A 30-day forearm work protocol increases maximal forearm blood flow.

To evaluate the local circulatory changes that accompany chronic localized work, we studied the effects of a 4-wk handgrip work protocol on maximal forearm work-related blood flow (ml X min-1 X 100 ml-1) in the nondominant forearms of six normal subjects. The reactive hyperemic blood flow response (RHBF) was also evaluated pre- and posttraining in both forearms of each subject to determine whether maximal vasodilatory capacity would be enhanced. In addition, maximal O2 consumption (VO2max) was measured. We found that chronic handgrip work led to an increase in work-related blood flow (before, 22.4; after, 32.1; P less than 0.05); a drop in work-related minimal resistance (R) (before, 6.4; after, 4.1; P less than 0.05). RHBF rose in the chronically exercised extremity by 30% (before, 33.5; after, 43.7; P less than 0.05) as minimal R fell (before, 3.2; after, 2.2; P less than 0.05). RHBF and R in the unstimulated dominant forearm remained unchanged (blood flow: before, 33.5; after, 31.0; NS; R before, 3.2; after, 3.2; NS). VO2max (ml X kg-1 X min-1) did not change (before, 35.7; after, 34.0). These findings show that localized skeletal muscle forearm work is associated with a localized increase in vasodilation (RHBF). Thus the vascular system appears to be an independent integral partner in the training process.