Hearing a sudden “pop” or “crack” during a deep tissue massage can be startling. While the sensation may feel like a tight muscle fiber has broken or released, the sound rarely originates from the muscle tissue itself. These noises are mechanical events originating from anatomical structures near the area the therapist is working on. Understanding the physical causes provides reassurance.
Sounds Originating in the Joints
The most frequent and loudest popping sound heard during a massage comes from joint cavitation, a phenomenon occurring within a joint’s capsule. Joints are lubricated by synovial fluid, a viscous substance containing dissolved gases, primarily carbon dioxide and nitrogen. When a therapist applies pressure, the joint surfaces may be quickly stretched or separated.
This rapid separation increases the joint cavity’s volume, dramatically lowering the internal pressure. The dissolved gases become less soluble in this low-pressure environment and rapidly form a bubble. The distinct “pop” is the sound of this gas bubble forming or rapidly collapsing.
This process is a normal, benign physiological event and does not indicate that bones are grinding. The sound often indicates a temporary release of tension in the joint, which can be beneficial for mobility. Once the joint has cavitated, it cannot produce another pop until the gases have fully re-dissolved, a process that takes approximately 20 minutes.
Snapping Sounds from Connective Tissue
A different audible event is a “snapping” or “clicking” sound, which originates from the movement of dense soft tissue, not gas bubbles. These sounds occur when a tight tendon or ligament quickly snaps over a bony prominence. The therapist’s pressure can cause a structure, such as the iliotibial band or a shoulder tendon, to momentarily catch and then slip past the underlying bone.
This movement is often called “snapping hip syndrome” and is frequently painless. The sound is purely frictional, generated by the tissue sliding over a hard surface, similar to a rubber band being stretched and released. Tight muscles surrounding a joint increase tension on the tendons, making the snapping event more likely during manipulation.
What Happens When Muscle Fibers Release
When clients feel a deep “crunchy” or “crackly” sensation, it is attributed to the release of soft tissue adhesions rather than a true muscle fiber “pop.” Muscle knots, or trigger points, are areas where muscle fibers and the surrounding connective tissue, called fascia, have become stiff and adhered.
When a therapist applies intense, sustained pressure, they work to release these fascial adhesions and trigger points. The sensation of “bubble wrap” or “crunchiness” is the sound of small, sticky layers of tissue separating and being smoothed out. This subtle sensation of tissue separation is distinct from the loud crack of joint cavitation.
True muscle fiber tearing, which would be a concerning “pop,” is associated with sudden, sharp, and intense pain indicative of a strain or tear. The benign sounds during deep tissue work are a sign that the therapist is successfully working through constricted tissue. Proper hydration is also a factor, as dehydrated fascia is more likely to exhibit this crackly feeling during a massage.
Understanding Normal Sounds and Warning Signs
For most people, hearing a pop or click during a massage is a reflection of normal joint and tissue mechanics. The sounds are harmless and often accompany a positive outcome, such as an immediate increase in range of motion or a reduction in muscle tension. These noises are referred to by the general term crepitus, which describes any joint-related sound.
It is important to communicate with the massage therapist about any sounds or sensations experienced. While painless noises are not a concern, a sound accompanied by sharp, intense, or persistent pain requires immediate attention. Pain, swelling, or an inability to move the affected area could signal a more significant issue, such as a strain or a pre-existing joint problem.
The primary goal of the massage is therapeutic release, not the production of a sound. If a sound occurs without associated pain, it is a normal part of the body adjusting to the manual manipulation. Maintaining good hydration helps keep the fascial tissues pliable, which may reduce the intensity of crunchy sensations felt during deep work.