Electromyographic, cerebral, and muscle hemodynamic responses during intermittent, isometric contractions of the biceps brachii at three submaximal intensities

Abstract

This study examined the electromyographic, cerebral and muscle hemodynamic responses during intermittent isometric contractions of biceps brachii at 20, 40, and 60% of maximal voluntary contraction (MVC). Eleven volunteers completed 2 min of intermittent isometric contractions (12/min) at an elbow angle of 90° interspersed with 3 min rest between intensities in systematic order. Surface electromyography (EMG) was recorded from the right biceps brachii and near infrared spectroscopy (NIRS) was used to simultaneously measure left prefrontal and right biceps brachii oxyhemoglobin (HbO2), deoxyhemoglobin (HHb), and total hemoglobin (Hbtot). Transcranial Doppler ultrasound was used to measure middle cerebral artery velocity (MCAv) bilaterally. Finger photoplethysmography was used to record beat-to-beat blood pressure and heart rate. EMG increased with force output from 20 to 60% MVC (P < 0.05). Cerebral HbO2 and Hbtot increased while HHb decreased during contractions with differences observed between 60% vs. 40% and 20% MVC (P < 0.05). Muscle HbO2 decreased while HHb increased during contractions with differences being observed among intensities (P < 0.05). Muscle Hbtot increased from rest at 20% MVC (P < 0.05), while no further change was observed at 40 and 60% MVC (P > 0.05). MCAv increased from rest to exercise but was not different among intensities (P > 0.05). Force output correlated with the root mean square EMG and changes in muscle HbO2 (P < 0.05), but not changes in cerebral HbO2 (P > 0.05) at all three intensities. Force output declined by 8% from the 1st to the 24th contraction only at 60% MVC and was accompanied by systematic increases in RMS, cerebral HbO2 and Hbtot with a leveling off in muscle HbO2 and Hbtot. These changes were independent of alterations in mean arterial pressure. Since cerebral blood flow and oxygenation were elevated at 60% MVC, we attribute the development of fatigue to reduced muscle oxygen availability rather than impaired central neuronal activation.

New Insights into Mechanical, Metabolic and Muscle Oxygenation Signals During and After High-Intensity Tethered Running

“…Thus, years ago these authors suggested as a possible future direction the association of the muscle oxygenation measurement with other physiological responses monitored during tests and training (for example, HR and blood lactate concentration). Recently, this way has been accomplished and some studies aimed to adopt these recommendations 16,18 .…”

“…However, despite the significance of tissue oxygenation 18 there are very few studies investigating the more and less active muscle responses during and after exercise 14,42,[61][62][63] especially in running effort 12,19 . According to Perrey and Ferrari in a recent review 39 , the majority of the NIRS studies examined the responses of the vastus lateralis muscle.…”

“…Most investigations involving power efforts and muscle oxygenation analysis during high-intensity exercises were performed on a cycle ergometer [12][13][14][15] and in repeated sprint 13,16,17 but with measurements conducted in one muscle group 16,18 or in independent exercise to compare arm vs leg oxygen responses 13 . Rissanen et al 19 performed simultaneous analysis in biceps brachii and vastus lateralis in incremental treadmill running, observing differences between less and more active muscle oxygenation, especially in severe-intensity exercise.…”

The Influence of Thermal Alterations on Prefrontal Cortex Activation and Neuromuscular Function during a Fatiguing Task

“…Recently, Robertson and Marino [ 11 ] proposed that the prefrontal cortex (PFC) may interpret afferent feedback and play a role in tolerating or terminating fatiguing exercise. During submaximal unilateral contractions, as the intensity of exercise increases, there is an increase in oxygenation of the PFC, as measured by functional near infrared spectroscopy (fNIRS) [ 12 , 13 ]. Generally, increasing the intensity or duration of resistance exercise results in metabolite accumulation which stimulates metaboreceptive muscle afferents.…”

Combined surface electromyography, near-infrared spectroscopy and acceleration recordings of muscle contraction: The effect of motion

“…1 Multimodal studies of muscle function are becoming increasingly common, most of them based on a combination of NIRS and EMG. 18,22,23 Many of these studies focus on investigating the relationship between muscle electrophysiology and oxygenation or hemodynamics [24][25][26][27][28] or on gathering more reliable information on, for example, neuromuscular and metabolic activity in relation to muscle fatigue or injury. 29,30 Moreover, wireless hybrid sEMG/NIRS sensors have recently been proposed for multimodal analysis by such researchers as Guo et al 34 Surface EMG and accelerometer (ACM) have been previously used for example for sign language recognition, 45 fatigue assessment, 46 Parkinson's disease progress assessment 47 and for monitoring daily activities of patients who have had a stroke.…”