scholarly journals Corticomuscular Coherence and Motor Control Adaptations after Isometric Maximal Strength Training

2021 ◽  
Vol 11 (2) ◽  
pp. 254
Author(s):  
Dimitri Elie ◽  
Franck Barbier ◽  
Ghassan Ido ◽  
Sylvain Cremoux
Keyword(s):  
Motor Control ◽  
Strength Training ◽  
Muscle Activation ◽  
Force Production ◽  
Maximal Strength ◽  
Antagonist Muscle ◽  
Corticomuscular Coherence ◽  
Muscle Activations ◽  
Stability And Accuracy ◽  
Over Time

Strength training (ST) induces corticomuscular adaptations leading to enhanced strength. ST alters the agonist and antagonist muscle activations, which changes the motor control, i.e., force production stability and accuracy. This study evaluated the alteration of corticomuscular communication and motor control through the quantification of corticomuscular coherence (CMC) and absolute (AE) and variable error (VE) of the force production throughout a 3 week Maximal Strength Training (MST) intervention specifically designed to strengthen ankle plantarflexion (PF). Evaluation sessions with electroencephalography, electromyography, and torque recordings were conducted pre-training, 1 week after the training initiation, then post-training. Training effect was evaluated over the maximal voluntary isometric contractions (MVIC), the submaximal torque production, AE and VE, muscle activation, and CMC changes during submaximal contractions at 20% of the initial and daily MVIC. MVIC increased significantly throughout the training completion. For submaximal contractions, agonist muscle activation decreased over time only for the initial torque level while antagonist muscle activation, AE, and VE decreased over time for each torque level. CMC remained unaltered by the MST. Our results revealed that neurophysiological adaptations are noticeable as soon as 1 week post-training. However, CMC remained unaltered by MST, suggesting that central motor adaptations may take longer to be translated into CMC alteration.

scholarly journals Efectos de entrenamiento de fuerza en sistema isoinercial sobre la mejora del CMJ en jóvenes futbolistas de elite (Effects of strength training using a isoinertial device on jump ability in young elite soccer players)

Retos ◽  
2015 ◽  
pp. 180-182
Author(s):  
Sergio Romero Boza ◽  
Adrián Feria Madueño ◽  
Borja Sañudo Corrales ◽  
Moisés De Hoyo Lora ◽  
Juan José Del Ojo López
Keyword(s):  
Strength Training ◽  
Force Production ◽  
Team Sport ◽  
Soccer Players ◽  
Maximal Strength ◽  
Countermovement Jump ◽  
Palabras Clave ◽  
Jump Ability ◽  
Physical Skills

El fútbol es un deporte colectivo donde, para alcanzar el éxito, los jugadores necesitan de habilidades técnicas, tácticas y físicas, fundamentalmente de carácter intermitente siendo éstas acciones las que determinan el rendimiento. Un ejemplo de acciones de este tipo son los saltos. Este gesto deportivo esta correlacionado con la fuerza máxima, entendiendo que una mayor producción de fuerza permite una mayor generación de altura en dicho gesto. El objetivo de este trabajo es estudiar el efecto de entrenamiento de fuerza en sistema isoinercial sobre la mejora del Salto con Contramovimiento y analizar los cambios en la altura del mismo después de un programa de entrenamiento de 15 semanas, realizado sobre jóvenes futbolistas de élite. Los resultados obtenidos, muestran que no existen cambios significativos en esta variable de análisis (p< 0,05) por lo que se concluye que este tipo de entrenamiento con la duración especificada no tiene efectos sobre el rendimiento en la altura del salto (CMJ).Palabras clave: Entrenamiento Isoinercial, Futbolistas, Rendimiento, CMJ.Abstract: Soccer is a team sport where, to achieve success, players need of technical, tactical and physical skills, mainly intermittent character being such actions which determine the performance. An example of such actions is the jumpers. This sports actions is correlated with the maximal strength, understanding that force production allows greater height in this actions. The aim is to study the effects of strength training using a isoinertial device on Countermovement Jump ability and to analyze the changes in height after 15 weeks program training in young elite soccer players. There are no significant changes after to analyze the results (p< 0,05), so it is concluded that this type of training with certified duration has no effect on performance in height jump (CMJ).Keywords: Isoinertial Training, Soccers Players, Performance, CMJ.

Less precise motor control leads to increased agonist-antagonist muscle activation during stick balancing

2016 ◽  
Vol 47 ◽  
pp. 166-174
Author(s):  
N. Peter Reeves ◽  
John M. Popovich ◽  
Vilok Vijayanagar ◽  
Pramod K. Pathak
Keyword(s):  
Motor Control ◽  
Muscle Activation ◽  
Antagonist Muscle

scholarly journals Maximal strength training-induced increase in efferent neural drive is not reflected in relative protein expression of SERCA

2021 ◽  
Author(s):  
Tiril Tøien ◽  
Håvard Haglo ◽  
Stian Kwak Nyberg ◽  
Shalini Vasudev Rao ◽  
Astrid Kamilla Stunes ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Strength Training ◽  
High Intensity ◽  
Force Production ◽  
H Reflex ◽  
Maximal Strength ◽  
Neural Drive ◽  
M Wave ◽  
Neural Adaptations

Abstract Introduction Maximal strength training (MST), performed with heavy loads (~ 90% of one repetition maximum; 1RM) and few repetitions, yields large improvements in efferent neural drive, skeletal muscle force production, and skeletal muscle efficiency. However, it is elusive whether neural adaptations following such high intensity strength training may be accompanied by alterations in energy-demanding muscular factors. Methods Sixteen healthy young males (24 ± 4 years) were randomized to MST 3 times per week for 8 weeks (n = 8), or a control group (CG; n = 8). Measurements included 1RM and rate of force development (RFD), and evoked potentials recordings (V-wave and H-reflex normalized to M-wave (M) in the soleus muscle) applied to assess efferent neural drive to maximally contracting skeletal muscle. Biopsies were obtained from vastus lateralis and analyzed by western blots and real-time PCR to investigate the relative protein expression and mRNA expression of Sarcoplasmic Reticulum Ca2+ ATPase (SERCA) 1 and SERCA2. Results Significant improvements in 1RM (17 ± 9%; p < 0.001) and early (0–100 ms), late (0–200 ms) and maximal RFD (31–53%; p < 0.01) were observed after MST, accompanied by increased maximal Vmax/Msup-ratio (9 ± 14%; p = 0.046), with no change in H-reflex to M-wave ratio. No changes were observed in the CG. No pre- to post-training differences were found in mRNA or protein expressions of SERCA1 and SERCA2 in either group. Conclusion MST increased efferent neural drive to maximally contracting skeletal muscle, causing improved force production. No change was observed in SERCA expression, indicating that responses to high intensity strength training may predominantly be governed by neural adaptations.

scholarly journals Ankle Muscle Activations during Different Foot-Strike Patterns in Running

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3422
Author(s):  
Jian-Zhi Lin ◽  
Wen-Yu Chiu ◽  
Wei-Hsun Tai ◽  
Yu-Xiang Hong ◽  
Chung-Yu Chen
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Stance Phase ◽  
Inertial Sensors ◽  
Plantar Flexion ◽  
Intraclass Correlation ◽  
Biceps Femoris ◽  
Ankle Muscle ◽  
Foot Strike ◽  
Muscle Activations

This study analysed the landing performance and muscle activity of athletes in forefoot strike (FFS) and rearfoot strike (RFS) patterns. Ten male college participants were asked to perform two foot strikes patterns, each at a running speed of 6 km/h. Three inertial sensors and five EMG sensors as well as one 24 G accelerometer were synchronised to acquire joint kinematics parameters as well as muscle activation, respectively. In both the FFS and RFS patterns, according to the intraclass correlation coefficient, excellent reliability was found for landing performance and muscle activation. Paired t tests indicated significantly higher ankle plantar flexion in the FFS pattern. Moreover, biceps femoris (BF) and gastrocnemius medialis (GM) activation increased in the pre-stance phase of the FFS compared with that of RFS. The FFS pattern had significantly decreased tibialis anterior (TA) muscle activity compared with the RFS pattern during the pre-stance phase. The results demonstrated that the ankle strategy focused on controlling the foot strike pattern. The influence of the FFS pattern on muscle activity likely indicates that an athlete can increase both BF and GM muscles activity. Altered landing strategy in cases of FFS pattern may contribute both to the running efficiency and muscle activation of the lower extremity. Therefore, neuromuscular training and education are required to enable activation in dynamic running tasks.

scholarly journals Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats

2021 ◽  
Vol 2 ◽  
Author(s):  
Rand Hidayah ◽  
Dongbao Sui ◽  
Kennedi A. Wade ◽  
Biing-Chwen Chang ◽  
Sunil Agrawal
Keyword(s):  
Outcome Measures ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Lower Limbs ◽  
Flexion Angle ◽  
Coil Spring ◽  
Foot Pressure ◽  
Low Profile ◽  
Muscle Activations

Abstract Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

scholarly journals Early Maximal Strength Training Improves Leg Strength and Postural Stability in Elderly Following Hip Fracture Surgery

2021 ◽  
Vol 12 ◽  
pp. 215145932110151
Author(s):  
Ole Kristian Berg ◽  
Jens-Meinhard Stutzer ◽  
Jan Hoff ◽  
Eivind Wang
Keyword(s):  
Hip Fracture ◽  
Muscle Strength ◽  
Strength Training ◽  
Postural Stability ◽  
Maximal Strength ◽  
Leg Press ◽  
Hip Fracture Surgery ◽  
Downward Spiral ◽  
Conventional Physiotherapy ◽  
Fracture Surgery

Introduction: Hip fractures predominantly occur in the geriatric population and results in increased physical inactivity and reduced independency, largely influenced by a downward spiral of ambulatory capacity, related to loss of skeletal muscle strength and postural stability. Thus, effective postoperative treatment, targeting improvements in muscle strength, is sought after. Materials & Methods: Twenty-one hip fracture patients (>65 yr) were randomized to 8 weeks of either conventional physiotherapy control group (CG), or leg press and hip abduction maximal strength training (MST) 3 times per week. MST was performed applying heavy loads (85-90% of 1 repetition maximum; 1RM) and 4-5 repetitions in 4 sets. Maximal strength (bi- and unilateral 1RM), postural stability (unipedal stance test; UPS), and DEXA-scan bone mineral content/ density (BMC/BMD) were measured before and after the 8-week rehabilitation. Results: Both MST and conventional physiotherapy improved bilateral leg press 1RM by 41 ± 27 kg and 29 ± 17 kg, respectively (both p < 0.01), while unilateral leg press 1RM only increased after MST (within group and between groups difference: both p < 0.05). MST also resulted in an increase in abduction 1RM in both the fractured (5 kg, 95%CI: 2-7; p < 0.01) and healthy limb (6 kg, 95%CI: 3-9; p < 0.01), while no such improvement was apparent in the CG (between groups difference: p < 0.01). Finally, MST improved UPS of the fractured limb (p < 0.05). No differences were observed in BMC or BMD following the 8 weeks. Discussion: Early postoperative MST improved lower extremities maximal muscle strength more than conventional physiotherapy and was accompanied by improvements in postural stability. Conclusion: Implementing MST in early rehabilitation after hip fracture surgery should be considered as a relevant treatment to curtail the downward spiral of reduced ambulatory capacity typical for this patient group, possibly reducing the risk of recuring falls and excess mortality. Trial Registration: https://clinicaltrials.gov/ct2/show/NCT03030092

Maximal Strength Training: The Effects on Intramuscular Economy and its Determinants

2010 ◽  
Vol 42 ◽  
pp. 241
Author(s):  
Zachary Barrett-O'Keefe ◽  
Jan Helgerud ◽  
Peter D. Wagner ◽  
Russell S. Richardson
Keyword(s):  
Strength Training ◽  
Maximal Strength

Neural Networks and Motor Control

1997 ◽  
Vol 3 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Apostolus P. Georgopoulos
Keyword(s):  
Motor Control ◽  
Spatial Information ◽  
Network Modeling ◽  
Central Place ◽  
Cooperative Interaction ◽  
Neural Network Modeling ◽  
Spinal Motor ◽  
Structural And Functional Properties ◽  
Motor Cortical ◽  
Muscle Activations

Motor control is accomplished by the cooperative interaction of many brain networks, among which the motor cortex holds a central place. This article reviews some of the structural and functional properties of neurons of the motor cortical network, some principles of connectivity with other motor networks, the handling of spatial information regarding reaching movements, and some ideas on how motor cortical commands could be translated to muscle activations by spinal motor networks. Finally, I review recent neural network modeling studies of motor cortical ensemble operations.

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