TY - JOUR A1 - Müller, Juliane A1 - Hadzic, Miralem A1 - Mugele, Hendrik A1 - Stoll, Josefine A1 - Müller, Steffen A1 - Mayer, Frank T1 - Effect of high-intensity perturbations during core-specific sensorimotor exercises on trunk muscle activation JF - Journal of biomechanics N2 - Core-specific sensorimotor exercises are proven to enhance neuromuscular activity of the trunk. However, the influence of high-intensity perturbations on training efficiency is unclear within this context. Sixteen participants (29 +/- 2 yrs; 175 +/- 8 cm; 69 +/- 13 kg) were prepared with a 12-lead bilateral trunk EMG. Warm-up on a dynamometer was followed by maximum voluntary isometric trunk (flex/ext) contraction (MVC). Next, participants performed four conditions for a one-legged stance with hip abduction on a stable surface (HA) repeated randomly on an unstable surface (HAP), on a stable surface with perturbation (HA + P), and on an unstable surface with perturbation (HAP + P). Afterwards, bird dog (BD) was performed under the same conditions (BD, BDP, BD + P, BDP + P). A foam pad under the foot (HA) or the knee (BD) was used as an unstable surface. Exercises were conducted on a moveable platform. Perturbations (ACC 50 m/sec(2);100 ms duration;10rep.) were randomly applied in the anterior-posterior direction. The root mean square (RMS) normalized to MVC (%) was calculated (whole movement cycle). Muscles were grouped into ventral right and left (VR;VL), and dorsal right and left (DR;DL). Ventral Dorsal and right-left ratios were calculated (two way repeated-measures ANOVA;alpha = 0,05). Amplitudes of all muscle groups in bird dog were higher compared to hip abduction (p <= 0.0001; Range: BD: 14 +/- 3% (BD;VR) to 53 +/- 4%; HA: 7 +/- 2% (HA;DR) to 16 +/- 4% (HA;DR)). EMG-RMS showed significant differences (p < 0.001) between conditions and muscle groups per exercise. Interaction effects were only significant for HA (p = 0.02). No significant differences were present in EMG ratios (p > 0.05). Additional high-intensity perturbations during core-specific sensorimotor exercises lead to increased neuromuscular activity and therefore higher exercise intensities. However, the beneficial effects on trunk function remain unclear. Nevertheless, BD is more suitable to address trunk muscles. KW - Split-belt treadmill KW - EMG KW - Core stability KW - MiSpEx Y1 - 2017 U6 - https://doi.org/10.1016/j.jbiomech.2017.12.013 SN - 0021-9290 SN - 1873-2380 VL - 70 SP - 212 EP - 218 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Baur, Heiner A1 - Hirschmüller, Anja A1 - Müller, Steffen A1 - Mayer, Frank T1 - Neuromuscular activity of the peroneal muscle after foot orthoses therapy in runners JF - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine N2 - BAUR, H., A. HIRSCHMULLER, S. MULLER, and F. MAYER. Neuromuscular Activity of the Peroneal Muscle after Foot Orthoses Therapy in Runners. Med. Sci. Sports Exerc., Vol. 43, No. 8, pp. 1500-1506, 2011. Purpose: Foot orthoses are a standard option to treat overuse injury. Biomechanical data providing mechanisms of foot orthoses' effectiveness are sparse. Stability of the ankle joint complex might be a key factor. The purpose was therefore to analyze neuromuscular activity of the musculus peroneus longus in runners with overuse injury symptoms treated with foot orthoses. Methods: A total of 99 male and female runners with overuse injury symptoms randomized in a control group (CO) and an orthoses group (OR) were analyzed on a treadmill at 3.3 m.s(-1) before and after an 8-wk foot orthoses intervention. Muscular activity of the musculus peroneus longus was measured and quantified in the time domain (initial onset of activation (T-ini), time of maximal activity (T-max), total time of activation (T-tot)) and amplitude domain (amplitude in preactivation (A(pre)), weight acceptance (A(wa)), push-off (A(po))). Results: Peroneal activity in the time domain did not differ initially between CO and OR, and no effect was observed after therapy (T-ini: CO = -0.88 +/- 0.09, OR = -0.88 +/- 0.08 / T-max: CO = 0.14 +/- 0.06, OR = 0.15 +/- 0.06 / T-tot: CO = 0.40 +/- 0.09, OR = 0.41 +/- 0.09; P > 0.05). In preactivation (Apre), muscle activity was higher in OR after intervention (CO = 0.97 +/- 0.32, 95% confidence interval = 0.90-1.05; OR = 1.18 +/- 0.43, 95% confidence interval = 1.08-1.28; P = 0.003). There was no group or intervention effect during stance (A(wa): CO = 2.33 +/- 0.66, OR = 2.33 +/- 0.74 / A(po): CO = 0.80 +/- 0.41, OR = 0.88 +/- 0.40; P > 0.05). Conclusions: Enhanced muscle activation of the musculus peroneus longus in preactivation suggests an altered preprogrammed activity, which might lead to better ankle stability providing a possible mode of action for foot orthoses therapy. KW - ANKLE JOINT KW - EMG KW - INSERT KW - INSOLE KW - JOINT STABILITY KW - OVERUSE INJURY Y1 - 2011 U6 - https://doi.org/10.1249/MSS.0b013e31820c64ae SN - 0195-9131 VL - 43 IS - 8 SP - 1500 EP - 1506 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - JOUR A1 - Baritello, Omar A1 - Khajooei, Mina A1 - Engel, Tilman A1 - Kopinski, Stephan A1 - Quarmby, Andrew James A1 - Müller, Steffen A1 - Mayer, Frank T1 - Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass JF - BMC sports science, medicine and rehabilitation N2 - Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p <= 0.05; Bonferroni adjusted alpha = 0.008). Results PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs. KW - EMG KW - instability KW - overhead athlete KW - unstable resistance training KW - water KW - pipe KW - rotator cuff Y1 - 2020 U6 - https://doi.org/10.1186/s13102-020-00168-x SN - 2052-1847 VL - 12 IS - 1 PB - BioMed Central CY - London ER - TY - GEN A1 - Baritello, Omar A1 - Khajooei, Mina A1 - Engel, Tilman A1 - Kopinski, Stephan A1 - Quarmby, Andrew James A1 - Müller, Steffen A1 - Mayer, Frank T1 - Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p <= 0.05; Bonferroni adjusted alpha = 0.008). Results PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 867 KW - EMG KW - instability KW - overhead athlete KW - unstable resistance training KW - water pipe KW - rotator cuff Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-509366 SN - 1866-8364 IS - 1 ER - TY - JOUR A1 - Müller, Juliane A1 - Engel, Tilman A1 - Kopinski, Stephan A1 - Mayer, Frank A1 - Müller, Steffen T1 - Neuromuscular trunk activation patterns in back pain patients during one-handed lifting JF - World journal of orthopedics N2 - AIM To analyze neuromuscular activity patterns of the trunk in healthy controls (H) and back pain patients (BPP) during one-handed lifting of light to heavy loads. METHODS RESULTS Seven subjects (3m/4f; 32 +/- 7 years; 171 +/- 7 cm; 65 +/- 11 kg) were assigned to BPP (pain grade >= 2) and 36 (13m/23f; 28 +/- 8 years; 174 +/- 10 cm; 71 +/- 12 kg) to H (pain grade <= 1). H and BPP did not differ significantly in anthropometrics (P > 0.05). All subjects were able to lift the light and middle loads, but 57% of BPP and 22% of H were not able to lift the heavy load (all women) chi(2) analysis revealed statistically significant differences in task failure between H vs BPP (P = 0.03). EMG-RMS ranged from 33% +/- 10%/30% +/- 9% (DL, 1 kg) to 356% +/- 148%/283% +/- 80% (VR, 20 kg) in H/BPP with no statistical difference between groups regardless of load (P > 0.05). However, the EMG-RMS of the VR was greatest in all lifting tasks for both groups and increased with heavier loads. CONCLUSION Heavier loading leads to an increase (2-to 3-fold) in trunk muscle activity with comparable patterns. Heavy loading (20 kg) leads to task failure, especially in women with back pain. KW - Lifting KW - Core KW - Trunk KW - EMG KW - MISPEX Y1 - 2016 U6 - https://doi.org/10.5312/wjo.v8.i2.142 SN - 2218-5836 VL - 8 IS - 2 SP - 142 EP - 148 PB - Baishideng Publishing Group CY - Pleasanton ER - TY - JOUR A1 - Müller, Juliane A1 - Müller, Steffen A1 - Engel, Tilman A1 - Reschke, Antje A1 - Baur, Heiner A1 - Mayer, Frank T1 - Stumbling reactions during perturbed walking: Neuromuscular reflex activity and 3-D kinematics of the trunk - A pilot study JF - Journal of biomechanics N2 - Stumbling led to an increase in ROM, compared to unperturbed gait, in all segments and planes. These increases ranged between 107 +/- 26% (UTA/rotation) and 262 +/- 132% (UTS/lateral flexion), significant only in lateral flexion. EMG activity of the trunk was increased during stumbling (abdominal: 665 +/- 283%; back: 501 +/- 215%), without significant differences between muscles. Provoked stumbling leads to a measurable effect on the trunk, quantifiable by an increase in ROM and EMG activity, compared to normal walking. Greater abdominal muscle activity and ROM of lateral flexion may indicate a specific compensation pattern occurring during stumbling. (C) 2015 Elsevier Ltd. All rights reserved. KW - Trunk kinematics KW - Treadmill walking KW - Gait perturbation KW - EMG Y1 - 2016 U6 - https://doi.org/10.1016/j.jbiomech.2015.09.041 SN - 0021-9290 SN - 1873-2380 VL - 49 SP - 933 EP - 938 PB - Elsevier CY - Oxford ER -