Tag Archives: torsion

An alternative theory as to why torsion can increase height growth

I have previously stated that torsion may increase height growth by dynamically altering the fluid movement of bone and thereby enhancing the longitudinal bone growth of bone including bone which is skeletally mature but these papers offer an alternative theory.

The Phylogeny and Ontogeny of Humeral Torsion

“In a series of specimens extending from fossil material through
recent vertebrates including man there occurs a gradual phylogenetic increase
in the degree of humeral torsion. A further (ontogenetic) torsion is superimposed upon the phylogenetic one in man which increases from birth until the proximal epiphysial cartilage of the humerus disappears and bony fusion occurs.

There is a distinct correlation between the calculated strength of humeral rotator muscles inserting above and below the proximal epiphysis; this suggests that they provide the forces involved in the production of humeral torsion. It is shown that ontogenetic or secondary torsion occurs proximally and not along the shaft of the bone.
Differences in the degree of humeral torsion in either sex of adult Whites and Negroes are given and discussed.”

So this paper is basically saying that it’s the muscular rotator cuffs causing the change in humeral torsion and not the fluid mechanics to bone. However, in practice in contrast to this theory it seems that dynamically loaded bones generate more longitudinal bone growth than just people with muscle imbalances. Ultimately, more experimentation would need to be done to see which theory is correct.

“Our phylogenetic survey shows that the torsion angle increases progressively from crossopterygian fishes through recent mammals to man.”

“Mean torsion values proved to be greater in Whites and more marked on the right side, but bilaterally similar in Negroes.”<-the use of the word Negro shows how old this paper is.

“There are distinct correlations between humeral length and thickness. The longer
bone of a pair usually shows the greater torsion angle. However, in Whites, the
thicker bone is more twisted. while the thinner one has more torsion in Negroes.
The right humerus is usually longer in both groups. The average torsion angle is 74 4″ in
Whites and 72.6″ in American Negroes.

It is suggested that the differences in torsion and thickness of right humeri may be attributable to the predominance of right handedness in the population (about 95% on the right).”

“muscular forces produced humeral torsion at the level of the proximal epiphysial cartilage prior to bony fusion at that level.“

“(a) torsion, indeed, occurs at the proximal epiphysial plate of the humerus, (b) the forces involved are attributable to lateral rotator muscles inserting proximal to the epiphysial line of the humerus and to medial rotators which insert distal to it (I found no evidence that torsion occurs along the humeral shaft); and

(c) my studies of humeri of subjects of known age showed that torsion ceases with the disappearance of the proximal epiphysial cartilage.”<-the problem with this is is that most people do not do dynamic torsional training.

“I found a strong correlation between the degree of torsion and the strength of medial and lateral humeral rotators”

So basically muscular imbalances are what generates torsion in the humerus. So theoretically people who only train bench press pre-skeletal maturity should have more rotated humeri than individuals who engage in more balanced movements. The problem with this theory is that it only looked at small subset of cadavers and most people do not do dynamic torsional activities.

Here’s a more recent study:

Humeral Torsion Revisited: A Functional and Ontogenetic Model for Populational Variation

“Anthropological interest in humeral torsion has a long history, and several functional explanations
for observed variation in the orientation of the humeral head have been proposed. Recent clinical studies have revived this topic by linking patterns of humeral torsion to habitual activities such as overhand throwing. However, the precise functional implications and ontogenetic history of humeral torsion remain unclear. This study examines the ontogeny of humeral torsion in a
large sample of primarily immature remains from six different skeletal collections. The results of this research confirm that humeral torsion displays consistent developmental variation within all populations of growing children; neonates display relatively posteriorly oriented humeral heads, and the level of torsion declines steadily into adulthood. As in adults, variation in the angle of humeral torsion in immature individuals varies by population, and these differences arise early in development. However, when examined in the context of the developing muscles of the shoulder complex, it becomes apparent that variation in the angle of humeral torsion is not necessarily related to specific habitual activities. Variability in this feature is more likely caused by a generalized functional imbalance between muscles of medial and lateral rotation that can be produced by a wide variety of upper limb activity patterns during growth.”

So this more recent paper is saying that torsion is produced by muscular imbalance and not dynamic torsional loads.

“While the association of humeral torsion with a specific habitual activity is suggestive of an underlying functional cause for this morphological pattern, it does not entirely clarify the precise biomechanical and muscular forces acting during ontogeny that produce variation in this feature.”

“humeral torsion was initiated by embryological rotation of the forearm,”

“Several studies have found that, in contrast to nonthrowing control groups, individuals who engage in overhand throwing activity during adolescence and young adulthood display high levels of bilateral asymmetry in their angle of humeral torsion, with the dominant throwing arm possessing a more posteriorly oriented humeral head“

“the difference in humeral torsion between the dominant throwing and contralateral arms in professional handball players averaged 9.48, with a side-to-side difference of up to 298. In contrast, no statistically significant differences were found between right and left arms in the nonthrowing control groups”<-this suggests a functional fluid based mechanism for humeral torsion and therefore the possibility that torsion can induce morphological changes in the bone.

“medieval populations known to be engaging in strenuous weapons training might display similar changes in humeral architecture.”<-but apparently they did not. But that could just mean they did meet the threshold.

“Humeral torsion decreases with age, with infants between birth and 2 years postnatal displaying the highest values”

“While humeral torsion does decrease by 258 from birth to adulthood, it is difficult to determine when adult levels of torsion are attained.”

“Levels of humeral torsion are generally elevated in the populations predicted to be participating in high levels of strenuous activity and lower in less active, more urban groups.”

“In the normal individual, balanced forces of medial and lateral rotators produce a modest degree of humeral torsion. In the individual with a functional imbalance, unopposed forces of medial rotators results in a more posterior orientation of the humeral head.”

“professional throwing athletes experience the same imbalance of medial and lateral
rotators that are characteristic of individuals with obstetric brachial plexus injuries. In this case, however, this imbalance seems to be a product of a slight reduction in the power of the muscles of lateral rotation in combination with a dramatic increase in the power of muscles in medial rotation. In comparison to nonthrowing controls, throwing athletes display relatively stronger muscles of medial rotation”<-I just don’t see throwing creating a sufficient muscle imbalance to cause torsion. I think dynamic loading is more likely.

There’s really not much to say which theory is correct(dynamic torsional loading produces changes in bone architecture versus muscle imbalance produces pull on the growth plate) other than more exprimentation.

Is Scoliosis overgrowth of the spine due to torsion?

With my latest focus on research and experimentation of torsion leading potential bone overgrowth(new longitudinal bone growth). I did some research on scoliosis as in scoliosis there is a lot of research on the spine. Therefore, if torsion could stimulate longitudinal bone growth we’d expect to see overgrowth of the spinal column. It may still be possible however that even if scoliosis did not increase longitudinal bone growth that torsion may still increase longitudinal bone growth as scoliosis may not meet the dynamic threshold over which torsion stimulates longitudinal bone growth. However, I think the papers do suggest that scoliosis causes bone overgrowth.

Three-Dimensional Characterization of Torsion and Asymmetry of the Intervertebral Discs Versus Vertebral Bodies in Adolescent Idiopathic Scoliosis

“High-resolution computed tomographic scans of 77 patients with severe adolescent idiopathic scoliosis were included. Torsion and anterior-posterior and right-left asymmetry of each individual vertebral body and intervertebral disc were studied from T2 to L5, using semiautomatic analysis software. True transverse sections were reconstructed along the anterior-posterior and right-left axis of all endplates. These “endplate-vectors” were calculated semiautomatically, taking rotation and tilt into account. Torsion was defined as the difference in axial rotation between 2 subsequent endplates. Asymmetry was defined as the relative anterior-posterior or right-left height difference of the discs and the vertebrae.”

“There were at least 3 times more torsion, anterior overgrowth, and coronal wedging in the discs than in the vertebrae in the thoracic as well as in the (thoraco) lumbar curves (P < 0.001). These values correlated significantly with the Cobb angle (r ≥ 0.37; P < 0.001). Anterior overgrowth and coronal asymmetry were greater in the apical regions whereas torsion was most pronounced in the transitional segments between the curves.”<-just because torsion is more pronounced in certain segments does not mean that other segments did not undergo torsion overall.

“The discs contribute more to 3-D deformity than the bony structures, and there is significant regional variability. This suggests an adaptive rather than an active phenomenon.”<-the adaptative phenomenon could be torsion.

“On conventional 2-dimensional radiographs, it was observed that the discs were more wedge-shaped than the vertebral bodies in mild scoliotic curves whereas the wedging of the discs and vertebrae became more or less equal in more severe scolioses. These findings suggest that AIS[adolescent idiophatic scoliosisi] is primarily a deformation of the discs and that, according to Hueter-Volkmann’s law[compressed growth plates grow less, stretched growth plates grow more], the deformation of the vertebral bodies is secondary. However, at the same time, others reported increased coronal wedge angles of the vertebral bodies already in mild AIS, indicating abnormal vertebral growth.”

“Torsion per centimeter height: This was defined as the angle between the anterior-posterior axis of the superior endplate and the anterior-posterior axis of the inferior one of the same vertebra or disc in the axial plane divided by the height in centimeters. For example, if we found 3 vertebrae with a total height of 6.0 cm and a total torsion of 15°, torsion was 2.5°/cm.”

“In the thoracic curves, torsion was significantly greater in the IVDs than that in the vertebral bodies (6.2 ± 2.3°/cm height vs. 1.9 ± 0.7°/cm height, respectively; P < 0.001). In the (thoraco) lumbar curves as well, torsion of the IVDs was greater than vertebral torsion: 4.1 ± 2.6°/cm versus 1.2 ± 0.4°/cm; P < 0.001. In the apical as well as transitional levels of the thoracic curves, significantly more torsion was found in the discs than in the vertebral bodies (apex, respectively, 6.0 ± 2.4°/cm vs. 1.8 ± 0.9°/cm; transitional region, 6.3 ± 3.1°/cm vs. 2.1 ± 0.9°/cm; P < 0.001). In addition, a trend was observed that torsion was more pronounced in the transitional levels than around the apex[apex is the peak of the curve]; however, this did not reach statistical significance. In the different regions of the (thoraco) lumbar curves, we also observed that the discs were significantly more affected by torsion than the vertebral bodies: apical region, 3.8 ± 2.5°/cm torsion in the disc versus 0.9 ± 0.4°/cm in the vertebrae; transitional region, 4.7 ± 3.2°/cm versus 1.5 ± 0.8°/cm, respectively (P < 0.001). Again, a trend was observed that torsion was more pronounced in the transitional, nonapical levels of the curvature. In the (thoraco) lumbar curves, this trend became statistically significant (P ≤ 0.001).”
So torsion is correlated with length difference but the degree of torsion does not directly correlate with the difference but there could be different factors than just the degree of torsion like how dynamically the torsion is applied.

” all individual AIS curves were longer anteriorly than posteriorly and rotated both between and within vertebrae in the axial plane. This rotated lordosis has been described by a number of authors, leading to the hypothesis that lordosis is the initiating deformity, and that scoliosis is the result of a disturbed anterior versus posterior growth process”

“anterior “overgrowth” of the discs versus vertebrae in the sagittal plane”

“These findings support that AIS is mainly a 3-D deformity of the discs, suggesting that abnormal vertebral growth is, according to Hueter-Volkmann’s law, rather a consequence than a cause of the deformity”

“scoliosis as a rotatory instability of the spine, and the development of AIS depends on disturbance of the delicate balance between rotational stiffness of the spine on the one hand and rotation-inducing forces on the other. Once the spine decompensates into rotation around the stiff posteriorly located ligamentous axis, the vertebral bodies swing farther away from the midline than the posterior structures. At that point by definition, a lordosis starts to develop, leading to greater anterior length of the spine.”

“In conclusion, the IVDs contribute more to the 3-D deformity in AIS than the vertebral bodies. Because the processes of torsional deformation, anterior overgrowth, and coronal wedging are greater in the discs than in the vertebral bodies and are uniform in primary as well as compensatory AIS curves, it seems more logical that these morphological modifications are rather a consequence (among others through Hueter-Volkmann’s law) than a cause of the deformity.”<-so this suggests that torsion could potentially cause overgrowth.

Since scoliosis can be altered through exercise as suggested by studies such as Scoliosis-Specific exercises can reduce the progression of severe curves in adult idiopathic scoliosis: a long-term cohort study, this suggests that mechanical loading via exercise can alter the discs and vertebral bodies in the same way that scoliosis alters the mechanical loading of discs and vertebral bodies and alters their shape. IN the paper it suggests that the reduction may be due to “concave ligament stretching.” The authors of this study refuse to indulge the possibility that the change may be due to reduction in bon

Relative anterior spinal overgrowth in adolescent idiopathic scoliosis deformity.

“. The differential growth between the anterior and the posterior elements of each thoracic vertebra in the patients with AIS was significantly different from that in the controls (p < 0.01). There was also a significant positive correlation between the scoliosis severity score and the ratio of differential growth between the anterior and posterior columns for each thoracic vertebra (p < 0.01). Compared with age-matched controls, the longitudinal growth of the vertebral bodies in patients with AIS is disproportionate and faster and mainly occurs by endochondral ossification. In contrast, the circumferential growth by membranous ossification is slower in both the vertebral bodies and pedicles”<-the faster growth could be due to mechanical stimulation by torsion.

“Relative anterior spinal overgrowth in AIS has been reported in morphological studies”

Here’s what’s meant by anterior:

“

The longitudinal growth of the anterior column occurs at the growth plates by endochondral ossification and continues until the girl is between 16 and 18 years of age. In contrast, endochondral ossification of the posterior elements is complete by the end of the first decade of life”

“The posterior elements subsequently only grow circumferentially by membranous ossification. We speculated that the pathomechanism of the disproportionate spinal growth in AIS might be a loss of coupling between endochondral and membranous ossification during adolescence.”

“the relatively shorter posterior column acts as a tether which hinders the lengthening of the anterior column during the period of rapid growth, forcing the spine to bend and rotate. Different tissues such as
bone, spinal cord, ligaments, and muscles are included in the posterior column. The issue is which structure in the posterior column causes the tethering.”

“Tethering of the posterior soft tissues such as the posterior ligaments has been presumed to
be the force acting on the spine to create the complicated deformity”<-I have seen other people theorize that the ligaments constrain longitudinal bone growth.

“There is much indirect evidence supporting the hypothesis that uncoupled endochondral-membranous bone formation causes the relative anterior spinal overgrowth in AIS. It is well known that girls with AIS have a tendency to be taller and thinner than their peers.”<-it is also possible that the scoliosis causes the overgrowth itself via torsional mechanical loading.

so this study suggests an alternative mechanism than torsion to cause the overgrowth but it does not rule out the torsion.

Devon Larratt grew longer arms as a result of arm wrestling

https://youtube.com/watch?v=E1DTwpRFcfk&feature=shares

Torsional stress like tennis, swimming, etc. tends to lengthen the arms. The reason for this is likely due to the fact that torsional stress is the most efficient way to drive fluid forces in the bone(think like wringing out a sponge).

Devon Larratt is 47 years old BTW. A 53.6cm to 54.1cm increase over two years is a pretty good growth rate. And that’s not accounting for the humerus. Also imagine if you grew the clavicle and other arm length too. That would be a solid increase in wingspan over two years.

There are many sports that cause torsional force on the arms but the only sport I could find that could really exert torsional force was on the legs and I did find some evidence of leg height increase however there is a high rate of selection bias towards shorter divers.

I am currently testing exercises that could potentially exert spiral/torsional/rotation forces in bone. There are many for the arms(think hammer curls for instance). For legs, I am trying things like split legged woodchop exercises. Something like kicking could potential work. The problem is that the kicks have to be sufficiently weighted and you still have to maintain momentum.