People often wonder if a simple spinal adjustment or self-manipulation can unlock extra inches, fueled by the desire for a quick fix to increase height. The belief that cracking your back can make you taller is widespread, often stemming from the immediate feeling of release and improved posture. While the idea of gaining permanent height through this action is appealing, the science of human biology provides a clear answer. This article explores the biological reality of height, the temporary effects of spinal manipulation, and the science behind the “cracking” sound.
The Myth vs. Biological Reality
The definitive answer is that cracking your back does not lead to a permanent increase in your adult height. Once the skeletal growth process is complete, the fixed length of your bones cannot be altered by mechanical manipulation. Any perceived increase in height immediately following a spinal adjustment is temporary, related to the decompression of soft tissues. This momentary change is quickly lost as the spine naturally re-compresses throughout the day due to gravity and normal activity.
What Determines Your True Height?
Genetics and Growth Plates
Permanent human height is primarily determined by genetics and the lengthening of the long bones. Genetic factors are highly significant, with estimates suggesting that up to 90% of height variation is genetically determined. The growth hormone-insulin-like growth factor 1 axis plays a major role in regulating linear growth during childhood and adolescence. Linear growth occurs at the epiphyseal plates, or growth plates, located near the ends of the long bones. These cartilaginous structures produce new bone, causing the bones to elongate until the end of puberty, when the plates fuse and harden into solid bone, permanently sealing the potential for further height gain.
Spinal Structure
The spine contributes significantly to overall height, but the individual bony blocks, or vertebrae, do not change size through manipulation. The spine is made up of 33 vertebrae separated by soft, fluid-filled intervertebral discs. While these discs are subject to daily compression, their permanent structure is fixed. Once the growth plates are closed, the body’s permanent skeletal framework is established.
The Science Behind Joint Cracking and Posture
Joint Cavitation
The cracking sound heard during spinal manipulation is a phenomenon known as joint cavitation. This sound is created when a rapid separation of the joint surfaces, such as the facet joints in the spine, causes a sudden drop in pressure within the synovial fluid. This decrease in pressure draws dissolved gases out of the solution, forming a temporary gas cavity or bubble. The noise is produced as this cavity rapidly forms.
Posture Improvement
Cracking the back or receiving a professional spinal adjustment can lead to a noticeable, though short-lived, height gain by improving poor posture. Gravity and daily activities cause the intervertebral discs to lose fluid and compress, which often results in a slight hunch or slouched posture. Manipulation can temporarily relieve some of this spinal compression, allowing the discs to return to a more relaxed state. This temporary spinal decompression and the straightening of a stooped posture can account for a measurable height increase. However, this effect is fleeting; the spine will naturally re-compress as a person sits, stands, and moves throughout the day.