Barbell assembly

A barbell assembly comprising:

• an axle having two connection holes respectively defined in two ends thereof;
• two outer tubes rotatably mounted to the two ends of the axle and each outer tube having a space defined therein, two collars respectively located in the spaces of the two outer tubes, the two collars respectively mounted to the two ends of the axle, and
• two locking units each having a control ring, a locking member and a cap, the control ring located in the space of the outer tube corresponding thereto, each locking member having an engaging portion which extends through the control ring, a length of the engaging portion of each of the locking members being larger than a thickness of the control ring corresponding thereto so as to define a gap between the engaging portion, the control ring and a head of the locking member, which is configured to allow rotation of the outer tube together with weights mounted to the outer tube, each locking member is connected with the connection hole of the axle corresponding thereto, the cap fixed to the outer tube and pressing the control ring to contact against the collar and the axle;
• wherein each of the outer tubes has inner threads which arc located close to a distal end thereof.