Spinal and corticospinal excitability in response to reductions in skin and core temperature via whole-body cooling

Cold stress impairs fine and gross motor movements. Although peripheral effects of muscle cooling on performance are well understood, less is known about central mechanisms. This study characterized corticospinal and spinal excitability during surface cooling, reducing skin (Tsk) and core (Tes) temperature. Ten subjects (3 female) wore a liquid-perfused suit and were cooled (9°C perfusate, 90 min) and rewarmed (41°C perfusate, 30 min). Transcranial magnetic stimulation [eliciting motor evoked potentials (MEPs)], as well as transmastoid [eliciting cervicomedullary evoked potentials (CMEPs)] and brachial plexus [eliciting maximal compound motor action potentials (Mmax)] electrical stimulation, were applied at baseline, every 20 min during cooling, and following rewarming. Sixty minutes of cooling, reduced Tsk by 9.6°C (P<0.001) but Tes remained unchanged (P=0.92). Tes then decreased ~0.6℃ in the next 30 minutes of cooling (P<0.001). Eight subjects shivered. During rewarming, shivering was abolished, and Tsk returned to baseline while Tes did not increase. During cooling and rewarming, Mmax, MEP, and MEP/Mmax were unchanged from baseline. However, CMEP and CMEP/Mmax increased during cooling by ~85% and 79% (P<0.001) respectively, and remained elevated post-rewarming. Results suggest that spinal excitability is facilitated by reduced Tsk during cooling, and reduced Tes during warming, while corticospinal excitability remains unchanged. ClinicalTrials.gov ID NCT04253730 Novelty: • This is the first study to characterize corticospinal, and spinal excitability during whole body cooling, and rewarming in humans. • Whole body cooling did not affect corticospinal excitability. • Spinal excitability was facilitated during reductions in both skin and core temperatures.

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Intensity matters: effects of cadence and power output on corticospinal excitability during arm cycling are phase and muscle dependent

Journal of Neurophysiology ◽

10.1152/jn.00358.2018 ◽

2018 ◽

Vol 120 (6) ◽

pp. 2908-2921 ◽

Cited By ~ 5

Author(s):

E. J. Lockyer ◽

R. J. Benson ◽

A. P. Hynes ◽

L. R. Alcock ◽

A. J. Spence ◽

...

Keyword(s):

Evoked Potentials ◽

Power Output ◽

Motor Evoked Potentials ◽

Elbow Flexion ◽

Corticospinal Excitability ◽

Peak Power Output ◽

Triceps Brachii ◽

Arm Cycling ◽

Power Outputs ◽

Spinal Excitability

The present study investigated the effects of cadence and power output on corticospinal excitability to the biceps (BB) and triceps brachii (TB) during arm cycling. Supraspinal and spinal excitability were assessed using transcranial magnetic stimulation (TMS) of the motor cortex and transmastoid electrical stimulation (TMES) of the corticospinal tract, respectively. Motor-evoked potentials (MEPs) elicited by TMS and cervicomedullary motor-evoked potentials (CMEPs) elicited by TMES were recorded at two positions during arm cycling corresponding to mid-elbow flexion and mid-elbow extension (i.e., 6 and 12 o’clock made relative to a clock face, respectively). Arm cycling was performed at combinations of two cadences (60 and 90 rpm) at three relative power outputs (20, 40, and 60% peak power output). At the 6 o’clock position, BB MEPs increased ~11.5% as cadence increased and up to ~57.2% as power output increased ( P < 0.05). In the TB, MEPs increased ~15.2% with cadence ( P = 0.013) but were not affected by power output, while CMEPs increased with cadence (~16.3%) and power output (up to ~19.1%, P < 0.05). At the 12 o’clock position, BB MEPs increased ~26.8% as cadence increased and up to ~96.1% as power output increased ( P < 0.05), while CMEPs decreased ~29.7% with cadence ( P = 0.013) and did not change with power output ( P = 0.851). In contrast, TB MEPs were not different with cadence or power output, while CMEPs increased ~12.8% with cadence and up to ~23.1% with power output ( P < 0.05). These data suggest that the “type” of intensity differentially modulates supraspinal and spinal excitability in a manner that is phase- and muscle dependent. NEW & NOTEWORTHY There is currently little information available on how changes in locomotor intensity influence excitability within the corticospinal pathway. This study investigated the effects of arm cycling intensity (i.e., alterations in cadence and power output) on corticospinal excitability projecting to the biceps and triceps brachii during arm cycling. We demonstrate that corticospinal excitability is modulated differentially by cadence and power output and that these modulations are dependent on the phase and the muscle examined.

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Arm-cycling sprints induce neuromuscular fatigue of the elbow flexors and alter corticospinal excitability of the biceps brachii

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2015-0438 ◽

2016 ◽

Vol 41 (2) ◽

pp. 199-209 ◽

Cited By ~ 12

Author(s):

Gregory E.P. Pearcey ◽

David J. Bradbury-Squires ◽

Michael Monks ◽

Devin Philpott ◽

Kevin E. Power ◽

...

Keyword(s):

Evoked Potentials ◽

Biceps Brachii ◽

Motor Evoked Potentials ◽

Neuromuscular Fatigue ◽

Corticospinal Excitability ◽

Voluntary Activation ◽

Elbow Flexors ◽

Mean Power ◽

Arm Cycling ◽

Spinal Excitability

We examined the effects of arm-cycling sprints on maximal voluntary elbow flexion and corticospinal excitability of the biceps brachii. Recreationally trained athletes performed ten 10-s arm-cycling sprints interspersed with 150 s of rest in 2 separate experiments. In experiment A (n = 12), maximal voluntary contraction (MVC) force of the elbow flexors was measured at pre-sprint 1, post-sprint 5, and post-sprint 10. Participants received electrical motor point stimulation during and following the elbow flexor MVCs to estimate voluntary activation (VA). In experiment B (n = 7 participants from experiment A), supraspinal and spinal excitability of the biceps brachii were measured via transcranial magnetic and transmastoid electrical stimulation that produced motor evoked potentials (MEPs) and cervicomedullary motor evoked potentials (CMEPs), respectively, during a 5% isometric MVC at pre-sprint 1, post-sprint 1, post-sprint 5, and post-sprint 10. In experiment A, mean power output, MVC force, potentiated twitch force, and VA decreased 13.1% (p < 0.001), 8.7% (p = 0.036), 27.6% (p = 0.003), and 5.6% (p = 0.037), respectively, from pre-sprint 1 to post-sprint 10. In experiment B, (i) MEPs decreased 42.1% (p = 0.002) from pre-sprint 1 to post-sprint 5 and increased 40.1% (p = 0.038) from post-sprint 5 to post-sprint 10 and (ii) CMEPs increased 28.5% (p = 0.045) from post-sprint 1 to post-sprint 10. Overall, arm-cycling sprints caused neuromuscular fatigue of the elbow flexors, which corresponded with decreased supraspinal and increased spinal excitability of the biceps brachii. The different post-sprint effects on supraspinal and spinal excitability may illustrate an inhibitory effect on supraspinal drive that reduces motor output and, therefore, decreases arm-cycling sprint performance.

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Corticospinal excitability to the biceps and triceps brachii during forward and backward arm cycling is direction- and phase-dependent

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2019-0043 ◽

2020 ◽

Vol 45 (1) ◽

pp. 72-80

Author(s):

Anna. P. Nippard ◽

Evan. J. Lockyer ◽

Duane. C. Button ◽

Kevin. E. Power

Keyword(s):

Evoked Potentials ◽

Biceps Brachii ◽

Motor Evoked Potentials ◽

Elbow Flexion ◽

Corticospinal Excitability ◽

Extension Phase ◽

Triceps Brachii ◽

Arm Cycling ◽

Spinal Excitability ◽

Flexion And Extension

The purpose of this study was to evaluate corticospinal excitability to the biceps and triceps brachii during forward (FWD) and backward (BWD) arm cycling. Corticospinal and spinal excitability were assessed using transcranial magnetic stimulation and transmastoid electrical stimulation to elicit motor evoked potentials (MEPs) and cervicomedullary evoked potentials (CMEPs), respectively. MEPs and CMEPs were recorded from the biceps and triceps brachii during FWD and BWD arm cycling at 2 positions, 6 and 12 o’clock. The 6 o’clock position corresponded to mid-elbow flexion and extension during FWD and BWD cycling, respectively, while 12 o’clock corresponded to mid-elbow extension and flexion during FWD and BWD cycling, respectively. During the flexion phase, MEP and CMEP amplitudes of the biceps brachii were higher during FWD cycling. However, during the extension phase, MEP and CMEP amplitudes were higher during BWD cycling. For the triceps brachii, MEP amplitudes were higher during FWD cycling regardless of phase. However, CMEP amplitudes were phase-dependent. During the flexion phase, CMEPs of the triceps brachii were higher during FWD cycling compared with BWD, but during the extension phase CMEPs were higher during BWD cycling compared with FWD. The data suggest that corticospinal and spinal excitability to the biceps brachii is phase- and direction-dependent. In the triceps brachii, spinal, but not corticospinal, excitability is phase-dependent when comparing FWD and BWD cycling. Novelty This is the first study to assess corticospinal excitability during FWD and BWD locomotor output. Corticospinal excitability during arm cycling depends on the direction, phase, and muscle being assessed.

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Corticospinal excitability to the biceps and triceps brachii during forward and backward arm cycling is direction- and phase-dependent

10.31236/osf.io/wtszy ◽

2019 ◽

Author(s):

Anna Nippard ◽

Evan Lockyer ◽

Duane Button ◽

Kevin Power

Keyword(s):

Evoked Potentials ◽

Biceps Brachii ◽

Motor Evoked Potentials ◽

Elbow Flexion ◽

Corticospinal Excitability ◽

Extension Phase ◽

Triceps Brachii ◽

Arm Cycling ◽

Spinal Excitability ◽

Flexion And Extension

The purpose of this study was to evaluate corticospinal excitability to the biceps and triceps brachii during forward (FWD) and backward (BWD) arm cycling. Corticospinal and spinal excitability were assessed using transcranial magnetic stimulation (TMS) and transmastoid electrical stimulation (TMES) to elicit motor evoked potentials (MEPs) and cervicomedullary evoked potentials (CMEPs), respectively. MEPs and CMEPs were recorded from the biceps and triceps brachii during FWD and BWD arm cycling at two positions, 6 and 12 o’clock. The 6 o’clock position corresponded to mid-elbow flexion and extension during FWD and BWD cycling, respectively, while 12 o’clock corresponded to mid-elbow extension and flexion during FWD and BWD cycling, respectively. During the flexion phase, MEP and CMEP amplitudes of the biceps brachii were higher during FWD than BWD cycling. However, during the extension phase, MEP and CMEP amplitudes were higher during BWD than FWD cycling. For the triceps brachii, MEP amplitudes were higher during FWD cycling compared to BWD regardless of phase. However, CMEP amplitudes were phase-dependent. During the flexion phase, CMEPs of the triceps brachii were higher during FWD cycling compared to BWD, but during the extension phase CMEPs were higher during BWD cycling compared to FWD. The data suggests that corticospinal and spinal excitability to the biceps brachii is phase- and direction-dependent. In the triceps brachii, spinal, but not corticospinal, excitability is phase-dependent when comparing FWD and BWD cycling.

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Distribution and Severity of Hypoxic-Ischemic Lesions on Brain MRI Following Therapeutic Cooling: Selective Head Versus Whole Body Cooling

Pediatric Research ◽

10.1038/pr.2011.947 ◽

2011 ◽

Vol 70 ◽

pp. 722-722

Author(s):

S Sarkar ◽

J R Bapuraj ◽

S M Donn ◽

I Bhagat ◽

J D Barks

Keyword(s):

Brain Mri ◽

Whole Body ◽

Body Cooling ◽

Whole Body Cooling

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Muscle length and joint angle influence spinal but not corticospinal excitability to the biceps brachii across forearm postures

Journal of Neurophysiology ◽

10.1152/jn.00620.2018 ◽

2019 ◽

Vol 122 (1) ◽

pp. 413-423 ◽

Cited By ~ 2

Author(s):

Davis A. Forman ◽

Daniel Abdel-Malek ◽

Christopher M. F. Bunce ◽

Michael W. R. Holmes

Keyword(s):

Isometric Contraction ◽

Elbow Joint ◽

Joint Angle ◽

Biceps Brachii ◽

Motor Evoked Potentials ◽

Muscle Length ◽

Elbow Flexion ◽

Corticospinal Excitability ◽

Biceps Brachii Muscle ◽

Spinal Excitability

Forearm rotation (supination/pronation) alters corticospinal excitability to the biceps brachii, but it is unclear whether corticospinal excitability is influenced by joint angle, muscle length, or both. Thus the purpose of this study was to separately examine elbow joint angle and muscle length on corticospinal excitability. Corticospinal excitability to the biceps and triceps brachii was measured using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation. Spinal excitability was measured using cervicomedullary motor evoked potentials (CMEPs) elicited via transmastoid electrical stimulation. Elbow angles were manipulated with a fixed biceps brachii muscle length (and vice versa) across five unique postures: 1) forearm neutral, elbow flexion 90°; 2) forearm supinated, elbow flexion 90°; 3) forearm pronated, elbow flexion 90°; 4) forearm supinated, elbow flexion 78°; and 5) forearm pronated, elbow flexion 113°. A musculoskeletal model determined biceps brachii muscle length for postures 1–3, and elbow joint angles ( postures 4–5) were selected to maintain biceps length across forearm orientations. MEPs and CMEPs were elicited at rest and during an isometric contraction of 10% of maximal biceps muscle activity. At rest, MEP amplitudes to the biceps were largest during supination, which was independent of elbow joint angle. CMEP amplitudes were not different when the elbow was fixed at 90° but were largest in pronation when muscle length was controlled. During an isometric contraction, there were no significant differences across forearm postures for either MEP or CMEP amplitudes. These results highlight that elbow joint angle and biceps brachii muscle length can each independently influence spinal excitability. NEW & NOTEWORTHY Changes in upper limb posture can influence the responsiveness of the central nervous system to artificial stimulations. We established a novel approach integrating neurophysiology techniques with biomechanical modeling. Through this approach, the effects of elbow joint angle and biceps brachii muscle length on corticospinal and spinal excitability were assessed. We demonstrate that spinal excitability is uniquely influenced by joint angle and muscle length, and this highlights the importance of accounting for muscle length in neurophysiological studies.

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Corticospinal excitability of the biceps brachii is shoulder position dependent

Journal of Neurophysiology ◽

10.1152/jn.00527.2017 ◽

2017 ◽

Vol 118 (6) ◽

pp. 3242-3251 ◽

Cited By ~ 9

Author(s):

Brandon Wayne Collins ◽

Edward W. J. Cadigan ◽

Lucas Stefanelli ◽

Duane C. Button

Keyword(s):

Evoked Potentials ◽

Maximal Voluntary Contraction ◽

Biceps Brachii ◽

Motor Evoked Potentials ◽

Voluntary Contraction ◽

Corticospinal Excitability ◽

State Dependent ◽

Shoulder Flexion ◽

Erb’S Point ◽

Shoulder Position

The purpose of this study was to examine the effect of shoulder position on corticospinal excitability (CSE) of the biceps brachii during rest and a 10% maximal voluntary contraction (MVC). Participants ( n = 9) completed two experimental sessions with four conditions: 1) rest, 0° shoulder flexion; 2) 10% MVC, 0° shoulder flexion; 3) rest, 90° shoulder flexion; and 4) 10% MVC, 90° shoulder flexion. Transcranial magnetic, transmastoid electrical, and Erb’s point stimulation were used to induce motor-evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), and maximal muscle compound potentials (Mmax), respectively, in the biceps brachii in each condition. At rest, MEP, CMEP, and Mmax amplitudes increased ( P < 0.01) by 509.7 ± 118.3%, 113.3 ± 28.3%, and 155.1 ± 47.9%, respectively, at 90° compared with 0°. At 10% MVC, MEP amplitudes did not differ ( P = 0.08), but CMEP and Mmax amplitudes increased ( P < 0.05) by 32.3 ± 10.5% and 127.9 ± 26.1%, respectively, at 90° compared with 0°. MEP/Mmax increased ( P < 0.01) by 224.0 ± 99.1% at rest and decreased ( P < 0.05) by 51.3 ± 6.7% at 10% MVC at 90° compared with 0°. CMEP/Mmax was not different ( P = 0.22) at rest but decreased ( P < 0.01) at 10% MVC by 33.6 ± 6.1% at 90° compared with 0°. EMG increased ( P < 0.001) by 8.3 ± 2.0% at rest and decreased ( P < 0.001) by 21.4 ± 4.4% at 10% MVC at 90° compared with 0°. In conclusion, CSE of the biceps brachii was dependent on shoulder position, and the pattern of change was altered within the state in which it was measured. The position-dependent changes in Mmax amplitude, EMG, and CSE itself all contribute to the overall change in CSE of the biceps brachii. NEW & NOTEWORTHY We demonstrate that when the shoulder is placed into two common positions for determining elbow flexor force and activation, corticospinal excitability (CSE) of the biceps brachii is both shoulder position and state dependent. At rest, when the shoulder is flexed from 0° to 90°, supraspinal factors predominantly alter CSE, whereas during a slight contraction, spinal factors predominantly alter CSE. Finally, the normalization techniques frequently used by researchers to investigate CSE may under- and overestimate CSE when shoulder position is changed.

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Whole body cooling for infants with hypoxic-ischemic encephalopathy

Journal of Clinical Neonatology ◽

10.4103/2249-4847.96777 ◽

2012 ◽

Vol 1 (2) ◽

pp. 101 ◽

Cited By ~ 10

Author(s):

Rafat Mosalli

Keyword(s):

Hypoxic Ischemic Encephalopathy ◽

Whole Body ◽

Body Cooling ◽

Whole Body Cooling ◽

Ischemic Encephalopathy

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The Cooling Power of Pigeon Wings

Journal of Experimental Biology ◽

10.1242/jeb.155.1.193 ◽

1991 ◽

Vol 155 (1) ◽

pp. 193-202 ◽

Cited By ~ 1

Author(s):

ALBERT CRAIG ◽

JACQUES LAROCHELLE

Keyword(s):

Body Temperature ◽

Heat Production ◽

Heat Dissipation ◽

Experimental System ◽

Whole Body ◽

Cooling Power ◽

Wind Speeds ◽

Maximum Value ◽

Body Cooling ◽

Whole Body Cooling

The rate of heat loss through the stretched wings (Hwings) was studied in resting pigeons preheated to a body temperature (43.7°C) within the range of those recorded during flight. The experimental system was designed to allow the calculation of Hwings from the increase in whole-body cooling rates resulting from exposure of the wings to various wind speeds (0–50 km h−1) at 23°C. The maximum value of HWings was 3.8 W, less than twice the heat production of a resting pigeon. This indicates that the contribution of the wings to heat dissipation during flight may not be nearly as important as has been supposed. At low windspeeds (0–12.5 km h−1), HWings corresponded to about 40% of the resting rate of heat production, and this value is discussed in connection with the various wing postures observed in hyperthermic birds.

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