This card is confusing. According to Costanzo (6th ed, p 176), it is the alpha-1 receptors in the vascular smooth muscle of the arterioles that are in the skeletal muscle that cause vasoconstriction, not any alpha-1 receptors in the skeletal muscle itself.
Here is the paragraph:
"At rest, blood flow to skeletal muscle is regulated primarily by its sympathetic innervation. Vascular smooth muscle in the arterioles of skeletal muscle is densely innervated by sympathetic nerve fibers that are vasoconstricting (α1 receptors). There are also β2 receptors on the vascular smooth muscle of skeletal muscle that are activated by epinephrine and cause vasodilation. Thus activation of α1 recep- tors causes vasoconstriction, increased resistance, and decreased blood flow."