Movement Performance in Persons with Chronic Back Pain

The goal of this laboratory-based cross-over randomized controlled study is to study the immediate effects Spinal manipulative therapy (SMT) and medical exercise treatment (MET) compared to open-label placebo (OLP) on movement performance, gait, active trunk mobility and pain-intensity in persons with chronic non-specific back pain.

The main question this study aims to answer is: What are the immediate and measurable effects of SMT and MTT on work movements, gait, active trunk mobility and pain-intensity in people with chronic non-specific back pain, compared with and in combination with open-label placebo treatment (OP)?

The investigators hypothesize that the participants, after SMT and MET, will perform the lifting task faster, and use more range of motion in most of the joints. They also believe that a greater range of motion is used during gait and that the active ROM in the back is increased, while the pain intensity scores decrease after these interventions. The investigators hypothesize that the control intervention (OLP) could be effective as an add-on intervention, but not as a single intervention.

All participants will receive all three interventions SMT, MET and OLP and to study the immediate effects, the participants will be asked:

* to lift a box with two different weights
* to walk straight forward with and without a cognitive dual task
* perform two clinical tests of active range of motion (
* rate the intensity of their pain "right now"
* rank the treatment effects of these three treatment methods

The occurrence of chronic non-specific back pain (CBP) is costly for Western society and most persons with CBP are functionally limited in their everyday movements. Studies show positive subjective short-term effects after a period of both spinal manipulative therapy (SMT) and medical exercise treatment (MET), but the immediate effects on of one session SMT/MET on movement performance are unknown. Open placebo is a relatively new field of research and a promising form of treatment for people with nonspecific pain conditions.

The goal of this laboratory-based cross-over randomized controlled study is to study the immediate effects Spinal manipulative therapy (SMT) and medical exercise treatment (MET) compared to open-label placebo (OLP) on movement performance, gait, active trunk mobility and pain-intensity in persons with chronic non-specific back pain.

Participants with long-term back pain will be recruited through primary care, such as health centers, private clinics and occupational health services.

All participants will receive all three interventions (around 5-8 minutes each)

* SMT: a doctor of chiropractic will perform HVLA spinal manipulation of areas with restricted range of motion.The areas of interest can be from the neck to the pelvis and hips.
* MET: The participants will be asked to perform mobility and motor control exercises of the trunk and pelvic muscles under supervision.
* OLP: The participant takes two pieces of orange gelatin capsules filled with the inactive substance microcrystalline cellulose, following the procedure described in Carvalho et al (2016). In short, participants will be informed that the pills are placebos and will be shown a news report featuring patients with non-specific complaints, such as migraines and irritable bowel syndrome, who describe their positive experiences with placebo.

Movement performance will be studied in an advanced movement analyses laboratory (Qualisys) and operationalized using kinematic parameters such as movement time, relative phase time, range of motion in the spine and adjacent joints, inter-segmental coordination, etc.

To study the immediate effects on movement performance, the participants will be asked to perform the following functional movements before and immediately after each intervention:

* lifting a box with two different weights from just above ground level and place it on a table in front of them
* walking straight forward at a self-selected walking speed with and without a cognitive dual task
* two clinical tests of active range of motion (modified finger-to-floor test, and the modified m-Schober's test)

Moreover, the participants are asked to:

\* rate the intensity of their pain "right now" on an 11-point standard numerical rating scale (NRS)

At the end of the experiment, when all interventions have been applied, the participants are asked to:

\* rank the treatment effects of these three treatment methods based on their effectiveness, willingness and preference

Eligibility Criteria:
Inclusion Criteria:

* Persons who have either experienced continuous or recurring back pain for a period longer than 3 months). Back pain is defined as problems/discomfort from the spine Th1-S1 with associated costovertebral joints and sacroiliac joints, thus including both the lumbar spine and the thoracic spine. The area of pain extends from Th1 to the inferior gluteal fold but does not include the shoulder blades
* \>18 years old,
* those who can speak and understand Scandinavian or English.

Exclusion Criteria:

* "red flags"
* persons with specific back problems, rheumatic inflammatory joint- and/or back diseases, fractures, diagnosed hip osteoarthritis, fibromyalgia, or neurological co-morbidity.