I periodically have a problem with my Achilles tendon. The last bout I had was cured when I incorporated some steep hills into my running. Should I start singing from the hilltops that I have found the cure for Achilles tendonitis?; should I treat every runner I see with Achilles tendonitis by getting them to run up steep hills?; even better, should I write an eBook about how I found the secret cure and only share it with anyone who forks out $19.95? … of course I shouldn’t because the steep hills may have had absolutely nothing to do with my Achilles tendonitis getting better. I am not that silly to jump to those conclusions. Unfortunately you do see a lot of people doing just that and its not only for running injuries, but the more serious problems like bogus autism and cancer cures. Unfortunately the testimonial or n=1 is just that; it is not data.
So why do treatments that are infective sometimes appear as though they did actually work? (modified from Beyerstein):
- Natural history. Most conditions are self limiting and get better over time. Was my Achilles injury about to get better anyway and it was just a coincidence with starting the steep hill runs? If you change your shoes; running form; or whatever, was this the reason you got better or were you about to get better anyway because of the natural history?
- Cyclical nature of the condition. Most conditions are also cyclical in nature, they get better and worse over time. Was my Achilles just on a down cycle?
- Placebo. The placebo effect is powerful. Due to issues of suggestion, beliefs, expectancy and other cognitive processes a biologically inert intervention can make people better. Is that what happened to my Achilles?
- Credit the wrong thing. This means that something other than the intervention that worked was given credit for fixing the problem. For example say chemotherapy and prayer was used to treat the cancer and the prayer was given the credit for the cure. Was it the steep hills that fixed my Achilles or was it something else I changed around the same time and I just gave credit to the most obvious one? I was doing a lot of stretching round the same time.
- Incorrect diagnosis. Clinicians make mistakes (fortunately not too often). Was my Achilles problem a referred pain from my back and not running related?
- Self delusion or psychological needs. People make substantial emotional, time and financial investments in an intervention, whether that be a drug, an alternative therapy or, in our case here, a transition to a different running form, that they want it to work. This strong psychological investment can distort perceptions and they convince themselves that it helped. As Beyerstein noted “Core beliefs tend to be vigorously defended by warping perception and memory. Fringe practitioners and their clients are prone to misinterpret cues and remember things as they wish they had happened. They may be selective in what they recall, overestimating their apparent successes while ignoring, downplaying, or explaining away their failures“.
- Mood changes. Mood changes affect the perception of symptoms. Temporary improvements in mood can be misinterpreted as an improvement in symptoms. Did my Achilles really get better at the time or did I perceive it as being better as I had some really good days running the trails up in the mountains and my mood was better?¹
As Beyerstein notes:
Subtle forces can lead intelligent people (both patients and therapists) to think that a treatment has helped someone when it has not. This is true for new treatments in scientific medicine, as well as for nostrums in folk medicine, fringe practices in “alternative medicine,” and the ministrations of faith healers.
Many dubious methods remain on the market primarily because satisfied customers offer testimonials to their worth. Essentially, these people say: “I tried it, and I got better, so it must be effective.” The electronic and print media typically portray testimonials as valid evidence. But without proper testing, it is difficult or impossible to determine whether this is so.
It could be that the steep hills did actually help my Achilles tendon. The mechanism could easily have been the increased eccentric loading conditioning the tendon to take the load (uphill running has been shown to improve the mechanical properties of the achilles tendon in rats)… or it could have got better by one of the mechanisms above. That is why we have randomized controlled trials to determine if a treatment really does have an affect beyond that of a placebo or one of the other above explanations.
I go where the evidence takes me until convinced otherwise. … so no $19.95 eBook on how I found the magical cure for Achilles tendonitis.
¹For those in Melbourne, I am talking about the 1000 steps in Ferntree Gully.