I claim the ornamental design for a treadmill for use with a desk, as shown and described.
FIG. 1 is a perspective view of a treadmill for use with a desk of the present design;
FIG. 2 is a top view of the treadmill for use with a desk of FIG. 1;
FIG. 3 is a top view of the treadmill for use with a desk of FIG. 1 without environmental elements for clarity of disclosure;
FIG. 4 is a front view of the treadmill for use with a desk of FIG. 1; and,
FIG. 5 is a rear view of the treadmill for use with a desk of FIG. 1.
The broken (dashed) lines shown in FIGS. 1 through 5 are included only for the purpose of illustrating environmental elements, and form no part of the claimed design.