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Central command increases muscular oxygenation of the non ‐ exercising arm at the early period of voluntary one ‐ armed cranking

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ABSTRACT

This study aimed to examine whether central command increases oxygenation in non‐contracting arm muscles during contralateral one‐armed cranking and whether the oxygenation response caused by central command differs among skeletal muscles of the non‐exercising upper limb. In 13 male subjects, the relative changes in oxygenated‐hemoglobin concentration (Oxy‐Hb) of the non‐contracting arm muscles [the anterior deltoid, triceps brachii, biceps brachii, and extensor carpi radialis (ECR)] were measured during voluntary one‐armed cranking (intensity, 35–40% of maximal voluntary effort) and mental imagery of the one‐armed exercise for 1 min. Voluntary one‐armed cranking increased (P < 0.05) the Oxy‐Hb of the triceps, biceps, and ECR muscles to the same extent (15 ± 4% of the baseline level, 17 ± 5%, and 16 ± 4%, respectively). The greatest increase in the Oxy‐Hb was observed in the deltoid muscle. Intravenous injection of atropine (10–15 μg/kg) and/or propranolol (0.1 mg/kg) revealed that the increased Oxy‐Hb of the arm muscles consisted of the rapid atropine‐sensitive and delayed propranolol‐sensitive components. Mental imagery of the exercise increased the Oxy‐Hb of the arm muscles. Motor‐driven passive one‐armed cranking had little influence on the Oxy‐Hb of the arm muscles. It is likely that central command plays a role in the initial increase in oxygenation in the non‐contracting arm muscles via sympathetic cholinergic vasodilatation at the early period of one‐armed cranking. The centrally induced increase in oxygenation may not be different among the distal arm muscles but may augment in the deltoid muscle.

No MeSH data available.


(A) Experimental setup. (B) Representative recordings of the crank angular displacement and developed torque of the ergometer and integrated electromyogram (EMG) signals of the non‐contracting arm muscles during 1 min of voluntary one‐armed cranking in a subject. (C) Representative recordings of the integrated EMG signals of the contracting arm muscles during the exercise in the same subject. The EMG signals of the non‐contracting and contracting muscles were not simultaneously recorded. EMG activity was recorded in the anterior deltoid (Deltoid), triceps brachii (Triceps), biceps brachii (Biceps), and extensor carpi radialis (ECR) muscle.
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phy213237-fig-0001: (A) Experimental setup. (B) Representative recordings of the crank angular displacement and developed torque of the ergometer and integrated electromyogram (EMG) signals of the non‐contracting arm muscles during 1 min of voluntary one‐armed cranking in a subject. (C) Representative recordings of the integrated EMG signals of the contracting arm muscles during the exercise in the same subject. The EMG signals of the non‐contracting and contracting muscles were not simultaneously recorded. EMG activity was recorded in the anterior deltoid (Deltoid), triceps brachii (Triceps), biceps brachii (Biceps), and extensor carpi radialis (ECR) muscle.

Mentions: One‐armed cranking exercise with the right arm was performed for 1 min at 60 rpm in an upright sitting posture on a seat of a specially designed cycle ergometer (Strength Ergo 240 BK‐ERG‐003, Mitsubishi Electric Engineering, Tokyo, Japan) as shown in Figure 1. The positions of the crank and seat were adjusted so that the subjects remained in a comfortable and certain posture. Torque against the wheel shaft and angular displacement of the ergometer crank were continuously measured. The subjects performed two types of one‐armed cranking: voluntary and passive mode. In a voluntary trial, the subjects were given a verbal instruction of “please start exercise whenever you want after you calm down and rest sufficiently,” and then they started exercise arbitrarily without any cue. In a passive trial, one‐armed cranking movement was driven by a motor of the ergometer without any verbal cue and volitional effort. To minimize a chance to anticipate the start of passive movement, when the passive movement would start was not informed to the subjects. On a separate day prior to the main experiment, the subjects were familiarized to one‐armed cranking in the laboratory environment and performed an incremental one‐armed exercise test to determine the maximal voluntary effort (MVE) as previously reported (Ishii et al. 2012). The rating of perceived exertion (RPE) was asked after each bout of exercise, according to the Borg 6‐20 unit scale (Borg 1970).


Central command increases muscular oxygenation of the non ‐ exercising arm at the early period of voluntary one ‐ armed cranking
(A) Experimental setup. (B) Representative recordings of the crank angular displacement and developed torque of the ergometer and integrated electromyogram (EMG) signals of the non‐contracting arm muscles during 1 min of voluntary one‐armed cranking in a subject. (C) Representative recordings of the integrated EMG signals of the contracting arm muscles during the exercise in the same subject. The EMG signals of the non‐contracting and contracting muscles were not simultaneously recorded. EMG activity was recorded in the anterior deltoid (Deltoid), triceps brachii (Triceps), biceps brachii (Biceps), and extensor carpi radialis (ECR) muscle.
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phy213237-fig-0001: (A) Experimental setup. (B) Representative recordings of the crank angular displacement and developed torque of the ergometer and integrated electromyogram (EMG) signals of the non‐contracting arm muscles during 1 min of voluntary one‐armed cranking in a subject. (C) Representative recordings of the integrated EMG signals of the contracting arm muscles during the exercise in the same subject. The EMG signals of the non‐contracting and contracting muscles were not simultaneously recorded. EMG activity was recorded in the anterior deltoid (Deltoid), triceps brachii (Triceps), biceps brachii (Biceps), and extensor carpi radialis (ECR) muscle.
Mentions: One‐armed cranking exercise with the right arm was performed for 1 min at 60 rpm in an upright sitting posture on a seat of a specially designed cycle ergometer (Strength Ergo 240 BK‐ERG‐003, Mitsubishi Electric Engineering, Tokyo, Japan) as shown in Figure 1. The positions of the crank and seat were adjusted so that the subjects remained in a comfortable and certain posture. Torque against the wheel shaft and angular displacement of the ergometer crank were continuously measured. The subjects performed two types of one‐armed cranking: voluntary and passive mode. In a voluntary trial, the subjects were given a verbal instruction of “please start exercise whenever you want after you calm down and rest sufficiently,” and then they started exercise arbitrarily without any cue. In a passive trial, one‐armed cranking movement was driven by a motor of the ergometer without any verbal cue and volitional effort. To minimize a chance to anticipate the start of passive movement, when the passive movement would start was not informed to the subjects. On a separate day prior to the main experiment, the subjects were familiarized to one‐armed cranking in the laboratory environment and performed an incremental one‐armed exercise test to determine the maximal voluntary effort (MVE) as previously reported (Ishii et al. 2012). The rating of perceived exertion (RPE) was asked after each bout of exercise, according to the Borg 6‐20 unit scale (Borg 1970).

View Article: PubMed Central - PubMed

ABSTRACT

This study aimed to examine whether central command increases oxygenation in non‐contracting arm muscles during contralateral one‐armed cranking and whether the oxygenation response caused by central command differs among skeletal muscles of the non‐exercising upper limb. In 13 male subjects, the relative changes in oxygenated‐hemoglobin concentration (Oxy‐Hb) of the non‐contracting arm muscles [the anterior deltoid, triceps brachii, biceps brachii, and extensor carpi radialis (ECR)] were measured during voluntary one‐armed cranking (intensity, 35–40% of maximal voluntary effort) and mental imagery of the one‐armed exercise for 1 min. Voluntary one‐armed cranking increased (P < 0.05) the Oxy‐Hb of the triceps, biceps, and ECR muscles to the same extent (15 ± 4% of the baseline level, 17 ± 5%, and 16 ± 4%, respectively). The greatest increase in the Oxy‐Hb was observed in the deltoid muscle. Intravenous injection of atropine (10–15 μg/kg) and/or propranolol (0.1 mg/kg) revealed that the increased Oxy‐Hb of the arm muscles consisted of the rapid atropine‐sensitive and delayed propranolol‐sensitive components. Mental imagery of the exercise increased the Oxy‐Hb of the arm muscles. Motor‐driven passive one‐armed cranking had little influence on the Oxy‐Hb of the arm muscles. It is likely that central command plays a role in the initial increase in oxygenation in the non‐contracting arm muscles via sympathetic cholinergic vasodilatation at the early period of one‐armed cranking. The centrally induced increase in oxygenation may not be different among the distal arm muscles but may augment in the deltoid muscle.

No MeSH data available.