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Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

Tom 76 (2021): Zeszyt 1 (January 2021)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

14 Artykułów

Motor Control

Otwarty dostęp

Motor Control: A Young Field with Many Facets (Introduction to the Special Issue)

Data publikacji: 29 Jan 2021
Zakres stron: 5 - 8

Abstrakt

Otwarty dostęp

Learning to Use Muscles

Data publikacji: 29 Jan 2021
Zakres stron: 9 - 33

Abstrakt

Abstract

The human musculoskeletal system is highly complex mechanically. Its neural control must deal successfully with this complexity to perform the diverse, efficient, robust and usually graceful behaviors of which humans are capable. Most of those behaviors might be performed by many different subsets of its myriad possible states, so how does the nervous system decide which subset to use? One solution that has received much attention over the past 50 years would be for the nervous system to be fundamentally limited in the patterns of muscle activation that it can access, a concept known as muscle synergies or movement primitives. Another solution, based on engineering control methodology, is for the nervous system to compute the single optimal pattern of muscle activation for each task according to a cost function. This review points out why neither appears to be the solution used by humans. There is a third solution that is based on trial-and-error learning, recall and interpolation of sensorimotor programs that are good-enough rather than limited or optimal. The solution set acquired by an individual during the protracted development of motor skills starting in infancy forms the basis of motor habits, which are inherently low-dimensional. Such habits give rise to muscle usage patterns that are consistent with synergies but do not reflect fundamental limitations of the nervous system and can be shaped by training or disability. This habit-based strategy provides a robust substrate for the control of new musculoskeletal structures during evolution as well as for efficient learning, athletic training and rehabilitation therapy.

Key words

  • redundancy
  • synergies
  • primitives
  • musculoskeletal mechanics
  • motor habits
  • control theory
  • optimal control
  • servocontrol
Otwarty dostęp

Coordination of Axial Trunk Rotations During Gait in Low Back Pain. A Narrative Review

Data publikacji: 29 Jan 2021
Zakres stron: 35 - 50

Abstrakt

Abstract

Chronic low back pain patients have been observed to show a reduced shift of thorax-pelvis relative phase towards out-of-phase movement with increasing speed compared to healthy controls. Here, we review the literature on this phase shift in patients with low back pain and we analyze the results presented in literature in view of the theoretical motivations to assess this phenomenon. Initially, based on the dynamical systems approach to movement coordination, the shift in thorax-pelvis relative phase with speed was studied as a self-organizing transition. However, the phase shift is gradual, which does not match a self-organizing transition. Subsequent emphasis in the literature therefore shifted to a motivation based on biomechanics. The change in relative phase with low back pain was specifically linked to expected changes in trunk stiffness due to ‘guarded behavior’. We found that thorax-pelvis relative phase is affected by several interacting factors, including active drive of thorax rotation through trunk muscle activity, stride frequency and the magnitude of pelvis rotations. Large pelvis rotations and high stride frequency observed in low back pain patients may contribute to the difference between patients and controls. This makes thorax-pelvis relative phase a poor proxy of trunk stiffness. In conclusion, thorax-pelvis relative phase cannot be considered as a collective variable reflecting the orderly behaviour of a complex underlying system, nor is it a marker of specific changes in trunk biomechanics. The fact that it is affected by multiple factors may explain the considerable between-subject variance of this measure in low back pain patients and healthy controls alike.

Key words

  • low back pain
  • coordination
  • gait
  • trunk
  • relative phase
Otwarty dostęp

Production and Perception of Intentional and Unintentional Actions

Data publikacji: 29 Jan 2021
Zakres stron: 51 - 66

Abstrakt

Abstract

Physical approach to biological movement is based on the idea of control with referent spatial coordinates for effectors, from the whole body to single muscles. Within this framework, neural control signals induce changes in parameters of corresponding biology-specific laws of nature, and motor performance emerges as a result of interaction with the external force field. This approach is naturally compatible with the principle of abundance and the uncontrolled manifold hypothesis, which offer the framework for analysis of movement stability. The presence of two basic commands, reciprocal and co-activation, makes even single-effector tasks abundant and allows stabilizing their performance at the control level. Kinesthetic perception can be viewed as the process of estimating afferent signals within a reference system provided by the efferent process. Percepts are reflections of stable iso-perceptual manifolds in the combined afferent-efferent multi-dimensional space. This approach offers new, logical and based on laws of nature, interpretations for such phenomena as muscle co-activation, unintentional drifts in performance, and vibration-induced kinesthetic illusions. It also allows predicting new phenomena such as counter-intuitive effects of muscle co-activation of force production and perception, vibration-induced force illusions, performance drifts at two different speeds, and high variability in matching the contribution of individual elements in multi-element tasks. This approach can be developed for various subfields of movement studies including studies of athletics, movement disorders, and movement rehabilitation.

Key words

  • referent coordinate
  • back-coupling
  • uncontrolled manifold
  • iso-perceptual manifold
  • co-activation
Otwarty dostęp

Focused Review on Neural Correlates of Different Types of Motor Errors and Related Terminological Issues

Data publikacji: 29 Jan 2021
Zakres stron: 67 - 81

Abstrakt

Abstract

The Error-related negativity (Ne/ERN) and the feedback-related negativity (FRN), two event-related potentials in electroencephalogram tracings, have been used to examine error processing in conscious actions. In the classical terminology the Ne/ERN and the FRN are differentiated with respect to whether internal (Ne/ERN) or external (FRN) error information is processed. In motor tasks, however, errors of different types can be made: A wrong action can be selected that is not adequate to achieve the task goal (or action effect), or the correctly selected action can be mis-performed such that the task goal might be missed (movement error). Depending on the motor task and the temporal sequences of these events, internal and external error information can coincide. Hence, a clear distinction of the information source is difficult, and the classical terminology that differentiates the Ne/ERN and the FRN with respect to internal and external error information becomes ambiguous. But, a stronger focus on the characteristics of the definition of “task” and the cause of “errors”, as well as on temporal characteristics of event-related potentials with respect to the task action allows separate examination of the processing of movement errors, the processing of the prediction of action effect errors, or the processing of the detection of action effect errors. The present article gives an overview of example studies investigating the Ne/ERN and the FRN in motor tasks, classifies them with respect to action effect errors or movement errors, and proposes updated terminology.

Key words

  • error-related negativity
  • feedback-related negativity
  • movement error
  • action effect error
  • error prediction
  • error postdiction
Otwarty dostęp

Effect of Acute Heart Rate Variability Biofeedback on H-reflex Modulation: A Pilot Study

Data publikacji: 29 Jan 2021
Zakres stron: 83 - 88

Abstrakt

Abstract

Heart rate variability biofeedback (HRV BFB) is paced breathing scheme that stimulates resonance in the cardiovascular system. This study aimed to investigate the effect of a single-session HRV BFB on Hoffman reflex (H-reflex) of the soleus muscle. Twelve healthy males (height: 173.7 ± 7.18 cm; weight: 72.7 ± 17.7 kg; age: 24.0 ± 5.02 yrs) completed a randomized-crossover intervention involving a 10-minute HRV BFB and normal breathing (CON) separated by 48 hours. Results revealed significantly lower 1a afferent activation after HRV BFB. Similarly, the HRV BFB also demonstrated lower proportion of activated motor neurons from 1a afferents. In conclusion, an acute HRV BFB influenced the reduction in motoneuron excitability at resting condition.

Key words

  • biofeedback
  • resonance frequency breathing
  • H-reflex
  • neural excitation
Otwarty dostęp

Synergistic Activation Patterns of Hand Muscles in Left-and Right-Hand Dominant Individuals

Data publikacji: 29 Jan 2021
Zakres stron: 89 - 100

Abstrakt

Abstract

Handedness has been associated with behavioral asymmetries between limbs that suggest specialized function of dominant and non-dominant hand. Whether patterns of muscle co-activation, representing muscle synergies, also differ between the limbs remains an open question. Previous investigations of proximal upper limb muscle synergies have reported little evidence of limb asymmetry; however, whether the same is true of the distal upper limb and hand remains unknown. This study compared forearm and hand muscle synergies between the dominant and non-dominant limb of left-handed and right-handed participants. Participants formed their hands into the postures of the American Sign Language (ASL) alphabet, while EMG was recorded from hand and forearm muscles. Muscle synergies were extracted for each limb individually by applying non-negative-matrix-factorization (NMF). Extracted synergies were compared between limbs for each individual, and between individuals to assess within and across participant differences. Results indicate no difference between the limbs for individuals, but differences in limb synergies at the population level. Left limb synergies were found to be more similar than right limb synergies across left- and right-handed individuals. Synergies of the left hand of left dominant individuals were found to have greater population level similarity than the other limbs tested. Results are interpreted with respect to known differences in the neuroanatomy and neurophysiology of proximal and distal upper limb motor control. Implications for skill training in sports requiring dexterous control of the hand are discussed.

Key words

  • muscle synergy
  • handedness
  • electromyography
  • lateralization
  • upper limb
Otwarty dostęp

Motor Control and Achilles Tendon Adaptation in Adolescence: Effects of Sport Participation and Maturity

Data publikacji: 29 Jan 2021
Zakres stron: 101 - 116

Abstrakt

Abstract

An important but unresolved research question in adolescent children is the following: “Does sport participation interact with maturation to change motor control and the mechanical and morphological properties of tendons?” Here, we address this important research question with a longitudinal study around the age of peak height velocity (PHV). Our purpose was to characterize the interactive effects of maturation and sports participation on motor control and the mechanical and morphological properties of the Achilles tendon (AT) in adolescent athletes and non-athletes. Twenty-two adolescent athletes (13.1 ± 1.1 years) and 19 adolescent non-athletes (12.8 ± 1.1 years) volunteered for this study. We quantified motor control as the coefficient of variation of torque during a ramp task. In addition, we quantified the AT morphological and mechanical properties using ultrasonography from 18 months before to 12 months after PHV. We found that motor control improved with maturation in both athletes and non-athletes. We found that athletes have a greater increase in body mass with maturation that relates to greater plantarflexion peak force and AT peak stress. Also, athletes have a thicker and longer AT, as assessed with resting cross-sectional area and length. Although the rate of increase in the morphological change with maturation was similar for athletes and non-athletes, the rate of increase in normalized AT stiffness was greater for athletes. This increased AT stiffness in athletes related to peak force and stress. In summary, maturation improves motor control in adolescent children. Further, we provide novel longitudinal evidence that sport participation interacts with maturation in adolescents to induce adaptive effects on the Achilles tendon morphology and mechanical properties. These findings have the potential to minimize the risk of injuries and maximize athletic development in talented adolescents.

Key words

  • peak height velocity
  • athletes
  • motor control
  • stiffness
  • stress
  • strain
Otwarty dostęp

The Use of Frequency Analysis as a Complementary and Explanatory Element for Time Domain Analysis in Measurements of the Ability to Maintain Balance

Data publikacji: 29 Jan 2021
Zakres stron: 117 - 129

Abstrakt

Abstract

Assessment of human balance is one of the most common diagnostic tests, both in medical applications and during sports training. Many new methods of measuring are introduced in these studies; however, the analysis of results is still carried out mainly based on the values determined in the time domain – the average COP speed or the ellipse field of the prediction. The aim of the current work is to present the possibilities for the practical application of frequency analyses in assessment of the ability to maintain body balance as a method supplementing standard analyses. As part of the study, measurements of the ability to maintain balance in sensory conflict conditions introduced in the form of an oscillating, three-dimensional, virtual scenery were carried out. 27 healthy volunteers (13 women and 14 men) took part in the study. The three-dimensional scenery, presented by means of the Oculus system, oscillated in the sagittal plane with frequencies equal to 0.7 Hz and 1.4 Hz. The frequency value during the measurement was constant or changed in the middle of the test. Measurements were conducted on the FDM Zebris platform. The results were analyzed using developed coefficients determined on the basis of the Short-time Fourier transform (STFT). The use of frequency-domain analyses confirmed that in the COP movement, one can observe a cyclical component corresponding to following the scenery, as well as the appearance of other cyclical components whose observation is important in terms of assessing the ability to maintain balance. It has been shown that the changes in the average COP speed that occur during the measurement can result from changes related to the movement of following the scenery as well as additional body movements indicating a greater or lesser loss of balance. It has been shown that there are differences in the COP movement provoked by the movement of the surrounding scenery, which depend on the parameters of the introduced disturbances – something that can only be observed in results obtained in the frequency domain. The conducted research shows that in measurements involving the ability to maintain one’s balance conducted in sensory conflict conditions, standard time-domain analyses should be supplemented with other types of data analysis, e.g. frequency domain analyses.

Key words

  • balance
  • virtual reality
  • frequency domain analysis
Otwarty dostęp

Number of Trials Necessary to Apply Analysis within the Framework of the Uncontrolled Manifold Hypothesis at Different Levels of Hierarchical Synergy Control

Data publikacji: 29 Jan 2021
Zakres stron: 131 - 143

Abstrakt

Abstract

The uncontrolled manifold hypothesis is a method used to quantify motor synergies, defined as a specific central nervous system organization that maintains the task-specific stability of motor actions. The UCM allows for inter-trial variance analysis between consecutive trials. However, despite the large body of literature within this framework, there is no report on the number of movement repetitions required for reliable results. Based on the hypothetical hierarchical control of motor synergies, this study aims to determine the minimum number of trials necessary to achieve a good to excellent level of reliability. Thirteen young, healthy participants performed fifteen bilateral isometric contractions of elbow flexion when visual feedback was provided. The force and electromyography data were recorded to investigate synergies at different levels of hierarchical control. The intraclass correlation coefficient was used to determine the reliability of the variance indices. Based on the obtained results, at least twelve trials are required to analyze the inter-trial variance in both force and muscle synergies within the UCM framework.

Key words

  • motor synergies
  • reliability
  • intra-trial variance
  • force
  • muscle modes
  • EMG
Otwarty dostęp

Stability of Action and Kinesthetic Perception in Parkinson’s Disease

Data publikacji: 29 Jan 2021
Zakres stron: 145 - 159

Abstrakt

Abstract

We present a review of action and perception stability within the theoretical framework based on the idea of control with spatial referent coordinates for the effectors at a number of hierarchical levels. Stability of salient variables is ensured by synergies, neurophysiological structures that act in multi-dimensional spaces of elemental variables and limit variance to the uncontrolled manifold during action and iso-perceptual manifold during perception. Patients with Parkinson’s disease show impaired synergic control reflected in poor stability (low synergy indices) and poor agility (low indices of anticipatory synergy adjustments prior to planned quick actions). They also show impaired perception across modalities, including kinesthetic perception. We suggest that poor stability at the level of referent coordinates can be the dominant factor leading to poor stability of percepts.

Key words

  • referent coordinate
  • abundance
  • iso-perceptual manifold
  • basal ganglia
Otwarty dostęp

Progression of Fatigue Modifies Primary Contributors to Ground Reaction Forces During Drop Landing

Data publikacji: 29 Jan 2021
Zakres stron: 161 - 173

Abstrakt

Abstract

Few studies have focused on the effect of fatigue severity on landing strategy. This study aimed to investigate the effect of fatigue progression on ground reaction force during landing. Eighteen participants performed a fatigue exercise protocol. Then participants performed drop landings at three levels of fatigue: no fatigue, medium fatigue, and severe fatigue. Multiple linear regression was conducted to identify the predictors of the peak vertical ground reaction force at each level of fatigue. Two-way ANOVAs were conducted to test the effect of fatigue on the vertical ground reaction force and the predictors. For the vertical ground reaction force, the knee joint stiffness and the knee angle at initial contact were the main predictors at no fatigue. The peak knee flexion angle and knee power were the main predictors at medium fatigue. However, the peak ankle plantarflexion moments became the main predictor at severe fatigue. The vertical ground reaction force decreased from no to medium fatigue (p = 0.001), and then increased from medium to severe fatigue (p = 0.034). The knee joint stiffness decreased from no to medium fatigue (p = 0.049), and then remained unchanged from medium to severe fatigue. The peak knee flexion angle increased from no to medium fatigue (p = 0.001), and then slightly decreased from medium to severe fatigue (p = 0.051). The results indicate that fatigue progression causes a transition from stiff to soft landing, and then to stiff landing. Participants used ankle joints more to control the landing intensity at severe fatigue.

Key words

  • biomechanics
  • drop landing
  • fatigue
  • kinesiology
  • neuromuscular
Otwarty dostęp

The Effect of Crank Resistance on Arm Configuration and Muscle Activation Variances in Arm Cycling Movements

Data publikacji: 29 Jan 2021
Zakres stron: 175 - 189

Abstrakt

Abstract

Arm cycling on an ergometer is common in sports training and rehabilitation protocols. The hand movement is constrained along a circular path, and the user is working against a resistance, maintaining a cadence. Even if the desired hand trajectory is given, there is the flexibility to choose patterns of joint coordination and muscle activation, given the kinematic redundancy of the upper limb. With changing external load, motor noise and changing joint stiffness may affect the pose of the arm even though the endpoint trajectory is unchanged. The objective of this study was to examine how the crank resistance influences the variances of joint configuration and muscle activation. Fifteen healthy participants performed arm cranking on an arm-cycle ergometer both unimanually and bimanually with a cadence of 60 rpm against three crank resistances. Joint configuration was represented in a 3-dimensional joint space defined by inter-segmental joint angles, while muscle activation in a 4-dimensional "muscle activation space" defined by EMGs of 4 arm muscles. Joint configuration variance in the course of arm cranking was not affected by crank resistance, whereas muscle activation variance was proportional to the square of muscle activation. The shape of the variance time profiles for both joint configuration and muscle activation was not affected by crank resistance. Contrary to the prevailing assumption that an increased motor noise would affect the variance of auxiliary movements, the influence of noise doesn’t appear at the joint configuration level even when the system is redundant. Our results suggest the separation of kinematic- and force-control, via mechanisms that are compensating for dynamic nonlinearities. Arm cranking may be suitable when the aim is to perform training under different load conditions, preserving stable and secure control of joint movements and muscle activations.

Key words

  • load
  • joint configuration
  • muscle activation variance
  • kinematic control
  • force control
Otwarty dostęp

Acute and Delayed Effects of Fatigue on Ground Reaction Force, Lower Limb Stiffness and Coordination Asymmetries During a Landing Task

Data publikacji: 29 Jan 2021
Zakres stron: 191 - 199

Abstrakt

Abstract

Landing is a critical phase of movement for injury occurrence, in which lower limbs should be used equally to better absorb the shock. However, it has been suggested that fatigue can lead to the appearance of asymmetries. The aim of this study was to verify the acute and delayed effects of fatigue on the lower limb asymmetry indexes of peak ground reaction force, leg stiffness and intra-limb coordination during a landing task. Fifteen physically active men performed a fatigue protocol composed of 14 sets of 10 continuous vertical jumps, with a one-minute rest interval between the sets. A step-off landing task was performed before, immediately after, 24 h and 48 h after the fatigue protocol. Two force plates and a video analysis system were used. The symmetry index equation provided the asymmetry indexes. For statistical analysis, ANOVA and effect size analysis were utilized. Inferential statistics did not show the effect of fatigue in the asymmetry indexes for any variable or condition (p > .05). Moderate effect sizes were observed for peak ground reaction force (0.61) and leg stiffness (0.61) immediately after the application of the protocol. In conclusion, fatigue does not seem to significantly change the asymmetries of lower limbs, especially regarding intra-limb coordination. The moderate effects observed for peak ground reaction force and leg stiffness asymmetries suggest that these variables may be acutely affected by fatigue.

Key words

  • stretch-shortening cycle
  • shock absorption
  • spring-mass model
  • continuous relative phase
14 Artykułów

Motor Control

Otwarty dostęp

Motor Control: A Young Field with Many Facets (Introduction to the Special Issue)

Data publikacji: 29 Jan 2021
Zakres stron: 5 - 8

Abstrakt

Otwarty dostęp

Learning to Use Muscles

Data publikacji: 29 Jan 2021
Zakres stron: 9 - 33

Abstrakt

Abstract

The human musculoskeletal system is highly complex mechanically. Its neural control must deal successfully with this complexity to perform the diverse, efficient, robust and usually graceful behaviors of which humans are capable. Most of those behaviors might be performed by many different subsets of its myriad possible states, so how does the nervous system decide which subset to use? One solution that has received much attention over the past 50 years would be for the nervous system to be fundamentally limited in the patterns of muscle activation that it can access, a concept known as muscle synergies or movement primitives. Another solution, based on engineering control methodology, is for the nervous system to compute the single optimal pattern of muscle activation for each task according to a cost function. This review points out why neither appears to be the solution used by humans. There is a third solution that is based on trial-and-error learning, recall and interpolation of sensorimotor programs that are good-enough rather than limited or optimal. The solution set acquired by an individual during the protracted development of motor skills starting in infancy forms the basis of motor habits, which are inherently low-dimensional. Such habits give rise to muscle usage patterns that are consistent with synergies but do not reflect fundamental limitations of the nervous system and can be shaped by training or disability. This habit-based strategy provides a robust substrate for the control of new musculoskeletal structures during evolution as well as for efficient learning, athletic training and rehabilitation therapy.

Key words

  • redundancy
  • synergies
  • primitives
  • musculoskeletal mechanics
  • motor habits
  • control theory
  • optimal control
  • servocontrol
Otwarty dostęp

Coordination of Axial Trunk Rotations During Gait in Low Back Pain. A Narrative Review

Data publikacji: 29 Jan 2021
Zakres stron: 35 - 50

Abstrakt

Abstract

Chronic low back pain patients have been observed to show a reduced shift of thorax-pelvis relative phase towards out-of-phase movement with increasing speed compared to healthy controls. Here, we review the literature on this phase shift in patients with low back pain and we analyze the results presented in literature in view of the theoretical motivations to assess this phenomenon. Initially, based on the dynamical systems approach to movement coordination, the shift in thorax-pelvis relative phase with speed was studied as a self-organizing transition. However, the phase shift is gradual, which does not match a self-organizing transition. Subsequent emphasis in the literature therefore shifted to a motivation based on biomechanics. The change in relative phase with low back pain was specifically linked to expected changes in trunk stiffness due to ‘guarded behavior’. We found that thorax-pelvis relative phase is affected by several interacting factors, including active drive of thorax rotation through trunk muscle activity, stride frequency and the magnitude of pelvis rotations. Large pelvis rotations and high stride frequency observed in low back pain patients may contribute to the difference between patients and controls. This makes thorax-pelvis relative phase a poor proxy of trunk stiffness. In conclusion, thorax-pelvis relative phase cannot be considered as a collective variable reflecting the orderly behaviour of a complex underlying system, nor is it a marker of specific changes in trunk biomechanics. The fact that it is affected by multiple factors may explain the considerable between-subject variance of this measure in low back pain patients and healthy controls alike.

Key words

  • low back pain
  • coordination
  • gait
  • trunk
  • relative phase
Otwarty dostęp

Production and Perception of Intentional and Unintentional Actions

Data publikacji: 29 Jan 2021
Zakres stron: 51 - 66

Abstrakt

Abstract

Physical approach to biological movement is based on the idea of control with referent spatial coordinates for effectors, from the whole body to single muscles. Within this framework, neural control signals induce changes in parameters of corresponding biology-specific laws of nature, and motor performance emerges as a result of interaction with the external force field. This approach is naturally compatible with the principle of abundance and the uncontrolled manifold hypothesis, which offer the framework for analysis of movement stability. The presence of two basic commands, reciprocal and co-activation, makes even single-effector tasks abundant and allows stabilizing their performance at the control level. Kinesthetic perception can be viewed as the process of estimating afferent signals within a reference system provided by the efferent process. Percepts are reflections of stable iso-perceptual manifolds in the combined afferent-efferent multi-dimensional space. This approach offers new, logical and based on laws of nature, interpretations for such phenomena as muscle co-activation, unintentional drifts in performance, and vibration-induced kinesthetic illusions. It also allows predicting new phenomena such as counter-intuitive effects of muscle co-activation of force production and perception, vibration-induced force illusions, performance drifts at two different speeds, and high variability in matching the contribution of individual elements in multi-element tasks. This approach can be developed for various subfields of movement studies including studies of athletics, movement disorders, and movement rehabilitation.

Key words

  • referent coordinate
  • back-coupling
  • uncontrolled manifold
  • iso-perceptual manifold
  • co-activation
Otwarty dostęp

Focused Review on Neural Correlates of Different Types of Motor Errors and Related Terminological Issues

Data publikacji: 29 Jan 2021
Zakres stron: 67 - 81

Abstrakt

Abstract

The Error-related negativity (Ne/ERN) and the feedback-related negativity (FRN), two event-related potentials in electroencephalogram tracings, have been used to examine error processing in conscious actions. In the classical terminology the Ne/ERN and the FRN are differentiated with respect to whether internal (Ne/ERN) or external (FRN) error information is processed. In motor tasks, however, errors of different types can be made: A wrong action can be selected that is not adequate to achieve the task goal (or action effect), or the correctly selected action can be mis-performed such that the task goal might be missed (movement error). Depending on the motor task and the temporal sequences of these events, internal and external error information can coincide. Hence, a clear distinction of the information source is difficult, and the classical terminology that differentiates the Ne/ERN and the FRN with respect to internal and external error information becomes ambiguous. But, a stronger focus on the characteristics of the definition of “task” and the cause of “errors”, as well as on temporal characteristics of event-related potentials with respect to the task action allows separate examination of the processing of movement errors, the processing of the prediction of action effect errors, or the processing of the detection of action effect errors. The present article gives an overview of example studies investigating the Ne/ERN and the FRN in motor tasks, classifies them with respect to action effect errors or movement errors, and proposes updated terminology.

Key words

  • error-related negativity
  • feedback-related negativity
  • movement error
  • action effect error
  • error prediction
  • error postdiction
Otwarty dostęp

Effect of Acute Heart Rate Variability Biofeedback on H-reflex Modulation: A Pilot Study

Data publikacji: 29 Jan 2021
Zakres stron: 83 - 88

Abstrakt

Abstract

Heart rate variability biofeedback (HRV BFB) is paced breathing scheme that stimulates resonance in the cardiovascular system. This study aimed to investigate the effect of a single-session HRV BFB on Hoffman reflex (H-reflex) of the soleus muscle. Twelve healthy males (height: 173.7 ± 7.18 cm; weight: 72.7 ± 17.7 kg; age: 24.0 ± 5.02 yrs) completed a randomized-crossover intervention involving a 10-minute HRV BFB and normal breathing (CON) separated by 48 hours. Results revealed significantly lower 1a afferent activation after HRV BFB. Similarly, the HRV BFB also demonstrated lower proportion of activated motor neurons from 1a afferents. In conclusion, an acute HRV BFB influenced the reduction in motoneuron excitability at resting condition.

Key words

  • biofeedback
  • resonance frequency breathing
  • H-reflex
  • neural excitation
Otwarty dostęp

Synergistic Activation Patterns of Hand Muscles in Left-and Right-Hand Dominant Individuals

Data publikacji: 29 Jan 2021
Zakres stron: 89 - 100

Abstrakt

Abstract

Handedness has been associated with behavioral asymmetries between limbs that suggest specialized function of dominant and non-dominant hand. Whether patterns of muscle co-activation, representing muscle synergies, also differ between the limbs remains an open question. Previous investigations of proximal upper limb muscle synergies have reported little evidence of limb asymmetry; however, whether the same is true of the distal upper limb and hand remains unknown. This study compared forearm and hand muscle synergies between the dominant and non-dominant limb of left-handed and right-handed participants. Participants formed their hands into the postures of the American Sign Language (ASL) alphabet, while EMG was recorded from hand and forearm muscles. Muscle synergies were extracted for each limb individually by applying non-negative-matrix-factorization (NMF). Extracted synergies were compared between limbs for each individual, and between individuals to assess within and across participant differences. Results indicate no difference between the limbs for individuals, but differences in limb synergies at the population level. Left limb synergies were found to be more similar than right limb synergies across left- and right-handed individuals. Synergies of the left hand of left dominant individuals were found to have greater population level similarity than the other limbs tested. Results are interpreted with respect to known differences in the neuroanatomy and neurophysiology of proximal and distal upper limb motor control. Implications for skill training in sports requiring dexterous control of the hand are discussed.

Key words

  • muscle synergy
  • handedness
  • electromyography
  • lateralization
  • upper limb
Otwarty dostęp

Motor Control and Achilles Tendon Adaptation in Adolescence: Effects of Sport Participation and Maturity

Data publikacji: 29 Jan 2021
Zakres stron: 101 - 116

Abstrakt

Abstract

An important but unresolved research question in adolescent children is the following: “Does sport participation interact with maturation to change motor control and the mechanical and morphological properties of tendons?” Here, we address this important research question with a longitudinal study around the age of peak height velocity (PHV). Our purpose was to characterize the interactive effects of maturation and sports participation on motor control and the mechanical and morphological properties of the Achilles tendon (AT) in adolescent athletes and non-athletes. Twenty-two adolescent athletes (13.1 ± 1.1 years) and 19 adolescent non-athletes (12.8 ± 1.1 years) volunteered for this study. We quantified motor control as the coefficient of variation of torque during a ramp task. In addition, we quantified the AT morphological and mechanical properties using ultrasonography from 18 months before to 12 months after PHV. We found that motor control improved with maturation in both athletes and non-athletes. We found that athletes have a greater increase in body mass with maturation that relates to greater plantarflexion peak force and AT peak stress. Also, athletes have a thicker and longer AT, as assessed with resting cross-sectional area and length. Although the rate of increase in the morphological change with maturation was similar for athletes and non-athletes, the rate of increase in normalized AT stiffness was greater for athletes. This increased AT stiffness in athletes related to peak force and stress. In summary, maturation improves motor control in adolescent children. Further, we provide novel longitudinal evidence that sport participation interacts with maturation in adolescents to induce adaptive effects on the Achilles tendon morphology and mechanical properties. These findings have the potential to minimize the risk of injuries and maximize athletic development in talented adolescents.

Key words

  • peak height velocity
  • athletes
  • motor control
  • stiffness
  • stress
  • strain
Otwarty dostęp

The Use of Frequency Analysis as a Complementary and Explanatory Element for Time Domain Analysis in Measurements of the Ability to Maintain Balance

Data publikacji: 29 Jan 2021
Zakres stron: 117 - 129

Abstrakt

Abstract

Assessment of human balance is one of the most common diagnostic tests, both in medical applications and during sports training. Many new methods of measuring are introduced in these studies; however, the analysis of results is still carried out mainly based on the values determined in the time domain – the average COP speed or the ellipse field of the prediction. The aim of the current work is to present the possibilities for the practical application of frequency analyses in assessment of the ability to maintain body balance as a method supplementing standard analyses. As part of the study, measurements of the ability to maintain balance in sensory conflict conditions introduced in the form of an oscillating, three-dimensional, virtual scenery were carried out. 27 healthy volunteers (13 women and 14 men) took part in the study. The three-dimensional scenery, presented by means of the Oculus system, oscillated in the sagittal plane with frequencies equal to 0.7 Hz and 1.4 Hz. The frequency value during the measurement was constant or changed in the middle of the test. Measurements were conducted on the FDM Zebris platform. The results were analyzed using developed coefficients determined on the basis of the Short-time Fourier transform (STFT). The use of frequency-domain analyses confirmed that in the COP movement, one can observe a cyclical component corresponding to following the scenery, as well as the appearance of other cyclical components whose observation is important in terms of assessing the ability to maintain balance. It has been shown that the changes in the average COP speed that occur during the measurement can result from changes related to the movement of following the scenery as well as additional body movements indicating a greater or lesser loss of balance. It has been shown that there are differences in the COP movement provoked by the movement of the surrounding scenery, which depend on the parameters of the introduced disturbances – something that can only be observed in results obtained in the frequency domain. The conducted research shows that in measurements involving the ability to maintain one’s balance conducted in sensory conflict conditions, standard time-domain analyses should be supplemented with other types of data analysis, e.g. frequency domain analyses.

Key words

  • balance
  • virtual reality
  • frequency domain analysis
Otwarty dostęp

Number of Trials Necessary to Apply Analysis within the Framework of the Uncontrolled Manifold Hypothesis at Different Levels of Hierarchical Synergy Control

Data publikacji: 29 Jan 2021
Zakres stron: 131 - 143

Abstrakt

Abstract

The uncontrolled manifold hypothesis is a method used to quantify motor synergies, defined as a specific central nervous system organization that maintains the task-specific stability of motor actions. The UCM allows for inter-trial variance analysis between consecutive trials. However, despite the large body of literature within this framework, there is no report on the number of movement repetitions required for reliable results. Based on the hypothetical hierarchical control of motor synergies, this study aims to determine the minimum number of trials necessary to achieve a good to excellent level of reliability. Thirteen young, healthy participants performed fifteen bilateral isometric contractions of elbow flexion when visual feedback was provided. The force and electromyography data were recorded to investigate synergies at different levels of hierarchical control. The intraclass correlation coefficient was used to determine the reliability of the variance indices. Based on the obtained results, at least twelve trials are required to analyze the inter-trial variance in both force and muscle synergies within the UCM framework.

Key words

  • motor synergies
  • reliability
  • intra-trial variance
  • force
  • muscle modes
  • EMG
Otwarty dostęp

Stability of Action and Kinesthetic Perception in Parkinson’s Disease

Data publikacji: 29 Jan 2021
Zakres stron: 145 - 159

Abstrakt

Abstract

We present a review of action and perception stability within the theoretical framework based on the idea of control with spatial referent coordinates for the effectors at a number of hierarchical levels. Stability of salient variables is ensured by synergies, neurophysiological structures that act in multi-dimensional spaces of elemental variables and limit variance to the uncontrolled manifold during action and iso-perceptual manifold during perception. Patients with Parkinson’s disease show impaired synergic control reflected in poor stability (low synergy indices) and poor agility (low indices of anticipatory synergy adjustments prior to planned quick actions). They also show impaired perception across modalities, including kinesthetic perception. We suggest that poor stability at the level of referent coordinates can be the dominant factor leading to poor stability of percepts.

Key words

  • referent coordinate
  • abundance
  • iso-perceptual manifold
  • basal ganglia
Otwarty dostęp

Progression of Fatigue Modifies Primary Contributors to Ground Reaction Forces During Drop Landing

Data publikacji: 29 Jan 2021
Zakres stron: 161 - 173

Abstrakt

Abstract

Few studies have focused on the effect of fatigue severity on landing strategy. This study aimed to investigate the effect of fatigue progression on ground reaction force during landing. Eighteen participants performed a fatigue exercise protocol. Then participants performed drop landings at three levels of fatigue: no fatigue, medium fatigue, and severe fatigue. Multiple linear regression was conducted to identify the predictors of the peak vertical ground reaction force at each level of fatigue. Two-way ANOVAs were conducted to test the effect of fatigue on the vertical ground reaction force and the predictors. For the vertical ground reaction force, the knee joint stiffness and the knee angle at initial contact were the main predictors at no fatigue. The peak knee flexion angle and knee power were the main predictors at medium fatigue. However, the peak ankle plantarflexion moments became the main predictor at severe fatigue. The vertical ground reaction force decreased from no to medium fatigue (p = 0.001), and then increased from medium to severe fatigue (p = 0.034). The knee joint stiffness decreased from no to medium fatigue (p = 0.049), and then remained unchanged from medium to severe fatigue. The peak knee flexion angle increased from no to medium fatigue (p = 0.001), and then slightly decreased from medium to severe fatigue (p = 0.051). The results indicate that fatigue progression causes a transition from stiff to soft landing, and then to stiff landing. Participants used ankle joints more to control the landing intensity at severe fatigue.

Key words

  • biomechanics
  • drop landing
  • fatigue
  • kinesiology
  • neuromuscular
Otwarty dostęp

The Effect of Crank Resistance on Arm Configuration and Muscle Activation Variances in Arm Cycling Movements

Data publikacji: 29 Jan 2021
Zakres stron: 175 - 189

Abstrakt

Abstract

Arm cycling on an ergometer is common in sports training and rehabilitation protocols. The hand movement is constrained along a circular path, and the user is working against a resistance, maintaining a cadence. Even if the desired hand trajectory is given, there is the flexibility to choose patterns of joint coordination and muscle activation, given the kinematic redundancy of the upper limb. With changing external load, motor noise and changing joint stiffness may affect the pose of the arm even though the endpoint trajectory is unchanged. The objective of this study was to examine how the crank resistance influences the variances of joint configuration and muscle activation. Fifteen healthy participants performed arm cranking on an arm-cycle ergometer both unimanually and bimanually with a cadence of 60 rpm against three crank resistances. Joint configuration was represented in a 3-dimensional joint space defined by inter-segmental joint angles, while muscle activation in a 4-dimensional "muscle activation space" defined by EMGs of 4 arm muscles. Joint configuration variance in the course of arm cranking was not affected by crank resistance, whereas muscle activation variance was proportional to the square of muscle activation. The shape of the variance time profiles for both joint configuration and muscle activation was not affected by crank resistance. Contrary to the prevailing assumption that an increased motor noise would affect the variance of auxiliary movements, the influence of noise doesn’t appear at the joint configuration level even when the system is redundant. Our results suggest the separation of kinematic- and force-control, via mechanisms that are compensating for dynamic nonlinearities. Arm cranking may be suitable when the aim is to perform training under different load conditions, preserving stable and secure control of joint movements and muscle activations.

Key words

  • load
  • joint configuration
  • muscle activation variance
  • kinematic control
  • force control
Otwarty dostęp

Acute and Delayed Effects of Fatigue on Ground Reaction Force, Lower Limb Stiffness and Coordination Asymmetries During a Landing Task

Data publikacji: 29 Jan 2021
Zakres stron: 191 - 199

Abstrakt

Abstract

Landing is a critical phase of movement for injury occurrence, in which lower limbs should be used equally to better absorb the shock. However, it has been suggested that fatigue can lead to the appearance of asymmetries. The aim of this study was to verify the acute and delayed effects of fatigue on the lower limb asymmetry indexes of peak ground reaction force, leg stiffness and intra-limb coordination during a landing task. Fifteen physically active men performed a fatigue protocol composed of 14 sets of 10 continuous vertical jumps, with a one-minute rest interval between the sets. A step-off landing task was performed before, immediately after, 24 h and 48 h after the fatigue protocol. Two force plates and a video analysis system were used. The symmetry index equation provided the asymmetry indexes. For statistical analysis, ANOVA and effect size analysis were utilized. Inferential statistics did not show the effect of fatigue in the asymmetry indexes for any variable or condition (p > .05). Moderate effect sizes were observed for peak ground reaction force (0.61) and leg stiffness (0.61) immediately after the application of the protocol. In conclusion, fatigue does not seem to significantly change the asymmetries of lower limbs, especially regarding intra-limb coordination. The moderate effects observed for peak ground reaction force and leg stiffness asymmetries suggest that these variables may be acutely affected by fatigue.

Key words

  • stretch-shortening cycle
  • shock absorption
  • spring-mass model
  • continuous relative phase

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