Changes in cerebral blood flow during steady-state cycling exercise: a study using oxygen-15-labeled water with PET

J Cereb Blood Flow Metab. 2014 Mar;34(3):389-96. doi: 10.1038/jcbfm.2013.220. Epub 2013 Dec 4.


Cerebral blood flow (CBF) during dynamic exercise has never been examined quantitatively using positron emission tomography (PET). This study investigated changes in CBF that occur over the course of a moderate, steady-state cycling exercise. Global and regional CBF (gCBF and rCBF, respectively) were measured using oxygen-15-labeled water (H(2)(15)O) and PET in 10 healthy human subjects at rest (Rest), at the onset of exercise (Ex1) and at a later phase in the exercise (Ex2). At Ex1, gCBF was significantly (P<0.01) higher (27.9%) than at Rest, and rCBF was significantly higher than at Rest in the sensorimotor cortex for the bilateral legs (M1(Leg) and S1(Leg)), supplementary motor area (SMA), cerebellar vermis, cerebellar hemispheres, and left insular cortex, with relative increases ranging from 37.6% to 70.5%. At Ex2, gCBF did not differ from Rest, and rCBF was significantly higher (25.9% to 39.7%) than at Rest in only the M1(Leg), S1(Leg), and vermis. The areas showing increased rCBF at Ex1 were consistent with the central command network and the anatomic pathway for interoceptive stimuli. Our results suggest that CBF increases at Ex1 in parallel with cardiovascular responses then recovers to the resting level as the steady-state exercise continues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Pressure / physiology
  • Carbon Dioxide / blood
  • Cerebellum / blood supply
  • Cerebellum / diagnostic imaging
  • Cerebellum / physiology*
  • Cerebrovascular Circulation / physiology*
  • Exercise / physiology*
  • Exercise Test
  • Heart Rate / physiology
  • Humans
  • Male
  • Motor Cortex / blood supply
  • Motor Cortex / diagnostic imaging
  • Motor Cortex / physiology*
  • Oxygen Consumption / physiology
  • Oxygen Radioisotopes
  • Positron-Emission Tomography
  • Water / chemistry
  • Young Adult


  • Oxygen Radioisotopes
  • Water
  • Carbon Dioxide