@misc{JoostBrechtMayeretal.2020, author = {Joost, Theresa Anna and Brecht, Pia and Mayer, Frank and Cassel, Michael}, title = {Feasibility of open low-field MRI measurements in adolescent athletes with spondylolisthesis}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {52}, journal = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {17}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/01.mss.0000683832.74059.9d}, pages = {790 -- 790}, year = {2020}, abstract = {PURPOSE: To determine the feasibility of upright compared to supine MRI measurements to determine characteristics of the lumbar spine in AA with spondylolisthesis. METHODS: Ten AA (n=10; m/f: 4/6; 14.5±1.7y; 163±7cm; 52±8kg) from various sports, diagnosed with spondylolisthesis grade I-II Meyerding confirmed by x-ray in standing lateral view, were included. Open low-field MRI images (0.25 Tesla) in upright (82°) and supine (0°) position were evaluated by two observers. Medical imaging software was used to measure the anterior translation (AT, mm), lumbosacral joint angle (LSJA, °) and lordosis angle (LA, °). Reliability was analyzed by the intra-rater correlation coefficient (ICC) and standard error of measurements (SEM). RESULTS: Due to motion artifacts during upright position, measures of three participants had to be excluded. Between observers, AT ranged from 4.2±2.7mm to 5.5±1.9mm (ICC=0.94, SEM=0.6mm) in upright and from 4.9±2.4mm to 5.9±3.0mm (ICC=0.89, SEM=0.9mm) in supine position. LSJA varied from 5.1±2.2° to 7.3±1.5° (ICC=0.54, SEM=1.5°) in upright and from 9.8±2.5° to 10±2.4° (ICC=0.73, SEM=1.1°) in supine position. LA differed from 58.8±14.6° to 61.9±6° (ICC=0.94, SEM=1.19°) in upright and from 51.9±11.7° to 52.6±11.1° (ICC=0.98, SEM=1.59°) in supine position. CONCLUSIONS: Determination of AT and LA showed good to excellent reliability in both, upright and supine position. In contrast, reliability of LSJA had only moderate to good correlation between observers and should therefore be interpreted with caution. However, motion artifacts should be taken into consideration during upright imaging procedures.}, language = {en} } @misc{NairLinKhajooeietal.2020, author = {Nair, Alexandra and Lin, Chiao-I and Khajooei, Mina and Heikkila, Mika and Engel, Tilman and Mayer, Frank}, title = {Side comparison of knee muscle activities in response to perturbed walking of unilateral ankle instability}, series = {Medicine and science in sports and exercise : MSSE}, volume = {52}, journal = {Medicine and science in sports and exercise : MSSE}, number = {17}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/01.mss.0000671088.10003.6b}, pages = {97 -- 97}, year = {2020}, abstract = {Acute ankle sprain leads in 40\% of all cases to chronic ankle instability (CAI). CAI is related to a variety of motor adaptations at the lower extremities. Previous investigations identified increased muscle activities while landing in CAI compared to healthy control participants. However, it remains unclear whether muscular alterations at the knee muscles are limited to the involved (unstable) ankle or are also present at the uninvolved leg. The latter might potentially indicate a risk of ankle sprain or future injury on the uninvolved leg. Purpose: To assess if there is a difference of knee muscle activities between the involved and uninvolved leg in participants with CAI during perturbed walking. Method: 10 participants (6 females; 4 males; 26±4 years; 169±9 cm; 65±7 kg) with unilateral CAI walked on a split-belt treadmill (1m/s) for 5 minutes of baseline walking and 6 minutes of perturbed walking (left and right side, each 10 perturbations). Electromyography (EMG) measurements were performed at biceps femoris (BF) and rectus femoris (RF). EMG amplitude (RMS; normalized to MVIC) were analyzed for 200ms pre-heel contact (Pre200), 100ms post heel contact (Post100) and 200ms after perturbation (Pert200). Data was analyzed by paired t-test/Wilcoxon test based on presence or absence of normal distribution (Bonferroni adjusted α level p≤ 0.0125). Results: No statistical difference was found between involved and uninvolved leg for RF (Pre200: 4±2\% and 11± 22\%, respectively, p= 0.878; Post100: 10± 5 and 18±31\%, p=0.959; Pert200: 6±3\% and 13±24\%, p=0.721) as well as for BF (Pre200: 12±7\% and 11±6, p=0.576; Post100: 10±7\% and 9±7\%, p=0.732; Pert200: 7±4 and 7±7\%, p=0.386). Discussion: No side differences in muscle activity could be revealed for assessed feedforward and feedback responses (perturbed and unperturbed) in unilateral CAI. Reduced inter-individual variability of muscular activities at the involved leg might indicate a rather stereotypical response pattern. It remains to be investigated, whether muscular control at the knee is not affected by CAI, or whether both sides adapted in a similar style to the chronic condition at the ankle.}, language = {en} } @misc{LinKhajooeiNairetal.2020, author = {Lin, Chiao-I and Khajooei, Mina and Nair, Alexandra and Heikkila, Mika and Kaplick, Hannes and Tilman, Engel and Mayer, Frank}, title = {Activities of hip muscles in response to perturbed walking in individual with chronic ankle instability}, series = {Medicine and science in sports and exercise : MSSE}, volume = {52}, journal = {Medicine and science in sports and exercise : MSSE}, number = {17}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/01.mss.0000671060.98581.0b}, pages = {94 -- 94}, year = {2020}, abstract = {Chronic ankle instability (CAI) is not only an ankle issue, but also affects sensorimotor system. People with CAI show altered muscle activation in proximal joints such as hip and knee. However, evidence is limited as controversial results have been presented regarding changes in activation of hip muscles in CAI population. PURPOSE: To investigate the effect of CAI on activity of hip muscles during normal walking and walking with perturbations. METHODS: 8 subjects with CAI (23 ± 2 years, 171 ± 7 cm and 65 ± 4 kg) and 8 controls (CON) matched by age, height, weight and dominant leg (25 ± 3 years, 172 ± 7 cm and 65 ± 6 kg) walked shoed on a split-belt treadmill (1 m/s). Subjects performed 5 minutes of baseline walking and 6 minutes walking with 10 perturbations (at 200 ms after heel contact with 42 m/s2 deceleration impulse) on each side. Electromyography signals from gluteus medius (Gmed) and gluteus maximus (Gmax) were recorded while walking. Muscle amplitudes (Root Mean Square normalized to maximum voluntary isometric contraction) were calculated at 200 ms before heel contact (Pre200), 100 ms after heel contact (Post100) during normal walking and 200 ms after perturbations (Pert200). Differences between groups were examined using Mann Whitney U test and Bonferroni correction to account for multiple testing (adjust α level p≤ 0.0125). RESULT: In Gmed, CAI group showed lower muscle amplitude than CON group after heel contact (Post100: 18±7 \% and 47±21 \%, p< .01) and after walking perturbations ( 31±13 \% and 62±26 \%, p< .01), but not before heel contact (Pre200: 5±2 \% and 11±10 \%, p= 0.195). In Gmax, no difference was found between CAI and CON groups in all three time points (Pre200: 12±5 \% and 17±12 \%, p= 0.574; Post100: 41±21 \% and 41±13 \%, p= 1.00; Pert200: 79±46 \% and 62±35 \%, p= 0.505). CONCLUSION: People with CAI activated Gmed less than healthy control in feedback mechanism (after heel contact and walking with perturbations), but not in feedforward mechanism (before heel contact). Less activation on Gmed may affect the balance in frontal plane and increase the risk of recurrent ankle sprain, giving way or feeling ankle instability in patients with CAI during walking. Future studies should investigate the effect of Gmed strengthening or neuromuscular training on CAI rehabilitation.}, language = {en} } @misc{SchomoellerRischKaplicketal.2020, author = {Schom{\"o}ller, Anne and Risch, Lucie and Kaplick, Hannes and Schraplau, Anne and Wochatz, Monique and Engel, Tilman and Sonnenburg, Dominik and Mayer, Frank}, title = {Changes in paraspinal muscle T2 times and creatine kinase after a bout of eccentric exercise}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {52}, journal = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {17}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/01.mss.0000685648.68626.f1}, pages = {929 -- 929}, year = {2020}, abstract = {Eccentric (ECC) exercises might cause muscle damage, characterized by delayed-onset muscle soreness, elevated creatine kinase (CK) levels and local muscle oedema, shown by elevated T2 times in magnet resonance imaging (MRI) scans. Previous research suggests a high inter-individual difference regarding these systemic and local responses to eccentric workload. PURPOSE: To analyze ECC exercise-induced muscle damage in lumbar paraspinal muscles assessed via MRI. METHODS: Ten participants (3f/7m; 33±6y; 174±8cm; 71±12kg) were included in the study. Quantitative paraspinal muscle constitution of M. erector spinae and M. multifidius were assessed in supine position before and 72h after an intense eccentric trunk exercise bout in a mobile 1.5 tesla MRI device. MRI scans were recorded on spinal level L3 (T2-weighted TSE echo sequences, 11 slices, 2mm slice thickness, 3mm gap, echo times: 20, 40, 60, 80, 100ms, TR time: 2500ms). Muscle T2 times were calculated for manually traced regions of interest of the respective muscles with an imaging software. The exercise protocol was performed in an isokinetic device and consisted of 120sec alternating ECC trunk flexion-extension with maximal effort. Venous blood samples were taken before and 72h after the ECC exercise. Descriptive statistics (mean±SD) and t-testing for pre-post ECC exercises were performed. RESULTS: T2 times increased from pre- to post-ECC MRI measurements from 55±3ms to 79±28ms in M. erector spinae and from 62±5ms to 78±24ms in M. multifidius (p<0.001). CK increased from 126±97 U/L to 1447±20579 U/L. High SDs of T2 time and CK in post-ECC measures could be due to inter-individual reactions to ECC exercises. 3 participants showed high local and systemic reactions (HR) with T2 time increases of 120±24\% (M. erector spinae) and 73±50\% (M. multifidius). In comparison, the remaining 7 participants showed increases of 11±12\% (M. erector spinae) and 7±9\% (M. multifidius) in T2 time. Mean CK increased 9.5-fold in the 3 HR subjects compared with the remaining 7 subjects. CONCLUSIONS: The 120sec maximal ECC trunk flexion-extension protocol induced high amounts of muscle damage in 3 participants. Moderate to low responses were found in the remaining 7 subjects, assuming that inter-individual predictors play a role regarding physiological responses to ECC workload.}, language = {en} } @misc{SchraplauSonnenburgWochatzetal.2020, author = {Schraplau, Anne and Sonnenburg, Dominik and Wochatz, Monique and Engel, Tilman and Schom{\"o}ller, Anne and Risch, Lucie and Kaplick, Hannes and Mayer, Frank}, title = {Characterization of muscle damage and inflammation following repeated maximal eccentric loading of the trunk}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {52}, journal = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {7S}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/01.mss.0000679532.65880.af}, pages = {497 -- 497}, year = {2020}, abstract = {Eccentric exercises (ECC) induce reversible muscle damage, delayed-onset muscle soreness and an inflammatory reaction that is often followed by a systemic anti-inflammatory response. Thus, ECC might be beneficial for treatment of metabolic disorders which are frequently accompanied by a low-grade systemic inflammation. However, extent and time course of a systemic immune response after repeated ECC bouts are poorly characterized. PURPOSE: To analyze the (anti-)inflammatory response after repeated ECC loading of the trunk. METHODS: Ten healthy participants (33 ± 6 y; 173 ± 14 cm; 74 ± 16 kg) performed three isokinetic strength measurements of the trunk (concentric (CON), ECC1, ECC2, each 2 wks apart; flexion/extension, velocity 60°/s, 120s MVC). Pre- and 4, 24, 48, 72, 168h post-exercise, muscle soreness (numeric rating scale, NRS) was assessed and blood samples were taken and analyzed [Creatine kinase (CK), C-reactive protein (CRP), Interleukin-6 (IL-6), IL-10, Tumor necrosis factor-α (TNF-α)]. Statistics were done by Friedman's test with Dunn's post hoc test (α=.05). RESULTS: Mean peak torque was higher during ECC1 (319 ± 142 Nm) than during CON (268 ± 108 Nm; p<.05) and not different between ECC1 and ECC2 (297 ± 126 Nm; p>.05). Markers of muscle damage (peaks post-ECC1: NRS 48h, 4.4±2.9; CK 72h, 14407 ± 19991 U/l) were higher after ECC1 than after CON and ECC2 (p<.05). The responses over 72h (stated as Area under the Curve, AUC) were abolished after ECC2 compared to ECC1 (p<.05) indicating the presence of the repeated bout effect. CRP levels were not changed. IL-6 levels increased 2-fold post-ECC1 (pre: 0.5 ± 0.4 vs. 72h: 1.0 ± 0.8 pg/ml). The IL-6 response was enhanced after ECC1 (AUC 61 ± 37 pg/ml*72h) compared to CON (AUC 33 ± 31 pg/ml*72h; p<.05). After ECC2, the IL-6 response (AUC 43 ± 25 pg/ml*72h) remained lower than post-ECC1, but the difference was not statistically significant. Serum levels of TNF-α and of the anti-inflammatory cytokine IL-10 were below detection limits. Overall, markers of muscle damage and immune response showed high inter-individual variability. CONCLUSION: Despite maximal ECC loading of a large muscle group, no anti-inflammatory and just weak inflammatory responses were detected in healthy adults. Whether ECC elicits a different reaction in inflammatory clinical conditions is unclear.}, language = {en} } @misc{MartinezValdesNegroLaineetal.2016, author = {Martinez-Valdes, Eduardo and Negro, Francesco and Laine, Christopher M. and Falla, Deborah L. and Mayer, Frank and Farina, Dario}, title = {Identifying motor units in longitudinal studies with high-density surface electromyography}, series = {Converging clinical and engineering research on neurorehabilitation II}, volume = {15}, journal = {Converging clinical and engineering research on neurorehabilitation II}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-46669-9}, issn = {2195-3562}, doi = {10.1007/978-3-319-46669-9_27}, pages = {147 -- 151}, year = {2016}, abstract = {We investigated the possibility to identify motor units (MUs) with high-density surface electromyography (HDEMG) over experimental sessions in different days. 10 subjects performed submaximal knee extensions across three sessions in three days separated by one week, while EMG was recorded from the vastus medialis muscle with high-density electrode grids. The shapes of the MU action potentials (MUAPs) over multiple channels extracted from HDEMG decomposition were matched across sessions by cross-correlation. Forty and twenty percent of the MUs decomposed could be tracked across two and three sessions, respectively (average cross correlation 0.85 +/- 0.04). The estimated properties of the matched motor units were similar across the sessions. For example, mean discharge rate and recruitment thresholds were measured with an intra-class correlation coefficient (ICCs) > 0.80. These results strongly suggest that the same MUs were indeed identified across sessions. This possibility will allow monitoring changes in MU properties following interventions or during the progression of neuromuscular disorders.}, language = {en} } @misc{PuschmannBeckSchiltenwolfetal.2017, author = {Puschmann, Anne-Kathrin and Beck, Heidrun and Schiltenwolf, Marcus and Wippert, Pia-Maria and Mayer, Frank}, title = {Distress in a longitudinal study of a population with nonspecific low back pain}, series = {Psychosomatic medicine}, volume = {79}, journal = {Psychosomatic medicine}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0033-3174}, pages = {A20 -- A21}, year = {2017}, language = {en} } @misc{DeWittHubertsNiedererWippertetal.2017, author = {De Witt Huberts, Jessie and Niederer, Daniel and Wippert, Pia-Maria and Mayer, Frank}, title = {The effects of a new practical and synergetic multimodal treatment for chronic back pain on pain-related cognitions and wellbeing}, series = {Psychosomatic medicine}, volume = {79}, journal = {Psychosomatic medicine}, number = {4}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0033-3174}, pages = {A22 -- A23}, year = {2017}, language = {en} } @misc{MolnarKokEngeletal.2018, author = {Molnar, Marco and Kok, Manor and Engel, Tilman and Kaplic, Hannes and Mayer, Frank and Seel, Thomas}, title = {A method for lower back motion assessment using wearable 6D inertial sensors}, series = {21st International Conference on Information Fusion (FUSION)}, journal = {21st International Conference on Information Fusion (FUSION)}, publisher = {IEEE}, address = {New York}, isbn = {978-0-9964-5276-2}, pages = {799 -- 806}, year = {2018}, abstract = {Low back pain (LBP) is a leading cause of activity limitation. Objective assessment of the spinal motion plays a key role in diagnosis and treatment of LBP. We propose a method that facilitates clinical assessment of lower back motions by means of a wireless inertial sensor network. The sensor units are attached to the right and left side of the lumbar region, the pelvis and the thighs, respectively. Since magnetometers are known to be unreliable in indoor environments, we use only 3D accelerometer and 3D gyroscope readings. Compensation of integration drift in the horizontal plane is achieved by estimating the gyroscope biases from automatically detected initial rest phases. For the estimation of sensor orientations, both a smoothing algorithm and a filtering algorithm are presented. From these orientations, we determine three-dimensional joint angles between the thighs and the pelvis and between the pelvis and the lumbar region. We compare the orientations and joint angles to measurements of an optical motion tracking system that tracks each skin-mounted sensor by means of reflective markers. Eight subjects perform a neutral initial pose, then flexion/extension, lateral flexion, and rotation of the trunk. The root mean square deviation between inertial and optical angles is about one degree for angles in the frontal and sagittal plane and about two degrees for angles in the transverse plane (both values averaged over all trials). We choose five features that characterize the initial pose and the three motions. Interindividual differences of all features are found to be clearly larger than the observed measurement deviations. These results indicate that the proposed inertial sensor-based method is a promising tool for lower back motion assessment.}, language = {en} } @misc{KhajooeiLinSteffanetal.2018, author = {Khajooei, Mina and Lin, Chiao-I and Steffan, M{\"u}ller and Mayer, Frank}, title = {Effect of Instability in Legpress Testing on Strength \& Muscle Activity in Functional Ankle Instability}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {50}, journal = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5S}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {:10.1249/01.mss.0000537073.01736.db}, pages = {602 -- 602}, year = {2018}, language = {en} }