Friday, March 12, 2010

The best proof so far... Part II

I contacted H. Yokota and he referred me to this review paper for more information about knee loading and it's effect on longitudinal bone growth(height).

Joint loading modality: its application to bone formation and fracture healing

"Axial loading and bending are generally applied to long bones such as ulnae and tibiae. Axial loading exerts principally longitudinal compression, while bending generates lateral compression and tension. Since ulnae and tibiae are naturally curved, axial loading induces not only longitudinal stress but also a bending effect. In tibiae, for instance, axial loading and four-point bending have been reported to induce a significant increase in bone formation mostly in load bearing cortical bone."

An axial loading exercise would be like a walkout.  A bending exercise would be a curved back good morning for example.

"Based on previous animal studies with various loading modalities, it is generally accepted that bone adaptation occurs in response to dynamic (rather than static) loading. The effect of loading represents a composite of critical determinants including strain magnitude, strain rate and number of loading cycles and bouts."

"Joint loading is the most recently developed loading modality. It employs non-habitual loads applied to a synovial joint such as the elbow, knee, and ankle. Unlike other loading modalities, it does not appear to depend on load-induced strain at a site of bone formation. Instead, loads are applied laterally to the epiphysis of the synovial joint and induction of bone formation is observed in the metaphysis and diaphysis of long bone."

Metaphysis is the bone under the epiphyseal growth plate.  Non-habitual loads means that there is deconditioning involved to avoid a long term reduction in mechanosensativity.
"Joint loading is effective for inducing bone formation along the length of the entire long bone regardless of the longitudinal distance from the loading site. It has been shown that knee loading is able to induce bone formation not only in the distal diaphysis near the knee but also in the proximal diaphysis near the hip. Likewise, ankle loading is effective on the tibia along its length."

"Longitudinal bone growth is the result of chondrocyte proliferation and its subsequent differentiation in the epiphyseal growth plates. Although mechanical loading enhances bone formation and adaptation, its effect on bone length—more specifically, stimulatory or inhibitory influences on the growth plate—has been controversial. Some studies on physical exercises or mechanical loading report an increase in the height of the growth plate while others show its reduction. Using axial loading of the ulna in rats, it has been shown that longitudinal growth is suppressed in a dose-dependent manner."

Now remember just because the growth plate is one mechanism of longitudinal bone growth does not exclude other methods.

"Lengthening of legs due to unloading during space flight has been documented. An important question is whether joint loading, which applies mechanical loads laterally and thereby stretches long bones longitudinally, can mimic the unloading effects of bone lengthening. Preliminary data from a recent study using mouse long bones suggest that knee and elbow loading can lengthen the tibia and the femur, and the ulna and the humerus, respectively."

I did not know that unloading during space flight actually lengthened the bones of the legs.  I always thought it was due to a decompression of the intravertebral discs.  The reviewers do suggest that lateral loading can cause deformation such as to lengthen the long bones(independent of the growth plate).

A mechanism suggested for the effects of the synovial joint loading is a potential pressure increase in the cortex of the compact bone and potential fluid flow in the cortex of a fractured bone.

"joint loading generates a steep strain gradient along the length of long bone and induces oscillatory alterations in intramedullary pressure. The pressure alterations in turn drive fluid flow in the lacunocanalicular network, which might cause shear stress to osteocyte"

Now our goal with LSJL is an increase in hydrostatic pressure in the epiphysis.  But if LSJL is effective you should feel this fluid flow within your bone.

As of now I have added the following exercises to my routine:  60lbs dumbell(I'm up to 75 lbs now) on both lateral directions on the knee, elbow, and ankle.  Using more weight is difficult as it is a very disadvantageous strength position and the load might be on other parts than the "epiphysis of the synovial joint" but all that matters is that the load on the synovial joint(I am now loading all the epiphysis' individually and separately) is included not that other loads are excluded.  Also, according to the study not very much load is needed according to this method(0.5N and 2-15Hz, how exactly this corresponds with regular loads is unknown).


  1. WOW Very nice article about height and how everything works. I think height my also depend on on family history and genetics. This is really something to think about.

  2. how do you actually apply the loads...i dun understand wat u mean by lateral?? suppose i have an ankleweight..hwo should i use them in this case? u mean forces in opposite direction of the knee?