Is it time to turn our attention toward central mechanisms for post-exertional recovery strategies and performance?

The Effect of Combined Transcranial Direct Current Stimulation and Pneumatic Compression as Part of a Comprehensive Recovery Strategy in Professional Male Top-Level Soccer Players

ABSTRACT

Gonçalves, DS, Moscaleski, LA, da Silva, GM, Morgans, R, Okano, AH, and Moreira, A. The effect of combined transcranial direct current stimulation and pneumatic compression as part of a comprehensive recovery strategy in professional male top-level soccer players. J Strength Cond Res 38(9): 1658-1666, 2024-This retrospective study aimed to examine the effect of transcranial direct current stimulation (tDCS) combined with lower limb pneumatic compression during the postmatch recovery period in top-level professional male soccer players' physiological and perceptual markers of recovery status. During the 2022 season (baseline), pneumatic compression was performed as part of the recovery strategy, applied the day after official match play and psychophysiological measurements (pain, sleep, perceived recovery, and creatine kinase [CK] sampling) were performed on the second day postmatch. During the 2023 season, the tDCS protocol was introduced, with its application being performed simultaneously (in conjunction) with pneumatic compression. Recovery sessions following 10 matches in the 2022 season and following 10 matches in the 2023 season were included in the analyses. Compared with 2022 (baseline; pneumatic compression isolated), the players perceived an increased recovery on the second day postmatch when tDCS was used in conjunction with the pneumatic compression (mean = 12%; p = 0.008) and rated improved sleep quality for the nights after applying tDCS combined with pneumatic compression (mean = 7.5%; p = 0.029). On the second day postmatch, a significant reduction was observed in muscle pain/soreness (mean = 64%; p < 0.0001) and the CK concentration decreased when baseline (pneumatic compression isolated) was compared with tDCS + pneumatic compression (mean = 76%; p = 0.001). In summary, combining pneumatic compression with tDCS may enhance the effects of both interventions, leading to greater overall improvements in recovery. Further research is warranted to confirm these findings and explore the underlying mechanisms in more detail.

Effectiveness of Recovery Strategies After Training and Competition in Endurance Athletes: An Umbrella Review

BACKGROUND

Recovery strategies are used to enhance performance and reduce injury risk in athletes. In previous systematic reviews, individual recovery strategies were investigated to clarify their effectiveness for mixed groups of athletes. However, the current evidence is ambiguous, and a clear overview of (training) recovery for endurance athletes is still lacking.

METHODS

We conducted an umbrella review based on a literature search in PubMed, Cochrane Database of Systematic Reviews, and Web of Science. Reviews published in English and before December 2022 were included. Systematic reviews and meta-analyses were eligible if they investigated the effectiveness of one or more recovery strategies compared with a placebo or control group after a training session in endurance athletes.

RESULTS

Twenty-two reviews (nine systematic reviews, three meta-analyses, and ten systematic reviews with meta-analyses included) met the inclusion criteria. In total, sixty-three studies with 1100 endurance athletes were included in our umbrella review. Out of the sixty-three studies, eight provided information on training recovery time frame for data synthesis. Among them, cryotherapy and compression garments showed positive effects, while applying massage showed no effect. In general, none of the included recovery strategies showed consistent benefits for endurance athletes.

CONCLUSION

There is no particular recovery strategy that can be advised to enhance recovery between training sessions or competitions in endurance athletes. However, individual studies suggest that compression garments and cryotherapy are effective training recovery strategies. Further research should improve methodology and focus on the different time courses of the recovery process.

REGISTRATION

The review protocol was registered with the International Prospective Register of Systematic Reviews with the number CRD42021260509.

Real-World Fatigue Testing in Professional Rugby Union: A Systematic Review and Meta-analysis

BACKGROUND

Professional rugby union is a high-intensity contact sport with position-specific high training and match volumes across a season that may lead to periods of fatigue if above a typically experienced threshold. This study assesses the influence of match play and/or training on fatigue levels in rugby union players.

OBJECTIVE

We aimed to perform a systematic review and meta-analysis of measures used to assess fatigue status in male professional rugby union players.

METHODS

Using electronic databases (PubMed, SPORTDiscus, Web of Science, Cochrane Library, EMBASE, and MEDLINE), a systematic review of fatigue testing in rugby union was conducted on (1) neuromuscular, (2) subjective self-report, (3) biochemical, and (4) heart rate-derived measures.

RESULTS

Thirty-seven articles were included in this systematic review, of which 14 were further included in a meta-analysis. The results of the meta-analysis revealed small, yet not significant, decreases in countermovement jump height immediately after (effect size [ES] =  - 0.29; 95% confidence interval [CI] - 0.64 to 0.06), 24 h (ES =  - 0.43; 95% CI - 3.99 to 3.21), and 48 h (ES =  - 0.22; 95% CI - 0.47 to 0.02) after exposure to rugby union match play or training. Reported wellness (ES =  - 0.33; 95% CI - 1.70 to 1.04) and tiredness (ES =  - 0.14; 95% CI - 1.30 to 1.03) declined over a period of a few weeks (however, the results were not-statistically significant), meanwhile muscle soreness increased (ES = 0.91; 95% CI 0.06 to 1.75) within the 96 h after the exposure to rugby union match play or training. Finally, while cortisol levels (ES = 1.87; 95% CI - 1.54 to 5.29) increased, testosterone declined (ES =  - 1.54; 95% CI - 7.16 to 4.08) within the 24 h after the exposure. However, these results were not statistically significant.

CONCLUSIONS

Subjective measures of muscle soreness can be used to assess fatigue after match play and training in rugby union players. Within-study and between-study variability for countermovement jump height, biochemical markers, and heart rate-derived measures means the utility (practical application) of these measures to assess fatigue in professional rugby union players after matches and training is unclear.

CLINICAL TRIAL REGISTRATION

PROSPERO ID: CRD42020216706.

The effect of acute sleep extension vs active recovery on post exercise recovery kinetics in rugby union players

Background

Elite rugby players experience poor sleep quality and quantity. This lack of sleep could compromise post-exercise recovery. Therefore, it appears central to encourage sleep in order to improve recovery kinetics. However, the effectiveness of an acute ergogenic strategy such as sleep extension on recovery has yet to be investigated among athletes.

Aim

To compare the effects of a single night of sleep extension to an active recovery session (CON) on post-exercise recovery kinetics.

Methods

In a randomised cross-over design, 10 male rugby union players participated in two evening training sessions (19:30) involving collision activity, 7-days apart. After each session, participants either extended their sleep to 10 hours or attended an early morning recovery session (07:30). Prior to (PRE), immediately after (POST 0 hour [h]), 14h (POST 14) and 36h (POST 36) post training, neuromuscular, perceptual and cognitive measures of fatigue were assessed. Objective sleep parameters were monitored two days before the training session and over the two-day recovery period.

Results

The training session induced substantial decreases in countermovement jump mean power and wellness across all time points, while heart rate recovery decreased at POST 0 in both conditions. Sleep extension resulted in greater total sleep time (effect size [90% confidence interval]: 5.35 [4.56 to 6.14]) but greater sleep fragmentation than CON (2.85 [2.00 to 3.70]). Between group differences highlight a faster recovery of cognitive performance following sleep extension (-1.53 [-2.33 to -0.74]) at POST 14, while autonomic function (-1.00 [-1.85 to -0.16]) and upper-body neuromuscular function (-0.78 [-1.65 to 0.08]) were better in CON. However, no difference in recovery status between groups was observed at POST 36.

Conclusion

The main finding of this study suggests that sleep extension could affect cognitive function positively but did not improve neuromuscular function the day after a late exercise bout.

An Exploratory Comparison of Subjective Mental Fatigue Following a Task Designed to Replicate the Observation of Game Film

Laboratory-induced subjective mental fatigue (MF) has been shown to decrease sport-related performance (23, 38), yet there is a lack of research identifying tasks in real-world sport environments that induce MF (37). Since the identification of real-world tasks that induce MF may inform activities undertaken in the daily training and competition environments, the purpose of the current study was to compare changes in MF following a task designed to replicate the observation of game film to changes in MF following completion of a laboratory-based task (e.g., Stroop test). On separate counterbalanced visits, participants (N = 6) completed either (1) 35 min of replicated game film observation or (2) 35 min of the Stroop test. Visual analogue scales were used to measure MF, and a repeated measures analysis of variance [2 (time) x 2 (task)] was used to compare changes in MF following each task. No significant difference in changes in MF were found between conditions, F(1, 5) = 1.226, p = 0.319, and no main effect differences were found in MF pre-to-post for either task, F(1, 5) = 2.211, p = 0.197. Further efforts to identify real-world mentally fatiguing tasks are warranted.

Brain function during central fatigue induced by intermittent high-intensity cycling

BACKGROUND

The central governor model putatively explains the mechanism of endurance exercise-induced central fatigue, however high-intensity exercise-induced central fatigue strategies have not been investigated yet. This study aimed to examine how central fatigue affects neural response alterations, as measured by electroencephalographic (EEG) recordings, in intermittent high-intensity cycling.

METHODS

Neural responses were assessed by measuring the alteration of brainwaves based on spectral energy band estimates during an intermittent, high-intensity, 60-min exercise bout on a cycle ergometer. The cycle ergometer incline was changed every 10 min in an intermittent pattern (10-20-5-20-5-10°). EEG was used to analyze altering brain function. Heart rate (HR), blood lactate (BL), and rating of perceived exertion (RPE) were measured after the participants completed each change in incline.

RESULTS

The results showed that HR, BL, and RPE increased at an incline of 20° in comparison to a 5° incline. The spectral power of EEG was significantly increased (P ˂ 0.01) in the alpha and beta frequency ranges with a change in inclines between 5 and 20°. The spectral power of the EEG was significantly increased (P ˂ 0.01) over the whole frequency range from rest (theta + 251%, alpha + 165%, beta + 145%).

CONCLUSION

Higher, relative intensities (10 and 20°) increased brain function, regardless of fatigue occurrence. HIIT (high-intensity interval training) led to an alteration in the neural response. Further work investigating the usefulness of HIIT to improve brain function is warranted.

Effect of Transcranial Direct Current Stimulation on Professional Female Soccer Players' Recovery Following Official Matches

This study investigated the effect of transcranial direct current stimulation (tDCS) combined with a recovery training session on the well-being and self-perceived recovery of professional female soccer players after official matches. Data from 13 world-class players were analyzed after participating in four official soccer matches of the first division of the Brazilian Women's Soccer Championship (7-, 10-, and 13-day intervals). We applied anodal tDCS (a-tDCS) over the left dorsolateral prefrontal cortex with 2 mA for 20 minutes (+F3/-F4 montage) the day after each match. Participants underwent two randomly ordered sessions of a-tDCS or sham. Players completed the Well-Being Questionnaire (WBQ) and the Total Quality Recovery (TQR) scale before each experimental condition and again the following morning. A two-way repeated-measures ANOVA showed a significant time x condition interaction on the WBQ (F_(1,11)=5.21; p=0.043; η_p²=0.32), but not on the TQR (F_(1,12) = 0.552; p = 0.47; η_p² = 0.044). There was a large effect size (ES) for a-tDCS for the WBQ score (ES = 1.02; 95%CI = 0.17;1.88), and there was a moderate WBQ score increase (ES = 0.53; 95%CI = -0.29;1.34) for the sham condition. We found similar increases in the TQR score for a-tDCS (ES = 1.50; 95%CI = 0.63-2.37) and the sham condition (ES = 1.36; 95%CI = 0.51-2.22). These results suggest that a-tDCS (+F3/-F4 montage) combined with a recovery training session may slightly improve perceived well-being beyond the level of improvement after only the recovery training session among world-class female soccer players. Prior to widely adopting this recovery approach, further study is needed with larger and more diverse samples, including for female teams of different performance levels.

Can a tDCS treatment enhance subjective and objective sleep among student-athletes?

INTRODUCTION

Previous studies have shown that student-athletes suffer from sleep difficulties. This study explored the impact of tDCS on sleep parameters among student-athletes.

METHOD

Thirty student-athletes (15 females, 15 males, age 21.1 ± 2.1 years) were recruited. All participants underwent a series of questions to rule out depressive and anxiety disorders or any specific tDCS exclusion criteria. All participants were advised to maintain their usual sleep schedule.

RESULTS

Compared polysomnographic and Psychomotor Vigilance Task data analyses did not show any improvement after experimental tDCS. Regardless of groups, PVT mean reaction time was decreased. Regarding the questionnaires, data analyses showed improvement on the PSQI (p < .001), ISI (p < .001) and ASSQ (p < .007) scores after tDCS.

DISCUSSION

tDCS appears to increase total sleep time and should be further explored. Improvements in subjective sleep suggest that tDCS bears interesting possibilities into the enhancement of sleep among student-athletes.

Effect of tDCS on well-being and autonomic function in professional male players after official soccer matches

This study aimed to examine the effect of transcranial direct current stimulation (tDCS) used as a recovery strategy, on heart rate (HR) measures and perceived well-being in 12 male professional soccer players. tDCS was applied in the days after official matches targeting the left dorsolateral prefrontal cortex (DLPFC) with 2 mA for 20 min (F3-F4 montage). Participants were randomly assigned to anodal tDCS (a-tDCS) or sham tDCS sessions. Players completed the Well-Being Questionnaire (WBQ) and performed the Submaximal Running Test (SRT) before and after tDCS. HR during exercise (HRex) was determined during the last 30 s of SRT. HR recovery (HRR) was recorded at 60 s after SRT. The HRR index was calculated from the absolute difference between HRex and HRR. A significant increase was observed for WBQ (effect of time; p<0.001; η_p²=0.417) with no effect for condition or interaction. A decrease in HRR (p = 0.014; η_p²=0.241), and an increase in HRR index were observed (p = 0.045; η_p²=0.168), with no effect for condition or interaction. No change for HRex was evident (p>0.05). These results suggest that a-tDCS over the DLPFC may have a positive effect on enhancing well-being and parasympathetic autonomic markers, which opens up a possibility for testing tDCS as a promising recovery-enhancing strategy targeting the brain in soccer players. The findings suggest that brain areas related to emotional and autonomic control might be involved in these changes with a possible interaction effect of tDCS by placebo-related effects, but more research is needed to verify this effect.

Acute Effects of Mental Recovery Strategies After a Mentally Fatiguing Task

Both daily demands as well as training and competition characteristics in sports can result in a psychobiological state of mental fatigue leading to feelings of tiredness, lack of energy, an increased perception of effort, and performance decrements. Moreover, optimal performance will only be achievable if the balance between recovery and stress states is re-established. Consequently, recovery strategies are needed aiming at mental aspects of recovery. The aim of the study was to examine acute effects of potential mental recovery strategies (MR) on subjective-psychological and on cognitive performance outcomes after a mentally fatiguing task. A laboratory-based randomized cross-over study with twenty-four students (22.8 ± 3.6 years) was applied. Participants were run through a powernap intervention (PN), a systematic breathing intervention (SB), a systematic breathing plus mental imagery intervention (SB+), and a control condition (CC) with one trial a week over four consecutive weeks. Mental fatigue was induced by completion of the 60-min version of the AX-continuous performance test (AX-CPT). The Short Recovery and Stress Scale (SRSS) and Visual Analog Scales (VAS) were assessed to measure effects on perceptual outcomes. Cognitive performance was measured with a reaction time test of the Vienna Test System (VTS). During all three recovery interventions and CC portable polysomnography was applied. Results showed a significant increase from pre-AX-CPT to pre-MR on fatigue states and recovery-stress states indicating that the induction of mental fatigue was effective. Moreover, results underlined that analysis yielded no significant differences between recovery interventions and the control condition but they revealed significant time effects for VAS, SRSS items, and cognitive performance. However, it could be derived that the application of a rest break with 20 min of mental recovery strategies appears to enhance recovery on a mainly mental and emotional level and to reduce perceived mental fatigue.

Altered Neural Response Induced by Central-Fatigue in the Cortical Area During High-Intensity Interval Pedaling

Introduction

The central-governor model explains the mechanism of endurance exercise-induced central fatigue, but high-intensity exercise-induced central fatigue has not been investigated yet. This study aimed to research how central fatigue during high-intensity intermittent pedaling alters the neural response, which results in Electroencephalography (EEG) recordings.

Methods

We assessed neural response by measuring the alternation of brainwave spectral power during an intermittent high-intensity 60-minute exercise on an ergometer cycle. The cadences were changed every 10 minutes according to intermittent pattern altering (90-120-60-120-60-90 rpm). EEG was used to analyze altering brain function. Heart Rate (HR), Blood Lactate (BL), and Rating of Perceived Exertion (RPE) were measured after the change in cadences.

Results

HR, BL, and RPE increased at a cadence of 120 rpm compared with 60 rpm on the ergometer cycle. The spectral power of EEG, according to cadence × brainwaves, significantly increased (P<0.01) in the alpha and beta frequency ranges with a change in cadences between 60 rpm and 120 rpm. The spectral power of the EEG significantly increased (P<0.01) over the whole frequency range from rest to warming (theta: 251%, alpha: 165%, beta: 145%) and significantly reduced in theta, alpha, and beta (theta: 176%, alpha: 142%, beta: 77%) (P≤0.01).

Conclusion

High-intensity exercises (90 and 120 cadences) increased brain function, regardless of fatigue occurrence. High-intensity interval training (HIIT) led to altering the neural response. It would be required to investigate the usefulness of HIIT to treat some of the psychotic disorders.

Increased interhemispheric synchrony underlying the improved athletic performance of rowing athletes by transcranial direct current stimulation

To explore the mechanism of transcranial direct current stimulation (tDCS) on the improved performance of professional rowing athletes. Twelve male professional rowing athletes were randomly divided into two groups (low-stimulation group, 1 mA, n = 6; high-stimulation group, 2 mA, n = 6), and they accepted tDCS for two consecutive weeks while undergoing regular training (20 min each time, five times a week, totally ten times). The assessments of depression, anxiety, executive function, fatigue perception, lactate threshold power (LTP) and isokinetic muscle strength as well as the collection of functional magnetic resonance imaging (fMRI) data were performed at baseline and at follow-up (the end of the fourth week). The voxel-mirrored homotopic connectivity (VMHC) value was calculated in the whole brain. After stimulation, there were significant increases in executive function and athletic performance. Analysis of variance (ANOVA) analysis indicated time factor, stimulation intensity factor had a main effect on LTP and 60RK, respectively. There was no significant difference of VMHC value between the high- and low-stimulation groups at baseline. Comparing with low-stimulation group, significant increased VMHC values of the bilateral middle temporal gyrus (MTG), precentral gyrus and superior frontal gyrus (SFG) were found in high-stimulation group at follow-up. Correlation analyses showed that in high-stimulation group, the VMHC values of bilateral MTG and SFG were both positively correlated with the measures of athletic performance. tDCS may contribute to the improvement of athletic performance in professional rowing athletes, and the increased interhemispheric coordination may be involved in the mechanism of the improved athletic performance.

Aerobic Training and Mobilization Early Post-stroke: Cautions and Considerations

Knowledge gaps exist in how we implement aerobic exercise programs during the early phases post-stroke. Therefore, the objective of this review was to provide evidence-based guidelines for pre-participation screening, mobilization, and aerobic exercise training in the hyper-acute and acute phases post-stroke. In reviewing the literature to determine safe timelines of when to initiate exercise and mobilization we considered the following factors: arterial blood pressure dysregulation, cardiac complications, blood-brain barrier disruption, hemorrhagic stroke transformation, and ischemic penumbra viability. These stroke-related impairments could intensify with inappropriate mobilization/aerobic exercise, hence we deemed the integrity of cerebral autoregulation to be an essential physiological consideration to protect the brain when progressing exercise intensity. Pre-participation screening criteria are proposed and countermeasures to protect the brain from potentially adverse circulatory effects before, during, and following mobilization/exercise sessions are introduced. For example, prolonged periods of standing and static postures before and after mobilization/aerobic exercise may elicit blood pooling and/or trigger coagulation cascades and/or cerebral hypoperfusion. Countermeasures such as avoiding prolonged standing or incorporating periodic lower limb movement to activate the venous muscle pump could counteract blood pooling after an exercise session, minimize activation of the coagulation cascade, and mitigate potential cerebral hypoperfusion. We discuss patient safety in light of the complex nature of stroke presentations (i.e., type, severity, and etiology), medical history, comorbidities such as diabetes, cardiac manifestations, medications, and complications such as anemia and dehydration. The guidelines are easily incorporated into the care model, are low-risk, and use minimal resources. These and other strategies represent opportunities for improving the safety of the activity regimen offered to those in the early phases post-stroke. The timeline for initiating and progressing exercise/mobilization parameters are contingent on recovery stages both from neurobiological and cardiovascular perspectives, which to this point have not been specifically considered in practice. This review includes tailored exercise and mobilization prescription strategies and precautions that are not resource intensive and prioritize safety in stroke recovery.

Effect of caffeine on neuromuscular function following eccentric-based exercise

This study investigated the effect of caffeine on neuromuscular function, power and sprint performance during the days following an eccentric-based exercise. Using a randomly counterbalanced, crossover and double-blinded design, eleven male jumpers and sprinters (age: 18.7 ± 2.7 years) performed a half-squat exercise (4 x 12 repetitions at 70% of 1 RM), with eccentric action emphasized by using a flexible strip attached to their knees (Tirante Musculador^®). They ingested either a capsule of placebo or caffeine (5 mg.kg^-1 body mass) 24, 48 and 72 h after. Neuromuscular function and muscle power (vertical countermovement-jump test) were assessed before and after the half-squat exercise and 50 min after the placebo or caffeine ingestion at each time-point post-exercise. Sprint performance was measured at pre-test and 75 min after the placebo or caffeine ingestion at each time-point post-exercise. Maximal voluntary contraction (overall fatigue) and twitch torque (peripheral fatigue) reduced after the half-squat exercise (-11 and -28%, respectively, P < 0.05) but returned to baseline 24 h post-exercise (P > 0.05) and were not affected by caffeine ingestion (P > 0.05). The voluntary activation (central fatigue) and sprint performance were not altered throughout the experiment and were not different between caffeine and placebo. However, caffeine increased height and power during the vertical countermovement-jump test at 48 and 72 h post half-squat exercise, when compared to the placebo (P < 0.05). In conclusion, caffeine improves muscle power 48 and 72 h after an eccentric-based exercise, but it has no effect on neuromuscular function and sprint performance.

Decrease in Attentional Performance After Repeated Bouts of High Intensity Exercise in Association-Football Referees and Assistant Referees

Referees and assistant referees are submitted to high physical stress during matches. Pressure to make decisions in front of large crowds is another potential stressor. These two stressors can impair attention executive control, depending on physical fitness and individual vulnerability or resilience to situational pressure. Error percentage for referees and assistants may reach around 14% during a soccer match. Although previous studies have suggested that soccer referees and assistants should take cognitive assessments, they are only required by Fédération Internationale de Football Association (FIFA) to demonstrate knowledge of the rules and pass annually in a fitness test (FIFA-Test). This study aimed to assess attention performance in referees and assistants before and after the mandatory FIFA-Test. It is hypothesized that the high physical demands associated with the pressure to pass the FIFA-Test would interfere with attention performance. The sample included 33 referees and 20 assistants. The Continuous Visual Attention Test (CVAT) consisted of a 15-min Go/No-go task. Performance in the CVAT is based on four variables: omission and commission errors, reaction time, and variability of reaction time (VRT). Failure in the CVAT was defined by a performance below the 5th percentile of the age- and sex-matched normative data in at least one variable of the CVAT. Before the FIFA-Test all participants performed the CVAT. The second CVAT began 3-7 min directly following completion of the FIFA-test. Considering only the officials who passed both the FIFA-Test and the first CVAT (19 referees and 15 assistants), 44% (9 referees and 6 assistants) exhibited a performance decline in the second CVAT. A significant increase in VRT was found after the high intensity exercise. As increase in VRT is thought to reflect executive dysfunctions and lapses of attention, we concluded that physical fitness alone may not be enough to help officials cope with the physical and contextual stresses associated with the FIFA-Test. These data suggest that over 35% of soccer referees and their assistants who were considered physically able to referee matches may not be mentally prepared for the attentional demands of refereeing soccer matches.

The Temporal Relationship Between Exercise, Recovery Processes, and Changes in Performance

Physiological and psychological demands during training and competition generate fatigue and reduce an athlete’s sport-specific performance capacity. The magnitude of this decrement depends on several characteristics of the exercise stimulus (eg, type, duration, and intensity), as well as on individual characteristics (eg, fitness, profile, and fatigue resistance). As such, the time required to fully recover is proportional to the level of fatigue, and the consequences of exercise-induced fatigue are manifold. Whatever the purpose of the ensuing exercise session (ie, training or competition), it is crucial to understand the importance of optimizing the period between exercise bouts in order to speed up the regenerative processes and facilitate recovery or set the next stimulus at the optimal time point. This implies having a fairly precise understanding of the fatigue mechanisms that contribute to the performance decrement. Failing to respect an athlete’s recovery needs may lead to an excessive accumulation of fatigue and potentially “nonfunctional overreaching” or to maladaptive training. Although research in this area recently increased, considerations regarding the specific time frames for different physiological mechanisms in relation to exercise-induced fatigue are still missing. Furthermore, recommendations on the timing and dosing of recovery based on these time frames are limited. Therefore, the aim of this article is to describe time courses of recovery in relation to the exercise type and on different physiological levels. This summary supports coaches, athletes, and scientists in their decision-making process by considering the relationship of exercise type, physiology, and recovery.

The application of mental fatigue research to elite team sport performance: New perspectives

OBJECTIVES

Mental fatigue resulting from prolonged periods of demanding cognitive activity, has been found to impair endurance exercise performance and performance in some sport-specific tasks. The application of such research to the elite sporting environment however is limited.

DESIGN & METHODS

This article reviews the literature relevant to mental fatigue and team sporting performance with aim to provide perspectives on the transferability and significance of currently available evidence to the applied elite sporting context.

RESULTS

Inconsistent findings in the limited available literature can be attributed to large variations in the participants involved, the nature of the cognitively demanding tasks used to induce mental fatigue and the tests used to assess performance outcomes. Few studies have used trained athletes in combination with performance tests that accurately represent the physiological and technical demands experienced by athletes in competition. While there is growing interest in the acute influence of mental fatigue on exercise performance, a potential cumulative effect of mental fatigue on performance over, for example, a competitive season is an area yet to be investigated.

CONCLUSIONS

If it is accepted that mental fatigue impairs the performance of some athletes, then improving the ecological validity of research in the area of mental fatigue and sport will significantly advance our understanding of how to better monitor and manage mental fatigue. At the elite level of competition, where outcomes are determined by very small margins of difference, reducing the impact of mental fatigue on performance has potential to be significant.

'Take a Mental Break!' study: Role of mental aspects in running-related injuries using a randomised controlled trial

BACKGROUND

Running-related injuries (RRIs) can be considered the primary enemy of runners. Most literature on injury prediction and prevention overlooks the mental aspects of overtraining and under-recovery, despite their potential role in injury prediction and prevention. Consequently, knowledge on the role of mental aspects in RRIs is lacking.

OBJECTIVE

To investigate mental aspects of overtraining and under-recovery by means of an online injury prevention programme.

METHODS AND ANALYSIS

The 'Take a Mental Break!' study is a randomised controlled trial with a 12 month follow-up. After completing a web-based baseline survey, half and full marathon runners were randomly assigned to the intervention group or the control group. Participants of the intervention group obtained access to an online injury prevention programme, consisting of a running-related smartphone application. This app provided the participants of the intervention group with information on how to prevent overtraining and RRIs with special attention to mental aspects. The primary outcome measure is any self-reported RRI over the past 12 months. Secondary outcome measures include vigour, fatigue, sleep and perceived running performance. Regression analysis will be conducted to investigate whether the injury prevention programme has led to a lower prevalence of RRIs, better health and improved perceived running performance.

ETHICS AND DISSEMINATION

The Medical Ethics Committee of the University Medical Center Utrecht, the Netherlands, has exempted the current study from ethical approval (reference number: NL64342.041.17). Results of the study will be communicated through scientific articles in peer-reviewed journals, scientific reports and presentations on scientific conferences.

Multiple Cold-Water Immersions Attenuate Muscle Damage but not Alter Systemic Inflammation and Muscle Function Recovery: A Parallel Randomized Controlled Trial

The aim of this study was to investigate the effects of multiple cold-water immersions (CWIs) on muscle function, markers of muscle damage, systemic inflammation and ECM degradation following exercise-induced muscle damage (EIMD). Thirty physically active males were randomly assigned to either a control (n = 15) or cold-water immersion (CWI) group (n = 15). The CWI group performed one immersion (10 °C for 20 min) at post-exercise and every 24 h for the following 72 h, while the control group remained in a seated position during these corresponding periods. Muscle strength, vertical jump height, muscle thickness, delayed-onset muscle soreness (DOMS), systemic creatine kinase (CK), C-reactive protein (CRP), inflammatory cytokines and matrix metalloproteinase-2 (MMP-2) activity were assessed at Pre, Post, 24, 48, 72, 96 and 168 h following EIMD. No significant time × group interaction was obtained for muscle strength, vertical jump height recovery and MMP-2 activity (p > 0.05). At 24 h, muscle thickness from the CWI group returned to baseline and was lower than the control (p = 0.04). DOMS returned to baseline at 168 h for the CWI group (p = 0.109) but not for the control (p = 0.008). At 168 h, CK showed a time-group difference with a greater peak for the control group (p = 0.016). In conclusion, multiple CWIs attenuated muscle damage, but not altered systemic inflammation and muscle function recovery.

Effectiveness of Two Cold Water Immersion Protocols on Neuromuscular Function Recovery: A Tensiomyography Study

Cold water immersion (CWI) has become a highly used recovery method in sports sciences, which seeks to minimize fatigue and accelerate recovery processes; however, tensiomyography (TMG) is a new method to analyze the muscle mechanical response as a recovery indicator after CWI protocols, this relative new tool of muscle function assessment, can lead to new information of understand fatigue recovery trough CWI. The objective of the study was to compare the effect of two CWI protocols, on neuromuscular function recovery. Thirty-nine healthy males (21.8 ± 2.8 years, 73.2 ± 8.2 kg, 176.6 ± 5.3 cm and body fat 13.5 ± 3.4%) were included in the study. Participants were grouped into a continuous immersion (12 min at 12 ± 0.4°C) group, intermittent immersion (2 min immersion at 12 ± 0.4°C + 1 min out of water 23 ± 0.5°C) group, and a control group (CG) (12 min sitting in a room at 23 ± 0.5°C). Afterward, the participants performed eight sets of 30 s counter movement jumps (CMJs) repetitions, with a 90 s standing recovery between sets. Muscle contraction time (Tc), delay time (Td), muscle radial displacement (Dm), muscle contraction velocity at 10% of DM (V10), and muscle contraction velocity at 90% of DM (V90) in rectus, biceps femoris, and CMJ were measured. Neither CWI protocol was effective in showing improved recovery at 24 and 48 h after training compared with the CG (p > 0.05), in any TMG indicator of recovery in either muscle biceps or rectus femoris, nor was the CMJ performance (F_(6,111) = 0.43, p = 0.85, ωp2 = 0). Neither CWI protocol contributed to recovery of the neuromuscular function indicator.

Active recovery affects the recovery of the corticospinal system but not of muscle contractile properties

PURPOSE

Active recovery is often used by athletes after strenuous exercise or competition but its underlying mechanisms are not well understood. We hypothesized that active recovery speeds-up recovery processes within the muscle and the central nervous system (CNS).

METHODS

We assessed muscular and CNS recovery by measuring the voluntary activation (VA) in the vastus lateralis muscle with transcranial magnetic stimulation (VATMS) and peripheral nerve stimulation (VAPNS) during maximal voluntary contractions (MVC) of the knee extensors in 11 subjects. Measurements were performed before and after a fatiguing cycling time-trial, after an active and a passive recovery treatment and after another fatiguing task (1 min MVC). The measurements were performed a second time 24 h after the time-trial.

RESULTS

We observed a time × group interaction effect for VATMS (p = 0.013). Post-hoc corrected T-tests demonstrated an increased VATMS after active recovery when measured after the 1 min MVC performed 24 h after the time-trial (mean ± SD; 95.2 ± 4.1% vs. 89.2 ± 6.6%, p = 0.026). No significant effects were observed for all other variables.

CONCLUSIONS

Active recovery increased aspects of central, rather than muscle recovery. However, no effect on MVC was seen, implying that even if active recovery speeds up CNS recovery, without affecting the recovery of muscle contractile properties, this doesn´t translate into increases in overall performance.

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p <0.001) and rate of torque development (495.7 ± 136.9 Nm.s-1 vs. 163.4 ± 163.7 Nm.s-1; p <0.001) 48h post-exercise. Mean motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p <0.01) in high-threshold motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; p< 0.001) 48h post-exercise. The firing rate of high-threshold motor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures.

Development of the athlete sleep behavior questionnaire: A tool for identifying maladaptive sleep practices in elite athletes

Introduction

Existing sleep questionnaires to assess sleep behaviors may not be sensitive in determining the unique sleep challenges faced by elite athletes. The purpose of the current study was to develop and validate the Athlete Sleep Behavior Questionnaire (ASBQ) to be used as a practical tool for support staff working with elite athletes.

Methods

564 participants (242 athletes, 322 non-athletes) completed the 18-item ASBQ and three previously validated questionnaires; the Sleep Hygiene Index (SHI), the Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI). A cohort of the studied population performed the ASBQ twice in one week to assess test-retest reliability, and also performed sleep monitoring via wrist-actigraphy.

Results

Comparison of the ASBQ with existing sleep questionnaires resulted in moderate to large correlations (r=0.32 - 0.69). There was a significant difference between athletes and non-athletes for the ASBQ global score (44±6 vs. 41±6, respectively, p<0.01) and for the PSQI, but not for the SHI or the ESS. The reliability of the ASBQ was acceptable (ICC=0.87) when re-tested within 7 days. There was a moderate relationship between ASBQ and total sleep time (r=-0.42).

Conclusion

The ASBQ is a valid and reliable tool that can differentiate the sleep practices between athletes and non-athletes, and offers a practical instrument for practitioners and/or researchers wanting to evaluate the sleep behaviors of elite athletes. The ASBQ may provide information on areas where improvements to individual athletes’ sleep habits could be made.

Etiology and Recovery of Neuromuscular Fatigue following Competitive Soccer Match-Play

Aim: Previous research into the etiology of neuromuscular fatigue following competitive soccer match-play has primarily focused on peripheral perturbations, with limited research assessing central nervous system function in the days post-match. The aim of the present study was to examine the contribution and time-course of recovery of central and peripheral factors toward neuromuscular fatigue following competitive soccer match-play.

Methods: Sixteen male semi-professional soccer players completed a 90-min soccer match. Pre-, post- and at 24, 48, and 72 h participants completed a battery of neuromuscular, physical, and perceptual tests. Maximal voluntary contraction force (MVC) and twitch responses to electrical (femoral nerve) and transcranial magnetic stimulation (TMS) of the motor cortex during isometric knee-extension and at rest were measured to assess central nervous system (voluntary activation, VA) and muscle contractile (potentiated twitch force, Q_{tw, pot}) function. Electromyography responses of the rectus femoris to single- and paired-pulse TMS were used to assess corticospinal excitability and short-interval intracortical inhibition (SICI), respectively. Fatigue and perceptions of muscle soreness were assessed via visual analog scales, and physical function was assessed through measures of jump (countermovement jump height and reactive strength index) and sprint performance.

Results: Competitive match-play elicited significant post-match declines in MVC force (−14%, P < 0.001) that persisted for 48 h (−4%, P = 0.01), before recovering by 72 h post-exercise. VA (motor point stimulation) was reduced immediately post-match (−8%, P < 0.001), and remained depressed at 24 h (−5%, P = 0.01) before recovering by 48 h post-exercise. Q_tw,pot was reduced post-match (−14%, P < 0.001), remained depressed at 24 h (−6%, P = 0.01), before recovering by 48 h post-exercise. No changes were evident in corticospinal excitability or SICI. Jump performance took 48 h to recover, while perceptions of fatigue persisted at 72 h.

Conclusion: Competitive soccer match-play elicits substantial impairments in central nervous system and muscle function, requiring up to 48 h to resolve. The results of the study could have important implications for fixture scheduling, the optimal management of the training process, squad rotation during congested competitive schedules, and the implementation of appropriate recovery interventions.

Antifatigue Functions and Mechanisms of Edible and Medicinal Mushrooms

Fatigue is the symptom of tiredness caused by physical and/or psychological stresses. As fatigue is becoming a serious problem in the modern society affecting human health, work efficiency, and quality of life, effective antifatigue remedies other than pharmacological drugs or therapies are highly needed. Mushrooms have been widely used as health foods, because of their various bioactive constituents such as polysaccharides, proteins, vitamins, minerals, and dietary fiber. This paper reviews the major findings from previous studies on the antifatigue effects, the active components of mushrooms, and the possible mechanisms. Many studies have demonstrated the antifatigue effects of edible and medicinal mushrooms. These mushrooms probably mitigate human fatigue through effects on the functional systems, including the muscular, cardiovascular, hormone, and immune system. The bioactive constituents that contribute to the antifatigue effects of mushrooms may include polysaccharides, peptides, nucleosides, phenolic compounds, and triterpenoids. Further research is still needed to identify the active ingredients and to investigate their mechanism of action on the antifatigue effects. Since most previous studies have been carried out in animal models, more human trials should be performed to verify the antifatigue function of edible and medicinal mushrooms.

Preconditioning with peristaltic external pneumatic compression does not acutely improve repeated Wingate performance nor does it alter blood lactate concentrations during passive recovery compared with sham

Application of dynamic external pneumatic compression (EPC) during recovery from athletic activities has demonstrated favorable effects on flexibility, soreness, swelling, and blood lactate (BLa) concentrations. However, the effects of "preconditioning" with a peristaltic pulse EPC device on subsequent performance and BLa concentrations have not been characterized. Herein, we demonstrate that pretreatment for 30 min with EPC has no effect on subsequent supramaximal exercise performance or BLa concentrations during passive recovery.