ECSS Paris 2023: OP-BM20
INTRODUCTION: Pain experienced during exercise acts as an inhibitory factor that can alter motor output, reduce exercise tolerance, and limit the physiological and cognitive benefits of physical activity. Despite this evidence, the brain responses that characterize exercise-induced pain remain poorly understood. The present study sought to investigate electrical brain activity measured via electroencephalography (EEG) in response to exercise-relevant experimental muscle pain at rest and during cycling exercise. METHODS: Twenty-one healthy participants completed four experimental conditions twice, with each lasting 255 s: (i) resting (sitting) while fixating on a point (FIX), (ii) resting fixation with pain intervention (PAIN), (iii) submaximal (30% of peak power output) single-leg cycling (CYCL), and (iv) submaximal single-leg cycling while pain intervention applied to the non-exercising leg (CYCL+PAIN). Experimental pain was induced using a combination of blood flow occlusion and low-intensity electrically evoked quadriceps muscle contractions. A 32-channel EEG system was used to record brain signals throughout each condition and to determine spectral power for alpha, beta, and gamma frequency bands at four distinct brain regions, bilaterally encompassing fronto-central and centro-parietal cortices. Perceived leg pain (0-10 visual analog scale) was monitored throughout the tasks. RESULTS: Compared to FIX and CYCL, occlusion in the non-exercising leg during the PAIN and PAIN+CYCL conditions resulted in an average pain rating of ~6.52 ± 3.9 (P<0.001). At a resting state, pain induced a significant reduction in alpha (P<0.001) and beta (P<0.001) power in fronto-central, and centro-parietal brain areas, while gamma suppression was only observed in fronto-central brain areas (P<0.001). Changes occurred bilaterally with no observable differences between brain hemispheres. During cycling, superimposed pain did not significantly alter frequency band power compared to cycling alone. CONCLUSION: These findings suggest that tonic experimental muscle pain is characterized by distinct frequency band modulations at rest that are not observed during cycling. Pain-induced gamma suppression is a novel finding that may suggest unique cortical processing specific to exercise-relevant muscle pain. It is plausible that a greater pain stimulus may be required to detect pain-evoked modulations during cycling. Overall, this study provides novel insights into the neural responses to muscle pain, while contributing to understanding EEG spectral analysis’ utility for studying pain during exercise.
Read CV Jalal AboodardaECSS Paris 2023: OP-BM20
INTRODUCTION: A quick start to an imperative tone (starting gun) following a warning tone (“set”) is a crucial factor influencing sprint performance, though the neural mechanisms that support the quick start are still unclear. Previous neuroimaging studies have reported that when a response to an auditory stimulus is required, brain activity is modulated preceding that stimulus [1]. Thus, examining brain activity prior to a crouching start may help us understand a part of the neural mechanisms underlying the quick start. We aimed to investigate electrocortical activity during a crouching start using electroencephalography (EEG), which enables the examination of brain activity modulation within its limited time frame. METHODS: Seventeen sprinters (10 males, aged 19–27 years) performed the following tasks: a starting task and a non-starting task. In the starting task, participants were instructed to position their hands and feet on the starting line and starting blocks, lift their hips in response to a warning tone, and initiate the start upon hearing an imperative tone after about 1700 ms. In the non-starting task, they positioned their hands and feet but remained relaxed without focusing on starting. After the warning tone, they were asked to lift their hips but instructed to disregard the imperative tone and avoid starting. Each task consisted of 30 trials. EEG signals were recorded using a portable EEG system with 63 electrodes. EEG prior to the imperative tone was used for source analysis. Statistical significance for differences between the two tasks in event-related spectral perturbation was tested using bootstrap statistics with false discovery rate correction. The significance level was set at p < 0.05. RESULTS: Statistical analysis in the anterior cingulate cluster revealed, during the starting task, a significant increase in theta (4–8 Hz) and alpha (8–13 Hz) power during the first half of the interval between the warning and imperative tones (p < 0.05), while power across a broad frequency range, from theta to gamma (30–40 Hz), significantly increased during the second half of this interval (p < 0.05). CONCLUSION: The anterior cingulate cortex is thought to be involved in error detection and intentional motor control [2]. An enhancement of power has been considered to characterize brain states with reduced information processing [3]. In summary, our results suggest that during a crouching start, neural processing related to these cognitive functions in the anterior cingulate cortex is reduced. This reduction in neural processing may lead to an increase in attentional resources for the imperative stimulus, potentially contributing to the quick start. The findings may serve as fundamental knowledge for enhancing performance in sports requiring a quick response. REFERENCES: [1] M. Alegre et al., Clin. Neurophysiol., 2006. [2] T. Paus, Nat. Rev. Neurosci., 2001. [3] G. Pfurtscheller, Vision Res., 2001.
Read CV ATSUSHI OSHIMAECSS Paris 2023: OP-BM20
INTRODUCTION: Stroke may lead to plastic structural changes within areas of the ipsilesional and contralesional hemispheres of the brain, which increase cortical interhemispheric imbalance (1). Maximum joint range of motion (ROMmax) impairments may also occur in the paretic limb, leading to an increased ROMmax asymmetry between lower limbs and reduced motor performance in functional tasks, such as walking (2). However, the association between post-stroke connectivity of each cortical hemisphere, hip flexion ROMmax symmetry between limbs and walking performance is poorly understood. The present study examined the specific influence of post-stroke cortical connectivity in the ipsilesional and contralesional hemispheres of the brain on hip flexion ROMmax asymmetry and walking performance in stroke survivors. METHODS: Twenty hemiparetic chronic stroke patients (57.5 ± 14.8 yr, 26.7 ± 22.2 m post stroke) were assessed for cortical functional connectivity of the ipsilesional and contralesional general hemispheres and specific primary motor cortex (M1) areas of the brain with resting-state electroencephalography (EEG). Patients were also assessed for hip flexion active ROMmax of the paretic and non-paretic limbs and 10-m walk test, and their between-limb ROMmax asymmetry was further calculated. Relationships between changes in these variables were examined by Pearson product–moment (r), and linear and multiple regression analyses. RESULTS: Hip flexion ROMmax asymmetry was correlated (P < 0.05) with cortical connectivity of the entire contralesional hemisphere (r = 0.52) and specific contralesional M1 (r = 0.47) areas of the brain, while the time to complete 10-m walk test was correlated with cortical connectivity of the contralesional M1 area only (r = 0.51). Cortical connectivity of the contralesional hemisphere explained ~28% of the hip flexion ROMmax asymmetry, while cortical connectivity of the contralesional M1 explained ~25% of the total time to complete the 10-m walk test (P < 0.05). No correlations (P > 0.05) between the other variables were observed. CONCLUSION: Cortical connectivity networks seem to shift mainly to the contralesional hemisphere after stroke episodes (3), which may in turn increase lower limb ROMmax asymmetry and reduce the ability of stroke patients to perform daily tasks, such as walking.
Read CV Cassio V RuasECSS Paris 2023: OP-BM20