Centre of Rotation

Goal of the Study?

In this study 1, the authors investigated the flexion-extension range of motion (ROM) and centre of rotation (COR) of lumbar motion segments in a large population, as well as the relationship between lumbar movement and sex, age and intervertebral disc degeneration (IVD).

Why are they doing this study?

Research on the in vivo motion of the spine has a long history. However, many of these studies have used non-invasive technologies with inherent limitations impacting their accuracy and precision. Moreover, many studies have included a lower number of subjects, preventing the data’s ability to represent the general population.

The authors argue that the use of radiographic techniques in this study helps to overcome these limitations as the images allow for better visualization of each vertebra and movements of the lumbar segments. Additionally, the use of a large sample size for this study addresses the issue of representation and is the largest study to date looking at in vivo lumbar motion. 

What was done?

The researchers did a retrospective study looking at the lumbar spine radiographs in full flexion and extension for 602 patients, with the age and sex documented for each one.  Additionally, they used MRI scans of 354 patients. 

All spinal levels between T12-L1 and L5 – S1 were analyzed, resulting in 3612 lumbar motion segments from the radiographic images. They also examined 2124 images from the MRI scans looking at disc degeneration. ROM and COR were calculated for all lumbosacral segments using the software. They then examined the associations between motion and age, sex, spinal level and disc degeneration.

What did they find?

The median ROM in this study was 6.6 °. The researchers found an association between age and ROM, with older individuals, have lower ROMS. They argue these findings clearly demonstrate a relationship between age and lumbar spine flexibility independent of any signs of spinal degeneration. They also found that lower ROMS were associated with disc degeneration. However, they did not find any association between sex and ROM.   

In this study, they did not find an association between the COR and the spinal segment’s position. The most common COR was at the centre of the lower endplate of the IVD or slightly lower. With degeneration, particularly severe degeneration, they found the COR location spread randomly around the centre of the intervertebral space.


One of the main limitations of this study was the sole focus on the lumbar spine’s flexion-extension motion rather than including information on movements of different areas of the back. 

Why do these findings matter?

This study comprises the largest examination of the in vivo lumbar spine in flexion-extension, paying attention to age and spinal degeneration issues. Understanding the relationship between age and spinal mobility provides patients and doctors with information to better treat back pain and instability.


Goal of the Study?

The goal of this study 1 is to better understand whether the morphology of the facet joint contributes to spondylolysis.


Why are they doing this study?

Lumbar spondylolysis is one of the most common sports injuries in adolescents. This is a condition in the lower back where there is a defect in the part of the vertebra known as the pars interarticularis, which is a part of the bone that connects the facet joints at the back of the spine. 

Existing research suggests that individuals with more coronally (frontal) oriented facets in the lower lumbar vertebrae, combined with facet tropism (growth or turning) are at a greater risk of developing spondylolysis at L5. However, to date, there are only a few studies looking at how the morphology (shape or arrangement) of the facet joint is associated with unilateral and bilateral spondylolysis in adolescents. 


What was done?

The participants for the study were 68 junior athletes who went to the Funabashi Orthopedic Hospital due to lower back pain between April 2012 and June 2014. 

All participants had computer tomography (CT) and MRI scans done to determine their grouping. From this, they were classified into three groups:

  1. Group B – 22 athletes (18 males and 4 females) with L5 bilateral spondylolysis
  2. Group U – 27 athletes (21 males and 6 females) with L5 unilateral spondylolysis
    1. Reclassified into two groups: one with a spondylolysis side (UL group) and the other with a normal side (UN group)
  3. Group C – 19 athletes (13 male, 6 female) without spondylolysis whose back pain eventually disappeared. 

Patients with multivertebral spondylolysis and previous lumbar surgery were excluded. 

Using CT, a researcher measured the sagittal alignment of the L4/L5 and L5/S1 facet joint angles from the axial sections. These angles were compared for differences among the groups. All of the measurements were repeated three times by the same person to increase validity.


What did they find?

The researchers found that for participants in groups B and UL, the L4/L5 facet joint angles were significantly more coronally oriented (more in the frontal plane) than those in group C. However, there were no significant differences found in L4/L5 facet joint angle between groups:

  • B and UL
  • B and UN, UL
  • UN and C

Additionally, there were no significant differences in L5/S1 facet joint angle were found among the groups.


L4 Tropism Spondylolysis

L4 Vertebra from the Professional LxH Dynamic Disc Model. Tropism


Why do these findings matter?

Compared to a normal orientation, a more coronal (frontal) orientation of the L4/L5 facet joint angle is likely to increase the stress on the vertebral arch of L5 during trunk extension. Therefore, if an adolescent athlete has a coronally oriented L4/L5 facet joint, they are more at risk of developing unilateral spondylolysis at L5. This knowledge can assist in identifying which young athletes are more likely to develop spondylolysis and help to implement appropriate prevention efforts by limiting certain activities in young athletes. 





Goal of the study?


To evaluate the frequency of lesions (injuries) in the lumbar region (lower back) of asymptomatic adolescent soccer players using MRI.


Why are they doing this study?


To date, there are very few studies that look at the frequency of spinal lesions in young athletes. Most of the research has focused on adult athletes and has shown that the lower back region is the most common site for problems. However, we know that the pediatric musculoskeletal system is particularly at risk to injury because adolescent bodies have not finished growing. Injuries at such a young age can result in an imbalance in bone tissue and muscles, which may cause an increased risk of injury, pain and limit young adolescents’ daily activities. These injuries can also get worse as we age. Therefore, it’s important to know if adolescent soccer players are getting lower back lesions that are not being identified and treated.



Modic Model


Who was involved?


The study 1 looked at two groups of asymptomatic male adolescents aged 13-18. 


  1. Soccer players who practiced the sport for at least two consecutive years, at least three times per week for 1-3 hours.
  2. Control group was made up of asymptomatic adolescents and was matched for age, gender, height and weight. They could not play soccer or any other sport more than once a week for more than 1 hour.


  • No one in the study could have any history of lesions, surgery, chronic disease or a high BMI score.
  • While they originally recruited 60 adolescents (30 in each group), because of exclusions the final sample size was 45.


What was done?


The researchers used MRI to evaluate the spine and look for the frequency of lesions in the lower back of adolescent soccer players. 


Two different radiologists examined the MRI images looking for the presence or absence of swelling, protrusions and disc extrusions (bulges). They also looked at stress reactions, cracks or stress fractures in the vertebras, vertebras slipped out of place, enlargements or growths, as well as swelling of the interspinal ligaments and muscles. 


What did they find?


Comparing the two groups, the researchers found that the proportion of spinal lesions was 76% in the soccer players compared to only 35% of the control group. In particular, they found that the percentage of lesions in the anterior and posterior of the spine was significantly higher in the soccer players than the control group. They did not find any significant differences between the age and BMI Z-scores between the two groups.



This study was able to show a high number of lesions in soccer players compared to other youth soccer studies that did not use MRI. However, research on young athletes playing other sports shows a similar frequency of spinal lesions.


What are the limitations?


This study had a very small number of participants. Also, all of the soccer players were studied during their championship season. This means it is likely that they are doing more intense training and playing than during regular season. As of Dec 28, 2020, the paper is still under review and going through the editorial process.


Why do these findings matter?


Lower back injuries in childhood and adolescence can lead to early degenerative changes. Therefore, the high number of lower back lesions in adolescent soccer players should be considered in the changing landscape of a person’s spinal health. Sport specific prevention efforts are important to reduce the occurrence and impact of lower back injuries on young adolescents. Better identification and management of spinal lesions may help to ensure that young people are able to continue playing sport and reduce the impact of these injuries in adulthood and into their senior years to avoid conditions like lumbar spinal stenosis. Learning recovery strategies show promise.

The Dynamic Sitting Exercise (DSE)

Life can be busy. And with this busyness, people often do not have the time for lower back pain exercises. In 2010, Jerome Fryer (the owner and developer of Dynamic Disc Designs Corp.) set out to measure a simple seated decompression strategy for the lumbar spine. A pilot study used an upright MRI to investigate changes in the lumbar spine before and after this Dynamic Sitting Exercise (DSE) 1

It was originally coined “chair-care decompression exercise” to make it memorable. In a recent article written in the Indian Journal of Physiotherapy and Occupational Therapy, the researchers renamed it DSE and compared it to the popular McKenzie prone press-up. 2


Dynamic Sitting Exercise

Dynamic Sitting Exercise (DSE)


McKenzie Prone Press-up

McKenzie Prone Press-up

These researchers recruited thirty adults in the age range of 20-30 years with mechanical low back pain. To read the full inclusion and exclusion criteria, you can visit the full-text link in the references below. They randomly assigned the participants to two groups: the DSE group or the McKenzie prone press-up group. Each subject conducted 6 repetitions within the 5-minute interval with the exercises being conducted at the beginning of the 5 minutes, followed by 4 minutes of rest. Over the course of 30 minutes, each participant would have performed 6 repetitions multiplied by 5 sets for a total of 30 repetitions over the course of 30 minutes. This was equivalent to 2.5 minutes of active exercise over the course of 30 minutes.

Exercise Protocol

Exercise Protocol


The DSE instructions included:

  1. sit upright
  2. place hands-on seat pan
  3. push down on the seat pan to offload the lower spine
  4. participants should feel a slight stretching in the lower back
  5. hold for 5 seconds
  6. return to neutral for 5 seconds
  7. while returning to neutral, draw-in-abdomen.


The McKenzie Prone Press-Up instructions included:

  1. lie down on the abdomen
  2. extend back while on elbows and palms down (neutral position)
  3. perform press-up maneuver with straight arms for 5 seconds
  4. return to neutral for 5 seconds


Over 6 weeks, outcome measures included the Visual Analog Scale for pain and the Short Form-36 Health Survey Questionaire for quality of life.

What did they conclude?

Both forms of exercise demonstrated improvement of pain and quality of life. However, the DSE outperformed the McKenzie Prone Press-up in this group of mechanical low back pain adults.

Overall, this paper could have been written a little better. Their conclusions were bold and overly confident. It is still an important paper to share as the practicality of investing a few seconds of offloading to your work-day while sitting looks to be promising in those with lower back pain in this age range.


Mechanoreceptors in the Lumbar Spine’s

A study 1 published in the ‘Journal of Clinical Neuroscience’ decided to analyze mechanoreceptors present in the lumbar spine’s intervertebral discs. With such receptors linked to Low Back Pain, the study presented certain conclusive results.

What Was the Context?

Low back pain or LBP has been observed to impact people around the globe. Such ailment effects a person’s social, financial, physical, and psychological wellbeing. Research continues to create therapies to address LBP. When talking about such a condition, the nerve structures present in the intervertebral discs can’t be ignored. 

Intense muscle spasm of the vertebral musculature is an important component of LBP, elicited through reflex arches mediated by specialized nerve endings. Joint receptors have been classified into four categories. 

Type 1 is encapsulated mechanoreceptors with similarity to Ruffini endings. Type II are encapsulated mechanoreceptors that are similar to Pacinian corpuscles. Type III are encapsulated mechanoreceptors that share similarity to Golgi endings. And Type IV are unmyelinated free nerve endings as well as non-encapsulated plexuses that have nociceptive function.

While mechanoreceptors present in the human intervertebral disc have been studied, there is limited data available.

The objective of the current study was to help determine the different types of mechanoreceptors present in the two lower intervertebral discs. A review of available literature was also part of this study.

What Was the Methodology?

The current study involved a total of 25 intervertebral discs being removed during routine autopsy from a total of 15 human cadavers. The team only harvested the L4-L5 (13 discs) along with L5-S1 (12 discs). From the cadavers, 8 were male, while 7 were female. The mean age of the selected cadavers was 45.4 years from a range of 15-66 years.

Take note; none of the cadavers had a history of chronic LBP or underwent an operation on their vertebral column. Upon visual inspection, all of the specimens were deemed normal. Also, autopsy specimens were removed within 6 hours after death.

The discs’ anterior and posterior halves were dissected at the midsubstance between the endplates. Everything was studied separately. 

The team evaluated the degree of disc degeneration by using a semi-quantitative method. The morphologic criteria of Freeman and Wyke was used to distinguish the different receptors. A quantitative analysis was also performed for determining the mechanoreceptor’s density in each disc section.

A comparison was made through Fisher’s exact test. The Kruskal-Wallis test was administered to record the age comparison among the mechanoreceptor groups. Statistical analysis was conducted by using SPSS version 12.

What Were the Results?

According to the results, the team couldn’t find nerve structures in 2 of the 25 disc samples. The mean density of receptors per disc was 1.4 in the discs having Ruffini receptors. The density of Golgi receptors was 1.2, while it was 1.3 for free nerve fibers in each specimen. Take note; Pacinian receptors weren’t identified in the samples.

A significant association was seen between the type and level of mechanoreceptor present when observing the disc tissue’s anterior part. Discs with Golgi and Ruffini-type receptors were analyzed to be more frequent (around 78%) at the L5-S1 level. Also, a statistically significant difference wasn’t observed between the (type and frequency) of receptors and the sex, age, and degree of disc degeneration.  

Furthermore, the receptors that showed up a lot showed morphology similar to the Ruffini receptor. The second most frequency of corpuscular receptors showed similarities to the Golgi tendon organ. Free nerve fibers were another frequent finding.

What Was Concluded?

The current study confirmed the existence of an abundant network of non-encapsulated and encapsulated receptors in the human lower lumbar spine’s intervertebral discs.

According to data, it has been assumed that the primary role of encapsulated structures is the continuous monitoring of position, acceleration, and velocity. As for free nerve fibers, they are likely involved in nociception or regulation of vessel tone.

Through the results of this study, one can see that further research is required to better understand mechanoreceptors to aid with effectively addressing LBP and related ailments.

Beneficial for People with Desk Jobs and LBP

A study 1 published last year in the ‘Ergonomics’ Journal decided to see if perching was a good compromise between standing and sitting. The team concluded that certain custom-made seats could help with keeping low back pain and discomfort at bay. 

What was the Context?

Experiencing low back pain (LBP) and discomfort is linked to prolonged static standing and sitting postures. Studies have shown that taking breaks from standing or sitting can help relieve some discomfort. For example, changing postures from standing to sitting (and vice versa), standing on a sloped surface, walking around for a bit, and using a footrest for one leg are credited for temporarily reducing low back discomfort.

With LBP impacting millions of people around the globe, and professional life demanding people to sit at desks, it’s vital to address certain postures for a person’s wellbeing.

When compared, sitting is said to give rise to the most significant restriction on a person’s postural movements. This is because the frequency of M/L (medial/lateral) and A/P (anterior/posterior) shifts are less than half while sitting as opposed to standing or perching. Past data has led to the suggestion that humans might benefit from the option of sit-stand postures or perching. However, according to the current research team, limited empirical data about perching exists.

What was the Goal?

The primary objective of this study dealt with the identification of where lumbopelvic and pelvic angles in perching significantly deviated from standing and sitting.

This study looked at the possible differences between men and women when it came to standing, sitting, and postures that were in between. It also tested whether sitting and standing were different from hybrid postures. The physical demands related to each position was also observed.

What was the Methodology?

This study included 24 participants (who were divided equally into men and women). None of the participants (falling in the range of being 24-27 years old) had a history of severe lower limb injuries or LBP. The team collected kinematics, muscle activation levels, and ground reaction forces to characterize the range of postures existing between standing and sitting.

Furthermore, EMG (Electromyography) data from three muscles (vastus medialis obliquus, thoracic erector spinae, and lumbar erector spinae) was collected.

Each participant was asked to complete 19 trials (each trial being one-minute long). There was a two-minute standing rest between every trial. The seating device was custom-made. In each trial, the participants were asked to perform a standardized reading task being displayed on a computer monitor. During the task, they were to keep their feet flat on the ground while assuming a relaxed posture. Their hands were to rest on their thighs.

Seat Pan Angle Adjustability

Adjustable Tilt Ergonomic Saddle Seat by Dynamic Disc Designs

What were the Results?

According to the results, the direction of seat movement was observed as being consistent across the participants.

As for the sex differences, a greater lumbopelvic flexion, as well as posterior pelvic tilt (at the 90° trunk-thigh angle), was seen in men compared to women. There were no sex differences observed in other postures. 

Men and women had different standing lumbopelvic and pelvic angles from the rest of the trunk-thigh angles. According to collected data, the perching phase was determined by the team to be in the 145 to 175° range for males and in the 160 to 175° range for women.

The participating women showed significant differences in all of the muscles between phases for both trunk extensors, while men showed none.

The ground reaction force was observed to be different in all phases for both men and women in the A/P direction. Vertical and M/L forces increased in all participants as they moved to the standing position from sitting.

What was Concluded?

By considering collected data, the team concluded that the notable differences existing between the standing/sitting phases and perching came down to the level of leg effort required for a person to remain upright.

Currently, there isn’t an ideal seat that can offer the benefits of perching, sitting, and standing. However, future chair designs could focus on providing trunk-thigh angles in the 115 and 170° range to help address posture-related discomfort.

Said chair designs should also consider two key points:

  • The seat’s interface needs to focus on the alignment of the pelvis for improving lumbar angles as well as to offload some of the lower limb demands.
  • If foot support is featured, it should help redirect force from shear to compression for lower limb joints while decreasing the encumbrance from the user and the workstation being used.

Helping people maintain proper postures, especially during desk jobs, can aid in preventing low back pain and discomfort. More research is required to address such a situation effectively.

Armrests and Back Support During Cellphone Use

An interesting study 1 published in ‘Applied Ergonomics’ looked at neck and shoulder stress during cellphone use. The study concluded that people using cellphones should use armrests as well as have proper back support.

Why was this Study Conducted?

We all know that mobile phones are being used all around the world. Due to their versatility (covering academia, professional life, and leisure), the time spent on mobile phones continues to increase. According to data, almost 77% of the US population use their cellphones for 3-4 hours a day. While useful, such a device is also accompanied by certain side effects.

The risk of musculoskeletal injury and pain, especially in the upper extremities, is present because of mobile phone use. Previous studies have shared that prolonged neck flexion is linked to cellphone use, and this can increase the risk of a person experiencing neck pain. Using cellphones can also increase the risk of developing musculoskeletal pain in the fingers and wrists due to repetitive movements of the hands and awkward postures.

Offering support through armrests could be useful when it comes to alleviating physical demands experienced by the upper extremities. However, more research is required to systematically evaluate the efficacy of adequate ergonomic controls to aid with the decrease of biomechanical exposures when a person uses a cellphone while sitting.

The objective of this study was to quantify the kinematics of the head and neck, gravitational moment as well as the muscle activity in the neck when a cellphone is being used. It also set out to evaluate the effects of armrests and back support on biomechanical measures.

What was the Methodology?

This study had 20 young adults as participants. Their average age was 23 years old. The participants were equally distributed by sex. All of them had been using cellphones for around 6-7 years. None of them had any musculoskeletal pain in the past 7 days. They also didn’t have a history of musculoskeletal disorders in their neck and upper extremities. 

The participants were asked to use their cellphones under a total of eight different experimental conditions. Said conditions included 4 different cellphone positions and 2 different chair supports. The cellphone locations included chest, eye, lap, and a self-selected position. The chair support conditions were armrests and back support and no support.

The gaze distance (between the cellphone and eyes) was self-selected for each condition.

Take note; during each task, the participants accepted a series of standardized, general open-ended questions. They answered the questions via text for 5 minutes. Residual fatigue effects were reduced by giving participants 5-minute breaks between the texting sessions.

  • Kinematic Data

Kinematic data from the person’s head and neck were sampled at 100 Hz using an 8-camera optical motion capture system with reflective markers during the texting sessions.

The head, neck, craniocervical angle, gravitational moment, and gravitational moment-arms on the neck were calculated using a custom-built Matlab program.

  • Electromyography

Using Ag/AgCL surface electrodes and a wireless logger, TRAP (upper trapezius) and SPL (splenius capitis) muscle activities were bilaterally measured at a sampling rate of 1000 Hz.

What were the Results?

According to the collected results, a person’s neck flexion, head flexion, and craniocervical angles were significantly different depending on the phone position and chair support. The results showed that the eye (phone position) and chair supports showed the lowest neck flexion and head flexion angles, and the highest craniocervical angle. 

Furthermore, the Lap phone position without any chair support showed the highest neck flexion and head flexion angles, and the lowest craniocervical angle. There were also significant interactions between the phone position and the chair support in the neck flexion angle, head flexion angle, and craniocervical angle.

Depending on the chair support and phone position, the gravitational moment at C7-T1 varied significantly. Also, the Eye (phone position) and chair support showed the lowest gravitational moment. The Lap (phone position) without any chair support showed the most significant gravitational moment.

There were also significant interactions between phone positions and chair support on the gravitational moment.

  • Electromyography (EMG)

The results showed significant differences between phone position and chair support in muscle activity in the TRAP) and SPL.

Talking about TRAP, the Lap (phone position) and chair support showed the lowest muscle activities. The Eye (phone position) without chair support showed the highest muscle activities. 

For SPL, the Eye (phone position) and chair support showed the lowest muscle activities, while Lap (phone position) without chair support showed the highest muscle activities. Also, interactions between phone position and chair support were significant in TRAP.

What was Concluded?

The current study evaluated if there were any differences in a person’s head/neck flexion angle, the neck’s gravitational moment, and muscle activity in the neck/shoulder depending on the position of the phone (chest, eye, lap, and self-selected) and chair support (support and no support) when a cellphone is being used. 

The results showed that gravitational moment, flexion angle, and muscle activity in the neck and head of a person were significantly impacted by both factors.

This laboratory-based study indicated that using cellphones may lead to an increase in the risks for musculoskeletal pain and injuries in a person’s neck and shoulder regions. The increase in said risks is due to the rise in muscle activities, neck/ head flexion, and gravitational moment. 

The current results suggested that placing a cellphone at eye level while having adequate body support can aid with the reduction of biomechanical stresses in a person’s neck and upper extremities.

More research should be conducted to help people understand proper postures when using their cellphones to help address issues of pain and discomfort.