The results of our study revealed that the enjoyable activity of going to an amusement park alleviated, though temporarily, low back pain. There has been no other report in the past that actually took the subjects to an amusement park and measured their low back pain in real time, which makes our study valuable.
It may be well known that pain can be alleviated by concentrating on something fun or one’s favorite pastime, and this idea is applied as distraction therapies in clinical practice with the use of music, images, movies, video games, and other tools for distraction.13
However, all of these tools typically involve virtual reality experiences and imagination. Real-life-experience studies on the effects of distraction have been rare, but include studies of pain reduction by touching animals in hospitals16
or by traveling to have real experience of amusement park attractions as in our study. In this study, the severity of chronic low back pain was mild in all participants with low back pain. We believe that the results of this study are noteworthy and are novel in that even mild low back pain was alleviated by amusement park experiences.
The possibility of a Hawthorne effect17
cannot be excluded if some participants knew the purpose of this experiment and were biased to report a decrease in low back pain immediately after an enjoyable activity. However, we told the subjects of this study only that they were going to get on a bus and go to an amusement park, take a ride on a roller coaster and go into a haunted house there, and then come back; we did not tell them anything about the objective of the study, such as evaluation of the association between low back pain and stress.
Shirasaki et al19
reported that the salivary amylase level was significantly correlated with VAS score, and we measured it assuming that this measurement could objectively evaluate the degree of pain. However, it is still controversial whether the salivary amylase level can serve as a marker of stress and pain.20
Actually, the values measured in the amusement park were higher in our study, and we could not find collateral evidence that pain and stress were alleviated in the park. Adam et al22
reported that salivary amylase may reflect levels of emotional arousal including high arousal positive emotions (feeling strong, active, vigorous, excited), rather than being specific to stress or emotions of negative valence (angry, stressed, nervous, worried). Thus, the higher values of salivary amylase levels measured in this study when the participants were in the amusement park may also reflect excitement of the sympathetic nerve as a result of increased vigor on the part of the participants rather than an increased stress. As for the methods of saliva amylase measurements, unlike measurements in hospitals where quiet small rooms are available for participants to be alone for at least several minutes to assure comfortable resting to reduce the influence of physical activity and stress, individual participants in this study rested for several minutes in only a relatively quiet place within the constantly noisy amusement park before each saliva amylase measurement. Thus, a better environment for saliva amylase measurements with less physical activity and less stress may have provided better data. Moreover, it is supposed that measurements of calcitonin gene-related peptide (CGRP) in saliva23
are associated with chronic pain, and they may provide important data.
Limitations of this study include that the number of subjects was small, the subjects were only those with mild low back pain, the mean age of the studied group was rather low in this current study, and only those who liked amusement parks participated. Regrettably, we did not ask the study participants about whether they participated alone or with friends, or whether they had previously visited the amusement park, although these confounding factors could affect the study results.
In the future, we would like to increase the number of subjects to conduct similar studies in subjects with chronic low back pain with VAS scores ≥ 50 and in subjects who do not like amusement parks. Further studies should be designed to analyze potential confounding factors and to evaluate the impact of pleasurable activities other than amusement parks for the purpose of confirming the robustness of our conclusion.