Dawson Kidgell

• PhD in Neurophysiology
• Professor (Associate) at Deakin University

Experimental studies showed improvement in physical performance following acute application of transcranial direct current stimulation (tDCS). This study examined the neuromuscular and neural response to a single training session (Part 1) and after a 3-week resistance training (Part 2) performed with the knee extensors, preceded by tDCS over the pr...

To assess reticulospinal tract excitability, high‐intensity transcranial magnetic stimulation (TMS) has been used to elicit ipsilateral motor‐evoked potentials (iMEPs). However, there is no consensus on robust and valid methods for use in human studies. The present study proposes a standardized method for eliciting and analysing iMEPs in the biceps...

The StartReact test, increasingly popular for assessing cortico‐reticular functioning, is a valid method to influence the firing of reticulospinal tract neurons noninvasively. However, there remains limited evidence on how different stimuli employed in the StartReact test impact motor output in humans. The present study tested elbow flexor response...

Patellar tendinopathy (PT) typically affects jumping‐sport athletes with functional impairments frequently observed. Alterations to the functional organization of corticomotor neurons within the motor cortex that project to working muscles are evident in some musculoskeletal conditions and linked to functional impairments. We aimed to determine if...

Unaccustomed eccentric exercise (EE) is protective against muscle damage following a subsequent bout of similar exercise. One hypothesis suggests the existence of an alteration in motor unit (MU) behaviour during the second bout, which might contribute to the adaptive response. Accordingly, the present study investigated MU changes during repeated...

Aim of the study Interest continues investigating pathophysiology of athlete cohorts with a history involving cumulative career exposure of repeated concussion and non-concussion impacts. One area yet to be explored involves the somatosensory system. Using a novel sensorimotor technique, this study measured the somatosensory system in retired conta...

Aim Repetitive head impact exposure, from contact and collision sports, are increasingly being attributed to increased risk of neurodegenerative disease in aging athletes. This exploratory study investigated the association of playing career in retired professional contact sport athletes with cortical neurophysiology via transcranial magnetic stimu...

High Responders to Hypertrophic Strength Training Also Tend to Lose More Muscle Mass and Strength During Detraining Than Low Responders: Erratum Räntilä, Aapo; Ahtiainen, Juha P.; Avela, Janne; Restuccia, Joel; Kidgell, Dawson; Häkkinen, Keijo Journal of Strength and Conditioning Research 38(4):p 63 In the article “High Responders to Hypertrophic...

Prior studies suggest resistance exercise as a potential form of motor learning due to task-specific corticospinal responses observed in single sessions of motor skill and resistance training. While existing literature primarily focuses on upper limb muscles, revealing a task-dependent nature in eliciting corticospinal responses, our aim was to inv...

Introduction Strength training mitigates the age-related decline in strength and muscle activation but limited evidence exists on specific motor pathway adaptations. Methods Eleven young (22–34 years) and ten older (66–80 years) adults underwent five testing sessions where lumbar-evoked potentials (LEPs) and motor-evoked potentials (MEPs) were mea...

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...

Background Lower capacity to generate knee extension maximal voluntary force (MVF) has been observed in individuals affected with patellar tendinopathy (PT) compared to asymptomatic controls. This MVF deficit is hypothesized to emanate from alterations in corticospinal excitability (CSE). The modulation of CSE is intricately linked to the excitabil...

Background: Transcranial Alternating Current Stimulation (tACS) employs low-intensity sinusoidal currents to influence cortical plasticity and motor function. Despite extensive research, inconsistent results require a comprehensive review of tACS efficacy. Objective: This study systematically assesses tACS effects on corticospinal and intracortical...

Background: Transcranial Alternating Current Stimulation (tACS) employs low-intensity sinusoidal currents to influence cortical plasticity and motor function. Despite extensive research, inconsistent results require a comprehensive review of tACS efficacy. Objective: This study systematically assesses tACS effects on corticospinal and intracortica...

Sensorimotor training and strength training can improve balance control. Currently, little is known about how repeated balance perturbation training affects balance performance and its neural mechanisms. This study investigated corticospinal adaptation assessed by transcranial magnetic stimulation (TMS) and Hoffman-reflex (H-reflex) measurements du...

In addition to the established postural control role of the reticulospinal tract (RST), there has been an increasing interest on its involvement in strength, motor recovery, and other gross motor functions. However, there are no reviews that have systematically assessed the overall motor function of the RST. Therefore, we aimed to determine the rol...

Purpose The use of electrical stimulation to assess voluntary activation of muscle/s is a popular method employed in numerous exercise science and health research settings. This Delphi study aimed to collate expert opinion and provide recommendations for best practice when using electrical stimulation during maximal voluntary contractions. Methods...

International concern regarding the association between repetitive neurotrauma in sport and long term concerns with ageing continues. While previous studies have reported older (i.e. over 50 years) our study describes corticomotor changes across the lifespan between retired contact sport athletes, between the ages of 30 and 70 years. Retired athlet...

Motor skill training alters the human nervous system; however, lower limb motor tasks have been less researched compared to upper limb tasks. This meta-analysis with best evidence synthesis aimed to determine the cortical and subcortical responses that occur following lower limb motor skill training, and whether these responses are accompanied by i...

This study aimed to determine the test–retest reliability of a range of transcranial magnetic stimulation (TMS) outcomes in the biceps femoris during isometric, eccentric and concentric contractions. Corticospinal excitability (active motor threshold 120% [AMT120%] and area under recruitment curve [AURC]), short‐ and long‐interval intracortical inh...

There are observable decreases in muscle strength as a result of ageing that occur from the age of 40, which is thought to occur as a result of changes within the neuromuscular system. Strength-training in older adults is a suitable intervention that may counteract the age-related loss in force production. The neuromuscular adaptations (i.e., corti...

Background: Worldwide, 86 million individuals over the age of 20 were diagnosed with knee osteoarthritis (KOA) in 2020. Hallmark features of KOA are the loss in knee extensor strength, increasing knee pain severity, and deficits in functional performance. There is a critical need for the investigation into potential cost-effective therapeutic inter...

Purpose Long-term sports training, such as skill and endurance training, leads to specific neuroplasticity. However, it remains unclear if muscle stretch-induced proprioceptive feedback influences corticospinal facilitation/inhibition differently between skill- and endurance-trained athletes. This study investigated modulation of corticospinal exci...

Ballistic motor training induces plasticity changes and imparts a cross-transfer effect. However, whether there are age-related differences in these changes remain unclear. Thus, the purpose of this study was to perform a meta-analysis to determine the corticospinal responses and cross-transfer of motor performance following ballistic motor trainin...

Measurement of the adverse outcomes of repeated head trauma in contact sport athletes is often achieved using tests where the comparator is the score or the accuracy obtained. While it is expected that ex-athletes would perform worse than controls, previous studies have shown inconsistent results. Here we have attempted to address these inconsisten...

The corticospinal responses to high-intensity and low-intensity strength-training of the upper limb are modulated in an intensity-dependent manner. Whether an intensity-dependent threshold occurs following acute strength training of the knee extensors (KE) remains unclear. We assessed the corticospinal responses following high-intensity (85% of max...

Background Lower limb muscle strain injury is highly prevalent in running-based sports and is considered a risk factor for recurrent injury. It is possible that differences in muscle activity and activation in previously strain-injured limbs may contribute to the elevated risk of reinjury. Objectives To systematically review available literature i...

Räntilä, A, Ahtiainen, JP, Avela, J, Restuccia, J, Kidgell, DJ, and Häkkinen, K. High responders to hypertrophic strength training also tend to lose more muscle mass and strength during detraining than low responders. J Strength Cond Res 35(6): 1500-1511, 2021-This study investigated differences in individual responses to muscle hypertrophy during...

Optimal strategies for enhancing strength and improving motor skills are vital in athletic performance and clinical rehabilitation. Initial increases in strength and the acquisition of new motor skills have long been attributed to neurological adaptations. However, early increases in strength may be predominantly due to improvements in inter-muscul...

Background Neuroimaging studies show that nociceptive stimuli elicit responses in an extensive cortical network. Functional near-infrared spectroscopy (fNIRS) allows for functional assessment of changes in oxyhemoglobin (HbO), an indirect index for cortical activity. Unlike functional magnetic resonance imaging (fMRI), fNIRS is portable, relatively...

Background Cross-education refers to increased motor output (i.e., force generation, skill) of the opposite, untrained limb following a period of unilateral exercise training. Despite extensive research, several aspects of the transfer phenomenon remain controversial. Methods A modified two-round Delphi online survey was conducted among internatio...

Purpose: Cross-education (CE) increases strength of both the trained and untrained limb, with emerging evidence, suggesting CE could be used to attenuate muscle strength and thickness following periods of limb immobilization. This study examined the available evidence for the clinical efficacy of CE to attenuate muscle strength, thickness and neura...

The aim of this study was to examine the effects of 5 days of anodal-transcranial direct current stimulation (a-tDCS) over the primary motor cortex (M1) on lower extremity functional performance in healthy elderly people. This was a randomized, double-blinded, sham-controlled study whereby 32 healthy older individuals participated in two groups. Th...

Purpose: To determine whether corticospinal excitability (CSE) and inhibition are differentially modulated following high-volume light-load strength training compared to low-volume heavy-load strength training. We hypothesised high-volume light-load strength training would increase CSE and low-volume heavy-load strength training would reduce intrac...

Background. Resistance-training causes changes in the central nervous system (CNS); however, the sites of these adaptations remain unclear. Objective To determine sites of neural adaptation to resistance-training by conducting a systematic review and meta-analysis on the cortical and subcortical responses to resistance-training. Methods. Evidence f...

Background: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that utilizes weak direct currents to induce polarity-dependent modulation of corticospinal excitability. Although tDCS exerts a modulatory effect over the stimulation region, several studies have also demonstrated that distal areas of the brain...

New findings: What is the central question of the study? Neural adaptations to resistance training are known to be task-specific, however adaptation to resistance training using compound movements are typically assessed in a single-limb isometric task. This study aimed to assess whether corticospinal responses to acute and short-term squat resista...

Purpose: The motor cortex (M1) appears to be a primary site of adaptation following both a single session, and repeated strength-training sessions across multiple weeks. Given that a single session of strength-training is sufficient to induce modification at the level of the M1 and corticospinal tract, this study sought to determine how these acute...

Background With advancing age, changes in the central nervous system may lead to motor functional deficits. Non-invasive Brain stimulation techniques are suggested to help modifing brain function. Objectives The aim of the current study was to investigate the effect of using multi session anodal transcranial Direct Current Stimulation (a-tDCS) ove...

This study determined whether there are task-dependent differences in cortical excitability following different types of strength training. Transcranial magnetic stimulation (TMS) measured corticospinal excitability (CSE) and intracortical inhibition (ICI) of the biceps brachii muscle in 42 healthy subjects that were randomised to either paced-stre...

Persistent post concussion symptoms (PPCS) describe the condition when an individual experiences chronic symptoms, particularly fatigue, beyond the expected time of recovery. The aim of this study was to quantify the effect of fatigue and related ongoing symptoms on somatosensory and corticomotor pathways using reaction time (RT) testing, and singl...

Muscle architecture is an important component of muscle function, and recent studies have shown changes in muscle architecture with fatigue. The stretch-shortening cycle is a natural way to study human locomotion, but little is known about how muscle architecture is affected by this type of exercise. This study investigated potential changes in med...

Purpose Transcranial magnetic stimulation (TMS) usually investigates the corticospinal responses of the agonist muscle to strength training, despite the role of the antagonist muscle in strength development. We examined the intracortical responses from an agonist and antagonist muscle following a single session of heavy-loaded strength training (do...

Background: Neck pain has been estimated to affect one in two people. Cognitive therapy and neck-specific strengthening exercises are two interventions that target different factors related to chronic neck pain in order to decrease pain and disability. Objectives: To critically appraise the effect of a combination of neck-specific strengthening exe...

Resistance training with blood flow restriction is typically performed during single exercises for the lower- or upper-body, which may not replicate real world programming. The present study examined the change in muscle strength and mass in a young healthy population during an 8-week whole body resistance training program, as well as monitoring th...

Determining a single compound maximal motor response (MMAX ) or an average superimposed MMAX response (MSUP ) are commonly used reference values in experiments eliciting raw electromyographic, motor evoked potentials, H-reflexes, and V-waves. However, existing literature is limited in detailing the most appropriate method to normalize these electro...

Recently, there have been several studies that have examined the acute effects of aerobic exercise on cognitive function. Importantly, one precise indicator of cognitive function is response time (RT), which has two main components; premotor time (PMT) and motor time (MT). PMT is the time for perception, decision making and response preparation, wh...

Background Resistance training causes changes in the central nervous system; however, the sites of these adaptations remain unclear. Objective The objective of this article was to determine sites of neural adaptation to resistance training by conducting a systematic review and meta-analysis on the cortical and subcortical responses to resistance t...

Mason, J, Frazer, AK, Jaberzadeh, S, Ahtiainen, JP, Avela, J, Rantalainen, T, Leung, M, and Kidgell, DJ. Determining the corticospinal responses to single bouts of skill and strength training. J Strength Cond Res XX(X): 000-000, 2019-Neuroplastic changes in the primary motor cortex accompany performance improvements following motor practice. Recent...

Numerous studies have indicated that non-invasive brain stimulation (NIBS) of the cerebellum could modulate corticospinal excitability (CSE) in young healthy individuals. However, there is no systematic review and meta-analysis that clarifies the effects of cerebellar NIBS on CSE. The aim of this study was to provide a meta-analytic summary of the...

Frazer, AK, Howatson, G, Ahtiainen, JP, Avela, J, Rantalainen, T, and Kidgell, DJ. Priming the motor cortex with anodal transcranial direct current stimulation affects the acute inhibitory corticospinal responses to strength training. J Strength Cond Res 33(2): 307-317, 2019-Synaptic plasticity in the motor cortex (M1) is associated with strength t...

Cross-education describes the strength gain in the opposite, untrained limb following a unilateral strength training program. Since its discovery in 1894, several studies now confirm the existence of cross-education in contexts that involve voluntary dynamic contractions, eccentric contraction, electrical stimulation, whole-body vibration and, more...

Recently, several studies have used Transcranial Magnetic Stimulation (TMS) to probe the corticospinal-motoneuronal responses to a single session of strength training; however, the findings are inconsistent. This systematic review and meta-analysis examined whether a single bout of strength training affects the excitability and inhibition of intrac...

New findings: What is the central question of this study? In order to discern information about testing modalities when assessing neuroplastic responses to squat resistance training, the present study investigated whether corticospinal and intracortical function was different between a joint-angle matched isometric squat, and isometric knee extens...

This study aimed to identify the ipsilateral corticospinal responses of the contralateral limb following different types of unilateral motor-training. Three groups performing unilateral slow-paced strength training (SPST), non-paced strength training (NPST) or visuomotor skill training (VT) were compared to a control group. It was hypothesised that...

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Purpose: The corticospinal responses to skill training may be different to strength training, depending on how the strength training is performed. It was hypothesised that the corticospinal responses would not be different following skill training and metronome-paced strength training (MPST), but would differ when compared with self-paced strength...

Strength-training results in changes in skeletal muscle, however, changes in the central nervous system also occur. Over the last 15 years, non-invasive brain stimulation techniques, such as transcranial magnetic stimulation, have been used to study the neural adaptations to strength-training. This review explored the hypothesis that the neural ada...

Background: Strength training results in adaptive changes in skeletal muscle, however, adaptive changes in the central nervous system also occur. Over the last 15 years, noninvasive brain stimulation techniques, such as transcranial magnetic stimulation, have been used to study the neural adaptations to strength training. The present review explore...

Cross-education of strength occurs when strength-training 1 limb increases the strength of the untrained limb and is restricted to the untrained homologous muscle. Cortical circuits located ipsilateral to the trained limb might be involved. We used transcranial magnetic stimulation (TMS) to determine the corticomotor responses from the untrained ho...

Purpose: We used transcranial magnetic stimulation (TMS) to determine the corticospinal responses from an agonist and synergist muscle following strength-training of the right elbow flexors. Methods: Motor evoked potentials were recorded from the Biceps Brachii and Flexor Carpi Radialis during a submaximal contraction from 20 individuals (10 women,...

Objective: This study aimed to compare the immediate analgesic effects of 2 resistance programs in in-season athletes with patellar tendinopathy (PT). Resistance training is noninvasive, a principle stimulus for corticospinal and neuromuscular adaptation, and may be analgesic. Design: Within-season randomized clinical trial. Data analysis was co...

PurposeWe examined the effect of priming the ipsilateral motor cortex (M1) using anodal transcranial direct current stimulation (tDCS) prior to a single bout of strength training on the cross-transfer of strength and corticospinal excitability and inhibition of the ipsilateral M1. Methods In a randomized double-blinded cross-over design, changes in...

Purpose Cross-education of strength has been proposed to be greater when completed by the dominant limb in right handed humans. We investigated whether the direction of cross-education of strength and corticospinal plasticity are different following right or left limb strength training in right-handed participants. Methods Changes in strength, musc...

Background Parkinson’s disease (PD) results from a loss of dopamine in the brain, leading to movement dysfunctions such as bradykinesia, postural instability, resting tremor and muscle rigidity. Furthermore, dopamine deficiency in PD has been shown to result in maladaptive plasticity of the primary motor cortex (M1). Progressive resistance training...

Background: Single sessions of bihemispheric transcranial direct-current stimulation (bihemispheric-tDCS) with concurrent rehabilitation improves motor function in stroke survivors, which outlasts the stimulation period. However few studies have investigated the behavioral and neurophysiological adaptations following a multi-session intervention of...

Repetitive transcranial magnetic stimulation (rTMS) is an established technique that can modulate excitability of the motor cortex, beyond the duration of the stimulation itself. More recently, a newer repetitive technique, known as I-wave periodicity TMS (iTMS) has been purported to show increases in motor cortex (corticospinal) excitability follo...

Introduction: We examined the cumulative effect of 4 consecutive bouts of non-invasive brain stimulation on corticospinal plasticity and motor performance, and whether these responses were influenced by the brain-derived neurotrophic factor (BDNF) polymorphism. Methods: In a randomized double-blinded cross-over design, changes in strength and in...

Tendinopathy can be resistant to treatment and often recurs, implying that current treatment approaches are suboptimal. Rehabilitation programmes that have been successful in terms of pain reduction and return to sport outcomes usually include strength training. Muscle activation can induce analgesia, improving self-efficacy associated with reducin...

We used transcranial magnetic stimulation (TMS) to investigate whether an acute bout of resistance exercise with blood flow restriction (BFR) stimulated changes in corticomotor excitability (motor evoked potential, MEP) and short-interval intracortical inhibition (SICI), and compared the responses to two traditional resistance exercise methods. Ten...

Background: Falls are a major public health concern with at least one third of people aged 65 years and over falling at least once per year, and half of these will fall repeatedly, which can lead to injury, pain, loss of function and independence, reduced quality of life and even death. Although the causes of falls are varied and complex, the age-...

Background Few interventions reduce patellar tendinopathy (PT) pain in the short term. Eccentric exercises are painful and have limited effectiveness during the competitive season. Isometric and isotonic muscle contractions may have an immediate effect on PT pain. Methods This single-blinded, randomised cross-over study compared immediate and 45 mi...