@phdthesis{Kopinski2016,
  author    = {Kopinski, Stephan},
  title     = {The neuromuscular efficiency of lower back muscles in low back pain},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-101241},
  school      = {Universit{\"a}t Potsdam},
  pages     = {117},
  year      = {2016},
  abstract  = {BACKGROUND: The etiology of low back pain (LBP), one of the most prevalent and costly diseases of our time, is accepted to be multi-causal, placing functional factors in the focus of research. Thereby, pain models suggest a centrally controlled strategy of trunk stiffening in LBP. However, supporting biomechanical evidence is mostly limited to static measurements during maximum voluntary contractions (MVC), probably influenced by psychological factors in LBP. Alternatively, repeated findings indicate that the neuromuscular efficiency (NME), characterized by the strength-to-activation relationship (SAR), of lower back muscles is impaired in LBP. Therefore, a dynamic SAR protocol, consisting of normalized trunk muscle activation recordings during submaximal loads (SMVC) seems to be relevant. This thesis aimed to investigate the influence of LBP on the NME and activation pattern of trunk muscles during dynamic trunk extensions. METHODS: The SAR protocol consisted of an initial MVC reference trial (MVC1), followed by SMVCs at 20, 40, 60 and 80\% of MVC1 load. An isokinetic trunk dynamometer (Con-Trex TP, ROM: 45° flexion to 10° extension, velocity: 45°/s) and a trunk surface EMG setup (myon, up to 12 leads) was used. Extension torque output [Nm] and muscular activation [V] were assessed in all trials. Finally, another MVC trial was performed (MVC2) for reliability analysis. For SAR evaluation the SMVC trial values were normalized [\%MVC1] and compared inter- and intra-individually. The methodical validity of the approach was tested in an isometric SAR single-case pilot study (S1a: N = 2, female LBP patient vs. healthy male). In addition, the validity of the MVC reference method was verified by comparing different contraction modes (S1b: N = 17, healthy individuals). Next, the isokinetic protocol was validated in terms of content for its applicability to display known physiological differences between sexes in a cross-sectional study (S2: each n = 25 healthy males/females). Finally, the influence of acute pain on NME was investigated longitudinally by comparing N = 8 acute LBP patients with the retest after remission of pain (S3). The SAR analysis focused on normalized agonistic extensor activation and abdominal and synergistic extensor co-activation (t-tests, ANOVA, α = .05) as well as on reliability of MVC1/2 outcomes. RESULTS: During the methodological validation of the protocol (S1a), the isometric SAR was found to be descriptively different between individuals. Whereas torque output was highest during eccentric MVC, no relevant difference in peak EMG activation was found between contraction modes (S1b). The isokinetic SAR sex comparison (S2), though showing no significant overall effects, revealed higher normalized extensor activation at moderate submaximal loads in females (13 ± 4\%), primarily caused by pronounced thoracic activation. Similarly, co-activation analysis resulted in significantly higher antagonistic activation at moderate loads compared to males (33 ± 9\%). During intra-individual analysis of SAR in LBP patients (S3), a significant effect of pain status on the SAR has been identified, manifesting as increased normalized EMG activation of extensors during acute LBP (11 ± 8\%) particularly at high load. Abdominal co-activation tended to be elevated (27 ± 11\%) just as the thoracic extensor parts seemed to take over proportions of lumbar activation. All together, the M. erector spinae behaviour during the SAR protocol was rather linear with the tendency to rise exponentially during high loads. For the level of normalized EMG activation during SMVCs, a clear increasing trend from healthy males to females over to non-acute and acute LBP patients was discovered. This was associated by elevated antagonistic activation and a shift of synergistic towards lumbar extensor activation. The MVC data revealed overall good reliability, with clearly higher variability during acute LBP. DISCUSSION: The present thesis demonstrates that the NME of lower back muscles is impaired in LBP patients, especially during an acute pain episode. A new dynamic protocol has been developed that makes it possible to display the underlying SAR using normalized trunk muscle EMG during submaximal isokinetic loads. The protocol shows promise as a biomechanical tool for diagnostic analysis of NME in LBP patients and monitoring of rehabilitation progress. Furthermore, reliability not of maximum strength but rather of peak EMG of MVC measurements seems to be decreased in LBP patients. Meanwhile, the findings of this thesis largely substantiate the assumptions made by the recently presented 'motor adaptation to pain' model, suggesting a pain-related intra- and intermuscular activation redistribution affecting movement and stiffness of the trunk. Further research is needed to distinguish the grade of NME impairment between LBP subgroups.},
  language  = {en}
}
@phdthesis{Fliesser2018,
  author    = {Fließer, Michael},
  title     = {Der Einfluss unterschiedlicher Indikatoren des sozio{\"o}konomischen Status auf R{\"u}ckenschmerz},
  doi       = {10.25932/publishup-42345},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423455},
  school      = {Universit{\"a}t Potsdam},
  pages     = {84},
  year      = {2018},
  abstract  = {Obwohl der sozio{\"o}konomische Status (SES) eine in der Sozialepidemiologie h{\"a}ufig gebrauchte Variable darstellt, ist seine Verwendung mit methodischen Problemen verkn{\"u}pft: Seine latente Struktur f{\"u}hrt dazu, dass sich verschiedene M{\"o}glichkeiten der Operationalisierung er{\"o}ffnen. Diese reichen von klassischen Ungleichheitsindikatoren wie Bildung, Einkommen oder Berufsposition, {\"u}ber multidimensionale oder {\"u}ber Nachbarschaftsmerkmale konstruierte Indizes, bis hin zu subjektiven Statuseinsch{\"a}tzungen. Problematisch ist dies insofern, als verschiedene Indikatoren auf unterschiedlichen theoretischen Konstrukten beruhen und unterschiedliche Schlussfolgerungen erlauben. In dieser Arbeit wird deshalb in einem ersten Schritt anhand eines systematischen Reviews zum Zusammenhang von SES und R{\"u}ckenschmerzen {\"u}berpr{\"u}ft, welche Indikatoren in wissenschaftlichen Publikationen eingesetzt werden und wie die Auswahl begr{\"u}ndet wird. Das Ergebnis zeigt eine klare Pr{\"a}ferenz f{\"u}r klassische Indikatoren (Bildung, Einkommen und Berufsposition). Erl{\"a}utert wurde die jeweilige Auswahl allerdings nur in einem geringen Prozentsatz der untersuchten Artikel, obwohl die unterschiedlichen Studienergebnisse nahelegen, dass der gew{\"a}hlte Indikator einen Einfluss auf den gefundenen Zusammenhang aus{\"u}ben k{\"o}nnte. Deshalb wurde in einem weiteren Schritt {\"u}berpr{\"u}ft, wie unterschiedliche SES-Indikatoren mit der Verbesserung von R{\"u}ckenschmerzen nach einer Rehabilitation (Studie 1) und der Neuentstehung von R{\"u}ckenschmerzen (Studie 2) zusammenh{\"a}ngen. Außerdem wurde untersucht, ob ein einfaches Modell den Zusammenhang von SES und Gesundheit so darstellen kann, dass a priori abzusch{\"a}tzen ist, wie hoch der Einfluss unterschiedlicher Indikatoren auf einen bestimmten Gesundheitsoutput sein k{\"o}nnte. Es zeigt sich, dass sich der errechnete Zusammenhang zwischen den verschiedenen Indikatoren und chronischen R{\"u}ckenschmerzen erheblich unterscheidet: F{\"u}r Menschen, die bereits wegen R{\"u}ckenschmerzen in Rehabilitation waren, erwiesen sich Bildung und Berufsposition als {\"a}hnlich einflussreiche Einflussfaktoren, w{\"a}hrend f{\"u}r das Einkommen kein bedeutender Zusammenhang festgestellt werden konnte. F{\"u}r die Neuentstehung chronischer R{\"u}ckenschmerzen zeigte sich die Berufsposition als wichtigster Indikator, gefolgt von Bildung, w{\"a}hrend f{\"u}r Einkommen kein signifikanter Zusammenhang gefunden werden konnte. Folglich bestimmt die Wahl des Indikators die H{\"o}he des festgestellten Zusammenhangs stark mit. Unterschiedliche Indikatoren d{\"u}rfen deshalb nicht als austauschbar betrachtet werden und es muss bei jeder Forschungsfrage genau {\"u}berlegt werden, welcher Indikator f{\"u}r die jeweilige Fragestellung am besten verwendet werden kann. Das vorgeschlagene theoretische Modell kann dabei als Unterst{\"u}tzung dienen.},
  language  = {de}
}
@phdthesis{AppiahDwomoh2019,
  author    = {Appiah-Dwomoh, Edem Korkor},
  title     = {Postural control and back pain in adolescent athletes},
  doi       = {10.25932/publishup-44269},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-442692},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VI, 77, X},
  year      = {2019},
  abstract  = {Back pain is a problem in adolescent athletes affecting postural control which is an important requirement for physical and daily activities whether under static or dynamic conditions. One leg stance and star excursion balance postural control tests are effective in measuring static and dynamic postural control respectively. These tests have been used in individuals with back pain, athletes and non-athletes without first establishing their reliabilities. In addition to this, there is no published literature investigating dynamic posture in adolescent athletes with back pain using the star excursion balance test. Therefore, the aim of the thesis was to assess deficit in postural control in adolescent athletes with and without back pain using static (one leg stance test) and dynamic postural (SEBT) control tests. Adolescent athletes with and without back pain participated in the study. Static and dynamic postural control tests were performed using one leg stance and SEBT respectively. The reproducibility of both tests was established. Afterwards, it was determined whether there was an association between static and dynamic posture using the measure of displacement of the centre pressure and reach distance respectively. Finally, it was investigated whether there was a difference in postural control in adolescent athletes with and without back pain using the one leg stance test and the SEBT. Fair to excellent reliabilities was recorded for the static (one leg stance) and dynamic (star excursion balance) postural control tests in the subjects of interest. No association was found between variables of the static and dynamic tests for the adolescent athletes with and without back pain. Also, no statistically significant difference was obtained between adolescent athletics with and without back pain using the static and dynamic postural control test. One leg stance test and SEBT can be used as measures of postural control in adolescent athletes with and without back pain. Although static and dynamic postural control might be related, adolescent athletes with and without back pain might be using different mechanisms in controlling their static and dynamic posture. Consequently, static and dynamic postural control in adolescent athletes with back pain was not different from those without back pain. These outcome measures might not be challenging enough to detect deficit in postural control in our study group of interest.},
  language  = {en}
}