Table 1 In- and exclusion criteria

Healthy subjects

- no history of LBP of that kind that a doctor or physiotherapist was ever consulted

- fully pain-free at the moment of testing and 24 h before reflected by 0/10 on the NRS scale and 0 on the Rolland Morris disability questionnaire

- males and females

- 18–65 years old

- ≥ 1 years post-natal

- use of antidepressants or analgesics (except for NSAID’s or paracetamol), taken two weeks prior to the testing

- neurological, respiratory, circulatory or severe orthopaedic diseases

- back surgery

- pregnancy

- motor control training for LBP

RLBP

- non-specific RLBP in remission

- ≥ 6 months

- a frequency of ≥ 2 episodes in the past year

- a pain flare of ≥ 24 h, characterized by an increase of ≥ 2 on a NRS scale and/or ≥ 5 on the Rolland Morris Disability Questionnaire

- followed by a pain free episode of ≥ 1 month, characterized by a 0/10 on an NRS scale and/or < 2 on the Rolland Morris disability questionnaire

- applicate for medical help concerning low back complaints

Non-continuous CLBP

- non-specific CLBP

- ≥ 3 months

- 3 to 4 pain days a week

Continuous CLBP

- non-specific CLBP

- ≥ 3 months

- 7 pain days a week