Neuromechanical Differences between Pronated and Supinated Forearm Positions during Upper-Body Wingate Tests.

Arm-cycling is a versatile exercise modality with applications in both athletic enhancement and rehabilitation, yet the influence of forearm orientation remains understudied. Thus, this study aimed to investigate the impact of forearm position on upper-body arm-cycling Wingate tests. Fourteen adult males (27.3 ± 5.8 years) underwent bilateral assessments of handgrip strength in standing and seated positions, followed by pronated and supinated forward arm-cycling Wingate tests. Electromyography (EMG) was recorded from five upper-extremity muscles, including anterior deltoid, triceps brachii lateral head, biceps brachii, latissimus dorsi, and brachioradialis. Simultaneously, bilateral normal and propulsion forces were measured at the pedal-crank interface. Rate of perceived exertion (RPE), power output, and fatigue index were recorded post-test. The results showed that a pronated forearm position provided significantly (p < 0.05) higher normal and propulsion forces and triceps brachii muscle activation patterns during arm-cycling. No significant difference in RPE was observed between forearm positions (p = 0.17). A positive correlation was found between seated handgrip strength and peak power output during the Wingate test while pronated (dominant: p = 0.01, r = 0.55; non-dominant: p = 0.03, r = 0.49) and supinated (dominant: p = 0.03, r = 0.51; don-dominant: p = 0.04, r = 0.47). Fatigue changed the force and EMG profile during the Wingate test. In conclusion, this study enhances our understanding of forearm position's impact on upper-body Wingate tests. These findings have implications for optimizing training and performance strategies in individuals using arm-cycling for athletic enhancement and rehabilitation.

Interhemispheric inhibition is different during arm cycling than a position- and intensity-matched tonic contraction.

Task-dependent changes in inhibition may explain why supraspinal excitability is higher during arm cycling than an intensity- and position-matched tonic contraction. The present study investigated whether interhemispheric inhibition (IHI) associated with biceps brachii activity was different during arm cycling, a locomotor output, compared to a tonic contraction. IHI was quantified using an ipsilateral silent period (iSP) evoked via transcranial magnetic stimulation (TMS) of the ipsilateral motor cortex. TMS was delivered at 120% resting motor threshold during the mid-elbow flexion phase of arm cycling (6 o'clock position, made relative to a clock face) and during a position- and intensity-matched tonic contraction. In total, 36 participants took part in the study. However, only 14 participants demonstrated IHI during arm cycling and 10 participants during tonic contraction. Of these participants, eight displayed clear iSPs during arm cycling and tonic contraction. The iSP duration was longer during arm cycling than tonic contraction (p < 0.05), while iSP EMG amplitude and area were not different between tasks (p > 05 for both comparisons). The main finding from this study is that IHI appears to be stronger during arm cycling than an intensity- and position-matched tonic contraction. This does not support previous findings of higher supraspinal excitability during arm cycling.

Endurance-exercise training adaptations in spinal motoneurones: potential functional relevance to locomotor output and assessment in humans.

It is clear from non-human animal work that spinal motoneurones undergo endurance training (chronic) and locomotor (acute) related changes in their electrical properties and thus their ability to fire action potentials in response to synaptic input. The functional implications of these changes, however, are speculative. In humans, data suggests that similar chronic and acute changes in motoneurone excitability may occur, though the work is limited due to technical constraints. To examine the potential influence of chronic changes in human motoneurone excitability on the acute changes that occur during locomotor output, we must develop more sophisticated recording techniques or adapt our current methods. In this review, we briefly discuss chronic and acute changes in motoneurone excitability arising from non-human and human work. We then discuss the potential interaction effects of chronic and acute changes in motoneurone excitability and the potential impact on locomotor output. Finally, we discuss the use of high-density surface electromyogram recordings to examine human motor unit firing patterns and thus, indirectly, motoneurone excitability. The assessment of single motor units from high-density recording is mainly limited to tonic motor outputs and minimally dynamic motor output such as postural sway. Adapting this technology for use during locomotor outputs would allow us to gain a better understanding of the potential functional implications of endurance training-induced changes in human motoneurone excitability on motor output.

Drug network identification predicts injecting risk behavior among people who inject drugs on hepatitis C virus treatment in Tayside, Scotland.

The risk of Hepatitis C Virus (HCV) acquisition among People Who Inject Drugs (PWID) remains high when injecting risk behavior within networks endures. Several psychosocial factors influence such behavior. Following a drive within Tayside, a geographic region in Scotland, to achieve World Health Organization HCV elimination targets, addressing HCV re-infection risk as a barrier to elimination is critically important. This cross-sectional study seeks to address this barrier to elimination by investigating associations between group identification (one's subjective sense of belonging and connectedness to a social group coupled with a sense of shared goals, beliefs and values with the other members of the group) and injecting risk behavior among PWID on HCV treatment at needle and syringe provision sites in Tayside. Participants completed psychosocial questionnaires between treatment weeks zero and three of treatment. Correlation analyses were undertaken, and significant factors included in multiple linear regression models for injecting risk behavior. Injecting frequency, drug network identification, and family identification, were correlated with injecting risk behavior, and drug network identification had a positive predictive on injecting risk behavior. Identification with a social group, conventionally associated with improved health, may pose health risks in specific contexts. Healthcare providers should consider stratifying individuals with higher group identification with PWID networks for enhanced harm reduction engagement to mitigate transmissible infection risk among PWID. Additionally, psychological interventions to strengthen group identification with networks which impact positively on health behavior should be explored.

Moving forward: methodological considerations for assessing corticospinal excitability during rhythmic motor output in humans.

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.

Democratizing epilepsy care: Utility and usability of an electronic patient portal.

OBJECTIVES: Electronic patient portals (ePortals) can facilitate greater healthcare democratization by providing patients and/or their authorized care partners with secure access to their medical records when and where needed. Such democratization can promote effective healthcare provider-patient partnerships, shared decision-making, and greater patient engagement in managing their health condition. This study examined the usefulness of providing individualized services and care in epilepsy (PiSCES), an epilepsy ePortal, as an enabler of more democratized epilepsy care. METHODS: Seventy-two individuals with epilepsy and 18 care partners were invited to report on their experience of interacting via PiSCES with clinical documents (epilepsy care summary record; epilepsy clinic letters) authored about them by healthcare providers. The OpenNotes reporting tool was adapted to capture participant experience. RESULTS: Twenty-five percent of invited patients and 44% of invited care partners reported on interacting with their epilepsy care summary; 14% of patients and 67% of care partners invited reported on their epilepsy clinic letters. Participant testimonials illustrate the value of PiSCES in: promoting autonomy, aiding memory, developing the knowledgeable patient, and enhancing healthcare partnerships. Ninety-six percent and 100% of respondents, respectively, reported understanding their epilepsy care summary and epilepsy clinic letter; 77% said the summary described their epilepsy history to date; 96% indicated that the letter provided an accurate description of their clinical encounter; 92% and 96%, respectively, valued access to their summary record and clinic letters; 77% of summary record and 73% clinic letter respondents reported learning something about their epilepsy or the healthcare service via PiSCES. Illustrating their potential patient and care partner safety role, 42% respondents identified inaccuracies in their clinical documents which were subsequently resolved by a clinician. SIGNIFICANCE: In the post-digital world highly customized on-demand products and services have come to be expected. Similarly, in epilepsy care, technologies such as PiSCES can enable more personalized, transparent, and engaging services.

Coproducing health and well-being in partnership with patients, families, and healthcare providers: A qualitative study exploring the role of an epilepsy patient portal.

BACKGROUND: Coproduced epilepsy care sees people with epilepsy (PwE), their care-proxies, and healthcare providers (HCPs), working together as partners to build strong relationships, improve communication, trust, and share decision-making. Coproduction underpins good quality patient- and family-centered care (PFCC) that is responsive to individual patient needs, preferences, and values. By facilitating information sharing and exchange between partners, electronic patient portals (ePortal) can enable coproduction. This paper explores what HCPs, PwE, and their care-proxies value from their user experience of PiSCES, the Irish epilepsy ePortal. METHODS: A purposeful sample of actors involved in the receipt and delivery of epilepsy care and services were recruited via adult epilepsy centers at St James's and Beaumont Hospitals in Dublin. Interactive codesign sessions, surveys, and focus groups were used to elicit perspectives from PwE, care-proxies, and HCPs to understand their perception of how PiSCES could enhance or inhibit the epilepsy care process. RESULTS: Results illustrate that participants welcome the role PiSCES can play in: empowering PwE/care-proxies, strengthening confidence in the healthcare system; aiding memory; advancing health literacy, motivating PwE to understand their condition better; acting as a passport of care between different clinical settings; and creating a foundation for stronger coproduction partnerships. PiSCES was generally embraced; however, some HCPs expressed plausible concerns about how clinical implementation might impact their work practices. CONCLUSION: "Nothing about me without me" is a core value of the PiSCES initiative, recognizing that people need to be included in the planning of their own treatment and care. Our data show that PwE, their care-proxies, and HCPs value PiSCES potential, particularly in bolstering healthcare partnerships that foster inclusion, confidence, and trust.

Genomic considerations for FHIR®; eMERGE implementation lessons.

Structured representation of clinical genetic results is necessary for advancing precision medicine. The Electronic Medical Records and Genomics (eMERGE) Network's Phase III program initially used a commercially developed XML message format for standardized and structured representation of genetic results for electronic health record (EHR) integration. In a desire to move towards a standard representation, the network created a new standardized format based upon Health Level Seven Fast Healthcare Interoperability Resources (HL7® FHIR®), to represent clinical genomics results. These new standards improve the utility of HL7® FHIR® as an international healthcare interoperability standard for management of genetic data from patients. This work advances the establishment of standards that are being designed for broad adoption in the current health information technology landscape.

The development of an epilepsy electronic patient portal: Facilitating both patient empowerment and remote clinician-patient interaction in a post-COVID-19 world.

OBJECTIVES: The current coronavirus disease 2019 (COVID-19) pandemic stresses an urgency to accelerate much-needed health service reform. Rapid and courageous changes being made to address the immediate impact of the pandemic are demonstrating that the means and technology to enable new models of health care exist. For example, innovations such as electronic patient portals (ePortal) can facilitate (a) radical reform of outpatient care; (b) cost containment in the economically constrained aftermath of the pandemic; (c) environmental sustainability by reduction of unnecessary journeys/transport. Herein, the development of Providing Individualised Services and Care in Epilepsy (PiSCES), an ePortal to the Irish National Epilepsy Electronic Patient Record, is demonstrated. This project, which pre-dates the COVID-19 crisis, aims to facilitate better patient- and family-centered epilepsy care. METHODS: A combination of ethnographic research, document analysis, and joint application design sessions was used to elicit PiSCES requirements. From these, a specification of desired modules of functionality was established and guided the software development. RESULTS: PiSCES functional features include "My Epilepsy Care Summary," "My Epilepsy Care Goals," "My Epilepsy Clinic Letters," "Help Us Measure Your Progress," "Prepare For Your Clinic Visit," "Information for Your Healthcare Provider." The system provides people with epilepsy access to, and engages them as co-authors of, their own medical record. It can promote improved patient-clinician partnerships and facilitate patient self-management. SIGNIFICANCE: In the aftermath of COVID-19, it is highly unlikely that the healthcare sector will return to a "business as usual" way of delivering services. The pandemic is expected to accelerate adoption of innovations like PiSCES. It is therefore a catalyst for change that will deliver care that is more responsive to individual patient needs and preferences.

Health Professionals' Perceptions and Practice of Family Centred Care for Children Injured in Road Traffic Accidents: A Qualitative Study in Ghana.

The Family Centered Care (FCC) model is widely recognized as the standard for pediatric care practice in the context of families and hospitalized children. Healthcare professionals' knowledge of the FCC model is therefore central to its successful implementation. Nonetheless, there is paucity of scholarship in the Ghanaian context, regarding professionals' knowledge and practice of FCC. OBJECTIVES: This study, being the first in the Ghanaian context aimed to explore the perceptions of family centered care among healthcare professionals who provide the healthcare needs of children hospitalized through road traffic accidents. METHOD: Twenty-four (24) healthcare professionals were interviewed as part of a larger study which adopted a Grounded Theory approach. Data collection and analysis occurred concurrently. Here, we employed constant comparative methods to structure emerging categories and sub-categories. FINDINGS: Most health professionals in the study perceived family centered care to mean family involvement, although obvious inconsistencies characterized existing practices. Based on contextual perspectives, three categories emerged, namely; parental involvement, communication and setting boundaries. CONCLUSION: The concept of FCC is a familiar terminology among health professionals. However, its principles, components and dimensions in the western context are alien to healthcare professionals in Ghana. A context-specific FCC model which reflects social values and cultural norms is therefore required for healthcare services to children and families in Ghana.

Development of a genomics module within an epilepsy-specific electronic health record: Toward genomic medicine in epilepsy care.

OBJECTIVES: Both clinical genomics and e-Health technology are changing the way medicine is being practiced. Although the basic clinical methodology of good medical care will remain unchanged, the combined power of genomics and electronic health records has the capability of enhancing, and in some cases transforming, the practice of medicine. This is particularly true in the care of patients with complex long-term medical conditions such as chronic refractory epilepsy, especially in those with related complex comorbidities including intellectual disability and psychiatric disease. METHODS: Herein we outline the development and integration of an epilepsy genomics module into a preexisting epilepsy electronic patient record (EPR) system. RESULTS: We describe how this EPR infrastructure is used to facilitate discussion at multidisciplinary clinical meetings around molecular diagnosis and resulting changes in management. SIGNIFICANCE: This work illustrates the role of eHealth technology in embedding genomics into the clinical pathway.

Short-interval intracortical inhibition to the biceps brachii is present during arm cycling but is not different than a position- and intensity-matched tonic contraction.

We have previously shown that supraspinal excitability is higher during arm cycling than a position- and intensity-matched tonic contraction. The present study sought to determine if short-interval intracortical inhibition (SICI) was present during arm cycling and if so, if the amount of SICI was different from an intensity-matched tonic contraction. SICI was assessed using conditioning stimuli (CS) of 70 and 90% of active motor threshold (AMT) and a test stimulus (TS) of 120% AMT at an interstimulus interval (ISI) of 2.5 ms. SICI was elicited in all participants; on average (i.e., cycling and tonic contraction grouped) test MEP amplitudes were reduced by 64.2% (p < 0.001) and 62.8% (p = 0.001) following conditioning stimuli of 70% and 90% AMT, respectively. There was no significant difference in extent of SICI between tasks (p = 0.360). These data represent the novel finding that SICI is present during arm cycling, a motor output partially mediated by spinal interneuronal networks. The amount of SICI, however, was not different from that during a position- and intensity-matched tonic contraction, suggesting that SICI is not likely a cortical mechanism contributing to higher supraspinal excitability during arm cycling compared to tonic contraction.

Short-interval intracortical inhibition of the biceps brachii in chronic-resistance versus non-resistance-trained individuals.

The purpose of this study was to investigate the effects of chronic resistance training on corticospinal excitability and short intracortical inhibition of the biceps brachii. Eight chronic resistance-trained (RT) and eight non-RT participants completed one experimental session including a total of 30 brief (7 s) elbow flexors isometric contractions at various force outputs [15, 25 and 40% of maximum voluntary contraction (MVC)]. Before the contractions, MVC, maximal compound muscle action potential (Mmax) during 5% MVC and active motor threshold (AMT) at the three various force outputs were recorded. MVC force of the chronic-RT group was 24% higher than the non-RT group (p ≤ 0.001; ω2 = 0.72). The chronic-RT group had lower AMTs at targeted forces of 15 and 25% MVC (p = 0.022 and p = 0.012, respectively) compared to the non-RT group. During 25 and 40% of MVC, the non-RT group exhibited decreased SICI in comparison to the chronic-RT group (p = 0.008; ω2 = 0.35 and p = 0.03; ω2 = 0.21, respectively). However, SICI did not differ between groups at 15% MVC (p = 0.62). In conclusion, chronic resistance training significantly reduces SICI. This suggests the presence of an adaptive process of inhibitory and facilitatory network activation, which may cancel out the SICI, allowing for increased corticomotor drive to the exercised muscle following a long period of resistance training.

Quantitative feature analysis of continuous analytic wavelet transforms of electrocardiography and electromyography.

Theoretical and practical advances in time-frequency analysis, in general, and the continuous wavelet transform (CWT), in particular, have increased over the last two decades. Although the Morlet wavelet has been the default choice for wavelet analysis, a new family of analytic wavelets, known as generalized Morse wavelets, which subsume several other analytic wavelet families, have been increasingly employed due to their time and frequency localization benefits and their utility in isolating and extracting quantifiable features in the time-frequency domain. The current paper describes two practical applications of analysing the features obtained from the generalized Morse CWT: (i) electromyography, for isolating important features in muscle bursts during skating, and (ii) electrocardiography, for assessing heart rate variability, which is represented as the ridge of the main transform frequency band. These features are subsequently quantified to facilitate exploration of the underlying physiological processes from which the signals were generated.This article is part of the theme issue 'Redundancy rules: the continuous wavelet transform comes of age'.

Multiple traumatic experiences, post-traumatic stress disorder and offending behaviour in female prisoners.

BACKGROUND: Although it is well established that prisoners commonly have histories of childhood trauma, little is known about mediators between exposure to trauma and criminal behaviour. HYPOTHESES: We hypothesised that the experience of trauma in adulthood, post-traumatic stress disorder (PTSD) and emotional dysregulation would mediate the relationship between childhood traumatic events and later criminal behaviour. METHODS: Eighty-nine female prisoners were interviewed using standardised scales, in a cross-sectional study design. History of traumatic events, DSM-5 PTSD and emotional regulation were assessed, along with offending and demographic information. A series of regression and mediation analyses were undertaken on the data. RESULTS: Almost all (91%) of the 89 women reported both childhood and adulthood trauma. Over half (58%) met the criteria for DSM-5 PTSD. Multiple traumas were significantly associated with seriousness of offence, as indicated by sentence length. Adult experience of trauma was the only significant mediator between childhood trauma and subsequent offending. CONCLUSIONS/IMPLICATIONS FOR PRACTICE: Women who have experienced multiple traumatic events may be more likely to commit serious offences, so it is very important to assess and meet their trauma-related needs. While prisons should never be used as substitutes for healthcare facilities, when women or girls are sent to prison, the opportunity for constructive interventions must be seized. Copyright © 2017 John Wiley & Sons, Ltd.

Posttraumatic stress disorder (PTSD) symptoms mediate the relationship between substance misuse and violent offending among female prisoners.

PURPOSE: Despite empirical evidence suggesting complex associations between psychological trauma, substance misuse, and violent offending, there is a dearth of research investigating these associations in the female prison population. METHODS: A cross-sectional, interview-format questionnaire study was undertaken with a sample of 89 female prisoners. History of traumatic events, DSM-5 PTSD, drug use, and offending behaviour were assessed. RESULTS: Traumatic experiences had occurred in 97.8 % of the sample, while 60.5 % met criteria for a PTSD diagnosis. The majority of the sample (70.8 %) reported using illicit drugs, and 59.6 % had committed at least one violent offence. History of drug use was significantly correlated with trauma, PTSD status, and violent offending. A mediation analysis identified an indirect effect of PTSD symptoms on the relationship between history of drug use and violent offending. CONCLUSIONS: The result of our mediation analysis further highlights the importance of addressing PTSD symptoms and substance misuse, among female offenders, to help prevent violent offending.

Effectiveness of Positive Youth Development Interventions: A Meta-Analysis of Randomized Controlled Trials.

Positive youth development is thought to be essential to the prevention of adolescent risk behavior and the promotion of thriving. This meta-analysis examined the effects of positive youth development interventions in promoting positive outcomes and reducing risk behavior. Ten databases and grey literature were scanned using a predefined search strategy. We included studies that focused on young people aged 10-19 years, implemented a positive youth development intervention, were outside school hours, and utilized a randomized controlled design. Twenty-four studies, involving 23,258 participants, met the inclusion criteria and were included in the analysis. The impact of the interventions on outcomes including behavioral problems, sexual risk behavior, academic achievement, prosocial behavior and psychological adjustment were assessed. Positive youth development interventions had a small but significant effect on academic achievement and psychological adjustment. No significant effects were found for sexual risk behaviors, problem behavior or positive social behaviors. Intervention effects were independent of program characteristics and participant age. Low-risk young people derived more benefit from positive youth development interventions than high-risk youth. The studies examined had several methodological flaws, which weakened the ability to draw conclusions. Substantial progress has been made in the theoretical understanding of youth development in the past two decades. This progress needs to be matched in the intervention literature, through the use of high-quality evaluation research of positive youth development programs.

From Childhood Trauma to Self-Harm: An Investigation of Theoretical Pathways among Female Prisoners.

BACKGROUND: Despite empirical evidence suggesting complex associations between childhood trauma and self-harm, there is a dearth of research investigating this association in the female prison population. The current study explored pathways to self-harm following childhood trauma, by investigating the mediating roles of Post-traumatic Stress Disorder (PTSD) symptoms, emotion regulation and dissociation, in this relationship, within a sample of 89 female prisoners. METHODS: Cross-sectional, interview-format, questionnaire study within a female prison population. Measures of childhood trauma, self-harm, PTSD, emotion regulation and dissociation were administered. RESULTS: The majority of the sample (58.4%) reported history of self-harm. Bootstrapped mediation analyses indicated an indirect effect of emotion regulation on the relationship between childhood trauma and self-harm. An indirect effect was also found for PTSD arousal/reactivity cluster of symptoms. Multiple mediation analyses revealed that interactional effects were present for emotion regulation and arousal/reactivity, and emotion regulation and dissociation, respectively. CONCLUSION: Self-harm is highly prevalent among female prisoners. Interventions promoting emotion regulation and addressing arousal/reactivity symptoms following traumatization may provide an effective way of addressing this problem. Copyright © 2016 John Wiley & Sons, Ltd. KEY PRACTITIONER MESSAGES: Self-harm is highly prevalent amongst female prisoners, occurring in 58.4% of this sample. Emotion regulation and the arousal/reactivity symptom cluster of PTSD were found to mediate the relationship between childhood trauma and self-harm, both independently and simultaneously. Emotion regulation and dissociation were found to interactionally mediate this relationship. Strategies targeting emotion dysregulation and hyperarousal symptoms, amongst female prisoners who have experienced childhood trauma, may be helpful in reducing self-harming behaviours.

Differences in corticospinal excitability to the biceps brachii between arm cycling and tonic contraction are not evident at the immediate onset of movement.

This is the first study to examine changes in corticospinal excitability to the biceps brachii during the onset of arm cycling from a resting position to a point when steady-state arm cycling was obtained. Supraspinal and spinal excitability were assessed using motor-evoked potentials (MEPs) elicited via transcranial magnetic stimulation and cervicomedullary evoked potentials (CMEPs) elicited via transmastoid electrical stimulation, respectively. Evoked responses were recorded from the biceps brachii during elbow flexion (6 o'clock relative to a clock face) for both arm cycling and an intensity-matched tonic contraction at three separate periods: (1) immediately at the onset of motor output and after completion of the (2) 4th revolution and (3) 9th revolution. There was no difference during initiation between tasks for MEP (P = 0.79) or CMEP amplitudes (P = 0.57). However, MEP amplitudes were significantly larger during arm cycling than an intensity-matched tonic contraction after the completion of the 4th (Cycling 76.48 ± 17.35 % of M max, Tonic 63.45 ± 18.45 % of M max, P < 0.05) and 9th revolutions (Cycling 72.37 ± 15.96 % of M max, Tonic 58.1 ± 24.23 % of M max, P < 0.05). There were no differences between conditions in CMEP amplitudes at the 4th (Cycling 49.6 ± 25.4 % of M max, Tonic 41.6 ± 11.2 % of M max, P = 0.31) or the 9th revolution (Cycling 47.2 ± 17.0 % of M max, Tonic 40.8 ± 13.6 % of M max, P = 0.29). These results demonstrate that corticospinal excitability is not different between arm cycling and a tonic contraction at motor output onset, but supraspinal excitability is enhanced during steady-state arm cycling. This suggests a similarity in the way the corticospinal tract initiates motor outputs in humans, regardless of the differences that present themselves in the later, steady-state stages.

Cadence-dependent changes in corticospinal excitability of the biceps brachii during arm cycling.

This is the first study to report the influence of different cadences on the modulation of supraspinal and spinal excitability during arm cycling. Supraspinal and spinal excitability were assessed using transcranial magnetic stimulation of the motor cortex and transmastoid electrical stimulation of the corticospinal tract, respectively. Transcranial magnetic stimulation-induced motor evoked potentials and transmastoid electrical stimulation-induced cervicomedullary evoked potentials (CMEPs) were recorded from the biceps brachii at two separate positions corresponding to elbow flexion and extension (6 and 12 o'clock relative to a clock face, respectively) while arm cycling at 30, 60 and 90 rpm. Motor evoked potential amplitudes increased significantly as cadence increased during both elbow flexion (P < 0.001) and extension (P = 0.027). CMEP amplitudes also increased with cadence during elbow flexion (P < 0.01); however, the opposite occurred during elbow extension (i.e., decreased CMEP amplitude; P = 0.01). The data indicate an overall increase in the excitability of corticospinal neurons which ultimately project to biceps brachii throughout arm cycling as cadence increased. Conversely, changes in spinal excitability as cadence increased were phase dependent (i.e., increased during elbow flexion and decreased during elbow extension). Phase- and cadence-dependent changes in spinal excitability are suggested to be mediated via changes in the balance of excitatory and inhibitory synaptic input to the motor pool, as opposed to changes in the intrinsic properties of spinal motoneurons.