790 Freizeitgestaltung, darstellende Künste, Sport
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Highlights
• Investigation of how the peripheral muscle system responds to imagination in interaction with proprioceptive information.
• Motor imagery altered time to contraction but not velocity and maximal displacement of the muscle belly.
• Findings indicate that MI might impact on the initiation of contraction.
Abstract
Many studies have investigated the activation of cortical areas and corticospinal excitability during motor imagery (MI) in relation to motor execution. Similar activation of cortical areas during imagined and executed bodily movements and increased corticospinal excitability while imagining movements has been demonstrated. Despite these similarities on the central nervous system level, there is no overt movement during MI. This suggests that centrally generated signals must be inhibited at some level. Second, even in the absence of movement, some studies find behavioral effects of MI interventions. Most of the studies have investigated the role of MI on the cortical or spinal level, but less is known about the peripheral level, such as the muscle system. Testing muscular excitability during MI will give further hints whether and how low-threshold motor commands during MI reach the muscular system. Furthermore, the extent of the shown effects during imagery depends considerably on type of imagery, available proprioceptive information, and imagery ability. Therefore, this study investigates muscular excitability of the biceps brachii muscle manipulating imagery mode (MI vs. visual imagery) and proprioceptive information (with or without muscle effort). 40 participants were included in the analysis. The mechanical response of the muscle after a single electrical stimulus was assessed via tensiomyography. The corresponding variables maximal displacement, delay time, and contraction velocity were used to calculate 2 × 2 ANOVAs with repeated measurements. The absence of interaction effects shows that possible imagery effects on the muscle system are not increased by effort. MI altered time to contraction with lower delay time compared to control condition. Velocity and maximal displacement of the muscle belly during contraction did not differ between imagery conditions. This indicates that MI might impact on the initiation of muscle contraction but does not change the contraction itself. Thus, neuronal factors are moving further into focus in the context of MI research.
Das Konflikterleben von Schiedsrichtern im Amateurfußball : eine empirisch-qualitative Arbeit
(2020)
Bei der Austragung von Amateurfußballspielen nehmen Schiedsrichter die Rolle von Beobachtern ein, die bei Konflikten selbst zu Betroffenen werden können. Dabei treten auch extreme Formen wie Beleidigungen und Diskriminierungen sowie physische und psychische Gewalt auf. Anliegen der Masterthesis „Das Konflikterleben von Schiedsrichtern im Amateurfußball“ ist es, die Wahrnehmung von Schiedsrichtern in Bezug auf Konflikte im Amateurfußball empirisch-qualitativ zu erfassen und bisherige Forschungsansätze zu erweitern. Grundlage der Arbeit bilden vom Autor geführte problemzentrierte Interviews mit hessischen Unparteiischen, deren Auswertung neue Perspektiven im Gewaltdiskurs des Amateurfußballs anbietet.
Die Fußball-Weltmeisterschaft ist ein internationales Sportereignis, an dem dank der Massenmedien die ganze Welt teilhaben kann. Ungeachtet dieser globalen Dimension steht zumindest in den Ländern, die an der WM teilnehmen, die eigene Nation im Mittelpunkt des Interesses. Aus sport- und mediensoziologischer Sicht stellt sich daher die Frage, auf welche Weise in der medialen Berichterstattung die eigene – und kontrastierend dazu auch die gegnerische – Nation thematisiert wird. Dieser Frage sind Studierende des Masterstudiengangs Sozialwissenschaften des Sports an der Goethe-Universität in einem Seminar zur Soziologie des Mediensports nachgegangen. Sie haben dazu das erste WM-Spiel der deutschen Mannschaft gegen Mexiko analysiert.
During dynamic ultrasound assessments, unintended transducer movement over the skin needs to be prevented as it may bias the results. The present study investigated the validity of two methods quantifying transducer motion. An ultrasound transducer was moved on a pre-specified 3 cm distance over the semitendinosus muscle of eleven adults (35.8 ± 9.8 years), stopping briefly at intervals of 0.5 cm. Transducer motion was quantified (1) measuring the 2-D displacement of the shadow produced by reflective tape (RT) attached to the skin and (2) using a marker-based, three-dimensional movement analysis system (MAS). Differences between methods were detected with Wilcoxon tests; associations were checked by means of intraclass correlation coefficients (ICC 3.1) and Bland–Altman plots. Values for RT (r = 0.57, p < 0.001) and MAS (r = 0.19, p = 0.002) were significantly higher than true distances (TD). Strong correlations were found between RT and TD (ICC: 0.98, p < 0.001), MAS and TD (ICC: 0.95, p < 0.001), and MAS and RT (ICC: 0.97, p < 0.001). Bland–Altman plots showed narrow limits of agreement for both RT (−0.49 to 0.13 cm) and MAS (−0.49 to 0.34 cm) versus TD. RT and MAS are valid methods to quantify US transducer movement. In view of its low costs and complexity, RT can particularly be recommended for application in research and clinical practice. View Full-Text
Keywords: ultrasound; reflective tape; transducer movement
The float serve is an effective weapon to impede the attack of the opposing team. Because of its great importance in indoor and beach volleyball, we measured and quantified the float effect. We recorded 24 float serves of 12 top athletes in beach volleyball and indoor volleyball, respectively, and analyzed them using video analysis. We determined the 3D trajectories of the ball flight and developed two measures to describe the size of the float effect, the mean residuals and the anticipation error. Both were derived from regression models. These measures suggest that the float effect is greater in the vertical plane than in the horizontal plane, both for indoor and beach volleyball. Analyses of ball release velocities suggest that a certain ball release velocity is a necessary, but not sufficient, condition for ball floating. A validation of the float measurements with subjective expert ratings showed a correlation with the horizontal deviations. This study provides a new approach to analyze floating in on-court volleyball serves and broadens the knowledge for float effects in sports.
Purpose: Medically recommended training often faces the dilemma that necessary mechanical intensities for muscle adaptations exceed patients' physical capacity. In this regard, blood flow restriction (BFR) training is becoming increasingly popular because it enables gains in muscle mass and strength despite using low-mechanical loads combined with external venous occlusion. Since the underlying mechanisms are still unknown, we applied invasive measurements during exercise with and without BFR to promote physiological understanding and safety of this popular training technique. Methods: In a randomized cross-over design, ten healthy men (28.1 ± 6.5 years) underwent two trials of unilateral biceps curls either with (BFR) and without BFR (CON). For analysis of changes in intravascular pressures, blood gases, oximetry and electrolytes, an arterial and a venous catheter were placed at the exercising arm before exercise. Arterial and venous blood gases and intravascular pressures were analyzed before, during and 5 min after exercise. Results: Intravascular pressures in the arterial and venous system were more increased during exercise with BFR compared to CON (p < 0.001). Furthermore, arterial and venous blood gas analyses revealed a BFR-induced metabolic acidosis (p < 0.05) with increased lactate production (p < 0.05) and associated elevations in [K+], [Ca2+] and [Na+] (p < 0.001). Conclusion: The present study describes for the first time the local physiological changes during BFR training. While BFR causes greater hypertension in the arterial and venous system of the exercising extremity, observed electrolyte shifts corroborate a local metabolic acidosis with concurrent rises in [K+] and [Na+]. Although BFR could be a promising new training concept for medical application, its execution is associated with comprehensive physiological challenges.
Functional circuit training (FCT) has been demonstrated to acutely enhance cognitive performance (CP). However, the moderators of this observation are unknown. This study aimed to elucidate the role of exercise intensity. According to an a priori sample size calculation, n = 24 healthy participants (26 ± 3 years, 13 females), in randomized order, performed a single 15-min bout of FCT with low (20–39% of the heart rate reserve/HRR), moderate (40–59% HRR) or high intensity (maximal effort). Immediately pre- and post-workout, CP was measured by use of the Digit Span test, Stroop test and Trail Making test. Non-parametric data analyses did not reveal significant differences between conditions (p > 0.05) although parameter-free 95% confidence intervals showed pre-post improvements in some outcomes at moderate and high intensity only. The effort level does not seem to be a major effect modifier regarding short-term increases in CP following HCT in young active adults.
Perceptual-cognitive function and unplanned athletic movement task performance: a systematic review
(2020)
The performance of choice-reaction tasks during athletic movement has been demonstrated to evoke unfavorable biomechanics in the lower limb. However, the mechanism of this observation is unknown. We conducted a systematic review examining the association between (1) the biomechanical and functional safety of unplanned sports-related movements (e.g., jumps/runs with a spontaneously indicated landing leg/cutting direction) and (2) markers of perceptual–cognitive function (PCF). A literature search in three databases (PubMed, ScienceDirect and Google Scholar) identified five relevant articles. The study quality, rated by means of a modified Downs and Black checklist, was moderate to high (average: 13/16 points). Four of five papers, in at least one parameter, found either an association of PCF with task safety or significantly reduced task safety in low vs. high PCF performers. However, as (a) the outcomes, populations and statistical methods of the included trials were highly heterogeneous and (b) only two out of five studies had an adequate control condition (pre-planned movement task), the evidence was classified as conflicting. In summary, PCF may represent a factor affecting injury risk and performance during unplanned sports-related movements, but future research strengthening the evidence for this association is warranted.
Resistance exercise has been demonstrated to improve brain function. However, the optimal workout characteristics are a matter of debate. This randomized, controlled trial aimed to elucidate differences between free-weight (REfree) and machine-based (REmach) training with regard to their ability to acutely enhance cognitive performance (CP). A total of n = 46 healthy individuals (27 ± 4 years, 26 men) performed a 45-min bout of REfree (military press, barbell squat, bench press) or REmach (shoulder press, leg press, chest press). Pre- and post-intervention, CP was examined using the Stroop test, Trail Making Test and Digit Span test. Mann–Whitney U tests did not reveal between-group differences for performance in the Digit Span test, Trail Making test and the color and word conditions of the Stroop test (p > 0.05). However, REfree was superior to REmach in the Stroop color-word condition (+6.3%, p = 0.02, R = 0.35). Additionally, REfree elicited pre-post changes in all parameters except for the Digit Span test and the word condition of the Stroop test while REmach only improved cognitive performance in part A of the Trail Making test. Using free weights seems to be the more effective RE method to acutely improve cognitive function (i.e., inhibitory control). The mechanisms of this finding merit further investigation.
Triathlon is a popular sport for both recreational and competitive athletes. This study investigated the rates and patterns of stress fractures in the German national triathlon squad. We developed a web-based retrospective questionnaire containing questions about the frequency of stress fractures, anatomic localisation and associated risk factors. The survey was conducted as an explorative cross-sectional study. Eighty-six athletes completed the questionnaire. Twenty athletes (23%) sustained at least one stress fracture. All documented stress fractures were located in the lower extremities. Factors associated with a higher risk for stress fractures were female gender, competitive sport prior to triathlon career, Vitamin D or iron deficiency, menstrual disturbances and a high number of annual training hours. Disseminating knowledge among athletes and their professional community in order to raise awareness about early symptoms and relevant risk factors could help to improve prevention and reduce the incidence of stress fractures.
The purpose of this study was to investigate whether a six-week, twice weekly resistance training (4 sets at 30% 1-RM until failure) with practical blood flow restriction (BFR) using 7cm wide cuffs with a twist lock placed below the patella is superior to training without BFR (NoBFR) concerning muscle mass and strength gains in calf muscles.
A two-group (BFR n = 12, mean age 27.33 (7.0) years, training experience 7.3 (7.0) years; NoBFR n = 9, mean age 28.9 (7.4) years, training experience 7.1 (6.6) years) randomized matched pair design based on initial 1-RM was used to assess the effects on structural and functional adaptations in healthy males (Perometer calf volume [CV], gastrocnemius muscle thickness using ultrasound [MT], 7-maximal hopping test for leg stiffness [LS], 1-RM smith machine calf raise [1-RM], and visual analogue scale as a measure of pain intensity [VAS]).
The mean number of repetitions completed per training session across the intervention period was higher in the NoBFR group compared to the BFR group (70 (16) vs. 52 (9), p = 0.002). VAS measured during the first session increased similarly in both groups from first to fourth set (p<0.001). No group effects or time×group interactions were found for CV, MT, LS, and 1-RM. However, there were significant time effects for MT (BFR +0.07 cm; NoBFR +0.04; p = 0.008), and 1-RM (BFR +40 kg; NoBFR +34 kg; p<0.001).
LS and CV remained unchanged through training. VAS in both groups were similar, and BFR and NoBFR were equally effective for increasing 1-RM and MT in trained males. However, BFR was more time efficient, due to lesser repetition per training session.
Introduction: The worldwide spread of the novel coronavirus (SARS-CoV2) has prompted numerous countries to restrict public life. Related measures, such as limits on social gatherings, business closures, or lockdowns, are expected to considerably reduce the individual opportunities to move outside the home. As physical activity (PA) and sport participation significantly contribute to health, this study has two objectives. The objectives of this study are to assess changes in PA and well-being since the coronavirus outbreak in affected countries. Additionally, we will evaluate the impact of digital home-based exercise programs on PA as well as physical and mental health outcomes.
Method: A multinational network trial will be conducted with three planned phases (A, B, and C). Part A consists of administering a structured survey. It investigates changes in PA levels and health during the coronavirus outbreak and measures the preferences of the participants regarding online training programs. Part B is a two-armed randomized-controlled trial. Participants assigned to the intervention group (IG) will complete a digital 4-week home exercise training (live streaming via internet) guided by the survey results on content and time of program. The control group (CG) will not receive the program. Part C is 4-week access of both CG and IG to a digital archive of pre-recorded workouts from Part B. Similar to Part A, questionnaires will be used in both Part B and C to estimate the effects of exercise on measures of mental and physical health.
Results and Discussion: The ASAP project will provide valuable insights into the importance of PA during a global pandemic. Our initial survey is the first to determine how governmental confinement measures impact bodily and mental well-being. Based on the results, the intervention studies will be unique to address health problems potentially arising from losses in PA. If proven effective, the newly developed telehealth programs could become a significant and easy-to-distribute factor in combating PA decreases. Results of the study may hence guide policy makers on methods to maintain PA and health when being forced to restrict public life.
Study Register: DRKS00021273.
Knee acoustic emissions provide information about joint health and loading in motion. As the reproducibility of knee acoustic emissions by vibroarthrography is yet unknown, we evaluated the intrasession and interday reliability of knee joint sounds. In 19 volunteers (25.6 ± 2.0 years, 11 female), knee joint sounds were recorded by two acoustic sensors (16,000 Hz; medial tibial plateau, patella). All participants performed four sets standing up/sitting down (five repetitions each). For measuring intrasession reliability, we used a washout phase of 30 min between the first three sets, and for interday reliability we used a washout phase of one week between sets 3 and 4. The mean amplitude (dB) and median power frequency (Hz, MPF) were analyzed for each set. Intraclass correlation coefficients (ICCs (2,1)), standard errors of measurement (SEMs), and coefficients of variability (CVs) were calculated. The intrasession ICCs ranged from 0.85 to 0.95 (tibia) and from 0.73 to 0.87 (patella). The corresponding SEMs for the amplitude were ≤1.44 dB (tibia) and ≤2.38 dB (patella); for the MPF, SEMs were ≤13.78 Hz (tibia) and ≤14.47 Hz (patella). The intrasession CVs were ≤0.06 (tibia) and ≤0.07 (patella) (p < 0.05). The interday ICCs ranged from 0.24 to 0.33 (tibia) and from 0 to 0.82 (patella) for both the MPF and amplitude. The interday SEMs were ≤4.39 dB (tibia) and ≤6.85 dB (patella) for the amplitude and ≤35.39 Hz (tibia) and ≤15.64 Hz (patella) for the MPF. The CVs were ≤0.14 (tibia) and ≤0.08 (patella). Knee joint sounds were highly repeatable within a single session but yielded inconsistent results for the interday reliability.
Competition anxiety has been demonstrated to decrease sports performance while increasing burnout risk. To date, its degree in CrossFit (CF) is unknown. The present study, therefore, examines competition fear and relevant coping skills as well as potential correlates of both in individuals participating in CF events. A total of n = 79 athletes answered a battery of three questionnaires (competition fear index, athletic coping skills inventory, mindfulness attention awareness scale). Substantial levels of anxiety, particularly regarding the somatic dimension of the competition fear index, were reported. The most pronounced coping skill was freedom of worry. While age or level of competition showed no/very small associations with survey data, sex was correlated to the psychological characteristics: women reported higher competition fears and lower coping skill levels (p > 0.05). Competition fears are highly prevalent in CF athletes and the preventive value of population-specific interventions, particularly in females, should be investigated in future trials.
Experiments in cadavers have demonstrated significant mechanical interactions between constituents of myofascial chains. However, evidence for such force transmission effects is scarce under in vivo conditions. The purpose of this trial was to examine the impact of ankle motion on soft tissue displacement of the dorsal thigh. Eleven healthy active individuals (26.8 ± 4.3 years, six males), in prone position and with the knee extended, underwent passive calf stretches (ankle dorsal extension) imposed by an isokinetic dynamometer. High-resolution ultrasound was used to simultaneously capture the displacement of the semimembranosus muscle, which was quantified by means of cross-correlation analysis. Inactivity of the leg muscles was controlled using surface electromyography (EMG). One participant had to be excluded due to major EMG activity during the experiment. According to a one-sample t test testing the difference to the neutral zero position, ankle dorsal extension induced substantial caudal muscle displacements (5.76 ± 2.67 mm, p < 0.0001). Correlation analysis (Spearman), furthermore, revealed a strong association between maximal dorsal extension and semimembranosus motion (rho = 0.76, p = 0.02). In conclusion, the present trial provides initial in vivo evidence for a mechanical force transmission between serially connected skeletal muscles. This means that local alterations of the mechanical tissue properties may modify flexibility in neighboring (superior or inferior) joints.
When sports are part of a person’s profession or education, their careers are often handicapped by pain, a complex physical and mental state that may already occur at lower career stages. This study was designed to assess the occurrence of pain among sports students and the prevalence of relevant contributing psychosocial co-factors. Exploratory cross-sectional study surveying students at 89 sports faculties of universities in the DACH region using the German Sports Pain Questionnaire. It includes several validated surveys related to pain occurrence in different body regions, injuries, pain diagnoses and pain intensity, depression, anxiety, stress, self-compassion, analgesic and alcohol consumption, as well as sleep quality, health-related quality of life and impairments of quality of life by pain. A total of 865 sports students gave consent to participate in the study, and 664 participants (78%; 23.3 ± 2.84 years, 60% female, 40% male) completed the full survey. More than half of the students (53%; n = 403) showed current pain in 2-5 regions of the body, while subjective pain tolerance was enhanced. General injuries or accidents, medically and self-diagnosed pain diagnoses during the last eight weeks were reported by 30%. A current pain intensity ≥ 3 NRS was prevalent in 28% (n = 205), which correlated with increased pain-related biopsychosocial scores. Sports students had increased scores for depression, anxiety and stress, and self-compassion was reduced (compared to age-controlled national reference data, sports students head increased scores). The mean weekly training workload was 5-7 hours. Analgesics and alcohol consumption was increased, 61% reported insomnia. Across sports students, pain and biopsychosocial burden seem significantly increased when compared to other students and age-controlled cohorts. The data implies the need of giving greater importance to pain management at least from the time of sports studies in order to prevent pain and health risks in sports.
Background: The fascia has been demonstrated to represent a potential force transmitter intimately connected to the underlying skeletal muscle. Sports-related soft tissue strains may therefore result in damage to both structures.
Purpose: To elucidate the prevalence of connective tissue lesions in muscle strain injury and their potential impact on return-to-play (RTP) duration.
Study Design: Systematic review; Level of evidence, 3.
Methods: Imaging studies describing frequency, location, and extent of soft tissue lesions in lower limb muscle strain injuries were identified by 2 independent investigators. Weighted proportions (random effects) were pooled for the occurrence of (1) myofascial or fascial lesions, (2) myotendinous lesions, and (3) purely muscular lesions. Study quality was evaluated by means of an adapted Downs and Black checklist, which evaluates reporting, risk of bias, and external validity.
Results: A total of 16 studies (fair to good methodological quality) were identified. Prevalence of strain injury on imaging studies was 32.1% (95% CI, 24.2%-40.4%) for myofascial lesions, 68.4% (95% CI, 59.6%-76.6%) for myotendinous lesions, and 12.7% (95% CI, 3.0%-27.7%) for isolated muscular lesions. Evidence regarding associations between fascial damage and RTP duration was mixed.
Conclusion: Lesions of the collagenous connective tissue, namely the fascia and the tendinous junction, are highly prevalent in athletic muscle strain injuries. However, at present, their impact on RTP duration is unclear and requires further investigation.
The role of attentional focusing in motor tasks has been highlighted frequently. The “internal–external” dimension has emerged, but also the spatial distance between body and attended location. In two experiments, an extended attentional focus paradigm was introduced to investigate distality effects of attentional foci on balance performance. First, the distality of the coordinates of the point of focus was varied between a proximal and distal position on an artificial tool attached to the body. Second, the distance of the displayed effect on the wall was varied between a 2.5 and 5 m condition. Subjects were instructed to focus on controlling either a proximal or distal spot on a tool attached to their head, represented by two laser pointers. Subsequently, they needed to visually track their own body-movement effect of one of the laser pointers at a wall while completing various single leg stance tasks. Center of pressure (COP) sway was analyzed using a linear method (classic sway variables) as well as a nonlinear method (multiscale entropy). In addition, laser trajectories were videotaped and served as additional performance outcome measure. Experiment 1 revealed differences in balance performance under proximal compared to distal attentional focus conditions. Moreover, experiment 2 yielded differences in balance-related sway measures and laser data between the 2.5 and 5 m condition of the visually observable movement effect. In conclusion, varying the distality of the point of focus between proximal and distal impacted balance performance. However, this effect was not consistent across all balance tasks. Relevantly, the distality of the movement effect shows a significant effect on balance plus laser performance with advantages in more distal conditions. This research emphasizes the importance of the spatial distality of movement effects for human behavior.
Organized running events have gained substantial popularity. This study aimed to elucidate the prevalence of musculoskeletal pain, knowledge about injury prevention as well as the attitudes and motivations of individuals participating in the JP Morgan Corporate Challenge in Frankfurt (Germany). A total of 720 recreational runners completed a digital questionnaire immediately prior to the start. The majority of them displayed low to moderate physical activity levels and were rather unambitious regarding targeted finishing time. One quarter (25.3%) participated for the first time in an organized race. The most stated reasons to register were team building (76.4%) and experiencing the run’s atmosphere (50.6%). In contrast, improving health played a minor role (19.4%). More than one in five individuals (n = 159 runners) reported pain, with the most common locations being the knee and lower back. Both at rest (3.2/10 on a numerical rating scale) and during activity (4.7/10), average pain intensity was clinically relevant. Almost three thirds of the participants believed that stretching and wearing appropriate shoes would be effective for injury prevention while other methods such as resistance training, balance exercise or wearing of orthoses were rarely named. Musculoskeletal pain is a significant burden in runners participating in an urban mass event. In view of the poor knowledge about injury prevention, organizers and coaches may consider offering structured preparation programs as well as tailored running-related health education.
We are glad to introduce the sixth Journal Club. This edition is focused on several relevant studies published in recent years in the field of Motor Control and Learning, chosen by our Editorial Board members and their colleagues. We hope to stimulate your curiosity in this field and to share with you the passion for sport seen also from the scientific point of view. The Editorial Board members wish you an inspiring lecture.
Background: We aimed to investigate the potential effects of a 4-week motor–cognitive dual-task training on cognitive and motor function as well as exercise motivation in young, healthy, and active adults.
Methods: A total of 26 participants (age 25 ± 2 years; 10 women) were randomly allocated to either the intervention group or a control group. The intervention group performed a motor–cognitive training (3×/week), while the participants of the control group received no intervention. Before and after the intervention period of 4 weeks, all participants underwent cognitive (d2-test, Trail Making Test) and motor (lower-body choice reaction test and time to stabilization test) assessments. Following each of the 12 workouts, self-reported assessments (rating of perceived exertion, enjoyment and pleasant anticipation of the next training session) were done. Analyses of covariances and 95% confidence intervals plotting for between group and time effects were performed.
Results: Data from 24 participants were analysed. No pre- to post-intervention improvement nor a between-group difference regarding motor outcomes (choice-reaction: F = 0.5; time to stabilization test: F = 0.7; p > 0.05) occurred. No significant training-induced changes were found in the cognitive tests (D2: F = 0.02; Trail Making Test A: F = 0.24; Trail Making Test B: F = 0.002; p > 0.05). Both enjoyment and anticipation of the next workout were rated as high.
Discussion: The neuro-motor training appears to have no significant effects on motor and cognitive function in healthy, young and physically active adults. This might be explained in part by the participants’ very high motor and cognitive abilities, the comparably low training intensity or the programme duration. The high degree of exercise enjoyment, however, may qualify the training as a facilitator to initiate and maintain regular physical activity. The moderate to vigorous intensity levels further point towards potential health-enhancing cardiorespiratory effects.
Background: Although anterior cruciate ligament (ACL) tear-prevention programs may be effective in the (secondary) prevention of a subsequent ACL injury, little is known, yet, on their effectiveness and feasibility. This study assesses the effects and implementation capacity of a secondary preventive motor-control training (the Stop-X program) after ACL reconstruction.
Methods and design: A multicenter, single-blind, randomized controlled, prospective, superiority, two-arm design is adopted. Subsequent patients (18–35 years) with primary arthroscopic unilateral ACL reconstruction with autologous hamstring graft are enrolled. Postoperative guideline rehabilitation plus Classic follow-up treatment and guideline rehabilitation plus the Stop-X intervention will be compared. The onset of the Stop-X program as part of the postoperative follow-up treatment is individualized and function based. The participants must be released for the training components. The endpoint is the unrestricted return to sport (RTS) decision. Before (where applicable) reconstruction and after the clearance for the intervention (aimed at 4–8 months post surgery) until the unrestricted RTS decision (but at least until 12 months post surgery), all outcomes will be assessed once a month. Each participant is consequently measured at least five times to a maximum of 12 times. Twelve, 18 and 24 months after the surgery, follow-up-measurements and recurrence monitoring will follow. The primary outcome assessement (normalized knee-separation distance at the Drop Jump Screening Test (DJST)) is followed by the functional secondary outcomes assessements. The latter consist of quality assessments during simple (combined) balance side, balance front and single-leg hops for distance. All hop/jump tests are self-administered and filmed from the frontal view (3-m distance). All videos are transferred using safe big content transfer and subsequently (and blinded) expertly video-rated. Secondary outcomes are questionnaires on patient-reported knee function, kinesiophobia, RTS after ACL injury and training/therapy volume (frequency – intensity – type and time). All questionnaires are completed online using the participants’ pseudonym only.
Group allocation is executed randomly. The training intervention (Stop-X arm) consists of self-administered home-based exercises. The exercises are step-wise graduated and follow wound healing and functional restoration criteria. The training frequency for both arms is scheduled to be three times per week, each time for a 30 min duration. The program follows current (secondary) prevention guidelines.
Repeated measurements gain-score analyses using analyses of (co-)variance are performed for all outcomes.
Trial registration: German Clinical Trials Register, identification number DRKS00015313. Registered on 1 October 2018.
Inhibition is a central component of human behavior. It enables flexible and adaptive behavior by suppressing prepotent motor responses. In former studies, it has been shown that sport athletes acting in dynamic environments exhibit superior motor inhibitory control based on sensory stimuli. So far, existing studies have corroborated this in manual motor response settings only. Therefore, this study addresses the effector specificity of the inhibition benefit in elite athletes compared to physically active controls. A sport-unspecific stop-signal task has been adapted for hand as well as feet usage and 30 elite handball players as well as 30 controls were tested. A repeated-measures ANOVA with the two factors “effector” (hands, feet) and “group” (expert, recreational athletes) was conducted. Our results suggest no group differences in two-choice response times, but a convincing superiority of handball players in inhibitory control (i.e., shorter stop-signal reaction times), predominantly when responding with their hands, with weaker differential effects when responding with their feet. This suggests that motor inhibition might be a comprehensive performance characteristic of sport athletes acting in dynamic environments, detectable predominantly in eye-hand coordination tasks.
Background: The nature of perceptual-cognitive expertise in interactive sports has gained more and more scientific interest over the last two decades. Research to understand how this expertise can be developed has not been addressed profoundly yet. In approaches to study this with interventional designs, only few studies have scrutinized several levels of transfer such as to the field. Therefore, the aim of this study was to examine the efficacy of a generic off-court perceptual-cognitive training in elite volleyball players on three different levels: task-specific, near-transfer, and far-transfer effects. Based on overlapping cognitive processes between training and testing, we hypothesized task-specific improvements as well as positive near- and far-transfer effects after a multiple-object tracking training intervention.
Methods: Twenty-two volleyball experts completed a 8-week three-dimensional (3D) multiple-object tracking (3D-MOT) training intervention. A control group (n = 21; volleyball experts also) participated in regular ball practice only. Before and after training, both groups performed tests on the 3D-MOT, four near-transfer tests in cognitive domains, and a far-transfer, lab-based, and volleyball-specific blocking test.
Results: The results of the 2 × 2 analysis of variance (ANOVA) (group, time) showed significant interaction effects in the 3D-MOT task [F(1,40) = 93.10; p < 0.001; η2p = 0.70] and in two near-transfer tests [sustained attention: F(1,40) = 15.45; p < 0.001; η2p = 0.28; processing speed: F(1,40) = 12.15; p = 0.001; η2p = 0.23]. No significant interaction effects were found in the far-transfer volleyball test.
Conclusions: Our study suggests positive effects in task-specific and two near-transfer tests of a perceptual-cognitive intervention in elite volleyball athletes. This supports a partial overlap in cognitive processing between practice and tests with the result of positive near-transfer. However, there are no significant effects in far-transfer testing. Although these current results are promising, it is still unclear how far-transfer effects of a generic perceptual-cognitive training intervention can be assured.
Multitasking is ubiquitous in our everyday life. Accordingly, situations in which two or more tasks need to be handled concurrently or in close temporal succession have been studied intensely. Different paradigms have been developed in that context (Koch et al., 2018). Over the last decades, the psychological refractory period (PRP) paradigm has dominated dual-task research, because it allows quantitative predictions of reaction time increases coupled to stimulus onset asynchrony. Part of the success of this paradigm is grounded in the fact that most of the studies are run under strict experimental control with very elementary tasks, mostly characterized by a definite start and ending. However, it remains unclear whether these limited settings sufficiently reflect the range of eventualities we find in real life. Rather, there is accumulating evidence that important factors modulating multitask performance are not sufficiently captured by the PRP approach. Here we focus on evidence that motor responses that involve continuous interaction with the environment may engage processes that alter the coordination of concurrently performed tasks in fundamental ways. ...
Background: This study evaluated the effects of a combined innovative training regime consisting of stochastic resonance whole-body vibration (SR-WBV) and a dance video game (DVG) on physical performance and muscle strength in long-term-care dwelling elderly.
Methods: Thirthy long-term-care elderly were randomly allocated to an intervention group (IG; n = 16) receiving combined SR-WBV training and DVG, or a sham group (SG; n = 14). IG performed five sets one minute of SR-WBV, with one minute rest between sets (base frequency 3 Hz up to 6 Hz, Noise 4) during the first five weeks on three days per week. From week five to eight a DVG was added to SR-WBV for IG on three days per week. SG performed a five-set SR-WBV program (1 Hz, Noise 1) lasting five times one minute, with one minute rest in between, three days a week. From week five to eight stepping exercises on a trampoline were added on three days per week. Primary outcome: Short physical performance battery (SPPB). Secondary outcome: isometric maximal voluntary contraction (IMVC), and sub phases of IMVC (Fsub), isometric rate of force development (IRFD) and sub time phases of IRFD (IRFDsub) were measured at baseline, after four and eight weeks. ANOVA with repeated measures was used for analyses of time and interaction effects and MANOVA determined between group intervention effects.
Results: Between group effects revealed significant effects on the SPPB primary outcome after four weeks F(1, 27) = 6.17; p = 0.02) and after eight weeks F(1,27) = 11.8; p = 0.002). Secondary muscle function related outcome showed significant between group effects in IG on IRFD, Fsub 30 ms, 100 ms, 200 ms and IRFDsub 0-30 ms, 0-50 ms, 0-100 ms and 100-200 ms compared to SG (all p < 0.05).
Conclusions: Eight weeks SR-WBV and DVG intervention improved lower extremity physical function and muscle strength compared to a sham intervention in long-term-care elderly. SR-WBV and DVG seems to be effective as a training regime for skilling up in long-term-care elderly.
Altitude training and respiratory muscle training (RMT) have been reported to improve performance in elite and well-trained athletes. Several devices (altitude and RMT) have been developed to help athletes gain the competitive edge. The Elevation Training Mask 2.0 (ETM) purportedly simulates altitude training and has been suggested to increase aerobic capacity (VO2max), endurance performance, and lung function. Twenty-four moderately trained subjects completed 6 weeks of high-intensity cycle ergometer training. Subjects were randomized into a mask (n = 12) or control (n = 12) group. Pre and post-training tests included VO2max, pulmonary function, maximal inspiration pressure, hemoglobin and hematocrit. No significant differences were found in pulmonary function or hematological variables between or within groups. There was a significant improvement in VO2max and PPO in both the control (13.5% and 9.9%) and mask (16.5% and 13.6%) groups. There was no difference in the magnitude of improvement between groups. Only the mask group had significant improvements in ventilatory threshold (VT) (13.9%), power output (PO) at VT (19.3%), respiratory compensation threshold (RCT) (10.2%), and PO at RCT (16.4%) from pre to post-testing. The trends for improvements in VT and PO at VT between groups were similar to improvements in RCT and PO at RCT, but did not reach statistical significance (VT p = 0.06, PO at VT p = 0.170). Wearing the ETM while participating in a 6-week high-intensity cycle ergometer training program does not appear to act as a simulator of altitude, but more like a respiratory muscle training device. Wearing the ETM may improve specific markers of endurance performance beyond the improvements seen with interval training alone.
There are errors in the Funding section. The correct funding information is as follows: This study is part of the research project "Resistance Training in Youth Athletes" that was funded by the German Federal Institute of Sport Science (ZMVI1-08190114-18). In addition, we acknowledge the support of the Deutsche Forschungsgemeinschaft (DFG) and Open Access Publishing Fund of University of Potsdam, Germany. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Change of direction (COD) is a performance-limiting factor in team sports. However, there are no exact definitions describing which physical abilities limit COD performance in soccer. Nevertheless, different COD tests are used or have been recommended as being equally effective in the professional practice of measuring COD performance. Therefore, the aim of this study was to evaluate the relationship between different COD tests, and to test the independence and generalizability of these COD tests in soccer. As such, 27 elite youth soccer players were randomly recruited and were tested in different COD tests (i.e., Illinois agility test (IAT), T agility test (TT), 505 agility test (505), Gewandtheitslauf (GewT), triangle test (Tri-t), and square test (SQT)). Bivariate Pearson correlation analysis was used to assess the relationships between the COD tests. The Benjamini–Hochberg method was used to control for the false discovery rate of the study at 0.05. This investigation calculated explained variances of 10% to 55% between performances in the different COD tests. This suggested that the tests covered different aspects or task-specific characteristics of the COD. Therefore, coaches and sport scientists should review and select different tests with a logical validity, based on the requirement profiles of the corresponding sport.
"Spielen und Sich-Bewegen sind elementare kindliche Bedürfnisse. Als positive Lebensäußerungen fördern sie Gesundheit und Wohlbefinden. Sie unterstützen die psychomotorische, emotionale und soziale Entwicklung und tragen zur Ausbildung kognitiver Strukturen bei. Durch Spiel und Bewegung macht das Kind Erfahrungen seiner selbst: Es erprobt Bewegungs- und Handlungsabläufe, lernt, sich einzuschätzen und erlebt eigenes Können und seine Grenzen. Im gemeinsamen Tun mit anderen Kindern entwickeln sich seine Kooperations- und Kommunikationsfähigkeit." (Hessisches Kultusministerium, 1995, S. 20)
In diesem Auszug aus dem Rahmenplan für den Sportunterricht in hessischen Grundschulen werden dem Sporttreiben neben gesundheitsfördernden vor allem charakterbildende Eigenschaften zugeschrieben. Laut der "Charta des Deutschen Sports" zählt Sport sogar zu den "nicht austauschbare[n] Faktoren der Bildung" und als wichtiger Baustein "zur Entfaltung der Persönlichkeit" (zit. nach Singer, 1986, S. 295). Damit werden hohe Erwartungen an die sportliche Betätigung von Kindern formuliert, die von einer gesamtheitlichen Förderung der individuellen Entwicklung durch die Partizipation am Sport ausgehen und ein geradezu lobpreisendes Bild von Bewegungspraktiken zeichnet.
Dass auch die Welt des Sports ihre negativen Seiten hat, ist nicht von der Hand zu weisen. Ein Blick in die Tageszeitung genügt, um über aktuelle Doping- und Korruptionsvorwürfe rund um Olympische Spiele, Manipulationsverdächtigungen gegenüber Schiedsrichtern oder gar staatlichen Einrichtungen oder randalierende und sich prügelnde Fangruppen informiert zu werden. Diese Thematiken lassen sich von der internationalen Bühne herunterbrechen bis auf den heimischen Fußballplatz vor der Haustür. Gerade auf diesem haben sich in den vergangenen Jahren, man darf mittlerweile gar von Dekaden sprechen, Szenen ereignet, die den im oben angestellten Zitat mit dem Sport verbundenen Ansprüchen nicht gerecht werden.
Gerade im Amateur- und Breitensportbereich des Fußballs ist im Allgemeinen eine rauere Atmosphäre wahrzunehmen, die sich nicht zuletzt in Spielabbrüchen und physischen Auseinandersetzungen äußert und sich nicht auf den Seniorenspielbetrieb beschränkt, sondern gar Junioren- und Kinderspiele umfasst. Diese ausgemachten Tendenzen waren letztendlich ausschlaggebend für die von Ralf Klohr, damals selbst als Nachwuchstrainer aktiv, 2007 vollzogene Gründung der "Fair-Play-Liga", die den angesprochenen Entwicklungen entgegenwirken und das Bildungspotenzial des Sports wieder mehr in den Vordergrund rücken und schützen soll. Die jüngsten Fußballinteressierten, also Kinder ab 4 Jahren, spielen dort nach modifizierten Regeln, die zur Erfüllung ihrer altersentsprechenden Bedürfnisse beitragen und diese sicherstellen sollen. Mittlerweile ist das Konzept deutschlandweit im Einsatz und eine etablierte Organisationsform des Kinderfußballs, mit der Klohr (2018) die "nglaubliche Kraft im Fußball" bemühen und diese über eine dem Straßenfußball ähnliche, aber nach seinen Vorstellungen verbesserte Herangehensweise zurückholen will:
"Ich sehe die Fair-Play-Liga mit Trainer als eine Qualitätssteigerung zum ‚alten‘ Bolzplatz. Ich sehe die Fair-Play-Liga als ‚modernen‘ Bolzplatz. Die Trainer haben in erster Linie einen Betreuungsauftrag. Auf dem modernen Bolzplatz können sie dafür sorgen, dass alle Kinder gerecht behandelt, also nicht, benachteiligt, werden."
Ebenso wie an den Schulsport sind an die Fair-Play-Liga durch ihre Selbstdefinition einige Erwartungen geknüpft. Die vorliegende Masterthesis macht es sich zum Ziel herauszuarbeiten, inwiefern die Initiative ihren eigens auferlegten Ansprüchen gerecht wird, welche Interaktionsverhältnisse sie hervorbringt und was sie im Sinne eines "Vermittlers" bestimmter Wertvorstellungen im Stande ist zu leisten.
Dafür soll zunächst einmal aufgezeigt werden, was dem Sport generell im Sinne eines Fairnessbegriffs und der damit verknüpften Werte tatsächlich an "Übermittlerpotenzial" innewohnt sowie was über das Fairnessverständnis von Kindern und Jugendlichen bekannt ist (Kapitel 2). Im Anschluss daran werden das vom Deutschen Fußball-Bund (DFB) verfolgte Ausbildungskonzept, die Grundmerkmale und Ziele der Fair-Play-Liga und bereits diesbezüglich durchgeführte Untersuchungen vorgestellt (Kapitel 3), ehe die eigenen Fragestellungen der Forschungsarbeit dargelegt werden (Kapitel 4).
Nach einer Beschreibung des methodischen Vorgehens in seiner Theorie und Praxis (Kapitel 5) folgen die Zusammenführung der im Forschungsprozess erzeugten Resultate und die daran anknüpfende Thesenbildung (Kapitel 6). In der anschließenden Diskussion sollen die Ergebnisse hinsichtlich ihrer Relevanz und ihrer Genese bewertet und interpretiert werden (Kapitel 7), sodass in einem letzten Schritt sowohl Handlungs- und Verbesserungsvorschläge gebündelt und Anregungen für weitere empirische Arbeiten gegeben werden können.
Background: A central aim of physical education is the promotion of basic motor competencies (in German: Motorische Basiskompetenzen; MOBAK), which are prerequisites for children's active participation in sports culture. This article introduces the MOBAK-1 test instrument for 6- to 8-year-old children and determines the construct validity of this test instrument. In addition, the relationship between MOBAK and motor ability (i.e., strength) as well as body mass index (BMI), sex, and age is investigated.
Methods: We analyzed data of 923 first and second graders (422 girls, 501 boys, age = 6.80 ± 0.44 years). The children's basic motor competencies were assessed by the MOBAK-1 test instrument. Besides analyses of frequency, correlation, and variance, 3 confirmatory factor analyses with covariates were performed.
Results: We found 2 MOBAK factors consisting of 4 items each. The first factor, locomotion, included the items balancing, rolling, jumping, and side stepping; the second factor, object control, included the items throwing, catching, bouncing, and dribbling. The motor ability strength had a significant influence on the factors locomotion (β = 0.60) and object control (β = 0.50). Older pupils achieved better results than younger pupils on object control (β = 0.29). Boys performed better on object control (β = −0.44), whereas girls achieved better results in locomotion (β = 0.07). Pupils with a high BMI achieved lower performance only on the factor locomotion (β = −0.28).
Conclusion: The MOBAK-1 test instrument developed for this study meets psychometric validity demands and is suitable to evaluate effects of sports and physical education.
Lehre im Bewegungsfeld Kämpfen an den sportwissenschaftlichen Hochschuleinrichtungen in Deutschland
(2018)
Obwohl sich verschiedene Formen des Kämpfens in zahlreichen Lehrplänen der Bundesländer wiederfinden und ein entsprechender Qualifizierungsbedarf angehender Lehrkräfte gefordert wird, liegen bislang kaum Daten zur Lehre im Bewegungsfeld Kämpfen an sportwissenschaftlichen Hochschuleinrichtungen vor. Im Frühjahr 2017 wurden deutschlandweit Personen mit lehrender oder koordinierender Tätigkeit im Bewegungsfeld Kämpfen zu grundlegenden Daten ihrer Lehrveranstaltung (u. a. Zielgruppe, Umfang, Verbindlichkeit), zur didaktisch-methodischen Gestaltung (u. a. Ziele, Inhalte, Methoden, Prüfungen) sowie zu ihrem Beschäftigungsverhältnis befragt. An 14 von 60 Standorten konnte kein entsprechendes Lehrangebot identifiziert werden. Die erfassten 54 Lehrangebote (beschrieben von 48 Personen aus 31 Einrichtungen) sind bezüglich der organisatorischen Rahmenbedingungen relativ gut vergleichbar: Etwa 83 % umfassen zwei SWS und ca. 74 % sind Wahlpflichtveranstaltungen. Heterogenität herrscht u. a. hinsichtlich der Lernziele sowie der eingesetzten Lehr-Lernformen. Die Bestandserhebung bietet eine fachbezogene Diskussionsgrundlage für die Ausgestaltung von Theorie und Praxis des Bewegungsfelds Kämpfen.
Einleitung und Hintergrund: Self-Myofascial-Release (SMR), eine in den letzten Jahren populär gewordene Trainingsform, beschreibt das Training mit sog. Hartschaumrollen oder anderer Hilfsmittel zur Selbstmassage. Mit dem Ziel der Nachahmung einer manuellen Behandlung übt der Trainierende mit dem eigenen Körpergewicht oder etwa einem Massagestick Druck auf das zu behandelnde Gewebe aus und bewegt sich rollend über das Sportgerät. Aktuelle Forschungsergebnisse deuten auf einen positiven Effekt von SMR auf Parameter der Beweglichkeit sowie der Regeneration hin, die zu Grunde liegenden Mechanismen sind bisher allerdings noch unklar. Bezüglich der Beweglichkeitsverbesserung könnten neurophysiologische Veränderungen im Bereich der Dehnwahrnehmung und Dehntoleranz eine Rolle spielen. Auf mechanischer Ebene könnte es analog zum statischen Stretching zu einer akuten Veränderung der viskoelastischen Gewebeeigenschaften kommen. Ebenso werden Effekte von SMR auf Gleiteigenschaften einzelner Faszienschichten postuliert. Das Ziel der vorliegenden Arbeit war daher die Evaluation der Akuteffekte von SMR auf die Beweglichkeit, die passive Gewebespannung und -steifigkeit sowie die Gleitbewegungen einzelner Faszienschichten am vorderen Oberschenkel.
Methodik: Nach Fallzahlplanung durchliefen in einem Cross-Over Studiendesign insgesamt 16 Probanden (w=6, m=10, 32±3 Jahre, 177,6±2,4cm, 78,2±5,2kg) alle der drei folgenden Interventionen in ausbalancierter, randomisierter Reihenfolge: a) 2x60 Sekunden SMR am vorderen Oberschenkel, b) 2x60s passives, statisches Stretching des vorderen Oberschenkels und c) eine passive Kontrollbedingung. Mindestens drei Tage vor Beginn des ersten Messtermins erhielten alle Probanden eine standardisierte Gewöhnungseinheit, in der alle Messungen sowie die SMR Intervention durchgeführt wurden. Die passive Gewebespannung und -steifigkeit bei 13, 9, 5 und 1 Grad vor dem individuellen Bewegungsende sowie die Position der ersten Dehnwahrnehmung wurden mittels isokinetischem Dynamometer (Biodex System 3 Professional), die aktive und passive Kniegelenksbeweglichkeit mittels ultraschallbasiertem 3D-Bewegunsanalysesystem (Zebris CMS20) vor sowie direkt nach der jeweiligen Intervention erhoben. Ebenso wurden Gleitbewegung einzelner Faszienschichten vor und nach der jeweiligen Intervention anhand von Ultraschallvideos (Siemens Acuson X300) und anschließender Cross-Correlation-Analyse berechnet. Die statistische Überprüfung auf Inter- und Intragruppeunterschiede erfolge nach Überprüfung der Anwendungsvoraussetzungen mittels Friedmann-Test und anschließendem post-hoc Wilcoxon-Test oder ANCOVA (Baselinewerte als Covariate) und post-hoc Vergleichen mit geschätzten Randmitteln und zugehörigen 95%-Konfidenzintervallen.
Ergebnisse: Die aktive und passive Gelenkbeweglichkeit verbesserte sich nach SMR im Mittel um 1,8° bzw. 3,4° signifikant. Nach statischen Dehnen war lediglich die Verbesserung der passiven Kniegelenksbeweglichkeit von im Mittel 3,2° signifikant, nach der passiven Kontrolle blieben aktive und passive Beweglichkeit unverändert. Der Winkel der ersten Dehnwahrnehmung vergrößerte sich SMR (+4,3° (1,4°-7,2°)) und Stretching (+6,7° (3,7°-9,6°)), blieb nach Kontrollbedingung jedoch unverändert (+0,3° (-2,5°-3,1°)). Passiver Gewebewiderstand und -steifigkeit veränderten sich nach keiner der Interventionen in keinem getesteten Winkel signifikant. Veränderungen in der Gleitbewegung einzelner Faszienschichten ergaben sich lediglich nach SMR. Die Gleitbewegung der tiefen Schicht gegenüber des Muskels sowie die Gleitbewegung zwischen oberflächlicher und tiefer Schicht verringerten sich nach SMR signifikant zur Baseline (-5,7mm (-11,3mm – -0,1mm) bzw. (-4.9mm (-9.1mm – -0.7mm)).
Diskussion: Die vorliegenden Ergebnisse bestätigen den positiven Einfluss von SMR auf die aktive und passive Beweglichkeit und liefern erste Hinweise bezüglich der zu Grunde liegenden Mechanismen. Während biomechanische Parameter wie passive Gewebespannung nach SMR und Stretching unverändert blieben, deuten Veränderungen der Dehnwahrnehmung auf einen Einfluss neurophysiologischer Mechanismen hinsichtlich akuter Effekte auf die Beweglichkeit hin. Die Ausschüttung verschiedener Neurotransmitter wie z.B. Oxytocin könnte Schmerz- und auch Dehnwahrnehmung nach SMR beeinflussen. Die Ergebnisse zeigen weiter, dass SMR zu einer Veränderung der Gleitbewegung einzelner Bindegewebsschichten am vorderen Oberschenkel führte. Diesbezüglich könnten veränderte thixotrophe Eigenschaften des losen Bindegewebes zwischen Faszie und Muskels sowie Veränderungen des Hydratationsgrades eine Rolle spielen.
Aus den Ergebnissen der vorliegenden Studie lassen sich verschiedene Implikationen für die Trainings- und Therapiepraxis ableiten. So eignet sich SMR u.a. als Alternative zu statischen Dehnmethoden zur akuten Verbesserung der Beweglichkeit, zur Veränderung der Dehnwahrnehmung (etwa bei akuten und schmerzhaften Bewegungseinschränkungen) und möglicherweise zur Normalisierung der Gleiteigenschaften einzelner Bindegewebsschichten. Unklar bleiben bisher die Übertragbarkeit der Ergebnisse auf andere Körperregionen sowie die Effekte von SMR bei Patienten mit strukturellen Bindegewebsveränderungen. Ebenso sind die langfristigen Effekte von SMR bisher unklar und bieten Anschlusspunkte zukünftiger Studien.
Emotional Competence (EC) is regarded as a fundamental skill for sports coaches. However, the applications of EC in football coaching are not well understood. This study analyzed the specific emotional processes football coaches experience. We interviewed 18 football coaches and analyzed the interview transcripts by using a systematic analysis process based on Grounded Theory principles. We derived a model from this analysis that comprises a four-phase process: emotional triggers, emotional experiences, emotion regulation strategies, and emotional consequences. In this model, we identified four categories which act as triggers of emotions in football coaches. These emotions can be positive or negative and are manifested at three levels. However, the coaches vary in their capability to perceive emotions. Our model also shows that coaches’ emotion regulation strategies influence the effect of emotional experiences. Experienced emotions promote consequences with psychological and social implications for coaches and may influence their perception of future situations. In short, the process seems to be circular. This finding suggests that the ability to deal with emotions is an important aspect for football coaches.
Latent myofascial trigger points (MTrP) have been linked to several impairments of muscle function. The present study was conducted in order to examine whether a single bout of self-myofascial release using a foam roller is effective in reducing MTrP sensitivity. Fifty healthy, pain-free subjects (26.8±6 years, 21 men) with latent MTrP in the lateral gastrocnemius muscle were included in the randomized, controlled trial. One week after a familiarization session, they were randomly allocated to three groups: (1) static compression of the most sensitive MTrP using a foam roll, (2) slow dynamic foam rolling of the lateral calf and (3) placebo laser acupuncture of the most sensitive MTrP. Treatment duration in each group was 90 seconds. The pressure pain threshold (PPT) of the most sensitive MTrP was assessed using a handheld algometer prior to and after the intervention. A repeated measures analysis of variance (3x2) did not reveal significant between‑group interactions (p>.05) but showed a significant time effect (F=7.715, p<.05). While placebo and dynamic selfmyofascial release did not change MTrP sensitivity (p>.05), static compression of MTrP increased the PPT (2.6±0.8 to 3.0±1.1, d=.35; p<.05). Static self-myofascial release using a foam roller might represent an alternative to reduce pressure pain of latent MTrP. Additional research should aim to extend these findings to patients and athletes with myofascial pain syndromes.
Tapping the full potential? Jumping performance of volleyball athletes in game-like situations
(2018)
Background: One key issue in elite interactive team sports is the simultaneous execution of motor actions (e.g., dribbling a ball) and perceptual-cognitive tasks (e.g., visually scanning the environment for action choices). In volleyball, one typical situation is to prepare and execute maximal block jumps after multiple-options decision-making and concurrent visual tracking of the ongoing game dynamics to find an optimal blocking location. Based on resource-related dual- and multi-tasking theories simultaneous execution of visual-cognitive and motor tasks may interfere with each other. Therefore, the aim of this study was to investigate whether volleyball-specific perceptual-cognitive demands (i.e., divided attention, decision making) affect blocking performance (i.e., jumping performance and length of the first step after the ready-block-position) compared to relatively isolated jumping performance.
Methods: Twenty-two elite volleyball players (1st – 3rd German league) performed block jumps in front of a net construction in a single-task condition (ST) and in two perceptual (-cognitive) dual-task conditions including a dual-task low (DT_L; presenting a picture of an opponent attack on a screen) and a dual-task high condition (DT_H; presenting videos of an offensive volleyball set play with a two-alternative choice).
Results: The results of repeated-measures ANOVAs showed a significant effect of conditions on jumping performance [F(2,42) = 33.64, p < 0.001, ηp2 = 0.62] and on the length of the first step after the ready-block-position [F(2,42) = 7.90, p = 0.001, ηp2 = 0.27). Post hoc comparisons showed that jumping performance in DT_H (p < 0.001) and DT_L (p < 0.001) was significantly lower than in ST. Also, length of the first step after the ready-block-position in DT_H (p = 0.005) and DT_L (p = 0.028) was significantly shorter than in ST.
Conclusion: Our findings suggest that blocking performance (i.e., jumping height, length of the first step) decreases in elite volleyball players when a perceptual (-cognitive) load is added. Based on the theory of Wickens (2002), this suggests a resource overlap between visual-processing demands for motor performance and for tracking the dynamics of the game. Interference with the consequence of dual-task related performance costs can therefore also be found in elite athletes in their specific motor expert domain.
In the publication of this article, there are reference errors in four positions the respective references are missing since reference Fischer was omitted. In addition for reference Egli et al. the in text citation only appeared at the end of the paragraph, but not following important statements. This has now been included in this correction. ...
Introduction: To date, several meta-analyses clearly demonstrated that resistance and plyometric training are effective to improve physical fitness in children and adolescents. However, a methodological limitation of meta-analyses is that they synthesize results from different studies and hence ignore important differences across studies (i.e., mixing apples and oranges). Therefore, we aimed at examining comparative intervention studies that assessed the effects of age, sex, maturation, and resistance or plyometric training descriptors (e.g., training intensity, volume etc.) on measures of physical fitness while holding other variables constant.
Methods: To identify relevant studies, we systematically searched multiple electronic databases (e.g., PubMed) from inception to March 2018. We included resistance and plyometric training studies in healthy young athletes and non-athletes aged 6 to 18 years that investigated the effects of moderator variables (e.g., age, maturity, sex, etc.) on components of physical fitness (i.e., muscle strength and power).
Results: Our systematic literature search revealed a total of 75 eligible resistance and plyometric training studies, including 5,138 participants. Mean duration of resistance and plyometric training programs amounted to 8.9 ± 3.6 weeks and 7.1±1.4 weeks, respectively. Our findings showed that maturation affects plyometric and resistance training outcomes differently, with the former eliciting greater adaptations pre-peak height velocity (PHV) and the latter around- and post-PHV. Sex has no major impact on resistance training related outcomes (e.g., maximal strength, 10 repetition maximum). In terms of plyometric training, around-PHV boys appear to respond with larger performance improvements (e.g., jump height, jump distance) compared with girls. Different types of resistance training (e.g., body weight, free weights) are effective in improving measures of muscle strength (e.g., maximum voluntary contraction) in untrained children and adolescents. Effects of plyometric training in untrained youth primarily follow the principle of training specificity. Despite the fact that only 6 out of 75 comparative studies investigated resistance or plyometric training in trained individuals, positive effects were reported in all 6 studies (e.g., maximum strength and vertical jump height, respectively).
Conclusions: The present review article identified research gaps (e.g., training descriptors, modern alternative training modalities) that should be addressed in future comparative studies.
Introduction Current: evidence suggests that the loss of mechanoreceptors after anterior cruciate ligament (ACL) tears might be compensated by increased cortical motor planning. This occupation of cerebral resources may limit the potential to quickly adapt movements to unforeseen external stimuli in the athletic environment. To date, studies investigating such neural alterations during movement focused on simple, anticipated tasks with low ecological validity. This trial, therefore, aims to investigate the cortical and biomechanical processes associated with more sport-related and injury-related movements in ACL-reconstructed individuals.
Methods and analysis: ACL-reconstructed participants and uninjured controls will perform repetitive countermovement jumps with single leg landings. Two different conditions are to be completed: anticipated (n=35) versus unanticipated (n=35) successful landings. Under the anticipated condition, participants receive the visual information depicting the requested landing leg prior to the jump. In the unanticipated condition, this information will be provided only about 400 msec prior to landing. Neural correlates of motor planning will be measured using electroencephalography. In detail, movement-related cortical potentials, frequency spectral power and functional connectivity will be assessed. Biomechanical landing quality will be captured via a capacitive force plate. Calculated parameters encompass time to stabilisation, vertical peak ground reaction force, and centre of pressure path length. Potential systematic differences between ACL-reconstructed individuals and controls will be identified in dependence of jumping condition (anticipated/ unanticipated, injured/uninjured leg and controls) by using interference statistics. Potential associations between the cortical and biomechanical measures will be calculated by means of correlation analysis. In case of statistical significance (α<0.05.) further confounders (cofactors) will be considered.
Ethics and dissemination: The independent Ethics Committee of the University of Frankfurt (Faculty of Psychology and Sports Sciences) approved the study. Publications in peer-reviewed journals are planned. The findings will be presented at scientific conferences.
Trial status: At the time of submission of this manuscript, recruitment is ongoing.
Trial registration number: NCT03336060; Pre-results.
Es existieren keine Vergleichsstudien, die den Einfluss eines periodisierten Maximalkrafttrainings in der tiefen Frontkniebeuge, tiefen Nackenkniebeuge und in der maschinengeführten Viertel-Nackenkniebeuge bis zu einem Kniegelenkwinkel von 120 ° auf die Entwicklung der Schnellkraftleistung, die Technikausführung, den Beschleunigungsablauf und die willkürliche neuromuskuläre Aktivierungsfähigkeit im Countermovement Jump (CMJ) sowie die winkelspezifische Entwicklung des isometrischen Maximal- und Explosivkraftvermögens der Beinextensoren untersucht haben. Aus diesem Grund wurden in zwei Forschungsprojekten an 23 weiblichen und 36 männlichen Sportstudierenden (24,11 ± 2,88 Jahre) die Auswirkungen eines periodisierten Maximalkrafttrainings in der tiefen Frontkniebeuge (Gruppe FKB, n = 20), tiefen Nackenkniebeuge (Gruppe NKB, n = 20) und der Viertel-Nackenkniebeuge bis 120-Grad-Kniegelenkwinkel (Gruppe NKB¼, n = 19) auf die Schnellkraftleistung im Squat Jump (SJ) und CMJ untersucht. Die Ausführung des CMJ wurde mit einer Digitalkamera aufgenommen, um die jeweils fünf besten Sprünge aus den Eingangs- und Ausgangstests einer Bewegungsanalyse zu unterziehen. Zu diesem Zweck erfolgte die Analyse und Auswertung der Hüft- und Kniegelenkwinkel im Umkehrpunkt des CMJ von insgesamt 740 Sprüngen. Des Weiteren wurden elektromyographische (EMG-)Ableitungen von Vastus medialis, Vastus lateralis,Rectus femoris, Biceps femoris und Erector spinae während der Ausführung des CMJ vorgenommen. Die Parallelisierung der drei Versuchsgruppen erfolgte auf Basis der Sprunghöhen im CMJ. Zusätzlich wurde eine Kontrollgruppe (K, n = 16) gebildet (Alter: 24,38 ± 0,50 Jahre)...
Effects of single-point acupuncture (HT7) in the prevention of test anxiety : results of a RCT
(2018)
Background: The number of students using neuro enhancement to improve their performance and to prevent test anxiety is increasing. The acupuncture point Heart 7 (HT7) has been described as being prominent in reducing states of anxiety.
Methods: We conducted a randomized placebo-controlled, two-armed pilot trial to investigate the efficacy of a single-point acupuncture treatment at bilateral HT7 compared to sham laser acupuncture on test anxiety. Test anxiety was induced applying the standardised protocol of the Trier Social Stress Test. Outcome measures included saliva samples analysed for cortisol and amylase, anxiety questionnaires and heart rate variability.
Results: Twenty-five male subjects (age 28 ± 5 years) were allocated to either verum acupuncture (n = 12) or sham laser acupuncture (n = 13). Cortisol peaked 20 min after the stress test (2-fold, 18.11 ± 2 nmol/l) and amylase 10 min after (2-fold, 259 ± 49 U/ml) with no difference between groups. There were no differences between groups regarding either anxiety questionnaires or physiological parameters. Compared to reference data (3-fold increase in cortisol), increase in stress hormones and heart rate seemed somewhat reduced.
Conclusions: Acupuncture may be a possible approach for the treatment of anxiety. Due to the lack of a no control treatment group, we cannot determine the magnitude of possible specific needle effects at HT7 to promote specific effects in the neuroendocrine system. Finally this study only examines the efficacy of a single time treatment.