Abstract des Autors

Cutaneous blood flowmotion (CBF) can contribute to a reduction in the resistance in skin microvascular networks. The increase of CBF during exercise can improve the capacity of skin microvascular networks to transport and eliminate heat. In order to verify if the physical training could increase the skin blood flowmotion during exercise, we performed spectral analysis of cutaneous forearm laser Doppler signal, before and after acute maximal exercise in 15 healthy trained subjects (TS) and in 15 control sedentary subjects (SS). Within the total spectrum of 0.009 - 2.3 Hz, five frequency intervals of CBF were analysed: 0.009 - 0.02 Hz (endothelial activity), 0.02 - 0.06 Hz (sympathetic activity), 0.06 - 0.2 Hz (vascular myogenic activity), 0.2 - 0.6 Hz (respiratory activity), and 0.6 - 2.3 Hz (heart activity). In basal conditions, no difference between TS and SS was observed in the cutaneous blood perfusion (CBP), expressed in conventional perfusion units (PU), and in the mean value of CBF total spectrum power density (PD), measured in PU/Hz, while the absolute PD of the endothelial and myogenic CBF components was significantly higher (p<0.05) in TS (0.69 ± 0.62 PU/Hz and 0.47 ± 0.43 PU/Hz, respectively) than in SS (0.29 ± 0.16 PU/Hz and 0.23 ± 0.16 PU/Hz, respectively). In both TS and SS, acute exercise induced a significant increase of CBP mean value (30.91 ± 20.28 PU, p<0.0005 and 16.45 ± 7.02 PU, p<0.0005; respectively) and of CBF total spectrum PD (6.65 ± 4.13 Hz/PU, p<0.001 and 4.17 ± 1.86 Hz/PU, p<0.05; respectively), with a significant difference of these two parameters between the two groups (p<0.05). After exercise, CBF components regarding endothelial and myogenic activities maintained a higher PD mean value in TS in respect to SS (1.69 ± 1.34 PU/Hz and 1.59 ± 0.93 versus 0.91 ± 0.44 and 0.98 ± 0.48 PU/Hz respectively, p<0.05). These findings suggest that physical training is associated with the increase of CBF and particularly on its endothelial and myogenic components in response to exercise. This can favour a greater reduction of resistance in skin microvascular networks during exercise and consequently an increase of its capacity to transport and eliminate heat. Verf.-Referat