Tension spring is a spiral spring that bears axial tension. Tension springs are widely used in medical respiratory equipment, motion control, medical mobile equipment, hand tools, home care equipment, shock absorption, pump springs, mechanical and electronic protection hardware, fluid control valves, mechanical aviation parts, actuators, switching equipment machines and instruments. 1, pull up, mainly to exercise the muscles in the straight line where the arm is located. The ideal effect is to increase the thickness of the chest and the height of the pectoral muscles, so that the pectoral muscles are more stereoscopic. 2, pull down, the upper end of the chest. 3, single pull, that is, one end remains motionless, one end stretches, and the shoulder width is increased. 4, up and down, the lower end is static, you can hook it with your feet, and the upper part is stretched and bent by hand.