An endless belt (10) for use in exercising treadmills is provided. The endless belt includes at least an underlying ply (18) of low friction material, an internal core (38) of compressive and resilient material, and an overlying skin (42) of abrasion resistant material. The internal core (38) consists of a series of transverse projections (30) having inclined side walls (46, 47). The shape of projections (30) of the internal core (38) allows for the compression thereof while providing a suitable walking/running surface. The underlying ply (18) minimizes friction between the belt and any underlying support. The overlying skin (12) increases the durability of the belt while providing friction between a user's foot and the belt (10) for movement thereof. The belt may further include a reinforcing ply (32) disposed between the underlying ply (18) and the internal core (38).