicate that the anti-fibrotic miR-146 is a component of TGF-β signaling. It is down-regulated by Smad protein, and can inhibit the expression of Smad4. Our study suggests that miR-146 might have a therapeutic potential to reduce skeletal muscle fibrosis after injury.