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Archive for the ‘Pain’ Category

The Fear of Back pain !!

I have already done quite a few blogs on back pain (Part 1, 2 , 3) but the myths surrounding it still continue, so I decided to do one more.

80% of us will probably experience an episode of back pain at one point or another in our life (some studies say that it is even more) (1-3). So, if you think about it, back pain is very common. In fact, to not experience back pain at some point in our life would be quite abnormal. And it doesn´t matter if you have strong or weak abdominals, or if you have too much flexibility or too little, or if one leg is larger than the other, or if you walk in a funny way, none of these factors will influence you experiencing an episode of back pain (4-8). To tell you the truth, the biggest factor for developing back pain is a history of back pain!!! (9). Sounds crazy but it is true.

So, instead of focusing on prevention of back pain (which we have already done for the last 20 years and nothing has changed), maybe we should focus on ¨how do I prevent my back pain from lasting so long¨. You see, when they experience back pain people get really scared, and get fearful of movement, which are two things that can actually make the back pain worse (10-11). Remember, we know the body needs movement to heal. Disk and cartilage etc. need movement to get their blood supply. So in most cases we should try and keep movement. Only when the pain is really bad should we rest but that rest should never be longer than 2 days (12). Pain does not equal tissue damage and it can be influenced by stress, beliefs, fears, anxiety and a thousand other things (as I have stated in previous blogs click here). Our body, including our back, is a wonderful strong machine. We have to start changing our beliefs around the idea that our back can get damaged easily or that our back is vulnerable.

In conclusion, we will all probably experience an episode of back pain in the coming weeks, months, years or whenever, just like we will probably experience a headache or a stomach pain. It is part of life and we shouldn´t get too worried. Studies say that 85-90% percent of the time we have back pain it is due to ¨non specific mechanical factors¨. This basically means we have no IDEA why your back hurts but it does. Only 2% of the time the pain is caused by a tumor, infection or a fracture and 8% due to a nerve compression (13-15). So next time your back hurts don´t be so afraid and keep moving. 😉


  1. Biering-Soeren2012 Feb 4;379(9814):482-91. doi: 10.1016/S0140-6736(11)60610-7. Epub 2011 Oct F. A prospective study of low back pain in a general population. Occurence, recurrence, and etiology. Scand S Rehabilitation Med 1983;19:71.
  2.  Balague F, Mannion AF, Pellise F, Cedraschi. Non-specific low back pain2012 Feb 4;379(9814):482-91. doi: 10.1016/S0140-67
  3. Hashemi L, Webster BS, Clancy EA, Volinn E. Length of disability and cost of workers compensation on low back pain claims. J Occup Environ Med 1998:40:261-66.
  4. Biering-Sorense F. Physical measurements as risk indicators for low-back trouble over a one-year period. Spine, 1984: 9:106-19.
  5. Battie MC, Bigos SJ, Fisher LD, Spengler DM, Hansson TH, Nachemson AL, Wortley MD. The role of spinal flexibility in back pain complaints within industry: A prospective study. Spine 1.
  6. Axler CT, Mcgill SM. Choosing the best abdominal exercises based on knowledge of tissue loads. Medicine and Science in Sports and Exercise. 1997: 29:804-11.
  7. Hellsing AL. Tightness of hamstring and psoas major muscles. Upsala Journal of Medical Science 1988. 93:267-76.
  8. Sandler R, Xuemei Su, TImothy C, Fritz S, Beattie P, Blari S. Are flexibility and muscle-strengthening activities associated with a higher risk of developing low back pain. Journal of Sciend and Medicine in Sporte. 2013.
  9. Taylor JB, Goode AP, George SZ, & Cook CE. Incidence and risk factores for first-time incident low back pain: a systematic review and meta-analysis. Spine Journal 2014
  10. Gheldof EL, Crombez G, Van den Brussche E, et al. Pain related fear predicts disability, but not pain severity: a pathway analytic approach of the fear avoidance model. Eur J Pain.2010;14:870
  11. Awinkkels-Meewisse IE, Roelofs J, Schouten EG, Verbeek AL, Oostendorp RQ, Vlaeyen JW. Fear of movemen/ re injury predicting chronic disabling low back pain: a prospective inception cohort study. Spine( Phila Pa 1976) 2006;31:658-664.
  12. Deyo RA, Diehl Ak, Rosenthal M. How many days of bed rest for acute low back pain? New England Journal of Medicine 1986;315:1064.
  13. Agency for HEalth Care Policy and Research (AHCPR). Acute low back problems in adults. Clinical Practice Guideline Number 19. Washington DC, US. Government Printing. 1994.
  14. Danish Health Technology Assessment (DIMTA). Manniche C, et al. Low back pain. Frequency Managemente and Prevention from an HAD. Perspective. 1991.
  15. Royal College of General Practioners (ACGP). Clinical Guideline for the management of Acute Low Back Pain. London Royal College of General Practicioner.1999

Why does pain move?

I have already talked about pain numerous times, in fact three times (pain part 1,2,3), but this is a subject that people have a hard time understanding. So, I will do one more post to try to clarify things. The most important thing about pain that people should know is that pain is an output of the brain and that pain does NOT EQUAL TISSUE DAMAGE (1-5). It sounds almost crazy and scary but it is true. That is why sometimes you see people with lots of arthritis that have no pain and other people who have very little arthritis and have lots of pain. Pain depends on the situation, I will give an example: Imagine a soldier at war and a professional soccer player at a match, and they both experience the same devastating knee injury. For those two people the significance of their injury is going to mean two completely things. For the soldier it means he can get the hell out of there and go home, for the soccer player it means good-bye to his professional career and maybe even income. Take a wild guess and think who is going to experience more pain??

But anyway, let us get back to the topic at hand and try to clarify why pain moves. Pain is basically controlled by the nervous system, so imagine something happens to your back,  ¨nociceptors¨will send  this information to your spine and from there to the brain. Now, let us suppose this ¨injury¨ keeps bothering you for a while, and these ¨nociceptors¨ will be firing away 24/7 during this whole time. At the end, the pain becomes centralized. Now, this is where it gets interesting. Your spine is also receiving at the same time information from all the different parts of the body. Once the original pain has become ¨centralized¨, the spine can sometimes make an error and get confused with all the different types of information that it is receiving from its nerves (6). This confusion can lead to the pain moving from one place to another. Now, when this happens it doesn´t mean that you have injured yourself in a new area,  it just means that your central nervous system has made an error in its processing of the information.


Hope you liked it.


  1. Flor H, Nikolajse Li, Stachelin Jensen T. Phantom limb pain: a case of maladaptive CNS plasticity.Nat Rev Neuroscience 2006 Nov;7(11):873-81.
  2. Flor H, Braum C, Elber T, BIlbaumer N. Extensive reorganization of primary somatosensory cortex in chronic back pain patients. Neuroscience 1997: March 7.224(1)5-8.
  3. Ren K, Dubner R. Central nervous system plasticity and persistent pain. J Orofac. Pain.1999.Summer.13(3):155-63.
  4. Kim S, Lee Hoo T, Lim Mee S. Prevalence of Disc Degeneration in Asymptomatic Korean Subjects. Part 1: Lumbar Spine. Journal of Korean Neutrosurgical Society 2013 January;53(1): 31-8.
  5. Kendrick D, Fielding K, Bentler E, Kerslake R, Miller P, Pringle M. Radiography of the lumbar spine in primary care patients with low back pain: Randomized controlled trial. BMJ 2001;322:400-05.
  6. Hargrove T. A guide to better movement.  Better movement 2014. pg 101-4.


THE BOSS -The Central Nervous System-

Most people know that the central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord, and that is about it. But most people don´t know the importance of it and how it affects us in things like dealing with pain, strength, flexibility and a thousand other things (1-4). Let me explain.


Most of the information the body gets from our nerves arrives at our CNS and the CNS is going to decide what to do with that information. So for example, when you cut yourself in the hand, that is going to activate nociceptors that are going to reach your CNS. Your CNS will decide what to do with that information, so it could either ignore it or produce an ¨ouput¨ like pain (4). If you don´t believe me, just try to remember the times you have had a ¨black and blue¨and didn´t remember where that came from. You see, pain is an output of the brain to try to protect us, but if the brain decides for whatever reason (a lion chasing us down the street) that pain is not good, it is going to ignore that and concentrate itself on more important things. So, always remember that pain does not equal tissue damage and that pain is an output of the brain.


So, what about flexibility or stiffness? Well, recent studies have shown that that is probably controlled by the CNS also (2-3). You see, excess flexibility creates the threat of injury.  So to control this the CNS sends information to stiffen the muscle. When we stretch and gain flexibility we  aren´t stretching the muscle (although it feels like it), instead what we are doing is sending information to the brain, saying ¨hey, it is ok, the movement is under control and is not going to produce any harm, could you loosen up a little?¨


The same thing can be said about strength and fatigue. Also, when we go to the massage therapist or physical therapist and they say we have a ¨knot¨ and that is producing your pain and  that they are going to take it away. Well, they probably don´t take it away, what they are doing is sending information to the CNS and if the CNS decides that what they are doing is ¨nice¨ and ¨effective¨, it will send down commands  for the muscle to relax but if the CNS doesn´t like the ¨information¨ that it is receiving, the treatment will probably not work.

The brain  is the real boss in our body. We have to embrace it, protect it and take care of it. One way to do it is exercise. Even if it´s mindless! And when we warm-up to exercise, remember to warm up the CNS also. One easy way to do it is imagining  beforehand the movement you are going to practice, studies have shown that it will help (1).


Until next time.





  1. Ratey, Hagerman . Spark: The Revolutionary New Science of Exercise and the Brain. 2008
  2. Weppler et al. Increasing muscle extensibility: a matter of increasing length or modifying sensation? Phys Ther. 2010 Mar; 90(3):438-49
  3. Noakes. Fatique is a brain derived emotion that regulates the exercise behavior to ensure protection of whole body homeostasis. Front Physiol. 2012; 3: 82.
  4. Moseley and Butler. Explain pain. 2013
  5. Hodges P. Moving differently in pain: a new theory to explain the adaptation to pain. Pain. 2011 Mar; 152: S90-8






Clinical Trials- The importance of them; Ensayos clínicos

A lot of people sometimes base their claims on scientific studies, but the funny thing is they don´t even know how to understand that scientific study and, just because a scientific study comes out, it doesn´t really prove anything, especially if the scientific trial is not done correctly. So, I just want to highlight some interesting points that most people should know. Below I have also translated it into spanish.

The scientific study should be RANDOMIZED: This means that when we do a study, we should assign patients to each group ¨alternatively¨ and ¨indiscriminately¨. Let´s use an example: I´m testing this new pill for a headache. I have 2 groups, the group that is receiving a pill and the group that is not receiving anything. Imagine in one group I put young people, who exercise, eat properly and have no history of headaches, and in the other group I put obese people, who don´t do any sports and have a history of migraines. This would affect my results. But if the patients are randomly assigned to groups, then it can be assumed that both groups will be broadly similar in terms of any factor, such as age, income, gender.

The number: The more patients in a study, the better.

Sometimes it is not possibile to do a randomized scientific study so they do a ¨prospective cohort study¨ or an ¨observational study¨. This is a step down from a randomized trial but, if done properly, you can still come to decent conclusions. This studies are usually done for long term health issues. For example they did this kind of test in the 50´s to see if smoking was bad. What they did in this study was:

  1. The participants had to be established smokers or really Non-smokers, meaning they had never smoked in their life.
  2. The participants had to be reliable and dedicated.
  3. In order to control for other factors, it would help if all the participants were similar in terms of their backgrounds, income, working conditions.

So they got DOCTORS, over 30,000 doctors, and they observed them during 5-10 years. That is how they proved that smoking is horrible to our health.

Ok, so now that we know that there are at least 2 types of scientific studies.  And we  also know that a randomized trial is  usually better but it should follow certain rules:

  1. We have to test for PLACEBO. A genuine medicine offers a benefit that is largely due to the medicine itself and partly due to the placebo effect, whereas a fake medicine offers a benefit that is entirely due to the placebo effect. So for example, in the example I used about the headaches, I would also need a group that is taking a ¨fake pill¨ which would be my control group. In other words, I would have one group who takes the real medicine, another group that takes nothing, and a third group who takes a fake pill. If this is done then it´s called a RANDOMIZED, PLACEBO CONTROLLED TRIAL
  2. Blinding- meaning the patients don´t know what they are getting, the real or fake treatment. This is really important and can affect the outcome of the study!! But, it is also CRUCIAL that both the control group and the treatment group are treated in similar ways, because any variation can potentially affect the recovery of patients and bias the result. If this is done then it´s called a RANDOMIZED; PLACEBO CONTROLLED, BLIND CLINICAL TRIAL
  3. Double blinding-  Meaning whoever is administering the treatment or placebo should also be ¨blind¨. This is because a doctor´s demeanour, enthusiasm and tone of voice can all be affected by knowing that he or she is administering a placebo, which means that the doctor might unconsciously give hints to the patients that the medicine is merely a placebo. If this is done then it´s called a RANDOMIZED, PLACEBO CONTROLLED; DOUBLE-BLIND CLINICAL TEST and this is the GOLD STANDARD of clinical trials!!

So next time you see a study, lets try to look for these things to see how serious the study really is.


Este va a ser uno de mis post más importantes y por eso he decidido traducirlo al castellano. Muchas veces nos basamos nuestras conclusiones en diferentes estudios que hemos visto o leido, pero lo gracioso es que muchas veces verdaderamente no entendemos esos estudios. Y solo porque veamos un estudio que llegue a una conclusión, no signifique que la conclusión sea verdadera, ya que el estudio puede haber tenido varios fallos. Entonces, ¿en que cosas nos tenemos que fijar para saber si un estudio es válido?
1) Que el estudio se ALEATORIO: Esto quiere decir que cuando se hace un estudio los pacientes de este estudio tienen que haber sido elegidos ¨alternativamente ¨ e ¨ indiscriminadamente. Por ejemplo: Imaginaros que estoy haciendo un ensayo clinico sobre una pastilla que supuestamente quita el dolor de cabeza. Tengo 2 grupos y en uno de esos 2 grupos pongo a gente que es deportista, come bien, poco estres, y joven. Y en el otro grupo pongo a gente mayor, obesa, depresiva, y no hace deporte. Lo más seguro que esto afectaria los resultados de mi estudio. En cambio, si los pacientes son asignados al azar a los diferentes grupos, se puede suponer que ambos grupos serán muy similares en términos de cualquier factor, como la edad, el ingreso, el género y salud.
2) El número: Fijaros en el número de pacientes que tiene ese estudio. Si ese estudio se ha hecho en una persona o en pocas personas los resultados no se pueden extrapolar. En cambio, si el estudio tiene a 500 pacientes pues las conclusiones seran más validas e fiables. Entonces, cuantas más gente en un estudio mejor.

*A veces no se puede hacer un estudio científico aleatorizado así que se hacen otros estudios, cono un estudio de ¨cohorte prospectivo ¨ o ¨un estudio de observación ¨. Estos estudios no son tan fiables como los ensayo aleatorios, pero si se hace correctamente se puede todavía llegar a unas conclusiones dignas. Estos estudios se realizan cuando el estudio va a durar mucho años. Por ejemplo , un estudio muy famoso de este tipo fue el que se hizo en los años 50 para ver si tabaco era perjudicial para la salud. Lo que hicieron en este estudio fue:
•Los participantes tenian que ser fumadores ¨establecidos¨o no fumadores, es decir que NUNCA habian fumado
•Los participantes tenian que ser gente en la que se pueda confiar y dedicados
•Y para controlar otros variables, intentarón elegir a participantes con el mismo estilo de vida en lo que se refiere a, educación, dinero, condiciones de trabajo.

Pues para cumplir estos requisitos eligierón a MEDICOS. En total unos 30.000 médicos. El estudio tenia que durar 30 años pero al cabo de 5 años lo pararon porque ya tenian suficiente información para concluir que el tabaco era perjudicial para la salud humana.
Ok, así, que ahora sabemos que hay por lo menos 2 tipos de estudios científicos.También sabemos que un ensaño aleatorio suele ser mejor, pero para que esto sea cierto el estudio tiene que cumplir ciertas reglas .
Tenemos que contralar contra el efecto placebo. Un medicamento real ofrece un beneficio que es en gran parte debido a la propia medicina y en otra parte debido al efecto placebo, mientras que un medicamento falso ofrece un beneficio que es enteramente debido al efecto placebo. Así que por ejemplo, si estoy probando si un medicamento es efectivo contra el dolor de cabeza,tendre que tener un grupo ¨controlado¨. Es decir, un grupo que toma la medicación falsa sin que ellos sepan que el medicamento es falso. Si en el estudio se ha controlado contra el efecto placebo, al estudio se le llama ESTUDIO ALEATORIO, AL AZAR, Y PLACEBO CONTROLADO

E lciego- los pacientes no saben si están recibiendo el tratamiento real o falso. Esto es muy importante y puede influir en el resultado del estudio! Pero, también es fundamental que tanto el grupo control y el grupo de tratamiento son tratados de manera similar, ya que cualquier variación puede afectar potencialmente la recuperación de los pacientes y el sesgo de los resultados. Si esto se hace el estudia se le llama ESTUDIO ALEATORIO, CIEGO Y CONTROLADO CON PLACEBO .

El doble ciego-que significa que el que está administrando el tratamiento en el estudio no sabe si esta dando la pastilla verdadera o el placebo. Esto se debe a que la conducta de un médico puede influir en el resultado de un estudio. Inconscientemente puede dar pistas ( el entusiasmo, tono de voz) a los pacientes que el medicamento es un mero placebo o que es verdaderamente el real. Si se hace esto, entonces el estudio se le llama ESTUDIO ALEATORIO, DOBLE CIEGO Y CONTROLADO CON PLACEBO y este es el estándar de oro de los ensayos clínicos!

Normalmente los estudios de calidad han demostrado que la ¨medicina alternativa¨no tiene ningún efecto más que el placebo.

Placebo! How powerful can it be? part 2

So in the first part I gave some examples of what placebo is and how effective it can be.  In this second part I will  give one more example so that people really understand and see the power and the ¨magic¨ behind placebo.

I´ll start by mentioning a study that Dr. Tor Wager in Bolder Colorado did.  He wanted to see if ¨placebo¨ can influence the feeling of pain. I´ve already mentioned a couple of times that pain is a subjective feeling and it can vary depending and a lot of factors, like stress, anxiety, beliefs, and a thousand other things (pain part 1). Anyway, what he did that was new was that he scanned people as they were getting their placebo to see what the brain was doing, and the results were amazing. First, let me explain how the study went. He got some volunteers, and on one part of their arm he put a moisturizing cream and told them what it was, this would be the ¨control group¨. In another spot on their arm he put a local anesthetic and also told them what it was. Then on a different part of the arm he put the same moisturizing cream as before but told patients that this was also a local anesthetic. After this was done he put them under a scan and did a thermo pain test on them. The results, as you can imagine, were that the placebo cream was as effective (sometimes even more) than the local anesthetic. But what was really amazing is that the brain (they saw this on the scan), was releasing endogenous opioid  in the placebo group, meaning it was releasing its own morphine!!  Thanks to this study we can now begin to understand how a placebo works….. it works because placebo relies on chemicals, but those chemicals, unlike ¨real medicine¨, are being produced in the brain!!

This doesn´t mean that placebo works for everything, it sure won´t fix a broken leg or help to reduce a tumor, but in the area where it seems effective scientists are trying to figure out how to make the most of it. And what they have seen is that for a placebo to work we usually need to belief it´s real. In other words, it´s about expectations.  That is why the size and shape of a pill can influence how a placebo works. It´s also why a capsule is more effective than a tablet,  why a large capsule is more effective than a small tablet, why expensive medication is more effective than cheap medication, why color makes a difference; red pills are more effective for treating pain and blue pills are more effective for treating anxiety, unless of course you are a male italian (blue is the color of the national football team, and a symbol of immense excitement, passion and heart ache) (2-5).

So does this mean that if something is as good as placebo it should be allowed to be used as medicine? Well, in my opinion not really. In my opinion we should use medicine that has been proven to be more effective than placebo in clinical control studies. Meaning medication that no matter what the expectation of the patient is will work. But I do believe that once this medication has been proven to be effective, we should try to make use of the placebo effect, as it will help the real medication even more.

One last thing quick thing that a lot of people might not know. Any medication that comes out onto the market must have been proven to be more effective than placebo. If it is not more effective than placebo then that medication (pill, capsule), is not allowed to go onto the market.

Hoped you enjoyed!! Till next time



  2. McRae C, Cherin E, Yamazaki TG, Diem G, Vo AH, Russell D, Ellgring JH, Fahn S, Greene P, Dillon S, Winfield H, Bjugstad KB, Freed CR (2004). “Effects of perceived treatment on quality of life and medical outcomes in a double-blind placebo surgery trial”. Arch Gen Psychiatry 61 (4): 412–20. 
  3. de Craen AJ, Roos PJ, Leonard de Vries A, Kleijnen J (1996). “Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness. BMJ 313 (7072): 1624–6. .
  4. Buckalew LW, Ross S (1981). “Relationship of perceptual characteristics to efficacy of placebos”. Psychol. Rep. 49 (3): 955–61. doi:10.2466/pr0.1981.49.3.955. PMID 7330154.
  5.  Dolinska B (1999). “Empirical investigation into placebo effectiveness”. Ir J Psych Med 16 (2): 57–58.
  6. Blackwell B, Bloomfield SS, Buncher CR (1972). “Demonstration to medical students of placebo responses and non-drug factors”. Lancet 1 (7763): 1279–82. PMID 4113531.
  7.  Branthwaite A, Cooper P (1981). “Analgesic effects of branding in treatment of headaches”. Br Med J (Clin Res Ed) 282 (6276): 1576–8. doi:10.1136/bmj.282.6276.1576. PMC 1505530. PMID 6786566.

Placebo!! How can it be so powerful?

They are the miracle pills that shouldn’t really work at all. Placebos come in all shapes and sizes, but they contain no active ingredient. Now they are being shown to help treat pain, depression and even alleviate some of the symptoms of Parkinson’s disease. How is this possible?

Well, it all lies inside the brain and scientists are trying to figure out why, but I want to give you a couple of examples to show you how powerful a placebo can be.

In one test they had professional  bicycle riders do a time trial around a track as fast as they could. After that was done, they gave each cyclist a placebo pill. Now, the cyclist thought they were getting this ¨legal¨ caffeine pill that would improve their results but in reality there was NOTHING in the pill.  The normal thing would be that the second time trial they would go slower because they were already tired from the first. But all cyclist performed better and some even register their best record ever!! So how can a pill with nothing inside help someone cycle faster than ever before??

But a placebo doesn´t even have to be a pill, for instance lately there have been different studies where they have done ¨fake operations¨ and have gotten the same results as real operations (1). In one these ¨fake operations¨, patients thought they were getting a vertebroplasty. This means that ¨cement¨ is injected into a fracture spinal bone to provide extra strength to it. So what they did is they had thirty-six patients believing they were undergoing this procedure (while another group was actually getting the real surgery).  To mimic the effect of the operation, surgeons just tapped against the spine making the patients believe the needle containing medical cement was being inserted into the spinal bone. To make it even more authentic, they also made sure that the odour of the cement was present in the operating room. The results were that the patients who had the sham surgery reported that they experienced the same relief of pain as those who had the real operation (2)!!! This is not an isolated finding as they have done the same thing with knee arthroscopic surgery and found the same results!!! Incredible or what?

In another test, Professor Fabrizio Benedetti (University of Turin) is using low oxygen levels at high altitudes to conduct his investigations, to test whether placebos can cause real changes in the body. Subjects strapped with fake oxygen canisters were requested to hike for 30 minutes whilst their brain activity, heart rate and neurotransmitters were all monitored. You see, when we come to high altitudes the low oxygen levels cause our blood levels to fall, this makes our PGE2 (a neurotransmitter) levels to go up, and that leads us to feel some of the familiar symptoms of altitude sickness like pain, but extra oxygen can ease the problem. Well guess what, the fake oxygen cause those PGE2 levels go down.  A placebo, meaning nothing, has changed something physically in the body. How crazy is that?

I will leave it at that today so that you guys can digest all the information. But I will do a second part with more examples to try to explain a little more of what placebo is and how we can use it.

Hope you liked it!!


1)J. Bruce Moseley, M.D., Kimberly O’Malley, Ph.D., Nancy J. Petersen, Ph.D., Terri J. Menke, Ph.D., Baruch A. Brody, Ph.D., David H. Kuykendall, Ph.D., John C. Hollingsworth, Dr.P.H., Carol M. Ashton, M.D., M.P.H., and Nelda P. Wray, M.D., M.P.H. A controlled trial of Arthroscopic Surgery for Osteoarthritis of the Knee.N Engl J Med 2002; 347:81-88




¨After this, therefore because of this¨ – It´s a logical fallacy that we tend to make more often than we would like to admit. I already talked about this in one of my previous posts but I would like to explain it one more time by giving 2 examples.

A lot of people don´t know what a wonderful machine our body and mind is. It is by far the best thing you will own in your lifetime. For example, did you know that roughly 50% of all illnesses for which people seek medical help are ¨self limited¨, meaning they are cured by the body´s own healing processes without assistance from medical science. Let´s see a Porsche trying to fix a flat tire or a broken suspension……haven´t seen it yet. So the body, we can safely say, is a truly amazing machine with remarkable powers to set itself right.

With the body so effective in healing itself, many who seek medical assistance will experience a positive outcome even if the therapist or doctor does nothing. In other words, even a worthless treatment can appear effective, I mean we have a 50% change that our body will fix itself. So when an intervention is followed by improvement, the intervention is said to be ¨effective¨ according to the person´s experience. Now, don´t try to convince that person that maybe it may not have been the treatment that restored his health because he will not even listen to you, you have no chance. His ¨personal experience¨ tells him otherwise.  But what about if he would have tried another treatment or even no treatment at all? Maybe he would have learned something else. This is a classic example of  Post hoc ergo propter hoc.

Regression to the mean-  Many diseases are cyclical, meaning they get worse or better temporarily, but always move back to an average severity(1). Back pain, arthritis, allergies, and multiple sclerosis are cyclical, meaning sometimes they get worse and sometimes they get better. Usually, we go to the therapist or doctor when we have the most pain, so it´s bound to get better no matter what the therapist does to you (2). So as you can see this would be another classic example of post hoc ergo propter hoc.

Things are sometimes not  as clear as they appear and looking at things from a different perspective can give us a better idea of what´s really going on.


  1. Streiner DL. Regression toward the mean: Its etiology, diagnosis, and treatment. Can J Psychiatry. 2001;46:72–76
  2. Ernst E, Simon S. Trick or Treatment ? Alternative medicine on trial. Transworld Publishers.London,UK.2008
  3. Gilovich Thomas. How we know what isn´t so.The free press. 1991

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