FIG. 1 is a perspective view of a treadmill frame with visible cushion of the subject design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof, the right side elevational view being symmetric to the right side elevational view;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a perspective view showing the frame in a treadmill, wherein the broken line example of environmental structure is for illustrative purpose only and forms no part of the claimed design.