@misc{GorupecBrehmerTiberiusetal.2022, author = {Gorupec, Natalia and Brehmer, Nataliia and Tiberius, Victor and Kraus, Sascha}, title = {Tackling uncertain future scenarios with real options}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {1}, issn = {1866-8364}, doi = {10.25932/publishup-60891}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-608917}, pages = {22}, year = {2022}, abstract = {Real options are widely applied in strategic and operational decision-making, allowing for managerial flexibility in uncertaincontexts. Increased scholarly interest has led to an extensive but fragmented research landscape. We aim to measure andsystematize the research field quantitatively. To achieve this goal, we conduct bibliometric performance analyses and bibliographiccoupling analyses with an in-depth content review. The results of the performance analyses show an increasing interest in realoptions since the beginning of the 2000s and identify the most influential journals and authors. The science mappings reveal sixand seven research clusters over the last two decades. Based on an in-depth analysis of their themes, we develop a researchframework comprising antecedents, application areas, internal and external contingencies, and uncertainty resolution throughreal option valuation or reasoning. We identify several gaps in that framework, which we propose to tackle in future research.}, language = {en} } @misc{KuschelSonnenburgEngel2022, author = {Kuschel, Luciano Bruno and Sonnenburg, Dominik and Engel, Tilman}, title = {Factors of muscle quality and determinants of muscle strength}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {838}, issn = {1866-8364}, doi = {10.25932/publishup-58910}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-589104}, pages = {29}, year = {2022}, abstract = {Muscle quality defined as the ratio of muscle strength to muscle mass disregards underlying factors which influence muscle strength. The aim of this review was to investigate the relationship of phase angle (PhA), echo intensity (EI), muscular adipose tissue (MAT), muscle fiber type, fascicle pennation angle (θf), fascicle length (lf), muscle oxidative capacity, insulin sensitivity (IS), neuromuscular activation, and motor unit to muscle strength. PubMed search was performed in 2021. The inclusion criteria were: (i) original research, (ii) human participants, (iii) adults (≥18 years). Exclusion criteria were: (i) no full-text, (ii) non-English or -German language, (iii) pathologies. Forty-one studies were identified. Nine studies found a weak-moderate negative (range r: [-0.26]-[-0.656], p < 0.05) correlation between muscle strength and EI. Four studies found a weak-moderate positive correlation (range r: 0.177-0.696, p < 0.05) between muscle strength and PhA. Two studies found a moderate-strong negative correlation (range r: [-0.446]-[-0.87], p < 0.05) between muscle strength and MAT. Two studies found a weak-strong positive correlation (range r: 0.28-0.907, p < 0.05) between θf and muscle strength. Muscle oxidative capacity was found to be a predictor of muscle strength. This review highlights that the current definition of muscle quality should be expanded upon as to encompass all possible factors of muscle quality.}, language = {en} } @misc{WippertPuertoValenciaDriesslein2022, author = {Wippert, Pia-Maria and Puerto Valencia, Laura and Drießlein, David}, title = {Stress and pain}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {832}, issn = {1866-8364}, doi = {10.25932/publishup-58804}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-588040}, pages = {14}, year = {2022}, abstract = {Introduction: Low back pain (LBP) leads to considerable impairment of quality of life worldwide and is often accompanied by psychosomatic symptoms. Objectives: First, to assess the association between stress and chronic low back pain (CLBP) and its simultaneous appearance with fatigue and depression as a symptom triad. Second, to identify the most predictive stress-related pattern set for CLBP for a 1-year diagnosis. Methods: In a 1-year observational study with four measurement points, a total of 140 volunteers (aged 18-45 years with intermittent pain) were recruited. The primary outcomes were pain [characteristic pain intensity (CPI), subjective pain disability (DISS)], fatigue, and depressive mood. Stress was assessed as chronic stress, perceived stress, effort reward imbalance, life events, and physiological markers [allostatic load index (ALI), hair cortisol concentration (HCC)]. Multiple linear regression models and selection procedures for model shrinkage and variable selection (least absolute shrinkage and selection operator) were applied. Prediction accuracy was calculated by root mean squared error (RMSE) and receiver-operating characteristic curves. Results: There were 110 participants completed the baseline assessments (28.2 7.5 years, 38.1\% female), including HCC, and a further of 46 participants agreed to ALI laboratory measurements. Different stress types were associated with LBP, CLBP, fatigue, and depressive mood and its joint occurrence as a symptom triad at baseline; mainly social-related stress types were of relevance. Work-related stress, such as "excessive demands at work"[b = 0.51 (95\%CI -0.23, 1.25), p = 0.18] played a role for upcoming chronic pain disability. "Social overload" [b = 0.45 (95\%CI -0.06, 0.96), p = 0.080] and "over-commitment at work" [b = 0.28 (95\%CI -0.39, 0.95), p = 0.42] were associated with an upcoming depressive mood within 1-year. Finally, seven psychometric (CPI: RMSE = 12.63; DISS: RMSE = 9.81) and five biomarkers (CPI: RMSE = 12.21; DISS: RMSE = 8.94) could be derived as the most predictive pattern set for a 1-year prediction of CLBP. The biomarker set showed an apparent area under the curve of 0.88 for CPI and 0.99 for DISS. Conclusion: Stress disrupts allostasis and favors the development of chronic pain, fatigue, and depression and the emergence of a "hypocortisolemic symptom triad," whereby the social-related stressors play a significant role. For translational medicine, a predictive pattern set could be derived which enables to diagnose the individuals at higher risk for the upcoming pain disorders and can be used in practice.}, language = {en} } @misc{SchaeferDechWolffetal.2022, author = {Schaefer, Laura and Dech, Silas and Wolff, Lara L. and Bittmann, Frank}, title = {Emotional Imagery Influences the Adaptive Force in Young Women}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {816}, issn = {1866-8364}, doi = {10.25932/publishup-58201}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-582014}, pages = {23}, year = {2022}, abstract = {The link between emotions and motor function has been known for decades but is still not clarified. The Adaptive Force (AF) describes the neuromuscular capability to adapt to increasing forces and was suggested to be especially vulnerable to interfering inputs. This study investigated the influence of pleasant an unpleasant food imagery on the manually assessed AF of elbow and hip flexors objectified by a handheld device in 12 healthy women. The maximal isometric AF was significantly reduced during unpleasant vs. pleasant imagery and baseline (p < 0.001, dz = 0.98-1.61). During unpleasant imagery, muscle lengthening started at 59.00 ± 22.50\% of maximal AF, in contrast to baseline and pleasant imagery, during which the isometric position could be maintained mostly during the entire force increase up to ~97.90 ± 5.00\% of maximal AF. Healthy participants showed an immediately impaired holding function triggered by unpleasant imagery, presumably related to negative emotions. Hence, AF seems to be suitable to test instantaneously the effect of emotions on motor function. Since musculoskeletal complaints can result from muscular instability, the findings provide insights into the understanding of the causal chain of linked musculoskeletal pain and mental stress. A case example (current stress vs. positive imagery) suggests that the approach presented in this study might have future implications for psychomotor diagnostics and therapeutics.}, language = {en} } @misc{HenschkeKaplickWochatzetal.2022, author = {Henschke, Jakob and Kaplick, Hannes and Wochatz, Monique and Engel, Tilman}, title = {Assessing the validity of inertial measurement units for shoulder kinematics using a commercial sensor-software system}, 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-57827}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-578278}, pages = {1 -- 11}, year = {2022}, abstract = {Background and Aims Wearable inertial sensors may offer additional kinematic parameters of the shoulder compared to traditional instruments such as goniometers when elaborate and time-consuming data processing procedures are undertaken. However, in clinical practice simple-real time motion analysis is required to improve clinical reasoning. Therefore, the aim was to assess the criterion validity between a portable "off-the-shelf" sensor-software system (IMU) and optical motion (Mocap) for measuring kinematic parameters during active shoulder movements. Methods 24 healthy participants (9 female, 15 male, age 29 +/- 4 years, height 177 +/- 11 cm, weight 73 +/- 14 kg) were included. Range of motion (ROM), total range of motion (TROM), peak and mean angular velocity of both systems were assessed during simple (abduction/adduction, horizontal flexion/horizontal extension, vertical flexion/extension, and external/internal rotation) and complex shoulder movements. Criterion validity was determined using intraclass-correlation coefficients (ICC), root mean square error (RMSE) and Bland and Altmann analysis (bias; upper and lower limits of agreement). Results ROM and TROM analysis revealed inconsistent validity during simple (ICC: 0.040-0.733, RMSE: 9.7 degrees-20.3 degrees, bias: 1.2 degrees-50.7 degrees) and insufficient agreement during complex shoulder movements (ICC: 0.104-0.453, RMSE: 10.1 degrees-23.3 degrees, bias: 1.0 degrees-55.9 degrees). Peak angular velocity (ICC: 0.202-0.865, RMSE: 14.6 degrees/s-26.7 degrees/s, bias: 10.2 degrees/s-29.9 degrees/s) and mean angular velocity (ICC: 0.019-0.786, RMSE:6.1 degrees/s-34.2 degrees/s, bias: 1.6 degrees/s-27.8 degrees/s) were inconsistent. Conclusions The "off-the-shelf" sensor-software system showed overall insufficient agreement with the gold standard. Further development of commercial IMU-software-solutions may increase measurement accuracy and permit their integration into everyday clinical practice.}, language = {en} } @phdthesis{Dech2022, author = {Dech, Silas}, title = {Isometric muscle function}, doi = {10.25932/publishup-57126}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-571265}, school = {Universit{\"a}t Potsdam}, pages = {127}, year = {2022}, abstract = {The cumulative dissertation consists of four original articles. These considered isometric muscle ac-tions in healthy humans from a basic physiological view (oxygen and blood supply) as well as possibilities of their distinction. It includes a novel approach to measure a specific form of isometric hold-ing function which has not been considered in motor science so far. This function is characterized by an adaptation to varying external forces with particular importance in daily activities and sports. The first part of the research program analyzed how the biceps brachii muscle is supplied with oxygen and blood by adapting to a moderate constant load until task failure (publication 1). In this regard, regulative mechanisms were investigated in relation to the issue of presumably compressed capillaries due to high intramuscular pressures (publication 2). Furthermore, it was examined if oxygenation and time to task failure (TTF) differs compared to an-other isometric muscle function (publication 3). This function is mainly of diagnostic interest by measuring the maximal voluntary isometric contraction (MVIC) as a gold standard. For that, a person pulls on or pushes against an insurmountable resistance. However, the underlying pulling or pushing form of isometric muscle action (PIMA) differs compared to the holding one (HIMA). HIMAs have mainly been examined by using constant loads. In order to quantify the adaptability to varying external forces, a new approach was necessary and considered in the second part of the research program. A device was constructed based on a previously developed pneumatic measurement system. The device should have been able to measure the Adaptive Force (AF) of elbow ex-tensor muscles. The AF determines the adaptability to increasing external forces under isometric (AFiso) and eccentric (AFecc) conditions. At first, it was questioned if these parameters can be relia-bly assessed by use of the new device (publication 4). Subsequently, the main research question was investigated: Is the maximal AFiso a specific and independent variable of muscle function in comparison to the MVIC? Furthermore, both research parts contained a sub-question of how results can be influenced. Parameters of local oxygen saturation (SvO2) and capillary blood filling (rHb) were non-invasively recorded by a spectrophotometer during maximal and submaximal HIMAs and PIMAs. These were the main findings: Under load, SvO2 and rHb always adjusted into a steady state after an initial decrease. Nevertheless, their behavior could roughly be categorized into two types. In type I, both parameters behaved nearly parallel to each other. In contrast, their progression over time was partly inverse in type II. The inverse behavior probably depends on the level of deoxygenation since rHb increased reliably at a suggested threshold of about 59\% SvO2. This triggered mechanism and the found homeostatic steady states seem to be in conflict with the concept of mechanically compressed capillaries and consequently with a restricted blood flow. Anatomical configuration of blood vessels might provide one hypothetical explanation of how blood flow might be maintained. HIMA and PIMA did not differ regarding oxygenation and allocation to the described types. The TTF tended to be longer during PIMA. As a sub-question, oxygenation and TTF were compared between (HIMA) and intermittent voluntary muscle twitches during a weight holding task. TTF but not oxygenation differed significantly (Twitch > HIMA). A changed neuromuscular control might serve as a speculative explanation of how the results can be explained. This is supported by the finding that the TTF did not correlate significantly with the extent of deoxygenation irrespective of the performed task (HIMA, PIMA or Twitch). Other neuromuscular aspects of muscle function were considered in second part of the re-search program. The new device mentioned above detected different force capacities within four trials at two days each. Among AF measurements, the functional counterpart of a concentric muscle action merging into an isometric one was analyzed in comparison to the MVIC. Based on the results, it can be assumed that a prior concentric muscle action does not influence the MVIC. However, the results were inconsistent and possibly influenced by systematic errors. In con-trast, maximal variables of the AF (AFisomax and AFeccmax) could be measured in a reliable way which is indicated by a high test-retest reliability. Despite substantial correlations between force variables, the AFisomax differed significantly from MVIC and AFmax, which was identical with AFeccmax in almost all cases. Moreover, AFisomax revealed the highest variability between trials. These results indicate that maximal force capacities should be assessed separately. The adaptive holding capacity of a muscle can be lower compared to a commonly determined MVIC. This is of relevance since muscles frequently need to respond adequately to external forces. If their response does not correspond to the external impact, the muscle is forced to lengthen. In this scenario, joints are not completely stabilized and an injury may occur. This outlined issue should be addressed in future research in the field of sport and health sciences. At last, the dissertation presents another possibility to quantify the AFisomax by use of a handheld device applied in combination with a manual muscle test. This assessment delivers a more practical way for clinical purposes.}, language = {en} } @phdthesis{PerezChaparro2022, author = {P{\´e}rez Chaparro, Camilo Germ{\´a}n Alberto}, title = {Non-HIV comorbidities and exercise in German people living with HIV}, doi = {10.25932/publishup-56084}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-560842}, school = {Universit{\"a}t Potsdam}, pages = {149}, year = {2022}, abstract = {The post-antiretroviral therapy era has transformed HIV into a chronic disease and non-HIV comorbidities (i.e., cardiovascular and mental diseases) are more prevalent in PLWH. The source of these non-HIV comorbidities aside from traditional risk factor include HIV infection, inflammation, distorted immune activation, burden of chronic diseases, and unhealthy lifestyle like sedentarism. Exercise is known for its beneficial effects in mental and physical health; reasons why exercise is recommended to prevent and treat difference cardiovascular and mental diseases in the general population. This cumulative thesis aimed to comprehend the relation exercise has to non-HIV comorbidities in German PLWH. Four studies were conducted to 1) understand exercise effects in cardiorespiratory fitness and muscle strength on PLWH through a systematic review and meta-analyses and 2) determine the likelihood of German PLWH developing non-HIV comorbidities, in a cross-sectional study. Meta-analytic examination indicates PLWH cardiorespiratory fitness (VO2max SMD = 0.61 ml·kg·min-1, 95\% CI: 0.35-0.88, z = 4.47, p < 0.001, I2 = 50\%) and strength (of remark lowerbody strength by 16.8 kg, 95\% CI: 13-20.6, p< 0.001) improves after an exercise intervention in comparison to a control group. Cross-sectional data suggest exercise has a positive effect on German PLWH mental health (less anxiety and depressive symptoms) and protects against the development of anxiety (PR: 0.57, 95\%IC: 0.36 - 0.91, p = 0.01) and depression (PR: 0.62, 95\%IC: 0.41 - 0.94, p = 0.01). Likewise, exercise duration is related to a lower likelihood of reporting heart arrhythmias (PR: 0.20, 95\%IC: 0.10 - 0.60, p < 0.01) and exercise frequency to a lower likelihood of reporting diabetes mellitus (PR: 0.40, 95\%IC: 0.10 - 1, p < 0.01) in German PLWH. A preliminary recommendation for German PLWH who want to engage in exercise can be to exercise ≥ 1 time per week, at an intensity of 5 METs per session or > 103 MET·min·day-1, with a duration ≥ 150 minutes per week. Nevertheless, further research is needed to comprehend exercise dose response and protective effect for cardiovascular diseases, anxiety, and depression in German PLWH.}, language = {en} } @inproceedings{KlieglTeichGranacheretal.2022, author = {Kliegl, Reinhold and Teich, Paula and Granacher, Urs and F{\"u}hner, Thea Heidi}, title = {Developmental Gains in Physical Fitness Components of Keyage and Older-than-Keyage Third-Graders}, doi = {10.25932/publishup-56087}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-560870}, pages = {14}, year = {2022}, abstract = {Children who were enrolled according to legal enrollment dates (i.e., keyage third-graders aged eight to nine years) exhibit a positive linear physical fitness development (F{\"u}hner et al., 2021). However, children who were enrolled with a delay of one year or who repeated a grade (i.e., older-than-keyage children [OTK] aged nine to ten years in third grade) appear to exhibit a poorer physical fitness relative to what could be expected given their chronological age (F{\"u}hner et al., 2022). However, because F{\"u}hner et al. (2022) compared the performance of OTK children to predicted test scores that were extrapolated based on the data of keyage children, the observed physical fitness of these children could either indicate a delayed physical-fitness development or some physiological or psychological changes occurring during the tenth year of life. We investigate four hypotheses about this effect. (H1) OTK children are biologically younger than keyage children. A formula transforming OTK's chronological age into a proxy for their biological age brings some of the observed cross-sectional age-related development in line with the predicted age-related development based on the data of keyage children, but large negative group differences remain. Hypotheses 2 to 4 were tested with a longitudinal assessment. (H2) Physiological changes due to biological maturation or psychological factors cause a stagnation of physical fitness development in the tenth year of life. H2 predicts a decline of performance from third to fourth grade also for keyage children. (H3) OTK children exhibit an age-related (temporary) developmental delay in the tenth year of life, but later catch up to the performance of age-matched keyage children. H3 predicts a larger developmental gain for OTK than for keyage children from third to fourth grade. (H4) OTK children exhibit a sustained physical fitness deficit and do not catch up over time. H4 predicts a positive development for keyage and OTK children, with no greater development for OTK compared to keyage children. The longitudinal study was based on a subset of children from the EMOTIKON project (www.uni-potsdam.de/emotikon). The physical fitness (cardiorespiratory endurance [6-minute-run test], coordination [star-run test], speed [20-m sprint test], lower [standing long jump test] and upper [ball push test] limbs muscle power, and balance [one-legged stance test]) of 1,274 children (1,030 keyage and 244 OTK children) from 32 different schools was tested in third grade and retested one year later in fourth grade. Results: (a) Both keyage and OTK children exhibit a positive longitudinal development from third to fourth grade in all six physical fitness components. (b) There is no evidence for a different longitudinal development of keyage and OTK children. (c) Keyage children (approximately 9.5 years in fourth grade) outperform age-matched OTK children (approximately 9.5 years in third grade) in all six physical fitness components. The results show that the physical fitness of OTK children is indeed impaired and are in support of a sustained difference in physical fitness between the groups of keyage and OTK children (H4).}, language = {en} } @inproceedings{TeichFuehnerGolleetal.2022, author = {Teich, Paula and F{\"u}hner, Thea Heidi and Golle, Kathleen and Kliegl, Reinhold}, title = {How did the Sars-CoV-2 Pandemic affect the Physical Fitness of Primary School Children?}, doi = {10.25932/publishup-56085}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-560855}, pages = {20}, year = {2022}, abstract = {Throughout the years 2020 and 2021, schools were temporarily closed to slow the spread of SarsCoV-2. For some periods, children were locked out of sports in schools (physical education lessons, school sports working groups) and organized sports in sports clubs which often resulted in physical inactivity. Did these restrictions affect children's physical fitness? The EMOTIKON project (www.uni-potsdam.de/emotikon) annually assesses the physical fitness (cardiorespiratory endurance [6-minute-run test], coordination [star-run test], speed [20-m sprint test], lower [standing long jump test] and upper [ball push test] limbs muscle power, and balance [one-legged stance test]) of all third graders in the Federal State of Brandenburg, Germany. Participation is mandatory for all public primary schools. In the falls from 2016 to 2021, 83,476 keyage children (i.e., school enrollment according to the legal key date, between eight and nine years in third grade) from 512 schools were assessed with the EMOTIKON test battery. We tested the Covid pandemic effect on a composite score of the four highly correlated physical fitness tests assessing cardiorespiratory endurance, coordination, speed and powerLOW and on another composite score of the three running tests (cardiorespiratory endurance, coordination, speed), as well as separately on all six physical fitness components. Secular trends for each of the physical fitness components and differences between schools and children were taken into account in linear mixed models. We found a negative Covid pandemic effect on the two composite physical fitness scores, as well as on cardiorespiratory endurance, coordination, and speed. We found a positive Covid pandemic effect on powerLOW. Coordination was associated with the largest negative Covid pandemic effect, also passing the threshold of smallest meaningful change (SMC, i.e., 0.2 Cohen's d) when accumulated across two years. Given the educational context, Covid pandemic effects were also compared relative to the expected age-related development of the physical fitness components between eight and nine years. The Covid pandemic-related developmental costs/gains ranged from three to seven months relative to a longitudinal age effect, and from five to 17 months relative to a cross-sectional age effect. We propose that a longitudinal assessment yields a more reliable estimate of the developmental (age-related) gain than a cross-sectional one. Therefore, we consider the smaller Covid pandemic-related developmental costs/gains to be more credible. Interestingly, on the school level, „fitter" schools (relatively higher Grand Mean) exhibited larger negative Covid pandemic effects than schools with a lower physical fitness score. Negative Covid pandemic effects for the three run tasks were also found by B{\"a}hr et al. (2022), who tested the physical fitness of 16,496 Thuringian third-graders from 292 schools with the same six physical fitness tests used in EMOTIKON. Our results may be used to prioritize health-related interventions.}, language = {en} } @misc{SchaeferBittmann2022, author = {Schaefer, Laura and Bittmann, Frank}, title = {Case Study: Intra- and Interpersonal Coherence of Muscle and Brain Activity of Two Coupled Persons during Pushing and Holding Isometric Muscle Action}, 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-56194}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-561942}, pages = {1 -- 27}, year = {2022}, abstract = {Inter-brain synchronization is primarily investigated during social interactions but had not been examined during coupled muscle action between two persons until now. It was previously shown that mechanical muscle oscillations can develop coherent behavior between two isometrically interacting persons. This case study investigated if inter-brain synchronization appears thereby, and if differences of inter- and intrapersonal muscle and brain coherence exist regarding two different types of isometric muscle action. Electroencephalography (EEG) and mechanomyography/mechanotendography (MMG/MTG) of right elbow extensors were recorded during six fatiguing trials of two coupled isometrically interacting participants (70\% MVIC). One partner performed holding and one pushing isometric muscle action (HIMA/PIMA; tasks changed). The wavelet coherence of all signals (EEG, MMG/MTG, force, ACC) were analyzed intra- and interpersonally. The five longest coherence patches in 8-15 Hz and their weighted frequency were compared between real vs. random pairs and between HIMA vs. PIMA. Real vs. random pairs showed significantly higher coherence for intra-muscle, intra-brain, and inter-muscle-brain activity (p < 0.001 to 0.019). Inter-brain coherence was significantly higher for real vs. random pairs for EEG of right and central areas and for sub-regions of EEG left (p = 0.002 to 0.025). Interpersonal muscle-brain synchronization was significantly higher than intrapersonal one, whereby it was significantly higher for HIMA vs. PIMA. These preliminary findings indicate that inter-brain synchronization can arise during muscular interaction. It is hypothesized both partners merge into one oscillating neuromuscular system. The results reinforce the hypothesis that HIMA is characterized by more complex control strategies than PIMA. The pilot study suggests investigating the topic further to verify these results on a larger sample size. Findings could contribute to the basic understanding of motor control and is relevant for functional diagnostics such as the manual muscle test which is applied in several disciplines, e.g., neurology, physiotherapy.}, language = {en} }