Increases in blood flow and shear stress to nonworking limbs during incremental exercise.
OBJECTIVE
Regular exercise augments endothelium-dependent vasodilatory capacity in the vasculature located in the nonworking limbs. We determined whether blood flow as well as shear stress would change in inactive limbs during acute incremental exercise.


METHODS
Eight young healthy female subjects performed graded exercise on arm and leg cycle ergometers that had been modified to minimize the movement of nonworking limbs and to facilitate the placement of Doppler transducers. Both brachial and femoral blood flow was monitored using Doppler ultrasonography. EMG activity was also measured to document that there was no muscular activity in nonworking muscles.


RESULTS
During leg exercise, brachial blood flow and calculated shear stress gradually and curvilinearly increased (P < 0.05). At the peak work rate, there was an approximately fourfold increase in blood flow in the brachial artery (19 +/- 6 vs 77 +/- 16 mL x min(-1)). Femoral blood flow and calculated shear stress increased progressively and linearly during arm exercise (P < 0.05).


CONCLUSIONS
We concluded that blood flow to the nonworking limbs increases markedly in proportion to the work intensity. These results suggest that the conduit arteries in the nonworking limbs are exposed to increases in blood flow and shear stress during exercise.
Tanaka
Hirofumi
H
Research Institute of Physical Fitness, Japan Women's College of Physical Education, Setagaya, Tokyo, Japan. htanaka@mail.utexas.edu
Shimizu
Shizuyo
S
Ohmori
Fumiko
F
Muraoka
Yoshiho
Y
Kumagai
Mana
M
Yoshizawa
Mutsuko
M
Kagaya
Atsuko
A
D000328:Adult; D001132:Arm / Q000098:blood supply* / Q000000981:diagnostic imaging; D001642:Bicycling; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007564:Japan; D007866:Leg / Q000098:blood supply* / Q000000981:diagnostic imaging; D013314:Stress, Mechanical; D014463:Ultrasonography; D014664:Vasodilation