Refine
Has Fulltext
- no (32)
Document Type
- Article (32) (remove)
Is part of the Bibliography
- yes (32)
Keywords
- Resistance training (4)
- athletic performance (3)
- electromyography (3)
- Cognitive/motor interference (2)
- Electromyography (2)
- Gait (2)
- Jump height (2)
- Kampfsport (2)
- Proactive/reactive balance (2)
- Seniors (2)
Hintergrund:
Eine gut ausgeprägte Rumpfstabilität ist eine wichtige Voraussetzung für die Mobilität der oberen und unteren Extremitäten während des sportlichen Bewegungsvollzugs. Vor diesem Hintergrund könnte die Rumpfkraft ein leistungsdeterminierender Faktor bei der Ausführung judospezifischer Bewegungen darstellen. Das Ziel der vorliegenden Studie war es, statistische Zusammenhänge zwischen der Rumpfkraft und kinetischen Parametern bei Anriss-Bewegungen von Judoka zu untersuchen.
Methode:
An der Untersuchung nahmen 21 leistungsorientierte Judoka mit einem mittleren Alter von 22 ± 4 Jahre und einem Trainingsumfang von 15 ± 4 Stunden pro Woche teil. Das maximale isokinetische Drehmoment (PIT) der Rumpfflexoren (PITFlex), -extensoren (PITEx) und -rotatoren (PITRot) wurde unter Verwendung eines isokinetischen Dynamometers (IsoMed 2000) erfasst. Zusätzlich wurden kinetische Parameter (mechanische Arbeit [W], dynamisch-realisierte Maximalkraft [Fmax]) bei Anriss-Bewegung im Stand und bei Anriss- mit Eindrehbewegung (d. h. Morote-seoi-nage) mithilfe eines judospezifischen Mess- und Informationssystems (JERGo©) erhoben.
Ergebnisse:
Die statistische Analyse zeigte signifikante Korrelationen (0,62 ≤ r P ≤ 0,72) zwischen den maximalen isokinetischen Drehmomenten (PITFlex, PITEx, PITRot) und der Anriss-Bewegung im Stand (W). Zudem konnten signifikante Zusammenhänge (0,59 ≤ r P ≤ 0,65) zwischen den isokinetischen Tests (PITEx, PITRot) und Fmax auf der Hubarmseite bei der Anriss-Bewegung im Stand gefunden werden. Für die Anriss- mit Eindrehbewegung ergaben sich signifikante Korrelationen (0,47 ≤ r P ≤ 0,88) zwischen den isokinetischen Tests (PITFlex, PITEx, PITRot) und Leistungskennwerten der judospezifischen Bewegung (W und Fmax), unabhängig von der untersuchten Armseite. Es wurden vergleichbare Korrelationskoeffizienten zwischen PIT der Rumpfflexoren, -extensoren und -rotatoren und judospezifischen Leistungskennwerten festgestellt. Weiterhin identifizierte die Regressionsanalyse den Kennwert PIT bei Rumpfextension als besten Prädiktor für die mechanische Arbeit bei Anriss-Bewegung im Stand (46,9 %). Bei der Anriss- mit Eindrehbewegung konnte PIT der Rumpfrotatoren auf die Hubarmseite als bester Prädiktor für die mechanische Arbeit (69,4 %) ermittelt werden.
Schlussfolgerung:
Die Ergebnisse zeigen, dass die Rumpfkraft, insbesondere bei der Rumpfrotationsbewegung, mit Variablen der judospezifischen Leistungskennwerte bei der Anriss- mit Eindrehbewegung assoziiert ist. Dies impliziert, dass vor allem durch rumpfrotationskräftigende Übungen Einfluss auf die Anriss- mit Eindrehbewegung (d. h. Morote-seoi-nage) genommen werden könnte.
Hintergrund Schnellkräftige Wurfeingangsbewegungen stellen im Judo entscheidende Voraussetzungen für den Wettkampferfolg dar, weshalb das Training der Anrissbewegung ein zentrales Element des judospezifischen Trainings darstellt. Das Ziel der Studie bestand darin, die Effekte eines Anrisstrainings mit einem Judoergometer-System (ATJ) gegenüber einem tradierten Anrisstraining mit Partner (ATP) auf kinetische und elektromyografische Parameter des Anreißens bei Wurfeingangsbewegungen von Judoka zu untersuchen. Methode Männliche leistungsorientierte Judoka (N = 24, Alter: 22 ± 4 Jahre; Trainingserfahrung: 15 ± 3 Jahre) wurden randomisiert in zwei Gruppen aufgeteilt. Im Crossover-Design absolvierte die erste Gruppe über vier Wochen ein ATJ gefolgt von vier Wochen ATP (je 3x/ Woche). Die zweite Gruppe führte beide Trainingsvarianten in umgekehrter Reihenfolge durch. ATJ und ATP wurden zusätzlich zum bestehenden Training absolviert. Vor dem Training sowie nach vier und nach acht Wochen Training wurden Tests zur Erfassung kinetischer Parameter (dynamisch-realisierte Maximalkraft, Explosivkraft, mechanische Arbeit) und elektromyografischer (EMG) Schulter-/ Rumpfmuskelaktivitäten (M. biceps brachii, M. deltoideus, M. trapezius, M. erector spinae) für die Hub- und Zugarmseite bei Wurfeingangsbewegungen am Judoergometer sowie sportartunspezifische Krafttests (d. h. Liegend-Anreißen, Klimmziehen) durchgeführt.
Ergebnisse Die Ergebnisse der statistischen Analyse ergaben über den gesamten Interventionszeitraum (8 Wochen) für beide Trainingsgruppen signifikante Verbesserungen der kinetischen Parameter (p <,05; 0,83 ≤d≤ 1,77) und EMG-Aktivitäten (p <,05; 1,07 ≤d≤ 2,25). Darüber hinaus zeigten sich größere Zuwachsraten in der Explosivkraft, der mechanischen Arbeit und den Schulter-/Rumpfmuskelaktivitäten (M. deltoideus, M. erector spinae, M. trapezius) zugunsten von ATJ im Vergleich zu ATP (p <,05; 1,25 ≤d≤ 2,79). Für die sportartunspezifischen Kraftwerte wurden keine signifikanten Veränderungen festgestellt.
Schlussfolgerung Die vorliegenden Ergebnisse zeigen, dass ATJ gegenüber ATP größere Steigerungsraten von kinetischen und elektromyografischen Parametern des Anreißens bei Wurfeingangsbewegungen von Judoka bewirkt. Die trainingsbedingten Leistungssteigerungen scheinen zumindest teilweise auf neuronalen Anpassungen zu beruhen.
Background
Generating percentile values is helpful for the identification of children with specific fitness characteristics (i.e., low or high fitness level) to set appropriate fitness goals (i.e., fitness/health promotion and/or long-term youth athlete development). Thus, the aim of this longitudinal study was to assess physical fitness development in healthy children aged 9–12 years and to compute sex- and age-specific percentile values.
Methods
Two-hundred and forty children (88 girls, 152 boys) participated in this study and were tested for their physical fitness. Physical fitness was assessed using the 50-m sprint test (i.e., speed), the 1-kg ball push test, the triple hop test (i.e., upper- and lower- extremity muscular power), the stand-and-reach test (i.e., flexibility), the star run test (i.e., agility), and the 9-min run test (i.e., endurance). Age- and sex-specific percentile values (i.e., P10 to P90) were generated using the Lambda, Mu, and Sigma method. Adjusted (for change in body weight, height, and baseline performance) age- and sex-differences as well as the interactions thereof were expressed by calculating effect sizes (Cohen’s d).
Results
Significant main effects of Age were detected for all physical fitness tests (d = 0.40–1.34), whereas significant main effects of Sex were found for upper-extremity muscular power (d = 0.55), flexibility (d = 0.81), agility (d = 0.44), and endurance (d = 0.32) only. Further, significant Sex by Age interactions were observed for upper-extremity muscular power (d = 0.36), flexibility (d = 0.61), and agility (d = 0.27) in favor of girls. Both, linear and curvilinear shaped curves were found for percentile values across the fitness tests. Accelerated (curvilinear) improvements were observed for upper-extremity muscular power (boys: 10–11 yrs; girls: 9–11 yrs), agility (boys: 9–10 yrs; girls: 9–11 yrs), and endurance (boys: 9–10 yrs; girls: 9–10 yrs). Tabulated percentiles for the 9-min run test indicated that running distances between 1,407–1,507 m, 1,479–1,597 m, 1,423–1,654 m, and 1,433–1,666 m in 9- to 12-year-old boys and 1,262–1,362 m, 1,329–1,434 m, 1,392–1,501 m, and 1,415–1,526 m in 9- to 12-year-old girls correspond to a “medium” fitness level (i.e., P40 to P60) in this population.
Conclusions
The observed differences in physical fitness development between boys and girls illustrate that age- and sex-specific maturational processes might have an impact on the fitness status of healthy children. Our statistical analyses revealed linear (e.g., lower-extremity muscular power) and curvilinear (e.g., agility) models of fitness improvement with age which is indicative of timed and capacity-specific fitness development pattern during childhood. Lastly, the provided age- and sex-specific percentile values can be used by coaches for talent identification and by teachers for rating/grading of children’s motor performance.
Background
It has been demonstrated that core strength training is an effective means to enhance trunk muscle strength (TMS) and proxies of physical fitness in youth. Of note, cross-sectional studies revealed that the inclusion of unstable elements in core strengthening exercises produced increases in trunk muscle activity and thus provide potential extra training stimuli for performance enhancement. Thus, utilizing unstable surfaces during core strength training may even produce larger performance gains. However, the effects of core strength training using unstable surfaces are unresolved in youth. This randomized controlled study specifically investigated the effects of core strength training performed on stable surfaces (CSTS) compared to unstable surfaces (CSTU) on physical fitness in school-aged children.
Methods
Twenty-seven (14 girls, 13 boys) healthy subjects (mean age: 14 ± 1 years, age range: 13–15 years) were randomly assigned to a CSTS (n = 13) or a CSTU (n = 14) group. Both training programs lasted 6 weeks (2 sessions/week) and included frontal, dorsal, and lateral core exercises. During CSTU, these exercises were conducted on unstable surfaces (e.g., TOGU© DYNAIR CUSSIONS, THERA-BAND© STABILITY TRAINER).
Results
Significant main effects of Time (pre vs. post) were observed for the TMS tests (8-22%, f = 0.47-0.76), the jumping sideways test (4-5%, f = 1.07), and the Y balance test (2-3%, f = 0.46-0.49). Trends towards significance were found for the standing long jump test (1-3%, f = 0.39) and the stand-and-reach test (0-2%, f = 0.39). We could not detect any significant main effects of Group. Significant Time x Group interactions were detected for the stand-and-reach test in favour of the CSTU group (2%, f = 0.54).
Conclusions
Core strength training resulted in significant increases in proxies of physical fitness in adolescents. However, CSTU as compared to CSTS had only limited additional effects (i.e., stand-and-reach test). Consequently, if the goal of training is to enhance physical fitness, then CSTU has limited advantages over CSTS.
Effects of Backpack Carriage on Dual-Task Performance in Children During Standing and Walking
(2016)
Our experimental approach included two studies to determine discriminative validity and test-retest reliability (study 1) as well as ecological validity (study 2) of a judo ergometer system while performing judo-specific movements. Sixteen elite (age: 23 +/- 3 years) and 11 sub-elite (age: 16 +/- 1 years) athletes participated in study 1 and 14 male sub-elite judo athletes participated in study 2. Discriminative validity and test-retest reliability of sport-specific parameters (mechanical work, maximal force) were assessed during pulling movements with and without tsukuri (kuzushi). Ecological validity of muscle activity was determined by performing pulling movements using the ergometer without tsukuri and during the same movements against an opponent. In both conditions, electromyographic activity of trunk (e.g., m. erector spinae) and upper limb muscles (e.g., m. biceps brachii) were assessed separately for the lifting and pulling arm. Elite athletes showed mostly better mechanical work, maximal force, and power (0.12 <= d <= 1.80) compared with sub-elite athletes. The receiver operating characteristic analysis revealed acceptable validity of the JERGo(C) system to discriminate athletes of different performance levels predominantly during kuzushi without tsukuri (area under the curve = 0.27-0.90). Moreover, small-to-medium discriminative validity was found to detect meaningful performance changes for mechanical work and maximal force. The JERGo(C) system showed small-to-high relative (ICC = 0.37-0.92) and absolute reliability (SEM = 10.8-18.8%). Finally, our analyses revealed acceptable correlations (r = 0.41-0.88) between muscle activity during kuzushi performed with the JERGo(C) system compared with a judo opponent. Our findings indicate that the JERGo(C) system is a valid and reliable test instrument for the assessment and training of judo-specific pulling kinetics particularly during kuzushi movement without tsukuri.
Background: Age-related postural misalignment, balance deficits and strength/power losses are associated with impaired functional mobility and an increased risk of falling in seniors. Core instability strength training (CIT) involves exercises that are challenging for both trunk muscles and postural control and may thus have the potential to induce benefits in trunk muscle strength, spinal mobility and balance performance. Objective: The objective was to investigate the effects of CIT on measures of trunk muscle strength, spinal mobility, dynamic balance and functional mobility in seniors. Methods: Thirty-two older adults were randomly assigned to an intervention group (INT; n = 16, aged 70.8 +/- 4.1 years) that conducted a 9-week progressive CIT or to a control group (n = 16, aged 70.2 +/- 4.5 years). Maximal isometric strength of the trunk flexors/extensors/lateral flexors (right, left)/rotators (right, left) as well as of spinal mobility in the sagittal and the coronal plane was measured before and after the intervention program. Dynamic balance (i.e. walking 10 m on an optoelectric walkway, the Functional Reach test) and functional mobility (Timed Up and Go test) were additionally tested. Results: Program compliance was excellent with participants of the INT group completing 92% of the training sessions. Significant group x test interactions were found for the maximal isometric strength of the trunk flexors (34%, p < 0.001), extensors (21%, p < 0.001), lateral flexors (right: 48%, p < 0.001; left: 53%, p < 0.001) and left rotators (42%, p < 0.001) in favor of the INT group. Further, training-related improvements were found for spinal mobility in the sagittal (11%, p < 0.001) and coronal plane (11%, p = 0.06) directions, for stride velocity (9%, p < 0.05), the coefficient of variation in stride velocity (31%, p < 0.05), the Functional Reach test (20%, p < 0.05) and the Timed Up and Go test (4%, p < 0.05) in favor of the INT group. Conclusion: CIT proved to be a feasible exercise program for seniors with a high adherence rate. Age-related deficits in measures of trunk muscle strength, spinal mobility, dynamic balance and functional mobility can be mitigated by CIT. This training regimen could be used as an adjunct or even alternative to traditional balance and/or resistance training.
Background: The contractile history of a muscle or a muscle group can result in an acute enhancement of subsequent muscle force output. This phenomenon is referred to as postactivation potentiation (PAP) and it was frequently substantiated in original research manuscripts, systematic literature reviews, and meta-analyses. However, there is a lack in the literature regarding precise dose-response relations. This literature review describes the main determinants of PAP effects and additionally presents the state of the art regarding the acute effects of PAP protocols on measures of strength, power, and speed in subelite and elite athletes of different sport disciplines. Furthermore, an attempt is made to demonstrate evidence-based information concerning the design of effective PAP protocols.
Methods: Our literature search included the electronic databases Pubmed, SportDiscus, and Google Scholar (1995 - March 2013). In total, 23 studies met the inclusionary criteria for review.
Results: Findings from our literature review indicate that various conditioning activities produce acute PAP effects in subelite and particularly elite athletes. More specifically, conditioning activities that are characterised by multiple sets, moderate to high intensities (60 - 84 % of the one repetition maximum), and rest intervals of 7 - 10 min. following the conditioning activity have the potential to induce short-term improvements in muscle force output and sports performance.
Conclusion: It is recommended that subelite and particularly elite athletes from strength, power, and speed disciplines apply specifically tailored conditioning activities during the acute preparation process for competition to induce performance enhancing PAP effects.
Background: Therapeutic climbing exercises are employed for the treatment of shoulder-and knee-joint injuries. However, there is a void in the literature regarding muscle activation levels during the performance of these exercises. Thus, the purpose of this study was to investigate differences in muscle activation during therapeutic climbing exercises depending on the degree of task difficulty.
Participants/Material and Methods: A sample of 10 healthy subjects (sex: 4 females, 6 males; age: 27 +/- 3 years; climbing experience: 5 +/- 3 years) performed three shoulder girdle (i.e., wide shoulder pull, narrow shoulder pull, shoulder row) and two leg extensor (i.e., ascending frontal, ascending sidewards) exercises. Electromyographic (EMG) data were recorded on the right side for eleven muscles and then normalised using the maximum voluntary contractions for each muscle.
Results: With increasing task difficulty, muscle activity in all but one muscle (i.e., m. trapezius ascendens) increased significantly for the three shoulder girdle exercises. For the two leg extensor exercises, an increase in task difficulty produced a tendency towards yet not significantly higher muscle activity.
Conclusion: Shoulder row was the most effective therapeutic climbing exercise in the ability to activate muscles while showing the highest EMG signals. The absence of significant differences in muscle activity between the two leg extensor exercises indicates their equivalent use for muscle activation during therapy.
Muehlbauer, T, Gollhofer, A, and Granacher, U. Association of balance, strength, and power measures in young adults. J Strength Cond Res 27(3): 582-589, 2013-The purpose of this study was to investigate the relationship between variables of static/dynamic balance, isometric strength, and power. Twenty-seven young healthy adults (mean age: 23 6 4 years) performed measurements of static (unperturbed)/dynamic (perturbed) balance, isometric strength (i.e., maximal isometric torque [MIT]; rate of torque development [RTD] of the plantar flexor), and power (i.e., countermovement jump [CMJ] height and power). No significant associations were found between variables of static and dynamic balance (r = -0.090 to + 0.329, p > 0.05) and between measures of static/dynamic balance and isometric strength (r = +0.041 to +0.387, p > 0.05) and static/dynamic balance and power (r = -0.076 to + 0.218, p > 0.05). Significant positive correlations (r) were detected between variables of power and isometric strength ranging from +0.458 to +0.689 (p, 0.05). Furthermore, simple regression analyses revealed that a 10% increase in mean CMJ height (4.1 cm) was associated with 22.9 N.m and 128.4 N.m.s(-1) better MIT and RTD, respectively. The nonsignificant correlation between static and dynamic balance measures and between static/dynamic balance, isometric strength, and power variables implies that these capacities may be independent of each other and may have to be tested and trained complementarily.