2007, Piran, Slovenia
2007, Piran, Slovenia 2007, Piran, Slovenia
Environmental Ergonomics XII Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007 and the BF was calculated by multiplying the V by the cross-sectional area (=D/2*D/2*π). The BF variables of the basilic vein were measured in all subjects, but the variables of the brachial vein were measured in only nine subjects, because the brachial vein in five subjects was located behind the brachial artery, which inhibited accurate detection of the brachial vein. RESULTS AND DISCUSSION Figure 1 shows plots of the ∆ mean body temperature [∆Tb=0.9*Tes+0.1*Tsk (mean skin temperature)] vs. BF, V and D in the basilic and brachial veins. The BF in the basilic vein decreased slightly, and then increased linearly with the rise in ∆Tb at both exercise intensities. The BF at ∆Tb=0.3°C at the H intensity were significantly smaller than those at the L intensity (P
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. 257
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Environmental Ergonomics XII<br />
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana <strong>2007</strong><br />
and the BF was calculated by multiplying the V by the cross-sectional area (=D/2*D/2*π).<br />
The BF variables of the basilic vein were measured in all subjects, but the variables of the<br />
brachial vein were measured in only nine subjects, because the brachial vein in five subjects<br />
was located behind the brachial artery, which inhibited accurate detection of the brachial vein.<br />
RESULTS AND DISCUSSION<br />
Figure 1 shows plots of the ∆ mean body temperature [∆Tb=0.9*Tes+0.1*Tsk (mean skin<br />
temperature)] vs. BF, V and D in the basilic and brachial veins. The BF in the basilic vein<br />
decreased slightly, and then increased linearly with the rise in ∆Tb at both exercise intensities.<br />
The BF at ∆Tb=0.3°C at the H intensity were significantly smaller than those at the L intensity<br />
(P
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