1
|
Akalu Y, Tallent J, Frazer AK, Siddique U, Rostami M, Vallance P, Howatson G, Walker S, Kidgell DJ. Strength-trained adults demonstrate greater corticoreticular activation versus untrained controls. Eur J Neurosci 2024; 59:2336-2352. [PMID: 38419404 DOI: 10.1111/ejn.16297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 02/08/2024] [Accepted: 02/12/2024] [Indexed: 03/02/2024]
Abstract
The rapid increase in strength following strength-training involves neural adaptations, however, their specific localisation remains elusive. Prior focus on corticospinal responses prompts this study to explore the understudied cortical/subcortical adaptations, particularly cortico-reticulospinal tract responses, comparing healthy strength-trained adults to untrained peers. Fifteen chronically strength-trained individuals (≥2 years of training, mean age: 24 ± 7 years) were compared with 11 age-matched untrained participants (mean age: 26 ± 8 years). Assessments included maximal voluntary force (MVF), corticospinal excitability using transcranial magnetic stimulation (TMS), spinal excitability (cervicomedullary stimulation), voluntary activation (VA) and reticulospinal tract (RST) excitability, utilizing StartReact responses and ipsilateral motor-evoked potentials (iMEPs) for the flexor carpi radialis muscle. Trained participants had higher normalized MVF (6.4 ± 1.1 N/kg) than the untrained participants (4.8 ± 1.3 N/kg) (p = .003). Intracortical facilitation was higher in the strength-trained group (156 ± 49%) (p = .02), along with greater VA (98 ± 3.2%) (p = .002). The strength-trained group displayed reduced short-interval-intracortical inhibition (88 ± 8.0%) compared with the untrained group (69 ± 17.5%) (p < .001). Strength-trained individuals exhibited a greater normalized rate of force development (38.8 ± 10.1 N·s-1/kg) (p < .009), greater reticulospinal gain (2.5 ± 1.4) (p = .02) and higher ipsilateral-to-contralateral MEP ratios compared with the untrained group (p = .03). Strength-trained individuals displayed greater excitability within the intrinsic connections of the primary motor cortex and the RST. These results suggest greater synaptic input from the descending cortico-reticulospinal tract to α-motoneurons in strength-trained individuals, thereby contributing to the observed increase in VA and MVF.
Collapse
Affiliation(s)
- Yonas Akalu
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
- Department of Human Physiology, School of Medicine, University of Gondar, Gondar, Ethiopia
| | - Jamie Tallent
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester, UK
| | - Ashlyn K Frazer
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
| | - Ummatul Siddique
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
| | - Mohamad Rostami
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
| | - Patrick Vallance
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
| | - Glyn Howatson
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North-West University, Potchefstroom, South Africa
| | - Simon Walker
- NeuroMuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Dawson J Kidgell
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia
| |
Collapse
|
2
|
Del Vecchio A, Enoka RM, Farina D. Specificity of early motor unit adaptations with resistive exercise training. J Physiol 2024. [PMID: 38686581 DOI: 10.1113/jp282560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 04/10/2024] [Indexed: 05/02/2024] Open
Abstract
After exposure of the human body to resistive exercise, the force-generation capacity of the trained muscles increases significantly. Despite decades of research, the neural and muscular stimuli that initiate these changes in muscle force are not yet fully understood. The study of these adaptations is further complicated by the fact that the changes may be partly specific to the training task. For example, short-term strength training does not always influence the neural drive to muscles during the early phase (<100 ms) of force development in rapid isometric contractions. Here we discuss some of the studies that have investigated neuromuscular adaptations underlying changes in maximal force and rate of force development produced by different strength training interventions, with a focus on changes observed at the level of spinal motor neurons. We discuss the different motor unit adjustments needed to increase force or speed, and the specificity of some of the adaptations elicited by differences in the training tasks.
Collapse
Affiliation(s)
- Alessandro Del Vecchio
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Roger Maro Enoka
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London, UK
| |
Collapse
|
3
|
Möck S, Del Vecchio A. Investigation of motor unit behavior in exercise and sports physiology: challenges and perspectives. Appl Physiol Nutr Metab 2024; 49:547-553. [PMID: 38100752 DOI: 10.1139/apnm-2023-0354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Several methods are in use to record and analyze neuronal activation, each with specific advantages and challenges. New developments like the decomposition of high-density surface electromyography (HDsEMG) have enabled novel insights into discharge characteristics noninvasively in laboratory settings but face certain challenges to be applied in sports physiology in a broader scope. Several challenges can be accounted for by methodological considerations, others require further technological developments to allow this technology to be used in more applied settings. This paper aims to describe the developments of surface electromyography and identify the challenges and perspectives of HDsEMG in the context of an application in sports physiology. We further discuss methodological possibilities to overcome some of the challenges to investigate specific research questions and identify areas that require further advancements.
Collapse
Affiliation(s)
- Sebastian Möck
- Department of Exercise Science, Olympic Training and Testing Center of Hessen, Frankfurt am Main, Germany
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence in Biomedical Engineering, Neuromuscular Physiology and Neural Interfacing Group, Friedrich-Alexander University, Erlangen-Nürnberg, Germany
| |
Collapse
|
4
|
Boccia G, D'Emanuele S, Brustio PR, Rainoldi A, Schena F, Tarperi C. Decreased neural drive affects the early rate of force development after repeated burst-like isometric contractions. Scand J Med Sci Sports 2024; 34:e14528. [PMID: 37899668 DOI: 10.1111/sms.14528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 10/05/2023] [Accepted: 10/12/2023] [Indexed: 10/31/2023]
Abstract
The neural drive to the muscle is the primary determinant of the rate of force development (RFD) in the first 50 ms of a rapid contraction. It is still unproven if repetitive rapid contractions specifically impair the net neural drive to the muscles. To isolate the fatiguing effect of contraction rapidity, 17 male adult volunteers performed 100 burst-like (i.e., brief force pulses) isometric contractions of the knee extensors. The response to electrically-evoked single and octet femoral nerve stimulation was measured with high-density surface electromyography (HD-sEMG) from the vastus lateralis and medialis muscles. Root mean square (RMS) of each channel of HD-sEMG was normalized to the corresponding M-wave peak-to-peak amplitude, while muscle fiber conduction velocity (MFCV) was normalized to M-wave conduction velocity to compensate for changes in sarcolemma properties. Voluntary RFD 0-50 ms decreased (d = -0.56, p < 0.001) while time to peak force (d = 0.90, p < 0.001) and time to RFDpeak increased (d = 0.56, p = 0.034). Relative RMS (d = -1.10, p = 0.006) and MFCV (d = -0.53, p = 0.007) also decreased in the first 50 ms of voluntary contractions. Evoked octet RFD 0-50 ms (d = 0.60, p = 0.020), M-wave amplitude (d = 0.77, p = 0.009) and conduction velocity (d = 1.75, p < 0.001) all increased. Neural efficacy, i.e., voluntary/octet force ratio, largely decreased (d = -1.50, p < 0.001). We isolated the fatiguing impact of contraction rapidity and found that the decrement in RFD, particularly when calculated in the first 50 ms of muscle contraction, can mainly be explained by a decrease in the net neural drive.
Collapse
Affiliation(s)
- Gennaro Boccia
- Neuromuscular Function research group, Department of Clinical and Biological Sciences, University of Turin, Turin, Italy
| | - Samuel D'Emanuele
- School of Sport and Exercise Sciences, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Paolo Riccardo Brustio
- Neuromuscular Function research group, Department of Clinical and Biological Sciences, University of Turin, Turin, Italy
| | - Alberto Rainoldi
- Neuromuscular Function research group, Department of Medical Sciences, University of Turin, Turin, Italy
| | - Federico Schena
- School of Sport and Exercise Sciences, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Cantor Tarperi
- School of Sport and Exercise Sciences, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| |
Collapse
|
5
|
Abstract
Rapid force production and its transmission to the skeleton are important factors in movements that involve the stretch-shortening cycle. Plyometric exercises are known to augment this cycle and thereby improve the neuromechanical function of the muscle. However, the training exercises that maximize translation of these gains to sports performance are not well defined. We discuss ways to improve this transfer.
Collapse
Affiliation(s)
- Jacques Duchateau
- Laboratory of Applied Biology and Neurophysiology, and Centre d'Aide à la Performance Sportive (CAPS), Université Libre de Bruxelles, Brussels, Belgium
| | - Ioannis G Amiridis
- Laboratory of Neuromechanics, Aristotle University of Thessaloniki, Serres, Greece
| |
Collapse
|
6
|
Kristensen NM, Taul-Madsen L, Gaemelke T, Riemenschneider M, Dalgas U, Hvid LG. Neuromuscular rate of force development discriminates fallers in ambulatory persons with multiple sclerosis - an exploratory study. Mult Scler Relat Disord 2023; 75:104758. [PMID: 37192588 DOI: 10.1016/j.msard.2023.104758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 04/18/2023] [Accepted: 05/09/2023] [Indexed: 05/18/2023]
Abstract
BACKGROUND Falls as well as fall-related injuries (e.g., bone fractures) are common in persons with multiple sclerosis (pwMS). Whilst some studies have identified lower extremity maximal muscle strength (Fmax) as one among several risk factors, no previous studies have investigated the association between rate of force development (RFD; ability to generate a rapid rise in muscle force) and falls in pwMS. Not only is RFD substantially compromised (and more so than Fmax) in pwMS, studies involving other neurodegenerative populations have shown that RFD - to a greater extent than Fmax - is crucial for counteracting unexpected perturbations and avoiding falling. OBJECTIVE To explore whether knee extensor RFD (and Fmax) can discriminate fallers from non-fallers in pwMS. METHODS Knee extensor neuromuscular function (comprising RFD50ms and RFD200ms (force developed in the interval 0-50 ms and 0-200 ms, respectively) as well as Fmax) of the weaker leg was assessed by isokinetic dynamometry. Falls were determined by 1-year patient recall, with pwMS subsequently being classified as non-fallers (0 falls), fallers (1-2 falls), or recurrent fallers (≥3 falls). RESULTS A total of n=53 pwMS were enrolled in the study, with n=24 classified as non-fallers (63% females, 48 years, EDSS 2.2), n=16 as fallers (88% females, 57 years, EDSS 3.3), and n=13 as recurrent fallers (46% females, 60 years, EDSS 4.2). Compared with non-fallers, neuromuscular function was reduced in both fallers (RFD50 -4.42 [-7.47;-1.37] Nm.s-1.kg-1, -48%; RFD200 -1.45 [-2.98;0.07] Nm.s-1.kg-1, -24%; Fmax -0.42 [-0.81;-0.03] Nm.kg-1, -21%) and recurrent fallers (RFD50 -5.69 [-8.94;-2.43] Nm.s-1.kg-1, -62%; RFD200 -2.26 [-3.89;-0.63] Nm.s-1.kg-1, -38%; Fmax -0.38 [-0.80;0.03] Nm.kg-1, -19%). Across all participants, associations were observed between RFD50ms and falls (rs = -0.46 [-0.67;-0.24], between RFD200ms and falls (rs = -0.34 [-0.59;-0.09]), and between Fmax and falls (rs = -0.24 [-0.48;0.01]). CONCLUSION In this exploratory study, knee extensor neuromuscular function was able to discriminate fallers from non-fallers in pwMS, with RFD being superior to Fmax. Routine assessment of lower extremity neuromuscular function (RFD50ms in particular) may be a helpful tool in identifying pwMS at future risk of falling.
Collapse
Affiliation(s)
- Nick M Kristensen
- Exercise Biology, Department of Public Health, Aarhus University, Denmark
| | | | - Tobias Gaemelke
- Exercise Biology, Department of Public Health, Aarhus University, Denmark
| | - Morten Riemenschneider
- Exercise Biology, Department of Public Health, Aarhus University, Denmark; The Danish MS Hospitals, Ry and Haslev, Denmark
| | - Ulrik Dalgas
- Exercise Biology, Department of Public Health, Aarhus University, Denmark
| | - Lars G Hvid
- Exercise Biology, Department of Public Health, Aarhus University, Denmark; The Danish MS Hospitals, Ry and Haslev, Denmark.
| |
Collapse
|
7
|
Poredoš D, Jenko Pražnikar Z, Kozinc Ž. Acute Effects of Beetroot Juice Supplementation on Isometric Muscle Strength, Rate of Torque Development and Isometric Endurance in Young Adult Men and Women: A Randomized, Double-Blind, Controlled Cross-Over Pilot Study. Nutrients 2022; 14:nu14224759. [PMID: 36432445 PMCID: PMC9692807 DOI: 10.3390/nu14224759] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/12/2022] Open
Abstract
This study was conducted to investigate the effect of concentrated beetroot juice on isometric strength and knee extensor muscle endurance in healthy adults. We conducted a randomized cross-over, double-blind experiment in which participants (18 healthy, physically active adults, 9 men, 9 women) consumed either concentrated beetroot juice (140 mL) or low-nitrate control supplement 2.5 h before the measurement. Isometric maximum strength (peak torque), explosive strength (isometric rate of torque development), and strength endurance at 50% of peak torque were measured on an isometric dynamometer. The results showed that concentrated beetroot juice had no effect on the maximum voluntary isometric strength and rate of torque development of the knee extensors. The only exception was the maximum rate of torque development, for which a positive influence was demonstrated only in men. As for the endurance of the knee extensors, the supplement had a positive effect in men (endurance time increased from 86.4 ± 46.1 s to 103.4 ± 53.7 s; p = 0.022), but not in women. The absence of effect on maximal voluntary strength is consistent with previous research. One the other hand, improvements in endurance and rate of torque development in men only point to an important aspect of a previously under-researched area of sex-specific responses to nitrate supplementation.
Collapse
Affiliation(s)
- David Poredoš
- Faculty of Health Sciences, University of Primorska, Polje 42, SI-6310 Izola, Slovenia
| | - Zala Jenko Pražnikar
- Andrej Marušič Institute, University of Primorska, Muzejski trg 2, SI-6000 Koper, Slovenia
| | - Žiga Kozinc
- Faculty of Health Sciences, University of Primorska, Polje 42, SI-6310 Izola, Slovenia
- Andrej Marušič Institute, University of Primorska, Muzejski trg 2, SI-6000 Koper, Slovenia
- Correspondence:
| |
Collapse
|