TY - THES A1 - Gebel, Arnd T1 - Postural control in youth: From performance to neural correlates T1 - Die posturale Kontrolle von Kindern und Jugendlichen: Von Gleichgewichtsleistung zu neuronalen Korrelaten N2 - Background and objectives: The intricate interdependencies between the musculoskeletal and neural systems build the foundation for postural control in humans, which is a prerequisite for successful performance of daily and sports-specific activities. Balance training (BT) is a well-established training method to improve postural control and its components (i.e., static/dynamic steady-state, reactive, proactive balance). The effects of BT have been studied in adult and youth populations, but were systematically and comprehensively assessed only in young and old adults. Additionally, when taking a closer look at established recommendations for BT modalities (e.g., training period, frequency, volume), standardized means to assess and control the progressive increase in exercise intensity are missing. Considering that postural control is primarily neuronally driven, intensity is not easy to quantify. In this context, a measure of balance task difficulty (BTD) appears to be an auspicious alternative as a training modality to monitor BT and control training progression. However, it remains unclear how a systematic increase in BTD affects balance performance and neurophysiological outcomes. Therefore, the primary objectives of the present thesis were to systematically and comprehensively assess the effects of BT on balance performance in healthy youth and establish dose-response relationships for an adolescent population. Additionally, this thesis aimed to investigate the effects of a graded increase in BTD on balance performance (i.e., postural sway) and neurophysiological outcomes (i.e, leg muscle activity, leg muscle coactivation, cortical activity) in adolescents. Methods: Initially, a systematic review and meta-analysis on the effects of BT on balance performance in youth was conducted per the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement guidelines. Following this complementary analysis, thirteen healthy adolescents (3 female/ 10 male) aged 16-17 years were enrolled for two cross-sectional studies. The participants executed bipedal balance tasks on a multidirectional balance board that allowed six gradually increasing levels of BTD by narrowing the balance boards’ base of support. During task performance, two pressure sensitive mats fixed on the balance board recorded postural sway. Leg muscle activity and leg muscle coactivation were assessed via electromyography while electroencephalography was used to monitor cortical activity. Results: Findings from the systematic review and meta-analysis indicated moderate-to-large effects of BT on static and dynamic balance performance in youth (static: weighted mean standardized mean differences [SMDwm] = 0.71; dynamic: SMDwm = 1.03). In adolescents, training-induced effects were moderate and large for static (SMDwm = 0.61) and dynamic (SMDwm = 0.86) balance performance, respectively. Independently (i.e. modality-specific) calculated dose-response relationships identified a training period of 12 weeks, a frequency of two training sessions per week, a total of 24-36 sessions, a duration of 4-15 minutes, and a total duration of 31-60 minutes as the training modalities with the largest effect on overall balance performance in adolescents. However, the implemented meta-regression indicated that none of these training modalities (R² = 0%) could predict the observed performance-increasing effects of BT. Results from the first cross-sectional study revealed that a gradually increasing level of BTD caused increases in postural sway (p < 0.001; d = 6.36), higher leg muscle activity (p < 0.001; 2.19 < d < 4.88), and higher leg muscle coactivation (p < 0.001; 1.32 < d < 1.41). Increases in postural sway and leg muscle activity were mainly observed during low and high levels of task difficulty during continuous performance of the respective balance task. Results from the second cross-sectional study indicated frequency-specific increases/decreases in cortical activity of different brain areas (p < 0.005; 0.92 < d < 1.80) as a function of BTD. Higher cortical activity within the theta frequency band in the frontal and central right brain areas was observed with increasing postural demands. Concomitantly, activity in the alpha-2 frequency band was attenuated in parietal brain areas. Conclusion: BT is an effective method to increase static and dynamic balance performance and, thus, improve postural control in healthy youth populations. However, none of the reported training modalities (i.e., training period, frequency, volume) could explain the effects on balance performance. Furthermore, a gradually increasing level of task difficulty resulted in increases in postural sway, leg muscle activity, and coactivation. Frequency and brain area-specific increases/decreases in cortical activity emphasize the involvement of frontoparietal brain areas in regulatory processes of postural control dependent on BTD. Overall, it appears that increasing BTD can be easily accomplished by narrowing the base of support. Since valid methods to assess and quantify BT intensity do not exist, increasing BTD appears to be a very useful candidate to implement and monitor progression in BT programs in healthy adolescents. N2 - Hintergrund und Ziele: Die postural Kontrolle des Menschen basiert auf der komplexen Interaktion von muskuloskelettalem und neuralem System. Gleichzeitig bildet sie eine Grund-voraussetzung für die erfolgreiche Ausführung von sport-spezifischen Aktivitäten sowie denen des täglichen Lebens. Das Gleichgewichtstraining ist eine gut etablierte Trainingsmetho-de, welche der Verbesserung der posturalen Kontrolle und seiner Komponenten (statisch/dynamisch-kontinuierliches, reaktives, proaktives Gleichgewicht) dient. Die Effekte dieser Trainingsmethode wurden bereits bei gesunden jungen und älteren Erwachsenen sys-tematisch untersucht, wurde aber bisher bei Kindern und Jugendlichen versäumt. Bei genauerer Betrachtung der gängigen Trainingsempfehlungen zur Ausgestaltung der Trainingsvariablen (z.B., Dauer, Frequenz, Umfang) für das Gleichgewichtstraining fällt auf, dass momentan keine standardisierte Methode existiert, welche es ermöglicht die Intensität des Gleichgewichtstrainings zu erfassen. Da die posturale Kontrolle primär neuronal gesteuert ist, lässt sich die Intensität einzelner Gleichgewichtsübungen bzw. eines ganzen Trainings schwer bestimmen. Der Schwierigkeitsgrad einer Gleichgewichtsaufgabe könnte daher eine aussichtsreiche Alternative als Trainingsvariable zur Steuerung der Trainingsbelastung im Rahmen des Gleichgewichtstrainings sein. Bisher ist jedoch unklar wie sich eine graduelle Steigerung der Aufgabenschwierigkeit auf die Gleichgewichtsleistung sowie neurophysiologische Parameter auswirkt. Das primäre Ziel dieser Doktorarbeit ist es daher, die Effekte des Gleichgewichtstrainings auf die Gleichgewichtsleistung von gesunden Kindern und Jugendlichen systematisch zu untersuchen und zu aggregieren sowie entsprechende Dosis-Wirkungs-Verhältnisse für Jugendliche herauszuarbeiten. Des Weiteren soll der Einfluss einer graduellen Steigerung des Schwierigkeitsgrades einer Gleichgewichtsaufgabe auf die Gleichgewichtsleistung (d.h., posturale Schwankung) sowie neurophysiologische Parameter (d.h., Aktivität und Koaktivität der Beinmuskulatur, kortikale Aktivität) von Jugendlichen untersucht werden. Methoden: Zu Beginn wurde ein systematischer Überblicksbeitrag mit Meta-Analyse angefertigt, welcher, basierend auf den PRISMA Richtlinien, die Effekte des Gleichgewichtstrainings auf die Gleichgewichtsleistung von Kindern und Jugendlichen zusammenfasste und quantifizierte. Im Anschluss an diese Übersichtsarbeit wurden zwei Querschnittsuntersuchungen durchgeführt. An beiden Untersuchungen nahmen 13 gesunde Jugendliche im Alter von 16 – 17 Jahren (3 weiblich/ 10 männlich) teil. Im Rahmen der experimentellen Untersuchung führten die Jugendlichen eine Gleichgewichtsaufgabe in bipedalem Stand auf einem multidirektionalen Balance Board aus. Der Schwierigkeitsgrad der Gleichgewichtsaufgabe wurde hierbei mittels Verkleinerung der Unterstützungsfläche des Balance Boards über sechs Stufen graduell gesteigert. Während der Aufgabenausführung wurde die posturale Schwankung mittels zweier drucksensitiver Messmatten erfasst. Die Beinmuskelaktivität und -koaktivität sowie die kortikale Aktivität wurden mittels Elektromyographie beziehungsweise Elektroenzephalographie aufgenommen. Ergebnisse: Insgesamt hat Gleichgewichtstraining einen moderaten bis großen Einfluss auf die statische und dynamische Gleichgewichtsleistung von Kindern und Jugendlichen (statisch: gewichtete mittlere standardisierte Mittelwertsdifferenz [SMDwm] = 0,71; dynamisch: SMDwm = 1,03). Eine altersspezifische Subgruppenanalyse für Jugendliche wies mittlere Trainingseffekte für das statische (SMDwm = 0,61) sowie große für das dynamische Gleich-gewicht (SMDwm = 0,86) aus. Unabhängig (d.h., für jede Trainingsvariable spezifisch) berechnete Dosis-Wirkungs-Beziehungen zeigten, dass eine Interventionsdauer von 12 Wochen, eine Trainingsfrequenz von zwei Einheiten pro Woche, eine Anzahl von 24 – 36 Trainings-einheiten, eine Dauer von 4 – 15 Minuten pro Einheit sowie eine wöchentliche Gesamttrainingszeit von 31 – 60 Minuten den größten Einfluss auf die Gleichgewichtsleistung von Jugendlichen hatten. Die zusätzlich durchgeführte Metaregression zeigte, dass keine der untersuchten Trainingsvariablen (R² = 0%) die leistungssteigernden Effekte des Gleichgewichtstrainings vorhersagen konnte. In Bezug auf die Daten der ersten Querschnittsstudie ergab die statistische Analyse, dass ein gradueller Anstieg des Schwierigkeitsgrades der Gleichgewichtsaufgabe zu einem Anstieg der posturalen Schwankungen (p < 0,001; d = 6,36), höherer Aktivität der Beinmuskulatur (p < 0,001; 2,19 < d < 4,88) sowie höherer Koaktivität der Beinmuskulatur (p < 0,001; 1,32 < d < 1,41). Während der Ausführung der Gleichgewichtsaufgabe mit ansteigendem Schwierig-keitsgrad war die Zunahme der posturalen Schwankungen und der Aktivität der Beinmuskulatur primär zwischen niedrigen und hohen Schwierigkeitsgraden zu beobachten. Die Ergebnisse der zweiten Querschnittsstudie zeigten, dass ein gradueller Anstieg des Schwierigkeitsgrades der Gleichgewichtsaufgabe einen frequenzspezifischen Anstieg bzw. Abfall der kortikalen Aktivität (p < 0,005; 0,92 < d < 1,80) in verschiedenen Hirnarealen zur Folge hat. Auf kortikaler Ebene nahm die Aktivität innerhalb der Thetafrequenz in frontalen und zentralen Hirnarealen mit höheren posturalen Anforderungen zu. Die Aktivität in der Alpha-2-Frequenz nahm hingegen gleichzeitig in parietalen Hirnarealen ab. Fazit: Gleichgewichtstraining ist eine effektive Methode, um die statische und dynamische Gleichgewichtsleistung und somit die postural Kontrolle von Kindern und Jugendlichen zu verbessern. Dennoch konnte keine der untersuchten Trainingsvariablen (d.h., Dauer, Frequenz, Umfang) die trainingsinduzierten Effekte auf die Gleichgewichtsleistung erklären. Die im Rahmen der Querschnittsuntersuchungen beobachteten Anstieg der posturalen Schwankung sowie der Aktivität und Koaktivität der Beinmuskulatur waren auf den Anstieg des Schwierigkeitsgrades der Gleichgewichtsaufgabe zurückzuführen. Gleichzeitig deuten die auf bestimmte Hirnareale begrenzte frequenzspezifischen Anstiege bzw. Abfälle der kortikalen Aktivität die Beteiligung frontoparietaler Areale bei regulatorischen Prozessen der posturalen Kontrolle bei ansteigender Aufgabenschwierigkeit an. Somit lässt sich konstatieren, dass die Steigerung des Schwierigkeitsgrades einer Gleichgewichtsaufgabe mittels Verkleinerung der Unterstützungsfläche leicht umgesetzt werden kann. Da es bis dato keine valide Methode zur Erfassung der Intensität eines Gleichgewichtstrainings gibt, erscheint die Steigerung der Aufgabenschwierigkeit als praktische Alternative, um Progression in Gleichgewichtstrainingsinterventionen bei gesunden Jugendlichen quantifizieren und implementierern zu können. KW - postural sway KW - muscle activity KW - cortical activity KW - balance trainin KW - task difficulty KW - postural Schwankung KW - Muskelaktivität KW - kortikale Aktivität KW - Gleichgewichtstraining KW - Aufgabenschwierigkeit Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-533034 ER - TY - GEN A1 - Zouita, Sghaier A1 - Zouhal, Hassane A1 - Ferchichi, Habiba A1 - Paillard, Thierry A1 - Dziri, Catherine A1 - Hackney, Anthony C. A1 - Laher, Ismail A1 - Granacher, Urs A1 - Ben Moussa Zouita, Amira T1 - Effects of Combined Balance and Strength Training on Measures of Balance and Muscle Strength in Older Women With a History of Falls T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - Objective: We investigated the effects of combined balance and strength training on measures of balance and muscle strength in older women with a history of falls. Methods: Twenty-seven older women aged 70.4 ± 4.1 years (age range: 65 to 75 years) were randomly allocated to either an intervention (IG, n = 12) or an active control (CG, n = 15) group. The IG completed 8 weeks combined balance and strength training program with three sessions per week including visual biofeedback using force plates. The CG received physical therapy and gait training at a rehabilitation center. Training volumes were similar between the groups. Pre and post training, tests were applied for the assessment of muscle strength (weight-bearing squat [WBS] by measuring the percentage of body mass borne by each leg at different knee flexions [0°, 30°, 60°, and 90°], sit-to-stand test [STS]), and balance. Balance tests used the modified clinical test of sensory interaction (mCTSIB) with eyes closed (EC) and opened (EO), on stable (firm) and unstable (foam) surfaces as well as spatial parameters of gait such as step width and length (cm) and walking speed (cm/s). Results: Significant group × time interactions were found for different degrees of knee flexion during WBS (0.0001 < p < 0.013, 0.441 < d < 0.762). Post hoc tests revealed significant pre-to-post improvements for both legs and for all degrees of flexion (0.0001 < p < 0.002, 0.697 < d < 1.875) for IG compared to CG. Significant group × time interactions were found for firm EO, foam EO, firm EC, and foam EC (0.006 < p < 0.029; 0.302 < d < 0.518). Post hoc tests showed significant pre-to-post improvements for both legs and for all degrees of oscillations (0.0001 < p < 0.004, 0.753 < d < 2.097) for IG compared to CG. This study indicates that combined balance and strength training improved percentage distribution of body weight between legs at different conditions of knee flexion (0°, 30°, 60°, and 90°) and also decreased the sway oscillation on a firm surface with eyes closed, and on foam surface (with eyes opened or closed) in the IG. Conclusion: The higher positive effects of training seen in standing balance tests, compared with dynamic tests, suggests that balance training exercises including lateral, forward, and backward exercises improved static balance to a greater extent in older women. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 699 KW - aging KW - exercise KW - postural sway KW - force KW - tasks Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-490932 SN - 1866-8364 IS - 699 ER - TY - JOUR A1 - Zouita, Sghaier A1 - Zouhal, Hassane A1 - Ferchichi, Habiba A1 - Paillard, Thierry A1 - Dziri, Catherine A1 - Hackney, Anthony C. A1 - Laher, Ismail A1 - Granacher, Urs A1 - Ben Moussa Zouita, Amira T1 - Effects of Combined Balance and Strength Training on Measures of Balance and Muscle Strength in Older Women With a History of Falls JF - Frontiers in Physiology N2 - Objective: We investigated the effects of combined balance and strength training on measures of balance and muscle strength in older women with a history of falls. Methods: Twenty-seven older women aged 70.4 ± 4.1 years (age range: 65 to 75 years) were randomly allocated to either an intervention (IG, n = 12) or an active control (CG, n = 15) group. The IG completed 8 weeks combined balance and strength training program with three sessions per week including visual biofeedback using force plates. The CG received physical therapy and gait training at a rehabilitation center. Training volumes were similar between the groups. Pre and post training, tests were applied for the assessment of muscle strength (weight-bearing squat [WBS] by measuring the percentage of body mass borne by each leg at different knee flexions [0°, 30°, 60°, and 90°], sit-to-stand test [STS]), and balance. Balance tests used the modified clinical test of sensory interaction (mCTSIB) with eyes closed (EC) and opened (EO), on stable (firm) and unstable (foam) surfaces as well as spatial parameters of gait such as step width and length (cm) and walking speed (cm/s). Results: Significant group × time interactions were found for different degrees of knee flexion during WBS (0.0001 < p < 0.013, 0.441 < d < 0.762). Post hoc tests revealed significant pre-to-post improvements for both legs and for all degrees of flexion (0.0001 < p < 0.002, 0.697 < d < 1.875) for IG compared to CG. Significant group × time interactions were found for firm EO, foam EO, firm EC, and foam EC (0.006 < p < 0.029; 0.302 < d < 0.518). Post hoc tests showed significant pre-to-post improvements for both legs and for all degrees of oscillations (0.0001 < p < 0.004, 0.753 < d < 2.097) for IG compared to CG. This study indicates that combined balance and strength training improved percentage distribution of body weight between legs at different conditions of knee flexion (0°, 30°, 60°, and 90°) and also decreased the sway oscillation on a firm surface with eyes closed, and on foam surface (with eyes opened or closed) in the IG. Conclusion: The higher positive effects of training seen in standing balance tests, compared with dynamic tests, suggests that balance training exercises including lateral, forward, and backward exercises improved static balance to a greater extent in older women. KW - aging KW - exercise KW - postural sway KW - force KW - tasks Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.619016 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Grabow, Lena A1 - Young, James D. A1 - Byrne, Jeannette M. A1 - Granacher, Urs A1 - Behm, David George T1 - Unilateral Rolling of the Foot did not Affect Non-Local Range of Motion or Balance JF - Journal of sports science & medicine N2 - Non-local or crossover (contralateral and non-stretched muscles) increases in range-of-motion (ROM) and balance have been reported following rolling of quadriceps, hamstrings and plantar flexors. Since there is limited information regarding plantar sole (foot) rolling effects, the objectives of this study were to determine if unilateral foot rolling would affect ipsilateral and contralateral measures of ROM and balance in young healthy adults. A randomized within-subject design was to examine non-local effects of unilateral foot rolling on ipsilateral and contralateral limb ankle dorsiflexion ROM and a modified sit-and-reachtest (SRT). Static balance was also tested during a 30 s single leg stance test. Twelve participants performed three bouts of 60 s unilateral plantar sole rolling using a roller on the dominant foot with 60 s rest intervals between sets. ROM and balance measures were assessed in separate sessions at pre-intervention, immediately and 10 minutes post-intervention. To evaluate repeated measures effects, two SRT pre-tests were implemented. Results demonstrated that the second pre-test SRT was 6.6% higher than the first pre-test (p = 0.009, d = 1.91). There were no statistically significant effects of foot rolling on any measures immediately or 10 min post-test. To conclude, unilateral foot rolling did not produce statistically significant increases in ipsilateral or contralateral dorsiflexion or SRT ROM nor did it affect postural sway. Our statistically non-significant findings might be attributed to a lower degree of roller-induced afferent stimulation due to the smaller volume of myofascia and muscle compared to prior studies. Furthermore, ROM results from studies utilizing a single pre-test without a sufficient warm-up should be viewed critically. KW - Crossover KW - flexibility KW - postural sway KW - myofascial KW - self massage Y1 - 2017 SN - 1303-2968 VL - 16 SP - 209 EP - 218 PB - Department of Sports Medicine, Medical Faculty of Uludag University CY - Bursa ER - TY - GEN A1 - Granacher, Urs A1 - Mühlbauer, Thomas A1 - Bridenbaugh, Stephanie A. A1 - Wolf, Madeleine A1 - Roth, Ralf A1 - Gschwind, Yves A1 - Wolf, Irene A1 - Mata, Rui A1 - Kressig, Reto W. T1 - Effects of a salsa dance training on balance and strength performance in older adults N2 - Background: Deficits in static and particularly dynamic postural control and force production have frequently been associated with an increased risk of falling in older adults. Objective: The objectives of this study were to investigate the effects of salsa dancing on measures of static/dynamic postural control and leg extensor power in seniors. Methods: Twenty-eight healthy older adults were randomly assigned to an intervention group (INT, n = 14, age 71.6 +/- 5.3 years) to conduct an 8-week progressive salsa dancing programme or a control group (CON, n = 14, age 68.9 +/- 4.7 years). Static postural control was measured during one-legged stance on a balance platform and dynamic postural control was obtained while walking on an instrumented walkway. Leg extensor power was assessed during a countermovement jump on a force plate. Results: Programme compliance was excellent with participants of the INT group completing 92.5% of the dancing sessions. A tendency towards an improvement in the selected measures of static postural control was observed in the INT group as compared to the CON group. Significant group X test interactions were found for stride velocity, length and time. Post hoc analyses revealed significant increases in stride velocity and length, and concomitant decreases in stride time. However, salsa dancing did not have significant effects on various measures of gait variability and leg extensor power. Conclusion: Salsa proved to be a safe and feasible exercise programme for older adults accompanied with a high adherence rate. Age-related deficits in measures of static and particularly dynamic postural control can be mitigated by salsa dancing in older adults. High physical activity and fitness/mobility levels of our participants could be responsible for the nonsignificant findings in gait variability and leg extensor power. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 330 KW - elderly KW - postural sway KW - gait KW - force production Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-399962 ER -