@phdthesis{Wochatz2021,
  author    = {Wochatz, Monique},
  title     = {Influence of different loading conditions on scapular movement and scapular muscle activation patterns},
  school      = {Universit{\"a}t Potsdam},
  pages     = {iv, 129, xiv},
  year      = {2021},
  abstract  = {The scapula plays a significant role in efficient shoulder movement. Thus, alterations from typical scapular motion during upper limb movements are thought to be associated with shoulder pathologies. However, a clear understanding of the relationship is not yet obtained.. Scapular alterations may only represent physiological variability as their occurrence can appear equally as frequent in individuals with and without shoulder disorders. Evaluation of scapular motion during increased load might be a beneficial approach to detect clinically relevant alterations. However, functional motion adaptations in response to maximum effort upper extremity loading has not been established yet. Therefore, the overall purpose of this research project was to give further insight in physiological adaptations of scapular kinematics and their underlying scapular muscle activity in response to high demanding shoulder movements in healthy asymptomatic individuals. Prior to the investigation of the effect of various load situation, the reproducibility of scapular kinematics and scapular muscle activity were evaluated under maximum effort arm movements. Healthy asymptomatic adults performed unloaded and maximal loaded concentric and eccentric isokinetic shoulder flexion and extension movements in the scapular plane while scapular kinematics and scapular muscle activity were simultaneously assessed. A 3D motion capture system (infra-red cameras \& reflective markers) was utilized to track scapular and humerus motion in relation to the thorax. 3D scapular position angles were given for arm raising and lowering between humerus positions of 20° and 120° flexion. To further characterize the scapular pattern, the scapular motion extent and scapulohumeral rhythm (ratio of scapular and humerus motion extent) were determined. Muscle activity of the upper and lower trapezius and the serratus anterior were assessed with surface electromyography. Amplitudes were calculated for the whole ROM and four equidistant movement phases. Reliability was characterized by overall moderate to good reproducibility across the load conditions. Irrespective of applied load, scapular kinematics followed a motion pattern of continuous upward rotation, posterior tilt and external rotation during arm elevation and a continuous downward rotation, anterior tilt and internal rotation during arm lowering. However, kinematics were altered between maximal loaded and unloaded conditions showing increased upward rotation, reduced posterior tilt and external rotation. Further, the scapulohumeral rhythm was decreased and scapular motion extent increased under maximal loaded movements. Muscle activity during maximum effort were of greater magnitude and differed in their pattern in comparison to the continuous increase and decrease of activity during unloaded shoulder flexion and extension. Relationships between scapular kinematics and their underlying scapular muscle activity could only be identified for a few isolated combinations, whereas the majority showed no associations. Scapular kinematics and scapular muscle activity pattern alter according to the applied load. Alterations between the load conditions comply in magnitude and partially in direction with differences seen between symptomatic and asymptomatic individuals. Even though long-term effects of identified adaptations in response to maximum load are so far unclear, deviations from typical scapular motion or muscle activation should not per se be seen as indicators of shoulder impairment. However, evaluation of alterations in scapular motion and activation in response to maximum effort may have the potential to identify individuals that are unable to cope with increased upper limb demands. Findings further challenge the understanding of scapular motion and stabilization by the trapezius and serratus anterior muscles, as clear relationships between the underlying scapular muscle activity and scapular kinematics were neither observed during unloaded nor maximal loaded shoulder movements.},
  language  = {en}
}
@phdthesis{Lesinski2019,
  author    = {Lesinski, Melanie},
  title     = {Modulating factors for drop jump performance},
  school      = {Universit{\"a}t Potsdam},
  pages     = {viii, 57, xiii},
  year      = {2019},
  abstract  = {Background and objectives: Drop jumps (DJs) are well-established exercise drills during plyometric training. Several sports are performed under unstable surface conditions (e.g., soccer, beach volleyball, gymnastics). To closely mimic sport-specific demands, plyometric training includes DJs on both stable and unstable surfaces. According to the mechanical properties of the unstable surface (e.g., thickness, stiffness), altered temporal, mechanical, and physiological demands have been reported from previous cross-sectional studies compared with stable conditions. However, given that the human body simultaneously interacts with various factors (e.g., drop height, footwear, gender) during DJs on unstable surfaces, the investigation of isolated effects of unstable surface conditions might not be sufficient for designing an effective and safe DJ stimulus. Instead, the combined investigation of different factors and their interaction with surface instability have to be taken into consideration. Therefore, the present doctoral thesis seeks to complement our knowledge by examining the main and interaction effects of surface instability, drop height, footwear, and gender on DJ performance, knee joint kinematics, and neuromuscular activation. Methods: Healthy male and female physically active sports science students aged 19-26 years participated in the cross-sectional studies. Jump performance, sagittal and frontal plane knee joint kinematics, and leg muscle activity were measured during DJs on stable (i.e., firm force plate) and (highly) unstable surfaces (i.e., one or two AIREX® balance pads) from different drop heights (i.e., 20 cm, 40 cm, 60 cm) or under multiple footwear conditions (i.e., barefoot, minimal shoes, cushioned shoes). Results: Findings revealed that surface instability caused a DJ performance decline, reduced sagittal plane knee joint kinematics, and lower leg muscle activity during DJs. Sagittal plane knee joint kinematics as well as leg muscle activity decreased even more with increasing surface instability (i.e., two vs. one AIREX® balance pads). Higher (60 cm) compared to lower drop heights (≤ 40 cm) resulted in a DJ performance decline. In addition, increased sagittal plane knee joint kinematics as well as higher shank muscle activity were found during DJs from higher (60 cm) compared to lower drop heights (≤ 40 cm). Footwear properties almost exclusively affected frontal plane knee joint kinematics, indicating larger maximum knee valgus angles when performing DJs barefoot compared to shod. Between the different shoe properties (i.e., minimal vs. cushioned shoes), no significant differences during DJs were found at all. Only a few significant surface-drop height as well as surface-footwear interactions were found during DJs. They mainly indicated that drop height- and footwear-related effects are more pronounced during DJs on unstable compared to stable surfaces. In this regard, the maximum knee valgus angle was significantly greater when performing DJs from high drop heights (60 cm), but only on highly unstable surface. Further, braking and push-off times were significantly longer when performing DJs barefoot compared to shod, but only on unstable surface. Finally, analyses indicated no significant interactions with the gender factor. Conclusions: The findings of the present cumulative thesis indicate that stable rather than unstable surfaces as well as moderate (≤ 40 cm) rather than high (60 cm) drop heights provide sufficient stimuli to perform DJs. Furthermore, findings suggest that DJs on highly unstable surfaces (i.e., two AIREX® balance pads) from high drop heights (60 cm) as well as barefoot compared to shod seem to increase maximal knee valgus angle/stress by providing a more harmful DJ stimulus. Neuromuscular activation strategies appear to be modified by surface instability and drop height. However, leg muscle activity is only marginally effected by footwear and by the interactions of various external factors i.e., surface instability, drop height, footwear). Finally, gender did not significantly modulate the main or interaction effects of the observed external factors during DJs.},
  language  = {en}
}
@phdthesis{Mueller2017,
  author    = {M{\"u}ller, Juliane},
  title     = {Trunk loading and back pain},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-102428},
  school      = {Universit{\"a}t Potsdam},
  pages     = {ix, 123},
  year      = {2017},
  abstract  = {An essential function of the trunk is the compensation of external forces and loads in order to guarantee stability. Stabilising the trunk during sudden, repetitive loading in everyday tasks, as well as during performance is important in order to protect against injury. Hence, reduced trunk stability is accepted as a risk factor for the development of back pain (BP). An altered activity pattern including extended response and activation times as well as increased co-contraction of the trunk muscles as well as a reduced range of motion and increased movement variability of the trunk are evident in back pain patients (BPP). These differences to healthy controls (H) have been evaluated primarily in quasi-static test situations involving isolated loading directly to the trunk. Nevertheless, transferability to everyday, dynamic situations is under debate. Therefore, the aim of this project is to analyse 3-dimensional motion and neuromuscular reflex activity of the trunk as response to dynamic trunk loading in healthy (H) and back pain patients (BPP). A measurement tool was developed to assess trunk stability, consisting of dynamic test situations. During these tests, loading of the trunk is generated by the upper and lower limbs with and without additional perturbation. Therefore, lifting of objects and stumbling while walking are adequate represents. With the help of a 12-lead EMG, neuromuscular activity of the muscles encompassing the trunk was assessed. In addition, three-dimensional trunk motion was analysed using a newly developed multi-segmental trunk model. The set-up was checked for reproducibility as well as validity. Afterwards, the defined measurement set-up was applied to assess trunk stability in comparisons of healthy and back pain patients. Clinically acceptable to excellent reliability could be shown for the methods (EMG/kinematics) used in the test situations. No changes in trunk motion pattern could be observed in healthy adults during continuous loading (lifting of objects) of different weights. In contrast, sudden loading of the trunk through perturbations to the lower limbs during walking led to an increased neuromuscular activity and ROM of the trunk. Moreover, BPP showed a delayed muscle response time and extended duration until maximum neuromuscular activity in response to sudden walking perturbations compared to healthy controls. In addition, a reduced lateral flexion of the trunk during perturbation could be shown in BPP. It is concluded that perturbed gait seems suitable to provoke higher demands on trunk stability in adults. The altered neuromuscular and kinematic compensation pattern in back pain patients (BPP) can be interpreted as increased spine loading and reduced trunk stability in patients. Therefore, this novel assessment of trunk stability is suitable to identify deficits in BPP. Assignment of affected BPP to therapy interventions with focus on stabilisation of the trunk aiming to improve neuromuscular control in dynamic situations is implied. Hence, sensorimotor training (SMT) to enhance trunk stability and compensation of unexpected sudden loading should be preferred.},
  language  = {en}
}
@phdthesis{Krueger2005,
  author    = {Kr{\"u}ger, Tom},
  title     = {Zum Einfluss der Lateralit{\"a}t in zyklischen Sportarten bei Nachwuchsathleten},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5810},
  school      = {Universit{\"a}t Potsdam},
  year      = {2005},
  abstract  = {Die Auspr{\"a}gung der Lateralit{\"a}t der K{\"o}rperextremit{\"a}ten steht in engem Zusammenhang mit der Hemisph{\"a}renspezialisierung des menschlichen Gehirns. Die Lateralit{\"a}t und die Dominanz einer Hemisph{\"a}re mit ihren Auswirkungen auf die Leistungsf{\"a}higkeit ist ein bislang unvollst{\"a}ndig untersuchtes Ph{\"a}nomen im Sport. In der vorliegenden Arbeit soll daher die Bedeutung der Seitigkeitsauspr{\"a}gung im Rahmen sportlicher Bewegungsabl{\"a}ufe gepr{\"u}ft werden. Sowohl bei Messungen im "Freiwasser", als auch in der "Kanu-Gegenstromanlage" im Bereich des Kanurennsportes werden seit einigen Jahren sich in Qualit{\"a}t und Quantit{\"a}t unterscheidende Kraft-Zeit-Funktionen der linken und rechten K{\"o}rperseite beobachtet, die zwar dokumentiert, aber bislang ungepr{\"u}ft in ihrer Bedeutung als leistungsbeeinflussend angenommen werden. Im Zeitraum von Oktober 1997 bis Oktober 2000 wurden 275 Kajakfahrer und Canadierfahrer im Alter zwischen 11 und 20 Jahren zweimal j{\"a}hrlich (M{\"a}rz und Oktober) mit einem umfangreichen trainings- und bewegungswissenschaftlichen sowie biomechanischen Instrumentarium untersucht. Die Athleten geh{\"o}ren zum Nachwuchs- und Anschlusskader des LKV Brandenburg. Schwerpunkt der Fragestellung ist der Zusammenhang von auftretenden Kraftdifferenzen zwischen der linken und rechten oberen Extremit{\"a}t und sportartspezifischen Leistungen unter Laborbedingungen und Feldbedingungen. Es wurden objektive Daten zu ausgew{\"a}hlten Kraftf{\"a}higkeiten der oberen Arm-Beuge-Schlinge an einem Kraftdiagnoseger{\"a}t, Kraftverl{\"a}ufe am Messpaddel w{\"a}hrend Leistungs{\"u}berpr{\"u}fungen im "Kanu-Gegenstromkanal" und im "Freiwasser" {\"u}ber 250 m und 2.000 m im Jahresverlauf erhoben. Die Ergebnisse zeigen einen Trend der im Altersverlauf ansteigenden Differenz der Mittelwertunterschiede in der Maximalkraft zwischen dem linken und rechten Arm. Bei bestehenden Maximalkraftdifferenzen zwischen linker und rechter oberer Extremit{\"a}t in der L{\"a}ngsschnittgruppe liegen die Leistungen mit dem rechten Arm deutlich {\"u}ber den Kraftleistungen des linken Arms und sind nicht zuf{\"a}llig. Mit steigendem Maximalkraftniveau nimmt {\"u}berraschenderweise auch die Differenz der Maximalkraft zwischen der linken und rechten oberen Extremit{\"a}t trotz bilateralen Trainings zu. Die Ergebnisse der EMG-Analyse best{\"a}tigen, dass die Maximalkraft leistungsbestimmend f{\"u}r die Bootsleistungen ist. In den EMG-Signalverl{\"a}ufen werden die unterschiedlichen Belastungen der Labor- und Feldbedingungen mit individuellen Charakteristika nachgezeichnet. Deutlich unterscheiden sich die Kraftverl{\"a}ufe im "Freiwasser" gegen{\"u}ber den Kraftverl{\"a}ufen in der "Kanu-Gegenstromanlage". Bei der vorliegenden Untersuchung handelt es sich um eine erste empirische Arbeit zur Auswirkung von Seitigkeitsunterschieden in zyklischen Sportarten auf der Expertiseebene. In der Untersuchung wurden methodische Verfahren eingesetzt, die dem derzeitigen Forschungsstand in der Trainings- und Bewegungswissenschaft entsprechen. Neben varianzanalytischen Verfahren der Auswertung zur Darstellung von Mittelwertunterschieden und Zusammenh{\"a}nge pr{\"u}fenden Verfahren wurden ebenso explorative EMG-Analysen angewandt. Die Ergebnisse aus dem L{\"a}ngsschnitt belegen bei ausschließlich rechtsh{\"a}ndigen Probanden, dass die Schlussfolgerung von bevorzugter Extremit{\"a}t auf ein h{\"o}heres Kraftniveau nicht eineindeutig ist. Zwischen den oberen Extremit{\"a}ten bei Kanurennsportlern bestehen nicht nur zuf{\"a}llige Kraftunterschiede, trotz des bilateralen Trainings. Kontrovers diskutiert wird die Beziehung von bevorzugter Extremit{\"a}t und der H{\"o}he der Kraftentfaltung. Im Alltagsverst{\"a}ndnis wird h{\"a}ufig angenommen, dass ein h{\"o}heres Maximalkraftniveau in der Extremit{\"a}t vorliegen muss, die auch die bevorzugte (z.B. Schreibhand) ist (WIRTH \& LIPHARDT, 1999). Diese Eindeutigkeit konnte in der durchgef{\"u}hrten Untersuchung nicht best{\"a}tigt werden. Wie die Ergebnisse dieser Untersuchung deutlich zeigen, nimmt mit der h{\"o}heren Maximalkraft aber auch die Differenz der Kraftleistungen zwischen dem linken und rechten Arm bei bilateral ausgerichtetem Training zu. FISCHER (1988; 1992) wies nach, dass sich ein Training auf der subdominanten Seite in einem kontralateralen Leistungstransfer auf der dominanten Seite positiv auswirkte. Erkenntnisse von KUHN (1986) und HOLLMANN \& HETTINGER (2000) unterst{\"u}tzen nachhaltig die Ergebnisse. Die EMG-Ergebnisse zeigen die individuelle Reaktion auf die Belastungsanforderungen. Die elektromyographischen Daten beziehen sich auf den neuromuskul{\"a}ren Komplex. Somit sprechen hohe Amplitudenwerte einerseits f{\"u}r eine hohe Innervation der beteiligten motorischen Einheiten an der Bewegungsausf{\"u}hrung und andererseits f{\"u}r einsetzende Erm{\"u}dungserscheinungen im Muskel. In Bezug auf die Erm{\"u}dung der oberen Extremit{\"a}tenmuskeln der rechten und linken Seite beschreiben WILLIAMS, SHARMA \& BILODEAU (2002) keine signifikanten Unterschiede zwischen der dominanten und nichtdominanten Handseite.},
  subject      = {Kanurennsport},
  language  = {de}
}