While doing pushups, the elbows will crack. The elbows crack when the arms are extended at the time of doing pushups. This cracking is not harmful if the cracking is not accompanied by any extent of pain. The cracking of joints will not cause any problem until the elbow is in good working condition and without any pain. There is an opinion that joint cracking enhances arthritis which might not be true always.
The actual thing that is happening in the joint cracking is that the negative pressure drags the nitrogen gas towards the joint and nitrogen gas releasing will give out cracking noise. If the tendons snap on the tissues because of twitch or alteration in the usual gliding path, the cracking noise comes out from the joints. Snapping of tendons will also happen because of scar tissue development and this might also result in cracking noise in the joints.
Elbow cracking sound will also occur when the person is experiencing tennis elbow which is accompanied by pain in the upper forearm on another side of the elbow. The arm is stiff and will hurt when the arm is extended fully in the morning time. The tennis elbow will be painful when the person is doing pushups. Some tasks such as coffee mug, doorknob and shaking the hand of someone can result in joint crack sound.
The elbow cracking occurs with pain when the condition is tennis elbow. The usage of screwdriver or any other movement which needs a strong grip on any object or while doing rotation of the wrist can cause discomfort and pain. Joints crack when the people walk upstairs or downstairs. When the people stretch their back or move their arms, cracking occurs involuntarily. As some people are involved in altering the knuckles of the fingers, the fingers will crack purposefully. The movement of tendons or ligaments can be the reason for joint cracks. The joint which is healthy comprises of bone that is surrounded by cartilage. This cartilage is protected by a capsule which is lined by the synovial membranes which secrete fluid. This fluid consists of oxygen, nitrogen, and carbon-di-oxide gases. The joints might crack due to the joint capsule which is usually stretched. This causes the creation of gas bubbles. The gaseous release will cause cracking sound in the joints that is felt or heard. The joint cracking can occur simply due to friction.