1
|
Goreau V, Hug F, Jannou A, Dernoncourt F, Crouzier M, Cattagni T. Estimates of persistent inward currents in lower limb muscles are not different between inactive, resistance-trained, and endurance-trained young males. J Neurophysiol 2024; 131:166-175. [PMID: 38116611 DOI: 10.1152/jn.00278.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/20/2023] [Accepted: 12/17/2023] [Indexed: 12/21/2023] Open
Abstract
Persistent inward currents (PICs) increase the intrinsic excitability of α-motoneurons. The main objective of this study was to compare estimates of α-motoneuronal PICs between inactive, chronic resistance-trained, and chronic endurance-trained young individuals. We also aimed to investigate whether there is a relationship in the estimates of α-motoneuronal PIC magnitude between muscles. Estimates of PIC magnitude were obtained in three groups of young individuals: resistance-trained (n = 12), endurance-trained (n = 12), and inactive (n = 13). We recorded high-density surface electromyography (HDsEMG) signals from tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SOL), vastus medialis (VM), and vastus lateralis (VL). Then, signals were decomposed with convolutive blind source separation to identify motor unit (MU) spike trains. Participants performed triangular isometric contractions to a peak of 20% of their maximum voluntary contraction. A paired-motor-unit analysis was used to calculate ΔF, which is assumed to be proportional to PIC magnitude. Despite the substantial differences in physical training experience between groups, we found no differences in ΔF, regardless of the muscle. Significant correlations of estimates of PIC magnitude were found between muscles of the same group (VL-VM, SOL-GM). Only two correlations (out of 8) between muscles of different groups were found (TA-GM and VL-GM). Overall, our findings suggest that estimates of PIC magnitude from lower-threshold MUs at low contraction intensities in the lower limb muscles are not influenced by physical training experience in healthy young individuals. They also suggest muscle-specific and muscle group-specific regulations of the estimates of PIC magnitude.NEW & NOTEWORTHY Chronic resistance and endurance training can lead to specific adaptations in motor unit activity. The contribution of α-motoneuronal persistent inward currents (PICs) to these adaptations is currently unknown in healthy young individuals. Therefore, we studied whether estimates of α-motoneuronal PIC magnitude are higher in chronically trained endurance- and resistance-trained individuals. We also studied whether there is a relationship between the estimates of α-motoneuronal PIC magnitude of different lower limb muscles.
Collapse
Affiliation(s)
- Valentin Goreau
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
| | | | - Anthony Jannou
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
| | - François Dernoncourt
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
- LAMHESS, Université Côte d'Azur, Nice, France
| | - Marion Crouzier
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
- Department of Movement Science, Human Movement Biomechanics Research Group, KU Leuven, Leuven, Belgium
| | - Thomas Cattagni
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
| |
Collapse
|
2
|
Rubin N, Hinson R, Saul K, Filer W, Hu X, Huang HH. Modified motor unit properties in residual muscle following transtibial amputation. J Neural Eng 2024; 21:016009. [PMID: 38176027 DOI: 10.1088/1741-2552/ad1ac2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 01/04/2024] [Indexed: 01/06/2024]
Abstract
Objective.Neural signals in residual muscles of amputated limbs are frequently decoded to control powered prostheses. Yet myoelectric controllers assume muscle activities of residual muscles are similar to that of intact muscles. This study sought to understand potential changes to motor unit (MU) properties after limb amputation.Approach.Six people with unilateral transtibial amputation were recruited. Surface electromyogram (EMG) of residual and intacttibialis anterior(TA) andgastrocnemius(GA) muscles were recorded while subjects traced profiles targeting up to 20% and 35% of maximum activation for each muscle (isometric for intact limbs). EMG was decomposed into groups of MU spike trains. MU recruitment thresholds, action potential amplitudes (MU size), and firing rates were correlated to model Henneman's size principle, the onion-skin phenomenon, and rate-size associations. Organization (correlation) and modulation (rates of change) of relations were compared between intact and residual muscles.Main results.The residual TA exhibited significantly lower correlation and flatter slopes in the size principle and onion-skin, and each outcome covaried between the MU relations. The residual GA was unaffected for most subjects. Subjects trained prior with myoelectric prostheses had minimally affected slopes in the TA. Rate-size association correlations were preserved, but both residual muscles exhibited flatter decay rates.Significance.We showed peripheral neuromuscular damage also leads to spinal-level functional reorganizations. Our findings suggest models of MU recruitment and discharge patterns for residual muscle EMG generation need reparameterization to account for disturbances observed. In the future, tracking MU pool adaptations may also provide a biomarker of neuromuscular control to aid training with myoelectric prostheses.
Collapse
Affiliation(s)
- Noah Rubin
- UNC/NC State Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America
| | - Robert Hinson
- UNC/NC State Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695, United States of America
- UNC/NC State Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America
| | - Katherine Saul
- Department of Mechanical & Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, United States of America
| | - William Filer
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America
| | - Xiaogang Hu
- Department of Mechanical Engineering, Pennsylvania State University, University Park, PA 16802, United States of America
| | - He Helen Huang
- UNC/NC State Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America
| |
Collapse
|
3
|
Jenz ST, Beauchamp JA, Gomes MM, Negro F, Heckman CJ, Pearcey GEP. Estimates of persistent inward currents in lower limb motoneurons are larger in females than in males. J Neurophysiol 2023; 129:1322-1333. [PMID: 37096909 PMCID: PMC10202474 DOI: 10.1152/jn.00043.2023] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/02/2023] [Accepted: 04/19/2023] [Indexed: 04/26/2023] Open
Abstract
Noninvasive recordings of motor unit (MU) spike trains help us understand how the nervous system controls movement and how it adapts to various physiological conditions. The majority of participants in human and nonhuman animal physiology studies are male, and it is assumed that mechanisms uncovered in these studies are shared between males and females. However, sex differences in neurological impairment and physical performance warrant the study of sex as a biological variable in human physiology and performance. To begin addressing this gap in the study of biophysical properties of human motoneurons, we quantified MU discharge rates and estimates of persistent inward current (PIC) magnitude in both sexes. We decomposed MU spike trains from the tibialis anterior (TA), medial gastrocnemius (MG), and soleus (SOL) using high-density surface electromyography and blind source separation algorithms. Ten participants of each sex performed slow triangular (10 s up and down) isometric contractions to a peak of 30% of their maximum voluntary contraction. We then used linear mixed-effects models to determine if peak discharge rate and estimates of PICs were predicted by the fixed effects of sex, muscle, and their interaction. Despite a lack of sex-differences in peak discharge rates across all muscles, estimates of PICs were larger [χ2(1) = 6.26, P = 0.012] in females [4.73 ± 0.242 pulses per second (pps)] than in males (3.81 ± 0.240 pps). These findings suggest that neuromodulatory drive, inhibitory input, and/or biophysical properties of motoneurons differ between the sexes and may contribute to differences in MU discharge patterns.NEW & NOTEWORTHY Sex-related differences in motoneuron analyses have emerged with greater inclusion of female participants, however, mechanisms for these differences remain unclear. Estimates of persistent inward currents (i.e., ΔF) in motoneurons of the lower limb muscles were larger in females than in males. This suggests neuromodulatory drive, monoaminergic signaling, intrinsic motoneuron properties, and/or descending motor commands may differ between the sexes, which provides a potential mechanism underlying previously reported sex-related differences in motoneuron discharge patterns.
Collapse
Affiliation(s)
- Sophia T Jenz
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
| | - James A Beauchamp
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, United States
| | - Matheus M Gomes
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Universita degli Studi di Brescia, Brescia, Italy
| | - C J Heckman
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
- Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
- Shirley Ryan AbilityLab, Chicago, Illinois, United States
| | - Gregory E P Pearcey
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| |
Collapse
|
4
|
Ricotta JM, Nardon M, De SD, Jiang J, Graziani W, Latash ML. Motor unit-based synergies in a non-compartmentalized muscle. Exp Brain Res 2023; 241:1367-1379. [PMID: 37017728 DOI: 10.1007/s00221-023-06606-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/23/2023] [Indexed: 04/06/2023]
Abstract
The concept of synergies has been used to address the grouping of motor elements contributing to a task with the covariation of these elements reflecting task stability. This concept has recently been extended to groups of motor units with parallel scaling of the firing frequencies with possible contributions of intermittent recruitment (MU-modes) in compartmentalized flexor and extensor muscles of the forearm stabilizing force magnitude in finger pressing tasks. Here, we directly test for the presence and behavior of MU-modes in the tibialis anterior, a non-compartmentalized muscle. Ten participants performed an isometric cyclical dorsiflexion force production task at 1 Hz between 20 and 40% of maximal voluntary contraction and electromyographic (EMG) data were collected from two high-density wireless sensors placed on the skin over the right tibialis anterior. EMG data were decomposed into individual motor unit frequencies and resolved into sets of MU-modes. Inter-cycle analysis of MU-mode magnitudes within the framework of the uncontrolled manifold (UCM) hypothesis was used to quantify force-stabilizing synergies. Two or three MU-modes were identified in all participants and trials accounting, on average, for 69% of variance and were robust to cross-validation measurements. Strong dorsiflexion force-stabilizing synergies in the space of MU-modes were present in all participants and for both electrode locations as reflected in variance within the UCM (median 954, IQR 511-1924) exceeding variance orthogonal to the UCM (median 5.82, IQR 2.9-17.4) by two orders of magnitude. In contrast, MU-mode-stabilizing synergies in the space of motor unit frequencies were not present. This study offers strong evidence for the existence of synergic control mechanisms at the level of motor units independent of muscle compartmentalization, likely organized within spinal cord circuitry.
Collapse
Affiliation(s)
- Joseph M Ricotta
- Department of Kinesiology, Rec.Hall-20, The Pennsylvania State University, University Park, PA, 16802, USA.
- Clinical and Translational Science Institute, Penn State College of Medicine, Hershey, PA, 17033, USA.
| | - Mauro Nardon
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Sayan D De
- Department of Kinesiology, Rec.Hall-20, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Jinrui Jiang
- Department of Kinesiology, Rec.Hall-20, The Pennsylvania State University, University Park, PA, 16802, USA
| | - William Graziani
- Department of Kinesiology, Rec.Hall-20, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mark L Latash
- Department of Kinesiology, Rec.Hall-20, The Pennsylvania State University, University Park, PA, 16802, USA
| |
Collapse
|
5
|
Beauchamp JA, Pearcey GEP, Khurram OU, Chardon M, Wang YC, Powers RK, Dewald JPA, Heckman CJ. A geometric approach to quantifying the neuromodulatory effects of persistent inward currents on individual motor unit discharge patterns. J Neural Eng 2023; 20:016034. [PMID: 36626825 PMCID: PMC9885522 DOI: 10.1088/1741-2552/acb1d7] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/11/2022] [Accepted: 01/10/2023] [Indexed: 01/11/2023]
Abstract
Objective.All motor commands flow through motoneurons, which entrain control of their innervated muscle fibers, forming a motor unit (MU). Owing to the high fidelity of action potentials within MUs, their discharge profiles detail the organization of ionotropic excitatory/inhibitory as well as metabotropic neuromodulatory commands to motoneurons. Neuromodulatory inputs (e.g. norepinephrine, serotonin) enhance motoneuron excitability and facilitate persistent inward currents (PICs). PICs introduce quantifiable properties in MU discharge profiles by augmenting depolarizing currents upon activation (i.e. PIC amplification) and facilitating discharge at lower levels of excitatory input than required for recruitment (i.e. PIC prolongation).Approach. Here, we introduce a novel geometric approach to estimate neuromodulatory and inhibitory contributions to MU discharge by exploiting discharge non-linearities introduced by PIC amplification during time-varying linear tasks. In specific, we quantify the deviation from linear discharge ('brace height') and the rate of change in discharge (i.e. acceleration slope, attenuation slope, angle). We further characterize these metrics on a simulated motoneuron pool with known excitatory, inhibitory, and neuromodulatory inputs and on human MUs (number of MUs; Tibialis Anterior: 1448, Medial Gastrocnemius: 2100, Soleus: 1062, First Dorsal Interosseus: 2296).Main results. In the simulated motor pool, we found brace height and attenuation slope to consistently indicate changes in neuromodulation and the pattern of inhibition (excitation-inhibition coupling), respectively, whereas the paired MU analysis (ΔF) was dependent on both neuromodulation and inhibition pattern. Furthermore, we provide estimates of these metrics in human MUs and show comparable variability in ΔFand brace height measures for MUs matched across multiple trials.Significance. Spanning both datasets, we found brace height quantification to provide an intuitive method for achieving graded estimates of neuromodulatory and inhibitory drive to individual MUs. This complements common techniques and provides an avenue for decoupling changes in the level of neuromodulatory and pattern of inhibitory motor commands.
Collapse
Affiliation(s)
- James A Beauchamp
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, United States of America
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Gregory E P Pearcey
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Obaid U Khurram
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States of America
| | - Matthieu Chardon
- Northwestern Argonne Institute for Science and Engineering (NAISE), Northwestern University, Evanston, IL, United States of America
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Y Curtis Wang
- Department of Electrical and Computer Engineering, California State University, Los Angeles, Los Angeles, CA, United States of America
| | - Randall K Powers
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, United States of America
| | - Julius P A Dewald
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, United States of America
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - CJ Heckman
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Shirley Ryan AbilityLab, Chicago, IL, United States of America
| |
Collapse
|
6
|
Ji B, Wojtaś B, Skup M. Molecular Identification of Pro-Excitogenic Receptor and Channel Phenotypes of the Deafferented Lumbar Motoneurons in the Early Phase after SCT in Rats. Int J Mol Sci 2022; 23:ijms231911133. [PMID: 36232433 PMCID: PMC9569670 DOI: 10.3390/ijms231911133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/19/2022] [Accepted: 09/19/2022] [Indexed: 02/07/2023] Open
Abstract
Spasticity impacts the quality of life of patients suffering spinal cord injury and impedes the recovery of locomotion. At the cellular level, spasticity is considered to be primarily caused by the hyperexcitability of spinal α-motoneurons (MNs) within the spinal stretch reflex circuit. Here, we hypothesized that after a complete spinal cord transection in rats, fast adaptive molecular responses of lumbar MNs develop in return for the loss of inputs. We assumed that early loss of glutamatergic afferents changes the expression of glutamatergic AMPA and NMDA receptor subunits, which may be the forerunners of the developing spasticity of hindlimb muscles. To better understand its molecular underpinnings, concomitant expression of GABA and Glycinergic receptors and serotoninergic and noradrenergic receptors, which regulate the persistent inward currents crucial for sustained discharges in MNs, were examined together with voltage-gated ion channels and cation-chloride cotransporters. Using quantitative real-time PCR, we showed in the tracer-identified MNs innervating extensor and flexor muscles of the ankle joint multiple increases in transcripts coding for AMPAR and 5-HTR subunits, along with a profound decrease in GABAAR, GlyR subunits, and KCC2. Our study demonstrated that both MNs groups similarly adapt to a more excitable state, which may increase the occurrence of extensor and flexor muscle spasms.
Collapse
Affiliation(s)
- Benjun Ji
- Group of Restorative Neurobiology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Bartosz Wojtaś
- Laboratory of Sequencing, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Małgorzata Skup
- Group of Restorative Neurobiology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
- Correspondence:
| |
Collapse
|
7
|
Lulic-Kuryllo T, Greig Inglis J. Sex differences in motor unit behaviour: A review. J Electromyogr Kinesiol 2022; 66:102689. [DOI: 10.1016/j.jelekin.2022.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 10/15/2022] Open
|
8
|
Khurram OU, Pearcey GEP, Chardon MK, Kim EH, García M, Heckman CJ. The Cellular Basis for the Generation of Firing Patterns in Human Motor Units. ADVANCES IN NEUROBIOLOGY 2022; 28:233-258. [PMID: 36066828 DOI: 10.1007/978-3-031-07167-6_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Motor units, which comprise a motoneuron and the set of muscle fibers it innervates, are the fundamental neuromuscular transducers for all motor commands. The one to one relationship between a motoneuron and its innervated muscle fibers allow motoneuron firing patterns to be readily measured in humans. In this chapter, we summarize the current understanding of the cellular basis for the generation of firing patterns in human motor units. We provide a brief review of landmark insights from classic studies and then proceed to consider the features of motor unit firing patterns that are most likely to be sensitive estimators of motoneuron inputs and properties. In addition, we discuss recent advances in technology for recording human motor unit firing patterns and highly realistic computer simulations of motoneurons. The final section presents our recent efforts to use the power of supercomputers for implementation of the motoneuron models, with a goal of achieving a true "reverse engineering" approach that maximizes the insights from motor unit firing patterns into the synaptic structure of motor commands.
Collapse
Affiliation(s)
- Obaid U Khurram
- Departments of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Gregory E P Pearcey
- Departments of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Matthieu K Chardon
- Departments of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Northwestern-Argonne Institute of Science and Engineering, Evanston, IL, USA
| | - Edward H Kim
- Departments of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Marta García
- Northwestern-Argonne Institute of Science and Engineering, Evanston, IL, USA
- Computational Science Division, Argonne National Laboratory, Lemont, IL, USA
| | - C J Heckman
- Departments of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
- Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
- Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, USA.
| |
Collapse
|
9
|
Beauchamp JA, Khurram OU, Dewald J, Heckman CJ, Pearcey G. A computational approach for generating continuous estimates of motor unit discharge rates and visualizing population discharge characteristics. J Neural Eng 2021; 19. [PMID: 34937005 DOI: 10.1088/1741-2552/ac4594] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/22/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Successive improvements in high density surface electromyography and decomposition techniques have facilitated an increasing yield in decomposed motor unit (MU) spike times. Though these advancements enhance the generalizability of findings and promote the application of MU discharge characteristics to inform the neural control of motor output, limitations remain. Specifically, 1) common approaches for generating smooth estimates of MU discharge rates introduce artifacts in quantification, which may bias findings, and 2) discharge characteristics of large MU populations are often difficult to visualize. APPROACH In the present study, we propose support vector regression (SVR) as an improved approach for generating smooth continuous estimates of discharge rate and compare the fit characteristics of SVR to traditionally used methods, including Hanning window filtering and polynomial regression. Furthermore, we introduce ensembles as a method to visualize the discharge characteristics of large MU populations. We define ensembles as the average discharge profile of a subpopulation of MUs, composed of a time normalized ensemble average of all units within this subpopulation. Analysis was conducted with MUs decomposed from the tibialis anterior (N = 2128), medial gastrocnemius (N = 2673), and soleus (N = 1190) during isometric plantarflexion and dorsiflexion contractions. MAIN RESULT Compared to traditional approaches, we found SVR to alleviate commonly observed inaccuracies and produce significantly less absolute fit error in the initial phase of MU discharge and throughout the entire duration of discharge. Additionally, we found the visualization of MU populations as ensembles to intuitively represent population discharge characteristics with appropriate accuracy for visualization. SIGNIFICANCE The results and methods outlined here provide an improved method for generating estimates of MU discharge rate with SVR and present a unique approach to visualizing MU populations with ensembles. In combination, the use of SVR and generation of ensembles represent an efficient method for rendering population discharge characteristics.
Collapse
Affiliation(s)
- James A Beauchamp
- Northwestern University Feinberg School of Medicine, 645 N Michigan Ave., Chicago, Illinois, 60611-3008, UNITED STATES
| | - Obaid U Khurram
- Northwestern University Feinberg School of Medicine, 645 N Michigan Ave., Chicago, Illinois, 60611-3008, UNITED STATES
| | - Julius Dewald
- Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, 645 N Michigan Ave., Chicago, Illinois, 60611-3008, UNITED STATES
| | - C J Heckman
- Northwestern University Feinberg School of Medicine, 311 E Superior, Chicago, Illinois, 60611-3008, UNITED STATES
| | - Gregory Pearcey
- Northwestern University Feinberg School of Medicine, 645 N Michigan Ave., Chicago, Illinois, 60611-3008, UNITED STATES
| |
Collapse
|
10
|
Zero AM, Kirk EA, Rice CL. Firing rate trajectories of human motor units during activity-dependent muscle potentiation. J Appl Physiol (1985) 2021; 132:402-412. [PMID: 34913736 DOI: 10.1152/japplphysiol.00672.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During activity-dependent potentiation (ADP) motor unit firing rates (MUFRs) are lower, however, the mechanism for this response is not known. During increasing torque isometric contractions at low contraction intensities, MUFR trajectories initially accelerate and saturate demonstrating a non-linear response due to the activation of persistent inward currents (PICs) at the motoneuron. The purpose was to assess whether PICs are a factor in the reduction of MUFRs during ADP. To assess this, MUFR trajectories were fit with competing functions of linear regression and a rising exponential (i.e., acceleration and saturation). Using fine-wire electrodes, discrete MU potential trains were recorded in the tibialis anterior during slowly increasing dorsiflexion contractions to 10% of maximal voluntary contraction following both voluntary (post-activation potentiation; PAP) and evoked (post-tetanic potentiation; PTP) contractions. In 8 participants, 25 MUs were recorded across both ADP conditions and compared to the control with no ADP effect. During PAP and PTP, the average MUFRs were 16.4% and 9.2% lower (both P≤ 0.001), respectively. More MUFR trajectories were better fit to the rising exponential during control (16/25) compared to PAP (4/25, P<0.001) and PTP (8/25, P=0.03). The MU samples that had a rising exponential MUFR trajectory during PAP and PTP displayed an ~11% lower initial acceleration compared to control (P<0.05). Thus, synaptic amplification and MUFR saturation due to PIC properties are attenuated during ADP regardless of the type of conditioning contraction. This response may contribute to lower MUFRs and likely occurred because synaptic input is reduced when contractile function is enhanced.
Collapse
Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
11
|
Kirk EA, Zero AM, Rice CL. Firing rate trajectories of human occipitofrontalis motor units in response to triangular voluntary contraction intensity. Exp Brain Res 2021; 239:3661-3670. [PMID: 34617127 DOI: 10.1007/s00221-021-06238-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 09/26/2021] [Indexed: 12/01/2022]
Abstract
During voluntary contractions, limb muscle motor unit (MU) firing rates accelerate over a small force range and saturate in response to increasing contraction intensity. In comparison, facial muscles are cranially innervated, and some function without crossing joints. Therefore, the MU firing rate behaviour and characteristics of saturation were explored in a facial muscle that moves skin and facia during voluntary contractions. We evaluated the firing rate trajectory in response to triangular voluntary contraction ramps in the occipitofrontalis muscle of 11 adult participants. Intramuscular electromyography of the frontalis aspect was used to record single MU trains followed up to maximal voluntary contraction intensities. Firing rates were measured from each MU sample, with the firing rate trajectory fit as both exponential (i.e., saturation) and linear models that were compared statistically. The rate coding behaviour of frontalis MUs was broad, as the peak firing rate (mean 76 Hz) was ninefold greater than the firing rate at recruitment threshold (mean 8 Hz). Across 20 MU samples, only 40% (8 MU samples) were determined to have a firing rate trajectory that saturated and had slow acceleration in response to increasing voluntary drive until maximum. The exponential curve of the firing rate trajectory had ~ tenfold lower acceleration as compared to prior reports in limb muscles. These results across all MU samples indicated that voluntary control of the frontalis muscle requires relatively slower accelerating or linear MU firing rate trajectories, suggesting that movements of facial muscles may be directly representative of extrinsic synaptic inputs.
Collapse
Affiliation(s)
- Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Canada
| | - Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Canada. .,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, Canada.
| |
Collapse
|
12
|
Hassan AS, Fajardo ME, Cummings M, McPherson LM, Negro F, Dewald JPA, Heckman CJ, Pearcey GEP. Estimates of persistent inward currents are reduced in upper limb motor units of older adults. J Physiol 2021; 599:4865-4882. [PMID: 34505294 DOI: 10.1113/jp282063] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/07/2021] [Indexed: 11/08/2022] Open
Abstract
Ageing is a natural process causing alterations in the neuromuscular system, which contributes to reduced quality of life. Motor unit (MU) contributes to weakness, but the mechanisms underlying reduced firing rates are unclear. Persistent inward currents (PICs) are crucial for initiation, gain control and maintenance of motoneuron firing, and are directly proportional to the level of monoaminergic input. Since concentrations of monoamines (i.e. serotonin and noradrenaline) are reduced with age, we sought to determine if estimates of PICs are reduced in older (>60 years old) compared to younger adults (<35 years old). We decomposed MU spike trains from high-density surface electromyography over the biceps and triceps brachii during isometric ramp contractions to 20% of maximum. Estimates of PICs (ΔFrequency; or simply ΔF) were computed using the paired MU analysis technique. Regardless of the muscle, peak firing rates of older adults were reduced by ∼1.6 pulses per second (pps) (P = 0.0292), and ΔF was reduced by ∼1.9 pps (P < 0.0001), compared to younger adults. We further found that age predicted ΔF in older adults (P = 0.0261), resulting in a reduction of ∼1 pps per decade, but there was no relationship in younger adults (P = 0.9637). These findings suggest that PICs are reduced in the upper limbs of older adults during submaximal isometric contractions. Reduced PIC magnitude represents one plausible mechanism for reduced firing rates and function in older individuals, but further work is required to understand the implications in other muscles and during a variety of motor tasks. KEY POINTS: Persistent inward currents play an important role in the neural control of human movement and are influenced by neuromodulation via monoamines originating in the brainstem. During ageing, motor unit firing rates are reduced, and there is deterioration of brainstem nuclei, which may reduce persistent inward currents in alpha motoneurons. Here we show that estimates of persistent inward currents (ΔF) of both elbow flexor and extensor motor units are reduced in older adults. Estimates of persistent inward currents have a negative relationship with age in the older adults, but not in the young. This novel mechanism may play a role in the alteration of motor firing rates that occurs with ageing, which may have consequences for motor control.
Collapse
Affiliation(s)
- Altamash S Hassan
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, USA.,Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Melissa E Fajardo
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Mark Cummings
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Laura Miller McPherson
- Program in Physical Therapy, Washington University School of Medicine, St Louis, MO, USA.,Department of Neurology, Washington University School of Medicine, St Louis, MO, USA
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Universita' degli Studi di Brescia, Brescia, Italy
| | - Julius P A Dewald
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, USA.,Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - C J Heckman
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Shirley Ryan AbilityLab, Chicago, IL, USA
| | - Gregory E P Pearcey
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Shirley Ryan AbilityLab, Chicago, IL, USA
| |
Collapse
|
13
|
Zero AM, Kirk EA, Hali K, Rice CL. Firing rate trajectories of human motor units during isometric ramp contractions to 10, 25 and 50% of maximal voluntary contraction. Neurosci Lett 2021; 762:136118. [PMID: 34280505 DOI: 10.1016/j.neulet.2021.136118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 07/14/2021] [Accepted: 07/14/2021] [Indexed: 11/16/2022]
Abstract
During low torque graded isometric contractions, motor units (MU) exhibit initial firing rate acceleration followed by saturation demonstrating a non-linear response attributed to persistent inward currents (PICs) which contribute to the net excitatory input. Firing rate saturation studies have been done exclusively at recruitment thresholds of low firing threshold MUs below 10% of isometric maximal voluntary contraction(MVC). It remains unclear whether later recruited (i.e. higher-threshold) MUs follow a similar firing rate trajectory as low-threshold units. Thus, MU firing rate trajectories were explored in relation to MU recruitment threshold (RT) at contraction levels between 10 and 50% of MVC. During graded isometric contractions to 10, 25 and 50% of MVC, single MU potentials were recorded from the tibialis anterior from 5 participants using tungsten microelectrodes. To characterize the firing rate trajectory, each MU train was fit by competing functions of torque as an exponential (i.e. saturated) and simple linear regression, using previous analysis methods (Fuglevand et al. 2015). Throughout a RT range of 0.02-41% of MVC, 261 MUs were compared. In 87% of MUs the better fit was by a linear function, whereas the remaining MUs (13%) were fit better with an exponential (saturated) firing rate trajectory. There was no statistical difference in the number of MUs better fit by the exponential function between low (<10% MVC) and relatively higher threshold MUs (>10% MVC; both p < 0.05). Increasing RT and rate of torque development (RTD) of the ramps were correlated with increased firing rate variability (larger error) in both fits (r = 0.3 and r = 0.4, both p < 0.01). Additionally, there was a 4-fold increase in peak antagonist surface electromyography (EMG) from 10 to 50% MVC contraction ramps. When all MUs were plotted with a normalized firing onset (i.e. 0% MVC) the data visually displayed an initial firing rate acceleration followed by a linear response (biphasic trajectory). Increased synaptic drive and greater antagonist surface EMG during moderate torque outputs may dampen PIC activity as compared with MUs during lower torque (<10% MVC) recruitment levels.
Collapse
Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Kalter Hali
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
| |
Collapse
|
14
|
Lockyer EJ, Compton CT, Forman DA, Pearcey GE, Button DC, Power KE. Moving forward: methodological considerations for assessing corticospinal excitability during rhythmic motor output in humans. J Neurophysiol 2021; 126:181-194. [PMID: 34133230 DOI: 10.1152/jn.00027.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The use of transcranial magnetic stimulation to assess the excitability of the central nervous system to further understand the neural control of human movement is expansive. The majority of the work performed to-date has assessed corticospinal excitability either at rest or during relatively simple isometric contractions. The results from this work are not easily extrapolated to rhythmic, dynamic motor outputs, given that corticospinal excitability is task-, phase-, intensity-, direction-, and muscle-dependent (Power KE, Lockyer EJ, Forman DA, Button DC. Appl Physiol Nutr Metab 43: 1176-1185, 2018). Assessing corticospinal excitability during rhythmic motor output, however, involves technical challenges that are to be overcome, or at the minimum considered, when attempting to design experiments and interpret the physiological relevance of the results. The purpose of this narrative review is to highlight the research examining corticospinal excitability during a rhythmic motor output and, importantly, to provide recommendations regarding the many factors that must be considered when designing and interpreting findings from studies that involve limb movement. To do so, the majority of work described herein refers to work performed using arm cycling (arm pedaling or arm cranking) as a model of a rhythmic motor output used to examine the neural control of human locomotion.
Collapse
Affiliation(s)
- Evan J Lockyer
- Human Neurophysiology Lab, School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.,Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Chris T Compton
- Human Neurophysiology Lab, School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.,Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Davis A Forman
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Gregory E Pearcey
- Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Shirley Ryan Ability Lab, Chicago, Illinois
| | - Duane C Button
- Human Neurophysiology Lab, School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.,Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Kevin E Power
- Human Neurophysiology Lab, School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.,Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| |
Collapse
|
15
|
Khurram OU, Negro F, Heckman CJ, Thompson CK. Estimates of persistent inward currents in tibialis anterior motor units during standing ramped contraction tasks in humans. J Neurophysiol 2021; 126:264-274. [PMID: 34133235 DOI: 10.1152/jn.00144.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Persistent inward currents (PICs) play an essential role in setting motor neuron gain and shaping motor unit firing patterns. Estimates of PICs in humans can be made using the paired motor unit analysis technique, which quantifies the difference in discharge rate of a lower threshold motor unit at the recruitment onset and offset of a higher threshold motor unit (ΔF). Because PICs are highly dependent on the level of neuromodulatory drive, ΔF represents an estimate of level of neuromodulation at the level of the spinal cord. Most of the estimates of ΔF are performed under constrained, isometric, seated conditions. In the present study, we used high-density surface EMG arrays to discriminate motor unit firing patterns during isometric seated conditions with torque or EMG visual feedback and during unconstrained standing anterior-to-posterior movements with root mean square EMG visual feedback. We were able to apply the paired motor unit analysis technique to the decomposed motor units in each of the three conditions. We hypothesized that ΔF would be higher during unconstrained standing anterior-to-posterior movements compared with the seated conditions, reflecting an increase in the synaptic input to motoneurons drive while standing. In agreement with previous work, we found that there was no evidence of a difference in ΔF between the seated and standing postures, although slight differences in the initial and peak discharge rates were observed. Taken together, our results suggest that both the standing and seated postures are likely not sufficiently different, both being "upright" postures, to result in large changes in neuromodulatory drive.NEW & NOTEWORTHY In the present study, we show that the discharge rate of a lower threshold motor unit at the recruitment onset and offset of a higher threshold motor unit (ΔF) is similar between standing and seated conditions in human tibialis anterior motor units, suggesting that at least for these two upright postures neuromodulatory drive is similar. We also highlight a proposed technological development in using high-density EMG arrays for real-time muscle activity feedback to accomplish standing ramped contraction tasks and demonstrate the validity of the paired motor unit analysis technique during these conditions.
Collapse
Affiliation(s)
- Obaid U Khurram
- Department of Physiology, Northwestern University, Chicago, Illinois.,Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Università degli Studi di Brescia, Brescia, Italy
| | - C J Heckman
- Department of Physiology, Northwestern University, Chicago, Illinois.,Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois.,Department of Physical Medicine and Rehabilitation, Shirley Ryan AbilityLab, Chicago, Illinois
| | - Christopher K Thompson
- Department of Health and Rehabilitation Sciences, Temple University, Philadelphia, Pennsylvania
| |
Collapse
|
16
|
Orssatto LBR, Mackay K, Shield AJ, Sakugawa RL, Blazevich AJ, Trajano GS. Estimates of persistent inward currents increase with the level of voluntary drive in low-threshold motor units of plantar flexor muscles. J Neurophysiol 2021; 125:1746-1754. [PMID: 33788617 DOI: 10.1152/jn.00697.2020] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This study tested whether estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. High-density surface electromyograms were collected from soleus and gastrocnemius medialis of 21 participants (29.2 ± 2.6 yr) during ramp-shaped isometric contractions to 10%, 20%, and 30% (torque rise and decline of 2%/s and 30-s duration) of each participant's maximal torque. Motor units identified in all the contraction intensities were included in the paired-motor unit analysis to calculate delta frequency (ΔF) and estimate the PICs. ΔF is the difference in discharge rate of the control unit at the time of recruitment and derecruitment of the test unit. Increases in PICs were observed from 10% to 20% [Δ = 0.6 pulse per second (pps); P < 0.001] and from 20% to 30% (Δ = 0.5 pps; P < 0.001) in soleus and from 10% to 20% (Δ = 1.2 pps; P < 0.001) but not from 20% to 30% (Δ = 0.09 pps; P = 0.724) in gastrocnemius medialis. Maximal discharge rate increased for soleus and gastrocnemius medialis from 10% to 20% [Δ = 1.75 pps (P < 0.001) and Δ = 2.43 pps (P < 0.001), respectively] and from 20% to 30% [Δ = 0.80 pps (P < 0.017) and Δ = 0.92 pps (P = 0.002), respectively]. The repeated-measures correlation identified associations between ΔF and increases in maximal discharge rate for soleus (r = 0.64; P < 0.001) and gastrocnemius medialis (r = 0.77; P < 0.001). An increase in voluntary drive tends to increase PIC strength, which has key implications for the control of force but also for comparisons between muscles or studies when relative force levels might be different. Increases in voluntary descending drive amplify PICs in humans and provide an important spinal mechanism for motor unit discharging, and thus force output modulation.NEW & NOTEWORTHY Animal experiments and computational models have shown that motor neurons can amplify the synaptic input they receive via persistent inward currents. Here we show in humans that this amplification varies proportionally to the magnitude of the voluntary drive to the muscle.
Collapse
Affiliation(s)
- Lucas B R Orssatto
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Karen Mackay
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Anthony J Shield
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Raphael L Sakugawa
- Biomechanics Laboratory, Department of Physical Education, Federal University of Santa Catarina, Florianopolis, Brazil
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research (CESSR), School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| |
Collapse
|