Influence of Expectations on Change in Pain Perception After a 3 Min Wallsquat Exercise.
Condition: Pain; Physical Activity
Study type: Interventional

Summary: 
      The purpose of this study is to investigate how expectations induced by information given
      prior to exercise influence the magnitude of exercise-induced hypoalgesia after a 3 min
      wallsquat exercise in healthy subjects. The study is a double blinded (participant,
      investigator) randomized controlled trial The results from the study may be of great
      importance to the understanding of exercise-induced hypoalgesia, and whether the information
      related to exercise as pain relief can be used in practice for patients with pain.

      The subjects are randomized to 1 in 3 groups. Hypoalgesia expectation, hyperalgesia
      expectation, neutral expectation. Each group (besides the neutral group) is given different
      information of what to expect on pain ratings after a 3 minutes wallsquat.
    

Detailed description: 
      Painful conditions are a major societal and economic problem and in Denmark, almost every
      fifth person suffers from long-lasting pain. Effective treatment of these conditions is vital
      not only to alleviate the pain but also to prevent repeated episodes of personal disorder and
      impaired work ability. Based on the hypothesis that physical activity and exercise lead to a
      change in pain perception, Pain Center South, Odense University Hospital has conducted a
      series of research projects which have investigated the immediate effect of various types of
      acute exercise on the pain sensitivity of both healthy subjects, patients with chronic pain
      in the knee and in patients with more 'complex' chronic pain who were referred to treatment
      at the Pain Center. The results showed that healthy subjects achieved a reduced overall pain
      sensitivity after both high intensity aerobic exercise (cycling) and low and high intensity
      isometric training (strength-like exercise on the arm and leg). This phenomenon is called
      'exercise-induced hypoalgesia' or 'training-induced pain relief'. A recently published study
      from Australia has also shown that the effect of exercise can be positively influenced by the
      information given prior to exercise, indicating that some of the experience of exercise may
      be related to expectations of the effect. This may be one of the reasons why patients with
      chronic pain do not experience a positive effect, as opposed to healthy people, as chronic
      pain patients may previously have experienced no effect of exercise or perhaps even worsening
      / flareup in post-workout pain.

      The purpose of this study is to investigate how expectations induced by information given
      prior to exercise influence the magnitude of exercise-induced hypoalgesia after a 3 min
      wallsquat exercise in healthy subjects. The pain sensitivity of the deep structures is
      investigated with two different pressure-gauges for the testing of mechanical pressure pain
      sensitivity. Pain sensitivity is examined on the leg and arm before and after the exercise.
      Pressure-sensitivity is evaluated using a handheld pressure-algometer for testing mechanical
      pressure pain-threshold in the deeper musculoskeletal structures. The pain-threshold is
      evaluated on the thigh and shoulder.

      To investigate additional facets of pain-sensitivity, computer-controlled cuff geometry is
      used. The computer-controlled cuff algorithm is less affected by local differences in pain
      sensitivity to the handheld pressure algometer and the cuff algorithm can also affect a
      larger portion of the deep tissue than the pressure algometer can.

      The cuff gauge consists of a blood pressure cuff placed around one lower leg and then slowly
      inflated. The pain response is registered continuously and the stimulus response function can
      then be established. The cuff algorithm has a maximum pressure that ensures no tissue damage
      to the subject and the device is automatically stopped at 100 kPa. Both the handheld pressure
      gauge and the cuff algorithm have proven to be a valid and reliable techniques for
      investigating the pain-sensitivity of healthy subjects.

      The person performing the measurements before and after the exercise is blinded to what
      information the subject has received, likewise the patient is blinded to the group
      randomization.
    

Intervention name(s): Hypoalgesia expectation; Hyperalgesia expectation; Neutral
Intervention type(s): Other; Other; Other
Intervention description(s): "Before and after the squat exercise, assessment of how you experience pressure pain with the 2 devices you have just become acquainted with will be repeated. While doing the squat exercise you will be asked to indicate pain in the thigh muscles.
What we currently know about the effect of exercise on the experience of pressure pain is that after eg. cycling or walking, more pressure can be applied before the pressure starts to hurt and more pressure is required before you can't withstand anymore.
Whether this applies to a squat exercise, as the one you are about to perform, has not yet been investigated, but we expect that the same applies here, namely, that more pressure is required before you feel the pressure begins to hurt you and you will be able to endure a greater pressure."
Supported by visual information.; "Before and after the squat exercise, assessment of how you experience pressure pain with the 2 devices you have just become acquainted with will be repeated. While doing the squat exercise you will be asked to indicate pain in the thigh muscles.
What we currently know is that exercise can cause muscle pain, both during and after training. You may have experienced muscle soreness yourself in relation to training? We expect that the same will apply here. Namely, after performing this squat exercise, which will likely hurt your thigh muscles while doing it, you will experience that the pressure applied afterwards, with the two devices you have just become acquainted with, should be less before it starts to hurt and that you can endure less pressure."
Supported by visual information.; "Soon you are going to do a training exercise in a squat position up against the wall for 3 min. Following the squat exercise, we will repeat the measurement of how you experience pressure pain with the 2 devices you have just become acquainted with. While doing the squat exercise you will be asked to indicate pain in the thigh muscles."
Other intervention name(s): Randomization group a; Randomization group b; Randomization group c
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Other
Keywords: Exercise-induced hypoalgesia, expectation, pain sensitivity