@article{GebelLehmannGranacher2020, author = {Gebel, Arnd and Lehmann, Tim and Granacher, Urs}, title = {Balance task difficulty affects postural sway and cortical activity in healthy adolescents}, series = {Experimental brain research}, volume = {238}, journal = {Experimental brain research}, number = {5}, publisher = {Springer}, address = {New York}, issn = {0014-4819}, doi = {10.1007/s00221-020-05810-1}, pages = {1323 -- 1333}, year = {2020}, abstract = {Electroencephalographic (EEG) research indicates changes in adults' low frequency bands of frontoparietal brain areas executing different balance tasks with increasing postural demands. However, this issue is unsolved for adolescents when performing the same balance task with increasing difficulty. Therefore, we examined the effects of a progressively increasing balance task difficulty on balance performance and brain activity in adolescents. Thirteen healthy adolescents aged 16-17 year performed tests in bipedal upright stance on a balance board with six progressively increasing levels of task difficulty. Postural sway and cortical activity were recorded simultaneously using a pressure sensitive measuring system and EEG. The power spectrum was analyzed for theta (4-7 Hz) and alpha-2 (10-12 Hz) frequency bands in pre-defined frontal, central, and parietal clusters of electrocortical sources. Repeated measures analysis of variance (rmANOVA) showed a significant main effect of task difficulty for postural sway (p < 0.001; d = 6.36). Concomitantly, the power spectrum changed in frontal, bilateral central, and bilateral parietal clusters. RmANOVAs revealed significant main effects of task difficulty for theta band power in the frontal (p < 0.001, d = 1.80) and both central clusters (left: p < 0.001, d = 1.49; right: p < 0.001, d = 1.42) as well as for alpha-2 band power in both parietal clusters (left: p < 0.001, d = 1.39; right: p < 0.001, d = 1.05) and in the central right cluster (p = 0.005, d = 0.92). Increases in theta band power (frontal, central) and decreases in alpha-2 power (central, parietal) with increasing balance task difficulty may reflect increased attentional processes and/or error monitoring as well as increased sensory information processing due to increasing postural demands. In general, our findings are mostly in agreement with studies conducted in adults. Similar to adult studies, our data with adolescents indicated the involvement of frontoparietal brain areas in the regulation of postural control. In addition, we detected that activity of selected brain areas (e.g., bilateral central) changed with increasing postural demands.}, language = {en} } @misc{GebelBuschStelzeletal.2022, author = {Gebel, Arnd and Busch, Aglaja and Stelzel, Christine and Hortob{\´a}gyi, Tibor and Granacher, Urs}, title = {Effects of Physical and Mental Fatigue on Postural Sway and Cortical Activity in Healthy Young Adults}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1866-8364}, doi = {10.25932/publishup-56441}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-564419}, pages = {1 -- 14}, year = {2022}, abstract = {Physical fatigue (PF) negatively affects postural control, resulting in impaired balance performance in young and older adults. Similar effects on postural control can be observed for mental fatigue (MF) mainly in older adults. Controversial results exist for young adults. There is a void in the literature on the effects of fatigue on balance and cortical activity. Therefore, this study aimed to examine the acute effects of PF and MF on postural sway and cortical activity. Fifteen healthy young adults aged 28 ± 3 years participated in this study. MF and PF protocols comprising of an all-out repeated sit-to-stand task and a computer-based attention network test, respectively, were applied in random order. Pre and post fatigue, cortical activity and postural sway (i.e., center of pressure displacements [CoPd], velocity [CoPv], and CoP variability [CV CoPd, CV CoPv]) were tested during a challenging bipedal balance board task. Absolute spectral power was calculated for theta (4-7.5 Hz), alpha-2 (10.5-12.5 Hz), beta-1 (13-18 Hz), and beta-2 (18.5-25 Hz) in frontal, central, and parietal regions of interest (ROI) and baseline-normalized. Inference statistics revealed a significant time-by-fatigue interaction for CoPd (p = 0.009, d = 0.39, Δ 9.2\%) and CoPv (p = 0.009, d = 0.36, Δ 9.2\%), and a significant main effect of time for CoP variability (CV CoPd: p = 0.001, d = 0.84; CV CoPv: p = 0.05, d = 0.62). Post hoc analyses showed a significant increase in CoPd (p = 0.002, d = 1.03) and CoPv (p = 0.003, d = 1.03) following PF but not MF. For cortical activity, a significant time-by-fatigue interaction was found for relative alpha-2 power in parietal (p < 0.001, d = 0.06) areas. Post hoc tests indicated larger alpha-2 power increases after PF (p < 0.001, d = 1.69, Δ 3.9\%) compared to MF (p = 0.001, d = 1.03, Δ 2.5\%). In addition, changes in parietal alpha-2 power and measures of postural sway did not correlate significantly, irrespective of the applied fatigue protocol. No significant changes were found for the other frequency bands, irrespective of the fatigue protocol and ROI under investigation. Thus, the applied PF protocol resulted in increased postural sway (CoPd and CoPv) and CoP variability accompanied by enhanced alpha-2 power in the parietal ROI while MF led to increased CoP variability and alpha-2 power in our sample of young adults. Potential underlying cortical mechanisms responsible for the greater increase in parietal alpha-2 power after PF were discussed but could not be clearly identified as cause. Therefore, further future research is needed to decipher alternative interpretations.}, language = {en} } @article{GebelBuschStelzeletal.2022, author = {Gebel, Arnd and Busch, Aglaja and Stelzel, Christine and Hortob{\´a}gyi, Tibor and Granacher, Urs}, title = {Effects of Physical and Mental Fatigue on Postural Sway and Cortical Activity in Healthy Young Adults}, series = {Frontiers in Human Neuroscience}, volume = {16}, journal = {Frontiers in Human Neuroscience}, publisher = {Frontiers Media S.A.}, address = {Lausanne, Schweiz}, issn = {1662-5161}, doi = {10.3389/fnhum.2022.871930}, pages = {1 -- 14}, year = {2022}, abstract = {Physical fatigue (PF) negatively affects postural control, resulting in impaired balance performance in young and older adults. Similar effects on postural control can be observed for mental fatigue (MF) mainly in older adults. Controversial results exist for young adults. There is a void in the literature on the effects of fatigue on balance and cortical activity. Therefore, this study aimed to examine the acute effects of PF and MF on postural sway and cortical activity. Fifteen healthy young adults aged 28 ± 3 years participated in this study. MF and PF protocols comprising of an all-out repeated sit-to-stand task and a computer-based attention network test, respectively, were applied in random order. Pre and post fatigue, cortical activity and postural sway (i.e., center of pressure displacements [CoPd], velocity [CoPv], and CoP variability [CV CoPd, CV CoPv]) were tested during a challenging bipedal balance board task. Absolute spectral power was calculated for theta (4-7.5 Hz), alpha-2 (10.5-12.5 Hz), beta-1 (13-18 Hz), and beta-2 (18.5-25 Hz) in frontal, central, and parietal regions of interest (ROI) and baseline-normalized. Inference statistics revealed a significant time-by-fatigue interaction for CoPd (p = 0.009, d = 0.39, Δ 9.2\%) and CoPv (p = 0.009, d = 0.36, Δ 9.2\%), and a significant main effect of time for CoP variability (CV CoPd: p = 0.001, d = 0.84; CV CoPv: p = 0.05, d = 0.62). Post hoc analyses showed a significant increase in CoPd (p = 0.002, d = 1.03) and CoPv (p = 0.003, d = 1.03) following PF but not MF. For cortical activity, a significant time-by-fatigue interaction was found for relative alpha-2 power in parietal (p < 0.001, d = 0.06) areas. Post hoc tests indicated larger alpha-2 power increases after PF (p < 0.001, d = 1.69, Δ 3.9\%) compared to MF (p = 0.001, d = 1.03, Δ 2.5\%). In addition, changes in parietal alpha-2 power and measures of postural sway did not correlate significantly, irrespective of the applied fatigue protocol. No significant changes were found for the other frequency bands, irrespective of the fatigue protocol and ROI under investigation. Thus, the applied PF protocol resulted in increased postural sway (CoPd and CoPv) and CoP variability accompanied by enhanced alpha-2 power in the parietal ROI while MF led to increased CoP variability and alpha-2 power in our sample of young adults. Potential underlying cortical mechanisms responsible for the greater increase in parietal alpha-2 power after PF were discussed but could not be clearly identified as cause. Therefore, further future research is needed to decipher alternative interpretations.}, language = {en} } @phdthesis{Gebel2021, author = {Gebel, Arnd}, title = {Postural control in youth: From performance to neural correlates}, doi = {10.25932/publishup-53303}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-533034}, school = {Universit{\"a}t Potsdam}, pages = {x, 121}, year = {2021}, abstract = {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.}, language = {en} } @misc{GebelLuederGranacher2019, author = {Gebel, Arnd and L{\"u}der, Benjamin and Granacher, Urs}, title = {Effects of Increasing Balance Task Difficulty on Postural Sway and Muscle Activity in Healthy Adolescents}, series = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, number = {583}, issn = {1866-8364}, doi = {10.25932/publishup-43921}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439211}, pages = {15}, year = {2019}, abstract = {Evidence-based prescriptions for balance training in youth have recently been established. However, there is currently no standardized means available to assess and quantify balance task difficulty (BTD). Therefore, the objectives of this study were to examine the effects of graded BTD on postural sway, lower limb muscle activity and coactivation in adolescents. Thirteen healthy high-school students aged 16 to 17 volunteered to participate in this cross-sectional study. Testing involved participants to stand on a commercially available balance board with an adjustable pivot that allowed six levels of increasing task difficulty. Postural sway [i.e., total center of pressure (CoP) displacements] and lower limb muscle activity were recorded simultaneously during each trial. Surface electromyography (EMG) was applied in muscles encompassing the ankle (m. tibialis anterior, medial gastrocnemius, peroneus longus) and knee joint (m. vastus medialis, biceps femoris). The coactivation index (CAI) was calculated for ankle and thigh muscles. Repeated measures analyses of variance revealed a significant main effect of BTD with increasing task difficulty for postural sway (p < 0.001; d = 6.36), muscle activity (p < 0.001; 2.19 < d < 4.88), and CAI (p < 0.001; 1.32 < d < 1.41). Multiple regression analyses showed that m. tibialis anterior activity best explained overall CoP displacements with 32.5\% explained variance (p < 0.001). The observed increases in postural sway, lower limb muscle activity, and coactivation indicate increasing postural demands while standing on the balance board. Thus, the examined board can be implemented in balance training to progressively increase BTD in healthy adolescents.}, language = {en} } @article{GebelLuederGranacher2019, author = {Gebel, Arnd and L{\"u}der, Benjamin and Granacher, Urs}, title = {Effects of Increasing Balance Task Difficulty on Postural Sway and Muscle Activity in Healthy Adolescents}, series = {Frontiers in Physiology}, volume = {10}, journal = {Frontiers in Physiology}, number = {9}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2019.01135}, pages = {13}, year = {2019}, abstract = {Evidence-based prescriptions for balance training in youth have recently been established. However, there is currently no standardized means available to assess and quantify balance task difficulty (BTD). Therefore, the objectives of this study were to examine the effects of graded BTD on postural sway, lower limb muscle activity and coactivation in adolescents. Thirteen healthy high-school students aged 16 to 17 volunteered to participate in this cross-sectional study. Testing involved participants to stand on a commercially available balance board with an adjustable pivot that allowed six levels of increasing task difficulty. Postural sway [i.e., total center of pressure (CoP) displacements] and lower limb muscle activity were recorded simultaneously during each trial. Surface electromyography (EMG) was applied in muscles encompassing the ankle (m. tibialis anterior, medial gastrocnemius, peroneus longus) and knee joint (m. vastus medialis, biceps femoris). The coactivation index (CAI) was calculated for ankle and thigh muscles. Repeated measures analyses of variance revealed a significant main effect of BTD with increasing task difficulty for postural sway (p < 0.001; d = 6.36), muscle activity (p < 0.001; 2.19 < d < 4.88), and CAI (p < 0.001; 1.32 < d < 1.41). Multiple regression analyses showed that m. tibialis anterior activity best explained overall CoP displacements with 32.5\% explained variance (p < 0.001). The observed increases in postural sway, lower limb muscle activity, and coactivation indicate increasing postural demands while standing on the balance board. Thus, the examined board can be implemented in balance training to progressively increase BTD in healthy adolescents.}, language = {en} } @misc{AlbertOwolabiGebeletal.2020, author = {Albert, Justin Amadeus and Owolabi, Victor and Gebel, Arnd and Brahms, Clemens Markus and Granacher, Urs and Arnrich, Bert}, title = {Evaluation of the Pose Tracking Performance of the Azure Kinect and Kinect v2 for Gait Analysis in Comparison with a Gold Standard}, series = {Postprints der Universit{\"a}t Potsdam : Reihe der Digital Engineering Fakult{\"a}t}, journal = {Postprints der Universit{\"a}t Potsdam : Reihe der Digital Engineering Fakult{\"a}t}, number = {3}, doi = {10.25932/publishup-48413}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-484130}, pages = {24}, year = {2020}, abstract = {Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people.}, language = {en} } @article{AlbertOwolabiGebeletal.2020, author = {Albert, Justin Amadeus and Owolabi, Victor and Gebel, Arnd and Brahms, Clemens Markus and Granacher, Urs and Arnrich, Bert}, title = {Evaluation of the Pose Tracking Performance of the Azure Kinect and Kinect v2 for Gait Analysis in Comparison with a Gold Standard}, series = {Sensors}, volume = {20}, journal = {Sensors}, number = {18}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s20185104}, pages = {22}, year = {2020}, abstract = {Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people.}, language = {en} } @misc{GebelLesinskiBehmetal.2018, author = {Gebel, Arnd and Lesinski, Melanie and Behm, David George and Granacher, Urs}, title = {Effects and dose-response relationship of balance training on balance performance in Youth}, series = {Sports medicine}, volume = {48}, journal = {Sports medicine}, number = {9}, publisher = {Springer}, address = {Northcote}, issn = {0112-1642}, doi = {10.1007/s40279-018-0926-0}, pages = {2067 -- 2089}, year = {2018}, abstract = {Background Effects and dose-response relationships of balance training on measures of balance are well-documented for healthy young and old adults. However, this has not been systematically studied in youth. Objectives The objectives of this systematic review and meta-analysis were to quantify effects of balance training (BT) on measures of static and dynamic balance in healthy children and adolescents. Additionally, dose-response relations for BT modalities (e.g. training period, frequency, volume) were quantified through the analysis of controlled trials. Data Sources A computerized systematic literature search was conducted in the electronic databases PubMed and Web of Science from January 1986 until June 2017 to identify articles related to BT in healthy trained and untrained children and adolescents. Study Eligibility Criteria A systematic approach was used to evaluate articles that examined the effects of BT on balance outcomes in youth. Controlled trials with pre- and post-measures were included if they examined healthy youth with a mean age of 6-19 years and assessed at least one measure of balance (i.e. static/dynamic steady-state balance, reactive balance, proactive balance) with behavioural (e.g. time during single-leg stance) or biomechanical (e.g. centre of pressure displacements during single-leg stance) test methods. Study Appraisal and Synthesis Methods The included studies were coded for the following criteria: training modalities (i.e. training period, frequency, volume), balance outcomes (i.e. static and dynamic balance) as well as chronological age, sex (male vs. female), training status (trained vs. untrained), setting (school vs. club), and testing method (biomechanical vs. physical fitness test). Weighted mean standardized mean differences (SMDwm) were calculated using a random-effects model to compute overall intervention effects relative to active and passive control groups. Between-study heterogeneity was assessed using I 2 and chi(2) statistics. A multivariate random effects meta-regression was computed to explain the influence of key training modalities (i.e. training period, training frequency, total number of training sessions, duration of training sessions, and total duration of training per week) on the effectiveness of BT on measures of balance performance. Further, subgroup univariate analyses were computed for each training modality. Additionally, dose-response relationships were characterized independently by interpreting the modality specific magnitude of effect sizes. Methodological quality of the included studies was rated with the help of the Physiotherapy Evidence Database (PEDro) Scale. Results Overall, our literature search revealed 198 hits of which 17 studies were eligible for inclusion in this systematic review and meta-analysis. Irrespective of age, sex, training status, sport discipline and training method, moderate to large BT-related effects were found for measures of static (SMDwm = 0.71) and dynamic (SMDwm = 1.03) balance in youth. However, our subgroup analyses did not reveal any statistically significant effects of the moderator variables age, sex, training status, setting and testing method on overall balance (i.e. aggregation of static and dynamic balance). BT-related effects in adolescents were moderate to large for measures of static (SMDwm = 0.61) and dynamic (SMDwm = 0.86) balance. With regard to the dose-response relationships, findings from the multivariate random effects meta-regression revealed that none of the examined training modalities predicted the effects of BT on balance performance in adolescents (R-2 = 0.00). In addition, results from univariate analysis have to be interpreted with caution because training modalities were computed as single factors irrespective of potential between-modality interactions. For training period, 12 weeks of training achieved the largest effect (SMDwm = 1.40). For training frequency, the largest effect was found for two sessions per week (SMDwm = 1.29). For total number of training sessions, the largest effect was observed for 24-36 sessions (SMDwm = 1.58). For the modality duration of a single training session, 4-15 min reached the largest effect (SMDwm = 1.03). Finally, for the modality training per week, a total duration of 31-60 min per week (SMDwm = 1.33) provided the largest effects on overall balance in adolescents. Methodological quality of the studies was rated as moderate with a median PEDro score of 6.0. Limitations Dose-response relationships were calculated independently for training modalities (i.e. modality specific) and not interdependently. Training intensity was not considered for the calculation of dose-response relationships because the included studies did not report this training modality. Further, the number of included studies allowed the characterization of dose-response relationships in adolescents for overall balance only. In addition, our analyses revealed a considerable between-study heterogeneity (I-2 = 66-83\%). The results of this meta-analysis have to be interpreted with caution due to their preliminary status. Conclusions BT is a highly effective means to improve balance performance with moderate to large effects on static and dynamic balance in healthy youth irrespective of age, sex, training status, setting and testing method. The examined training modalities did not have a moderating effect on balance performance in healthy adolescents. Thus, we conclude that an additional but so far unidentified training modality may have a major effect on balance performance that was not assessed in our analysis. Training intensity could be a promising candidate. However, future studies are needed to find appropriate methods to assess BT intensity.}, language = {en} } @misc{BohleRimpelSchauenburgetal.2019, author = {Bohle, Hannah and Rimpel, J{\´e}r{\^o}me and Schauenburg, Gesche and Gebel, Arnd and Stelzel, Christine and Heinzel, Stephan and Rapp, Michael Armin and Granacher, Urs}, title = {Behavioral and Neural Correlates of Cognitive-Motor Interference during Multitasking in Young and Old Adults}, series = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, number = {563}, issn = {1866-8364}, doi = {10.25932/publishup-43597}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435972}, pages = {20}, year = {2019}, abstract = {The concurrent performance of cognitive and postural tasks is particularly impaired in old adults and associated with an increased risk of falls. Biological aging of the cognitive and postural control system appears to be responsible for increased cognitive-motor interference effects. We examined neural and behavioral markers of motor-cognitive dual-task performance in young and old adults performing spatial one-back working memory single and dual tasks during semitandem stance. On the neural level, we used EEG to test for age-related modulations in the frequency domain related to cognitive-postural task load. Twenty-eight healthy young and 30 old adults participated in this study. The tasks included a postural single task, a cognitive-postural dual task, and a cognitive-postural triple task (cognitive dual-task with postural demands). Postural sway (i.e., total center of pressure displacements) was recorded in semistance position on an unstable surface that was placed on top of a force plate while performing cognitive tasks. Neural activation was recorded using a 64-channel mobile EEG system. EEG frequencies were attenuated by the baseline postural single-task condition and demarcated in nine Regions-of-Interest (ROIs), i.e., anterior, central, posterior, over the cortical midline, and both hemispheres. Our findings revealed impaired cognitive dual-task performance in old compared to young participants in the form of significantly lower cognitive performance in the triple-task condition. Furthermore, old adults compared with young adults showed significantly larger postural sway, especially in cognitive-postural task conditions. With respect to EEG frequencies, young compared to old participants showed significantly lower alpha-band activity in cognitive-cognitive-postural triple-task conditions compared with cognitive-postural dual tasks. In addition, with increasing task difficulty, we observed synchronized theta and delta frequencies, irrespective of age. Taskdependent alterations of the alpha frequency band were most pronounced over frontal and central ROIs, while alterations of the theta and delta frequency bands were found in frontal, central, and posterior ROIs. Theta and delta synchronization exhibited a decrease from anterior to posterior regions. For old adults, task difficulty was reflected by theta synchronization in the posterior ROI. For young adults, it was reflected by alpha desynchronization in bilateral anterior ROIs. In addition, we could not identify any effects of task difficulty and age on the beta frequency band. Our results shed light on age-related cognitive and postural declines and how they interact. Modulated alpha frequencies during high cognitive-postural task demands in young but not old adults might be reflective of a constrained neural adaptive potential in old adults. Future studies are needed to elucidate associations between the identified age-related performance decrements with task difficulty and changes in brain activity.}, language = {en} } @article{BohleRimpelSchauenburgetal.2019, author = {Bohle, Hannah and Rimpel, J{\´e}r{\^o}me and Schauenburg, Gesche and Gebel, Arnd and Stelzel, Christine and Heinzel, Stephan and Rapp, Michael Armin and Granacher, Urs}, title = {Behavioral and Neural Correlates of Cognitive-Motor Interference during Multitasking in Young and Old Adults}, series = {Neural Plasticity}, journal = {Neural Plasticity}, publisher = {Hindawi}, address = {New York}, issn = {2090-5904}, doi = {10.1155/2019/9478656}, pages = {20}, year = {2019}, abstract = {The concurrent performance of cognitive and postural tasks is particularly impaired in old adults and associated with an increased risk of falls. Biological aging of the cognitive and postural control system appears to be responsible for increased cognitive-motor interference effects. We examined neural and behavioral markers of motor-cognitive dual-task performance in young and old adults performing spatial one-back working memory single and dual tasks during semitandem stance. On the neural level, we used EEG to test for age-related modulations in the frequency domain related to cognitive-postural task load. Twenty-eight healthy young and 30 old adults participated in this study. The tasks included a postural single task, a cognitive-postural dual task, and a cognitive-postural triple task (cognitive dual-task with postural demands). Postural sway (i.e., total center of pressure displacements) was recorded in semistance position on an unstable surface that was placed on top of a force plate while performing cognitive tasks. Neural activation was recorded using a 64-channel mobile EEG system. EEG frequencies were attenuated by the baseline postural single-task condition and demarcated in nine Regions-of-Interest (ROIs), i.e., anterior, central, posterior, over the cortical midline, and both hemispheres. Our findings revealed impaired cognitive dual-task performance in old compared to young participants in the form of significantly lower cognitive performance in the triple-task condition. Furthermore, old adults compared with young adults showed significantly larger postural sway, especially in cognitive-postural task conditions. With respect to EEG frequencies, young compared to old participants showed significantly lower alpha-band activity in cognitive-cognitive-postural triple-task conditions compared with cognitive-postural dual tasks. In addition, with increasing task difficulty, we observed synchronized theta and delta frequencies, irrespective of age. Taskdependent alterations of the alpha frequency band were most pronounced over frontal and central ROIs, while alterations of the theta and delta frequency bands were found in frontal, central, and posterior ROIs. Theta and delta synchronization exhibited a decrease from anterior to posterior regions. For old adults, task difficulty was reflected by theta synchronization in the posterior ROI. For young adults, it was reflected by alpha desynchronization in bilateral anterior ROIs. In addition, we could not identify any effects of task difficulty and age on the beta frequency band. Our results shed light on age-related cognitive and postural declines and how they interact. Modulated alpha frequencies during high cognitive-postural task demands in young but not old adults might be reflective of a constrained neural adaptive potential in old adults. Future studies are needed to elucidate associations between the identified age-related performance decrements with task difficulty and changes in brain activity.}, language = {en} } @article{ZinkeGebelGranacheretal.2019, author = {Zinke, Fridolin and Gebel, Arnd and Granacher, Urs and Prieske, Olaf}, title = {Acute Effects of Short-Term Local Tendon Vibration on Plantar Flexor Torque, Muscle Contractile Properties, Neuromuscular and Brain Activity in Young Athletes}, series = {Journal of sports science \& medicine}, volume = {18}, journal = {Journal of sports science \& medicine}, number = {2}, publisher = {Department of Sports Medicine, Medical Faculty of Uludag University}, address = {Bursa}, issn = {1303-2968}, pages = {327 -- 336}, year = {2019}, abstract = {The purpose of this study was to examine the acute effects of short-term Achilles tendon vibration on plantar flexor torque, twitch contractile properties as well as muscle and cortical activity in young athletes. Eleven female elite soccer players aged 15.6 +/- 0.5 years participated in this study. Three different conditions were applied in randomized order: Achilles tendon vibration (80 Hz) for 30 and 300 s, and a passive control condition (300 s). Tests at baseline and following conditions included the assessment of peak plantar flexor torque during maximum voluntary contraction, electrically evoked muscle twitches (e.g., potentiated twitch peak torque [PT]), and electromyographic (EMG) activity of the plantar flexors. Additionally, electroencephalographic (EEG) activity of the primary motor and somatosensory cortex were assessed during a submaximal dynamic concentric-eccentric plantar flexion exercise using an elastic rubber band. Large-sized main effects of condition were found for EEG absolute alpha-1 and beta-1 band power (p <= 0.011; 1.5 <= d <= 2.6). Post-hoc tests indicated that alpha-1 power was significantly lower at 30 and 300 s (p = 0.009; d = 0.8) and beta-1 power significantly lower at 300 s (p < 0.001; d = 0.2) compared to control condition. No significant effect of condition was found for peak plantar flexor torque, electrical evoked muscle twitches, and EMG activity. In conclusion, short-term local Achilles tendon vibration induced lower brain activity (i.e., alpha-1 and beta-1 band power) but did not affect lower limb peak torque, twitch contractile properties, and muscle activity. Lower brain activity following short-term local Achilles tendon vibration may indicate improved cortical function during a submaximal dynamic exercise in female young soccer players.}, language = {en} }