One of the most common questions I get is whether kidney belts are useful to reduce back pain particularly in forklift or truck drivers and people handling goods.
It’s a good question. I often think of the image of the weight lifter with his kidney belt. They must know something?
To simplify the science, a lot of lower back pain can be contributed to spinal tissue failure from prolonged or recurrent high compression or shear forces through the spine that occur when:
Lifting heavy weights
Lifting lighter weights using poor posture e.g. with arms stretched out in front (functionally increasing spinal compression and shear forces) or with high repetition.
Sustaining postures that reduce the lumbar curve (such as bending or slouch sitting)
Being exposed to whole body vibration through sitting in a vehicle for more than 3 hours per day.
Is there anyway that we can reduce this spinal loading without changing our handling techniques?
Yes: if you hold your breathe for a few seconds, this raises the pressures in your abdominal cavity which reduces spinal loading by relaxing the spinal muscles (the back muscles increase spinal loading when they work) (5-7). However, you can’t hold your breathe forever and this advantage is lost. So not really a workable solution.
What about kidney belts? Research found that kidney belts can slightly lower spinal muscle contractions (8-11%) and limit the amount of forward bending during lifting and encourage squat lifting, therefore reducing spinal loading in this scenario (6), however, kidney belts tended to increase spinal muscle contractions in forklift drivers and make them more likely to experience back pain than forklift drivers who didn’t wear them (6,8).
Lower back pain is a very complex problem and may have many causes. One cause is when spinal tissue failure occurs as a result of high compression forces applied through the spine leading to spinal injuries. High spinal compression forces may lead to micro fractures in the vertebral endplates, compression fractures of the vertebral bodies and damage to the spinal discs (1-3).
Activities which cause high spinal compression forces include:
Lifting heavy weights.
Lifting lighter weights in weak postures which increase the functional weight of the object and thus the load on spinal tissues (e.g. lifting from the floor or above shoulder height).
Sustained spinal bending postures (with or without a load in the hand).
High repetition spinal bending postures (with or without a load in the hand).
Exposure to whole body vibration in vehicles that experience vibrational acceleration including shocks between 2-6g (11).
Certain body postures also create higher compression forces through the spine than others. For example, bending the spine while lifting, increases the pressures on the spinal discs by more than 100%. Spinal bending combined with twisting increases spinal disc pressures by more than 400%. On the other hand, when people recline backwards in a chair, even while adopting a slouching posture, spinal disc pressures reduce by 50-80% – a posture most of us adopt when we’re getting tired during extended bouts of sitting. Sitting up straight in a chair actually creates twice the spinal compression compared with reclining backwards in a chair – something to tell your granny or your teacher when they criticize your reclined slouching posture!
In 1979, it was noted that when heavy lifting was performed while holding one’s breath (for a few seconds), the intra-abdominal pressure was raised, the spinal extensor muscles activity reduced and both led to reduced compression loading on the lumbar spine, reducing the risk for spinal injury. However, if the heavy lifts extended for longer than a few moments, the breathe was released and the intra-abdominal pressure fell to much lower levels, reducing this spinal support mechanism substantially (5). This reduction in spinal compression due to raised intra-abdominal pressure was supported by research published in 2003, 2006 and 2010 and showed that the greatest benefit occurred when the body was in flexed (bent) postures (6-8).
The question arises as to how raised intra-abdominal pressure reduces spinal compression and helps to protect the spine from spinal compression failure leading to spinal injury and lower back pain.
Both abdominal and spinal extensor muscle contraction cause an increase in the spinal compression forces. However, the abdominal muscle contractions (0- 40% MVC) also assist in raising the intra-abdominal pressure, and when doing so, the net forces on the spine result in reduced spinal compression. In these circumstances it was also found that there was a reduction in the activity of the erector spinae muscles, with a greater reduction in these muscles’ activity corresponding to a greater increase in intra-abdominal pressure (8).
Furthermore, a 2013 published study revealed that chronic lower back pain sufferers who were experiencing a remission from their pain still exhibited lower levels of agonistic abdominal muscle activity and higher levels of antagonistic paraspinal muscle activity when compared to healthy individuals when performing spinal flexion (stooping/bending) with or without handling a load. This alteration in their abdominal and spinal muscle recruitment activity/ patterns could result in increased spinal loads (not measured in their study) and possibly contribute to the recurrence of lower back pain in individuals where these altered recruitment patterns have become the norm (9). On the other hand, research published in 2011 showed that activation of the core muscles showed no improvement in spinal stability, casting doubt on the mechanism in which core muscle rehabilitation is used to assist in the treatment of chronic lower back pain (10).
Chaffin D.B.; Park K.S (1973). A longitudinal study of low-back pain as associated with occupational weight lifting factors. Am Ind Hyg Assoc J. 34(12):513-25.
Freivalds A.; Chaffin D.B.; Garg A.; Lee K.S. (1984). A dynamic biomechanical evaluation of lifting maximum acceptable loads. J Biomech. 17(4):251-62.
Adams M.A.; McNally S.D.; Chinn H.; Dolan P. (1994). Posture and the compressive strength of the lumbar spine. J Biomech. 27(6):791-791.
Hutton, W. C.; Cyron, B. M.; Stott, J. R.R. (1979). The compressive strength of lumbar vertebrae. J Anatomy. 129(4): 753-758.
Daggfeldt, K.; Thorstensson, A. (2003). The mechanics of back-extensor torque production about the lumbar spine. J Biomech. 36(6): 815-823.
Arjmand, N.; Shirazi-Adl, A. (2006). Role of intra-abdominal pressure in the unloading and stabilization of the human spine during static lifting tasks. European Spine Journal. 15:1265–1275.
Stokes I.A.; Gardner-Morse M.G.; Henry S.M. (2010). Intra-abdominal pressure and abdominal wall muscular function: Spinal unloading mechanism. Clinical Biomechanics. Nov;25(9):859-66.
D’hooge, R.; Hodges, P.; Tsao H.; Hall L.; MacDonald D.; Danneels L. (2013). Altered trunk muscle coordination during rapid trunk flexion in people in remission of recurrent low back pain. J of Electromyograhy and Kinesiology. Feb;23(1):173-81.
Stokes I.A.; Gardner-Morse M.G.; Henry S.M. (2011). Abdominal muscle activation increases lumbar spinal stability: analysis of contributions of different muscle groups. Clinical Biomechanics. Oct;26(8):797-803.
Bazrgari, B.; Shirazi-Adl, A.; Kasra, M. (2008). Seated whole body vibrations with high-magnitude accelerations—relative roles of inertia and muscle forces. Journal of Biomechanics. 41:2639-2646.
If you’ve recently experienced a soft tissue injury, go see your doctor or physiotherapist as soon as possible to determine how serious your injury is and to find out how to allow swift and proper healing to occur.
In addition, the first 24-48 hours are very important following a soft tissue injury. What you do or do not do in this time may or may not prevent unnecessary secondary tissue damage following the original injury.
When tissue damage has occurred, the cells of the affected tissue break open releasing their contents into the surrounding area. This causes a whole set of inflammatory chain reactions that result in an increase in the blood supply to the area, further inflammation and swelling. A certain amount of inflammation is necessary for your healing to occur, however, too much inflammation, bleeding and swelling cause more damage than the original injury alone.
If the principles of RICE are not applied quickly following a soft tissue injury, too much bleeding, inflammation and swelling will occur. The side effects of this is that the swelling will cause compression of the surrounding tissue and reduce its oxygen supply. This in turn can lead tissue damage of this surrounding tissue increasing the general weakness of the area.
Generally speaking, the principles of RICE should be applied to prevent this unnecessary extension of your soft tissue damage:
R – Rest
One of the most important things to do when you have an injury, is to rest the affected area immediately and to reduce your general activity as well. This helps to reduce the general circulation of your body and in the injured area thus reducing the bleeding and swelling around your injury, helping to prevent secondary tissue damage.
Then, following your initial injury, you need to continue to rest the injured area through possibly restricted weight bearing and/or movement as determined by your doctor or physiotherapist according to the degree of your injury.
This is important since your body can’t heal if you keep straining your injured tissue. Think of a bridge that has collapsed and is being repaired. How helpful is it if people want to keep driving cars across it until it’s structurally sound again? Tissue damage in the body is a lot like that metaphor. If you place undue strain on a body part that hasn’t fully healed yet, you will cause mechanical failure of the injured tissue, placing you back at square one and possibly creating more damage.
The general guide to healing of injured tissue is 6 weeks to 50% healing and 3 months to 70-80% healing. This is true for both bone and soft tissue. Remember that ligaments and tendons also play a structural role in your body, so if you have injured 30%, 50%, 70% of your ligament or tendon, this will determine how much the rest of the remaining tissue will be available to take over the function of your damaged tissue. This will also determine how much you need to rest it, if you need crutches, strapping, a brace etc.
Ice should be applied immediately following a soft tissue injury. The application of ice helps to cause constriction of the blood vessels and limit further damage. The ice will also lower the metabolic rate of the tissue that you apply it to, thus reducing the demands of oxygen and nutrients in the area. This is useful since the circulation which is crucial in the function of tissue metabolism would have been damaged to some degree.
Another benefit of applying ice is that as it reduces the inflammation and swelling in the area, it will also reduce your pain and therefore any muscle spasm that would’ve occurred as the body tries to protect itself from unwanted movement.
Be careful not to apply ice directly to the skin or to use it for too long, you don’t want to create ice burn. The general recommendation is to apply the ice for 15-20 minutes every 1-2 hours. Apply it less often over the 48 hr period following your injury as your swelling and inflammation reduces. People who have poor circulation or a poor nerve supply to the area such as diabetics, smokers, people with paralysis, Raynaud’s disease, peripheral vascular disease etc. need to be careful when they use ice to avoid ice burn and tissue damage.
C – Compression
Compression of the injured area helps to reduce bleeding and swelling and the resulting secondary tissue damage if too much bleeding and swelling occurs. It also helps in part to provide structural support to the injured tissue .
The trick with compression is not to apply it too tightly which can severely reduce blood supply to the area altogether and also result in tissue damage.
The skin should not be white, tingly or blue (all indications that the compression bandage is too tight). The compression bandage should be placed in layers that partially overlap each other (about 50% overlap layer upon layer) and not in layers positioned directly over each other. If the bandage is applied in the latter scenario, it is likely that the bandage will cause too much direct compression and substantially reduce the bloody supply to the area.
There are special strapping techniques to create support for certain ligaments and tendons that are damaged until they are healed that your physiotherapist can teach you. If you’re not comfortable strapping, it might be better to buy an ankle support which won’t require you to know the intricate strapping methods and is more likely to be safe. Just make sure that you buy the correct size for your joint.
E – Elevation
Again , elevation is there to help with the circulation. Elevating the injured area helps to reduce the blood flow to the area, and thus the swelling. It also helps to encourage the return of venous blood and lymph into the general circulation which helps with tissue healing.
Khan K., Bruckner P., (2011). Clinical Sports Medicine 4th Edition. Australia. McGraw-Hill Australia
Anterior knee pain is a common injury for cyclists (read my post on cycling and knee pain). This injury is also present in the general population, typically amongst growing children and teenagers. Overall it affects 25% of the population at some point in their life.
Anterior knee pain occurs when the quadriceps muscles are unable to support the mechanical requirements placed upon them through activities in daily life (such as climbing up or down stairs) or sport and recreational activities (such as cycling or mountain climbing).
Mechanical failure of the quadriceps muscles results in compression of the underside of the knee cap (the cartilage) onto the thigh bone (femur) below. This results in pain and inflammation in this area and makes loading of the knee and knee cap as well as bending of the knee, painful. The result is a reduced ability to participate in previous activities, especially sport.
In cyclists, anterior knee pain is commonly created as a result of too rapid or too many increases to a training schedule, but, importantly, research also shows that anterior knee pain can also be due to your bike’s saddle height being set incorrectly.
From the research, it appears that the height of your bike’s saddle has an influence on the amount of compression that is placed through the knee cap, thus influencing the development of anterior knee pain or not. The lower the height of your saddle, the higher the compressive forces on your knee cap and the greater your risk of developing anterior knee pain.
Apparently there are a number of recommended ways to set your saddle height correctly, but not all are supported by scientific research. According to a research review published in 2011, the researchers determined that using the knee flexion angle method was the preferential method to determine the correct saddle height for your bike and that when using this method, your knee angle should be set at 25-30 degrees. Another benefit of this saddle height position is that it optimizes your oxygen consumption when cycling at a steady pace.
Now, how do you go about setting your bicycle saddle height according to the knee flexion angle method with the knee angles set between 25-30 degrees?
Firstly, you need to be seated on your bike and remain seated throughout the process.
Secondly, you need to place your foot on the pedal with your ankle in the neutral position and keep it neutral especially when you’re checking your knee angle. If you don’t keep your ankle neutral, and you place your foot into plantar flexion (toes facing downwards towards the earth), the greater your degree of plantar flexion, the greater you knee flexion angle will become and you will not have set your knee angle correctly.
The ball of your foot should be positioned slightly anterior (i.e. forwards) to the midpoint of your bike’s pedal. This improves hamstring function.
Once all the above are in place, then, drop one pedal to the 6 o’clock position. The knee joint angle of this leg should be bent (flexed) to 25-30 degrees when the pedal is at this 6 o’clock position. To accurately determine this angle, you may need a joint goniometer or someone with you who is good at judging angles. It may be useful to go see your sports physiotherapist to get them to help you set up your bike correctly.
Bini R., Hume P.A., Croft J.L. (2011). Effects of bicycle saddle height on knee injury risk and cycling performance. Sports Medicine, Jun 1;41(6):463-76. doi: 10.2165/11588740-000000000-00000.
Anterior knee pain is a very common cause of knee pain in people across all ages. Some people may also know it as patello-femoral syndrome.
Anterior knee pain (or patello-femoral syndrome) is pain that is found in the front of the knee.
Anterior knee pain will commonly get worse when you use stairs. Going downstairs is generally more painful than going upstairs, or going downhill is also generally more painful than going uphill. This is because going downstairs or going downhill places a greater demand on your quadriceps muscles than going uphill or upstairs. Anterior knee pain is also aggravated by any activity, movement or exercise that places strain on your quadriceps muscle and knee cap. Why is this?
Firstly, you need to understand the parts of the body involved when you get anterior knee pain (or patello-femoral syndrome). If you look at the illustration below, you will see that the knee cap is positioned above the thighbone (femur) and that there is a muscle that is attached to the knee cap via a tendon, that is called the quadriceps muscle. The quadriceps muscle is actually made up of 4 muscle bellies (recently a 5th muscle belly has been discovered).
The action of your quadriceps muscle is to straighten the knee when the quadriceps muscle contracts. Because the knee cap is attached to the quadriceps muscle, when you straighten and bend your knee, your knee cap moves up and down along the thigh bone in a groove. This action is controlled by the quadriceps muscle. In fact, your knee cap is there to shorten the lever of your quadriceps muscle and thus improve the contractile strength of your quadriceps muscle when it acts. Thus they work together like hand and glove.
If you have weak quadriceps muscles, however, the knee cap is no longer well controlled in its movement up and down the groove in the thigh bone. What happens is that when your quadriceps muscle contracts in this instance, your knee cap is pushed against the thigh bone and grinds the underside of your knee cap against your thigh bone, causing inflammation and your anterior knee pain/ patello-femoral syndrome.
What causes your quadriceps muscles to weaken and cause your knee cap to grind against your thigh bone creating anterior knee pain? There are various scenarios. A very common one occurs in children and teenagers, where a growth spurt has occurred and the bone is longer, but the quadriceps muscle and tendon haven’t caught up, causing a biomechanical imbalance resulting in anterior knee pain/patello-femoral syndrome. Another scenario is when an injury to the knee has occurred that results in pain and swelling. Any pain or swelling in the knee causes inhibition of your quadriceps muscle, which left untreated, can result in the development of secondary anterior knee pain/patello-femoral syndrome. If you have had a knee injury, make certain that you have been to see your sports or OMT physiotherapist. They are specially trained to help you resolve this problem quickly.
One of the factors that your sports or OMT physiotherapist will attend to is how to avoid anterior knee pain if you’ve had a growth spurt or knee injury or how to undo anterior knee pain caused by weak quadriceps muscles.
Have you been experiencing pain in your hand, especially in the thumb, index finger and middle finger area? Or maybe a fuzzy feeling or pins and needles and/or numbness in the same described area?
These are all symptoms of carpal tunnel syndrome.
What is carpal tunnel syndrome? Carpal tunnel syndrome is a problem where one of the nerves (the median nerve) that feeds the hand, becomes irritated and inflamed. This inflammation of the median nerve in the wrist area results in swelling of the tissue surrounding the median nerve. Because there is very little space in the area where the median nerve passes through the wrist, swelling in this area causes pressure on the median nerve. This pressure on the median nerve in turn causes your symptoms of pain, pins and needles and numbness in the thumb, ring finger and index finger and the area in the palm just below it.
Inflammation of the median nerve is normally due to overuse of the hand, and this condition is also known as repetitive strain injury or RSI. Office workers and factor workers are both at risk of developing carpal tunnel syndrome.
One of the reasons office workers end up with RSI/carpal tunnel syndrome is due to excessive use of the computer mouse. Strangely enough, too much typing is not associated with the development of carpal tunnel syndrome. Another reason office workers are susceptible to developing carpal tunnel syndrome is due to pressure on the underside of their wrist. People who use mouse pads place themselves at risk of developing carpal tunnel syndrome due to the pressure they place on their wrist when they rest their wrists on their mouse pad. This is slightly ironic, since the mouse pad was developed to help with carpal tunnel syndrome. Research has shown though, that mouse pads actually increase the incidence of carpal tunnel syndrome rather than reducing it. So, please throw your mouse pad away!
Factory workers are at risk of developing carpal tunnel syndrome due to excessive hand use, particularly in activities that cause them to bend their wrists, such as jobs that involve repetitively folding boxes all day.
Sometimes, carpal tunnel syndrome can also be due to mechanical compression that occurs as a result of scarring in the area from a wrist injury. Injuries result in inflammation, and inflammation always creates scarring in the inflamed area.
One of the reasons it’s always important to get physiotherapy when you have an injury, is because your physiotherapist will help to reduce secondary complications that in themselves can cause problems for you down the line, such as the scarring mentioned above. Your physiotherapist has many many years of training and specialising in injury management (Find a Physio near you).
How do you test whether you may or may not have carpal tunnel syndrome? Simply bend your wrist forwards (fingers and hand moving palm downwards towards the forearm) and sustain that position for a few moments (about a minute). If your symptoms appear or increase, you likely have carpal tunnel syndrome. If you go see a specialist (e.g. a neurosurgeon/neurologist), they may do a nerve conduction test to see if the nerve is functioning properly and to assist in diagnosing carpal tunnel syndrome. Ensure that you also go see your physiotherapist for your rehabilitation. Physios work hand in hand with your specialists to help get you back to normal as fast as possible.
Member of the Ergonomics Society and Health Professions Council of South Africa