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

Figures

• 

  Figure 1. (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.

• 

  Figure 2. A time schedule of the experiments. On the day 1 and 2, ten of the 13 subjects performed individual tasks (voluntary one‐armed cranking with 35–40% of the maximal voluntary effort, passive one‐armed cranking, cranking imagery, and circle imagery) before and after autonomic blockades. Three of the 13 subjects performed the tasks without autonomic blockades. The order of the tasks was randomized, although the cranking imagery task always followed the voluntary cranking task. The tissue thickness under the NIRS probes was measured on the day 3 after the main experiment. A transit time of indocyanine green dye from the left cephalic vein to the left fingertip was measured during resting and at the early period of exercise on the day 4.

• 

  Figure 3. Time courses of the oxygneated‐ and deoxygenated‐hemoglobin (Oxy‐ and Deoxy‐Hb) responses in the non‐contracting arm muscles during voluntary (white lines) and passive one‐armed cranking (black lines) in 13 subjects. Each variable was sequentially calculated every 1 sec. Values are mean ± SE. * Significant difference (P < 0.05) from the baseline before voluntary exercise. † Significant difference (P < 0.05) from the baseline before passive exercise.

• 

  Figure 4. Comparison in the average Oxy‐Hb responses among the non‐contracting arm muscles during voluntary one‐armed cranking (A) and cranking imagery (B) in 13 subjects. Values are mean ± SE. † Significant difference (P < 0.05) between the muscles. In both voluntary cranking exercise and cranking imagery, any of the Oxy‐Hb responses was significant from the baseline level.

• 

  Figure 5. Effects of atropine 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. Atropine injection was followed by subsequent injection of propranolol. HR, heart rate. SV, stroke volume. CO, cardiac output. MAP, mean arterial blood pressure. TPR, total peripheral resistance. 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 atropine condition (ATR). Black lines indicate the responses in the atropine and propranolol condition (ATR+PROP). 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 ATR. † Significant difference (P < 0.05) between CON and ATR+PROP. # Significant difference (P < 0.05) between ATR and ATR+PROP. Values are mean ± SE.

• 

  Figure 6. 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.

• 

  Figure 7. Effects of atropine and/or propranolol on the time courses of the Oxy‐Hb responses of the non‐contracting arm muscles during voluntary one‐armed cranking in 10 subjects. (A) Atropine injection was followed by subsequent injection of propranolol. (B) 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 atropine (A) or propranolol (B) condition (ATR or PROP). Black lines indicate the responses in the atropine and propranolol condition (ATR+PROP or 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 ATR or PROP. † Significant difference (P < 0.05) between CON and ATR+PROP or PROP+ATR. # Significant difference (P < 0.05) between ATR and ATR+PROP or between PROP and PROP+ATR. Values are mean ± SE.

• 

  Figure 8. Effects of atropine and/or propranolol on the percent changes in Oxy‐Hb of the non‐contracting arm muscles during voluntary one‐armed cranking in 10 subjects. (A) Atropine injection was followed by subsequent injection of propranolol. (B) Propranolol injection was followed by subsequent injection of propranolol and atropine. 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 ATR or PROP. † Significant difference (P < 0.05) between CON and ATR+PROP or PROP+ATR. # Significant difference (P < 0.05) between ATR and ATR+PROP or between PROP and PROP+ATR. Values are mean ± SE.

• 

  Figure 9. Time courses of the individual drug‐sensitive components of the Oxy‐Hb responses during voluntary one‐armed cranking in 10 subjects. (A) Atropine injection was followed by subsequent injection of propranolol. (B) Propranolol injection was followed by subsequent injection of atropine. An individual drug sensitive component was calculated by a difference in the Oxy‐Hb responses between the control (without any drug) and atropine or propranolol conditions, and by a difference in the Oxy‐Hb responses between the atropine or propranolol and the combined blockade conditions. White lines indicate the atropine‐sensitive component of the Oxy‐Hb response, while black lines indicate the propranolol‐sensitive component. Values are mean ± SE. * Significant difference (P < 0.05) in the atropine‐sensitive component from the baseline. † Significant difference (P < 0.05) in the propranolol‐sensitive component from the baseline.

• 

  Figure 10. (A) Representative recordings of arterial blood pressure (AP), HR, and the Oxy‐Hb of the non‐contracting arm muscles during mental imagery of voluntary one‐armed cranking in a subject. (B) The average changes of the Oxy‐ and Deoxy‐Hb in the non‐contracting arm muscles during cranking‐ (□) and circle imagery (■) in 13 subjects. Values are mean ± SE. * Significant difference (P < 0.05) from the baseline. † Significant difference (P < 0.05) between the two imagery tasks.