Arm elevation enhances muscle sympathetic nerve activity during static exercise.
The purpose of the present study was to evaluate the effect of hypoperfusion to the static-exercised-muscle induced by arm elevation on muscle sympathetic nerve activity (MSNA) recorded from the right tibial nerve (n= 10) by microneurography. Subjects performed static handgrip exercises (SHG) at 30% of maximal voluntary contraction (MVC) for 2 min, followed by 2 min of posthandgrip muscle ischemia (PHGMI) at the heart level (control) and with the arm elevated (50 cm above heart level). Basal heart rate, mean blood pressure and MSNA responses expressed as burst rate (bursts/min) and total MSNA (%) were unaffected by the arm-position. Heart rate response during SHG was not influenced by the arm elevation, while mean blood pressure and MSNA responses were increased by it (P<0.05). MSNA responses were increased during the second minute of the SHG period (P<0.05) and the PHGMI period (P<0.05) in the elevated arm position. In conclusion, arm elevation increased MSNA responses to SHG and PHGMI, suggesting an increased magnitude of muscle metaboreflex.
Michikami
D
D
Department of Autonomic Neuroscience, Division of Higher Nervous Control, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.
Kamiya
A
A
Qi
F
F
Niimi
Y
Y
Iwase
S
S
Mano
T
T
D000320:Adrenergic Fibers / Q000502:physiology; D000328:Adult; D001132:Arm / Q000098:blood supply / Q000294:innervation / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply / Q000294:innervation* / Q000502:physiology*; D011187:Posture / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*; D013979:Tibial Nerve / Q000502:physiology