Table 1 Standardized questionnaires

Physical Function Scale of Swiss Spinal Stenosis Questionnaire (PF Scale) [1]

The Physical Function Scale was designed to assess walking capacity in people with LSS. The score is calculated as the un-weighted mean of the five items in the scale. The resulting possible scores of 1–4 represent a range from mild to severe limitation in physical function/walking.

Symptom Severity Scale of the Swiss Spinal Stenosis Questionnaire (SS Scale) [1]

The Symptom Severity Scale of the SSSQ was designed to examine severity of symptoms related to LSS. It is scored as the un-weighted mean of the seven items in the scale, with scores from one to seven representing a range from mild to very severe pain.

Oswestry Disability Index (ODI) [37]

The ODI is a nine-item questionnaire, which assesses degree of back pain–related disability. Severity of pain and disability in activities, such as walking, sitting, standing, and personal care, are rated on Likert scales of five or six points. The ODI was calculated as a percentage of the total possible score of 53, with a greater score representing greater back pain–related disability.

Short-Form 36 (SF-36) [38]

Overall health and disability will be assessed using the 36-Item Short Form Health Survey. Using the 36 items, the following scales are calculated: General Health, Physical Functioning, Social Functioning, Role Limitation—Physical, Role Limitation—Emotional, Mental Health, Vitality, and Bodily Pain. Each scale score is calculated independently using algorithms defined by the developers.

Centres for Disease Control Depression Scale (CES-D) [39]

The 20 item Centres for Epidemiologic Studies Depression Scale was designed to assess depression. It is scored by totaling all item scores, with a higher total indicating greater depression. Scores range from 0 to 60, with higher scores indicating more symptoms of depression. CESD scores of 16 to 26 are considered indicative of mild depression and scores of 27 or more indicative of major depression.

Regulation for Eating Behaviors Scale (REBS) [40]

To assess healthy eating motives, participants will complete the 24-item Regulation of Eating Behaviour Scale. Six subscales comprised of 4 items/subscale formulate the REBS including (a) Amotivation, (b) External Regulation, (c) Introjected Regulation, (d) Identified Regulation, (e) Integrated Regulation, and (f) Intrinsic regulation. Participants respond to each REBS item on a 7-point Likert scale anchored at the extremes by (1) 'Does not correspond at all’ and (7) 'Corresponds exactly’.

Behavioral Regulation in Exercise Questionnaire 2-R (BREQ-2R) [41, 42]

•To assess exercise motive related to exercise, participants will complete the 19 item Behavioral Regulation in Exercise Questioniare-2 plus four items assessing Integrated Regulation. The BREQ-2 assesses the following constructs: (a) Amotivation, (b) External Regulation, (c) Introjected Regulation, (d) Identified Regulation, and (e) Intrinsic Regulation. Reponses to the BREQ-2 and Integrated Regulation items were made using a 5-point Likert scale anchored at the extremes by 0 ('Not true for me’) and 4 ('Very true for me’).

Pain Catastrophizing Questionnaire [43]

The PCS was designed to assess pain catastrophizing. The PCS is a 13-item instrument that asks participants to reflect on past painful experiences, and to indicate the degree to which they experience each of 13 thoughts or feelings when experiencing pain, on 5-point scales with the end points (0) not at all and (4) all the time. The PCS total score is computed by summing responses to all 13 items. PCS total scores range from 0 – 52. A score of 30 or above represents clinically relevant catastrophizing.

Tampa Scale for Kinesiophobia (TSK) [44, 45]

The TSK was designed to assess fear of movement (kinesiophobia). The TSK uses a 4-point Likert scale, with scoring options ranging from 1 = 'strongly disagree’ to 4 = 'strongly agree’. A total score is calculated after inversion of the individual scores of items 4, 8, 12 and 16. The total score ranges between 17 and 68. A high value on the TSK indicates a high degree of kinesiophobia. A score of 37 differentiates between high and low scores.