Australasian Science: Australia's authority on science since 1938

Values in Science Affect What Your Doctor Recommends

Credit: RFBSIP/Adobe

Credit: RFBSIP/Adobe

By Claire Hooker

Should a GP recommend exercise to chronic pain patients when the evidence doesn't match patient experience?

A GP is facing a common quandary: whether or not to recommend exercise to a patient suffering from chronic pain. The GP knows that many experimental studies have found that exercise temporarily reduces pain, a phenomenon called

“exercise-induced hypoalgesia” (EIH). The scientists involved in the studies have suggested that EIH might therefore be a way of helping patients who experience chronic pain, but our GP also knows that chronic pain patients often say that they experience no reductions in pain after exercise. A fair few even say they experience increased pain. So the GP is facing a difference between a fact established by scientific research, and the experience of her patients.

The GP notes that the EIH studies are experimental. The scientists have not simply asked people how they feel after exercise – they have used the scientific method of controlling other factors in order to measure changes in a single factor. They have measured pain as objectively as possible, by measuring (in milliseconds) the length of time a subject tolerates an uncomfortable sensation of heat, cold or pressure before they pull their hand or foot away. The phenomenon of EIH is a scientific fact established in many studies like this.

However, if the GP looks a bit more closely at the scientific research, she will notice that the science is not as simple as it first seemed. What she will see is scientists using this method to attempt to understand a phenomenon, EIH, without knowing what causes it, how it works in the body or its parameters; that is, when it works and when it doesn’t. One study might use a pressure test to measure the effect of 30 minutes of aerobic exercise on pain; another might use a thermal heat test to measure the effect of 50 isometric exercises (muscle contractions) on pain levels; another, the “cold pressor” (bowl of ice water) test to measure the effects of 15 minutes of resistance training. The types of exercise, their intensity and duration, and the types of pain test are quite different from one another, and there are few studies that compare different types at the same time.

The GP might wonder why the scientists were not testing how people differ in pain responses, or which chronic pain patients show EIH responses. Her chronic pain patient thinks this is because science does not value the views of patients, but this is not quite true. Certainly science is not set up to easily hear or be influenced by patients.

At a deeper level, though, other values have guided the choices the scientists have made as they designed one experiment after another. These values are unavoidably part of science itself, entangled in the scientific method. We refer to them as “epistemic values” – values about different ways of finding out knowledge. Here are some illustrations.

When an EIH researcher designs an experiment to test a new parameter, such as if EIH still occurs if subjects cycle as well as run, they prefer the epistemic value of field consistency: their study will fit with what is already known. A different scientist might choose to tests a bold conjecture, such as what happens to the EIH response if the researcher suppresses the endocannabinoid system, which modulates appetite, mood, memory and the cognitive effects of physical activity. This is less simple, but potentially more fruitful. If successful, this experiment would lead to more than a new data point; it would generate a new direction for research about a pain system. (It turns out that EIH comes from several pain-inhibition systems, each specialised to different kinds of nociceptive input.)

We think of science as objective, existing partly to make sure that human values do not influence experiments. But the GP can see now that making choices among epistemic values is unavoidable in science. So the uncertainty that a GP faces unavoidably reiterates the trade-offs and preferences in epistemic values that slowly shape science as it develops.

Claire Hooker is Director of Bioethics at Sydney Health Ethics.