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

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.


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Effects of propranolol on the time courses of the cardiovascular responses during voluntary one‐armed cranking in 10 subjects. A: absolute values. B: relative changes from the baseline levels. Propranolol injection was followed by subsequent injection of atropine. Each variable was sequentially calculated every 1 sec. Yellow areas indicate the early (10–20 sec) and later (40–60 sec) period of the exercise. White lines indicate the responses in the control condition without any drugs (CON). Gray lines indicate the responses in the propranolol condition (PROP). Black lines indicate the responses in the propranolol and atropine condition (PROP+ATR). The relative changes during the early and later period of the exercise were compared among the conditions using a two‐way ANOVA with repeated measures and a Holm‐Sidak post hoc test. * Significant difference (P < 0.05) between CON and PROP. † Significant difference (P < 0.05) between CON and PROP+ATR. # Significant difference (P < 0.05) between PROP and PROP+ATR. Values are mean ± SE.
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phy213237-fig-0006: Effects of propranolol on the time courses of the cardiovascular responses during voluntary one‐armed cranking in 10 subjects. A: absolute values. B: relative changes from the baseline levels. Propranolol injection was followed by subsequent injection of atropine. Each variable was sequentially calculated every 1 sec. Yellow areas indicate the early (10–20 sec) and later (40–60 sec) period of the exercise. White lines indicate the responses in the control condition without any drugs (CON). Gray lines indicate the responses in the propranolol condition (PROP). Black lines indicate the responses in the propranolol and atropine condition (PROP+ATR). The relative changes during the early and later period of the exercise were compared among the conditions using a two‐way ANOVA with repeated measures and a Holm‐Sidak post hoc test. * Significant difference (P < 0.05) between CON and PROP. † Significant difference (P < 0.05) between CON and PROP+ATR. # Significant difference (P < 0.05) between PROP and PROP+ATR. Values are mean ± SE.

Mentions: The RPE was not changed by single administration of either atropine or propranolol but was increased by the combined blockades (Tables 1 and 2), although the exercise intensity was identical in all conditions. Atropine increased baseline HR and CO and decreased SV, while baseline MAP and TPR were not affected by atropine (Table 1 and Fig. 5). Propranolol decreased baseline HR and CO and increased TPR (P < 0.05), while baseline SV and MAP were not affected by propranolol (Table 2 and Fig. 6). The combined blockades further influenced the baseline levels of the cardiovascular variables except for MAP, as compared to those with no drugs (Tables 1 and 2).


Central command increases muscular oxygenation of the non ‐ exercising arm at the early period of voluntary one ‐ armed cranking
Effects of propranolol on the time courses of the cardiovascular responses during voluntary one‐armed cranking in 10 subjects. A: absolute values. B: relative changes from the baseline levels. Propranolol injection was followed by subsequent injection of atropine. Each variable was sequentially calculated every 1 sec. Yellow areas indicate the early (10–20 sec) and later (40–60 sec) period of the exercise. White lines indicate the responses in the control condition without any drugs (CON). Gray lines indicate the responses in the propranolol condition (PROP). Black lines indicate the responses in the propranolol and atropine condition (PROP+ATR). The relative changes during the early and later period of the exercise were compared among the conditions using a two‐way ANOVA with repeated measures and a Holm‐Sidak post hoc test. * Significant difference (P < 0.05) between CON and PROP. † Significant difference (P < 0.05) between CON and PROP+ATR. # Significant difference (P < 0.05) between PROP and PROP+ATR. Values are mean ± SE.
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phy213237-fig-0006: Effects of propranolol on the time courses of the cardiovascular responses during voluntary one‐armed cranking in 10 subjects. A: absolute values. B: relative changes from the baseline levels. Propranolol injection was followed by subsequent injection of atropine. Each variable was sequentially calculated every 1 sec. Yellow areas indicate the early (10–20 sec) and later (40–60 sec) period of the exercise. White lines indicate the responses in the control condition without any drugs (CON). Gray lines indicate the responses in the propranolol condition (PROP). Black lines indicate the responses in the propranolol and atropine condition (PROP+ATR). The relative changes during the early and later period of the exercise were compared among the conditions using a two‐way ANOVA with repeated measures and a Holm‐Sidak post hoc test. * Significant difference (P < 0.05) between CON and PROP. † Significant difference (P < 0.05) between CON and PROP+ATR. # Significant difference (P < 0.05) between PROP and PROP+ATR. Values are mean ± SE.
Mentions: The RPE was not changed by single administration of either atropine or propranolol but was increased by the combined blockades (Tables 1 and 2), although the exercise intensity was identical in all conditions. Atropine increased baseline HR and CO and decreased SV, while baseline MAP and TPR were not affected by atropine (Table 1 and Fig. 5). Propranolol decreased baseline HR and CO and increased TPR (P < 0.05), while baseline SV and MAP were not affected by propranolol (Table 2 and Fig. 6). The combined blockades further influenced the baseline levels of the cardiovascular variables except for MAP, as compared to those with no drugs (Tables 1 and 2).

View Article: PubMed Central - PubMed

ABSTRACT

This study aimed to examine whether central command increases oxygenation in non&#8208;contracting arm muscles during contralateral one&#8208;armed cranking and whether the oxygenation response caused by central command differs among skeletal muscles of the non&#8208;exercising upper limb. In 13 male subjects, the relative changes in oxygenated&#8208;hemoglobin concentration (Oxy&#8208;Hb) of the non&#8208;contracting arm muscles [the anterior deltoid, triceps brachii, biceps brachii, and extensor carpi radialis (ECR)] were measured during voluntary one&#8208;armed cranking (intensity, 35&ndash;40% of maximal voluntary effort) and mental imagery of the one&#8208;armed exercise for 1&nbsp;min. Voluntary one&#8208;armed cranking increased (P&nbsp;&lt;&nbsp;0.05) the Oxy&#8208;Hb of the triceps, biceps, and ECR muscles to the same extent (15&nbsp;&plusmn;&nbsp;4% of the baseline level, 17&nbsp;&plusmn;&nbsp;5%, and 16&nbsp;&plusmn;&nbsp;4%, respectively). The greatest increase in the Oxy&#8208;Hb was observed in the deltoid muscle. Intravenous injection of atropine (10&ndash;15&nbsp;&mu;g/kg) and/or propranolol (0.1&nbsp;mg/kg) revealed that the increased Oxy&#8208;Hb of the arm muscles consisted of the rapid atropine&#8208;sensitive and delayed propranolol&#8208;sensitive components. Mental imagery of the exercise increased the Oxy&#8208;Hb of the arm muscles. Motor&#8208;driven passive one&#8208;armed cranking had little influence on the Oxy&#8208;Hb of the arm muscles. It is likely that central command plays a role in the initial increase in oxygenation in the non&#8208;contracting arm muscles via sympathetic cholinergic vasodilatation at the early period of one&#8208;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.


Related in: MedlinePlus