2007, Piran, Slovenia

Non-thermal factors
Table 1. Thresholds for vasodilation and slopes from linear regression analysis of plotting
blood flow, blood velocity, and diameter against the ∆ mean body temperature.
Basilic vein Brachial vein
Tb Threshold (°C)
L intensity
Slope Tb Threshold (°C) Slope
Blood flow 0.11 ± 0.05 464.6 ± 107.0 0.08 ± 0.03 93.8 ± 65.0 †
Blood 0.10 ± 0.03 27.2 ± 6.2 0.08 ± 0.03 12.5 ± 7.9
velocity
Diameter 0.05 ± 0.01
H intensity
2.1 ± 0.4 0.04 ± 0.03 0.3 ± 0.3 †
Blood flow 0.28 ± 0.05 * 530.1 ± 64.2 0.06 ± 0.03 † 41.7 ± 19.4 †
Blood
velocity
0.25 ± 0.04 * 53.7 ± 16.2 0.06 ± 0.03 † 6.0 ± 2.8 †
Diameter 0.18 ± 0.05 * 3.2 ± 0.4 0.07 ± 0.02 -0.1 ± 0.1 †
The units of the slope for blood flow: mL·min -1 ·°C -1 , the units of the slope for blood velocity:
cm·s -1 ·°C -1 , the units of the slope for diameter: mm·°C -1 , *: P < 0.05, L vs. H, †: P < 0.05,
basilic vein vs. brachial vein.
In this study, the BF in the basilic vein decreased slightly with increased exercise intensity at
the early stage of the rise in ∆Tb. Considering that the SkBF in the forearm did not change at
either exercise intensity during the time period of the present study and that the muscle BF in
the forearm decreased with increased exercise intensity at the early stage of exercise (Blair et
al. 1961), it is suggested that the exercise intensity-dependent decrease in the BF in the basilic
vein of the upper arm may relate to that of the muscle BF in the forearm. On the other hand,
the BF in the basilic vein increased linearly with the rise in ∆Tb at both exercise intensities.
The SkBF in the forearm also increased linearly with the rise in ∆Tb at both exercise
intensities in this study. In addition, the muscle BF in the forearm was found to decrease
during prolonged leg exercise (Johnson and Rowell 1975). Thus, the increase in the BF in the
basilic vein with a rise in ∆Tb may depend on the SkBF in the forearm. Moreover, there was
no significant difference in the slope of the ∆Tb-BF relationship between the exercise
intensities, suggesting that the difference between exercise intensities in this study was not
enough to affect the increase in the BF in the basilic vein with the rise in ∆Tb during exercise.
Although the change of V in the basilic vein was similar to that of the BF, there was no
significant difference between the exercise intensities. Moreover, the D in this vein decreased
with increased exercise intensity at the early stage of the rise in ∆Tb. These results suggest
that the exercise intensity-dependent decrease in the BF in the basilic vein depends primarily
on the decrease in D at the early stage of a rise in ∆Tb and that the increase in the BF with a
rise in ∆Tb relates to the increase in V.
On the other hand, the BF, V and D in the brachial vein did not substantially change at either
exercise intensity compared with the values in the basilic vein. When the internal temperature
increases, blood moves from deep veins into superficial veins to facilitate heat loss (Rowell.
1986). The characteristics of the vessels also differ between superficial and deep veins
(Abdel-Sayed et al. 1970). Thus, these reports and our results indicate that the responses of
BF variables in the basilic vein were different from those in the brachial vein during leg
cycling exercise.
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