An exercise/play loop is formed from a strap of predetermined length, cross-section, strength and extensibility, being selected from polyolefin and polyurethane elastomers and rubber, with a cross-section having a width to thickness ratio greater than five, and having the elastic extensibility of the loop limited to about 100%. A polyurethane elastomer is selected from the group consisting of polyester and polyether urethanes whch may be extruded and mechanically conditioned to provide a modified molecular structure of enhanced elasticity and reduced plasticity, having tensile strength of up to about 6,000 lbs per square inch. The polyolefin elastomers have a hardness number of at least about Shore 80. The ends of the plastic strap are thermally welded to each other, to form the loop. A method of mechanically enhancing the plastics is given.