All outcome variables, except for degree of recovery and body height, will be assessed three times: prior to the start of the intervention (T0), at the end of the six month intervention (T1) and 12 months after the start of the intervention (T2). Degree of recovery is assessed at T1 and T2 and body height is measured at baseline only.
Primary outcome variables
1. Degree of recovery from neck and upper limb symptoms assessed using a 7-point scale ranging from "much worse" to "completely recovered" compared to baseline.
2. Pain intensity (current pain, average pain and worst pain in the past four weeks), assessed using an 11-point numerical rating scale ranging from 0 "no pain" to 10 "worst pain ever" [
28].
3. Disability assessed using an 11-point numerical rating scale [
28]. Change in ability to work in the past four weeks is assessed with Von Korff scales ranging from 0 "no change" to 10 "extreme change". Interference of pain on daily activities in the past four weeks is assessed with Von Korff scales ranging from 0 "no interference" to 10 "unable to carry on any activities".
4. The Dutch musculoskeletal questionnaire [
29] is used to assess the six month prevalence of symptoms (pain, stiffness, tingles or numbness) in the neck, right shoulder, left shoulder, right arm, left arm, right wrist, left wrist, right hand and left hand in the past six months. In the same questionnaire, participants report the number of days with neck and upper limb symptoms in the past 6 months (no symptoms, 1–7 days, 8–30 days, 31–90 days, 91–180 days) and the past week (no symptoms, 1 day, 2–3 days, 4–7 days).
5. Number of months without neck and upper limb symptoms in the past six months (0–6 months).
Degree of recovery, pain intensity, number of days with neck and upper limb symptoms and disability will be assessed separately for the neck shoulder region and the arm/wrist/hand region.
Secondary outcome variables
1. Physical activity is assessed by means of the validated Short Questionnaire to Access health enhancing physical activity (SQUASH) [
30]. The SQUASH questionnaire contains questions about activities in the following four domains: 1) commuting activities (i.e. walking and cycling), 2) activities at work and school, 3) household activities, and 4) leisure time activities (i.e. walking, cycling, gardening, chores, and sports).
2. Body posture and workplace ergonomics during computer work (self reported). Participants rate themselves on the tendency of forward chin movement relative to the trunk in the direction of the computer screen (yes/no), using a document holder (yes/no), location of documents while working with them (right or left from keyboard, behind keyboard, in front of keyboard), keyboard height compared to elbow height (keyboard above elbow height, keyboard at or below elbow height), the tendency to work with raised shoulders (yes/no), keyboard flat on the desk (yes/no), use of mouse (yes/no), left handed (yes/no), hand that controls the mouse (left/right/both), convenient body posture while working with the keyboard and the mouse (yes/no).
3. Body posture and workplace ergonomics during computer work (observed). The following aspects will be observed, using a checklist while the participant is working: position of the participant in relationship to the position of the computer screen (rotation < 10°, rotation ≥ 10°), rotation of keyboard compared to table edge (rotated < 10°, rotated ≥ 10°), rotation of the neck (rotated < 20°, rotated ≥ 20°), height of the computer screen (top of screen far beneath eye height, at eye height, above eye height), viewing distance (shortest distance between the eyes and the computer screen) using a measuring tape, posture of the back while seated (straight/not straight), back supported up to shoulder blades (yes/no), body posture more or less symmetrical (yes/no), support of the elbows while typing (yes/no), ulnar deviation of wrists while typing (yes = ≥ 20°, no = < 20°), lower arm continuously supported (at least 50%) while working with the mouse (yes/no), ulnar wrist deviation while working with the mouse (yes = ≥ 20° or < -5° ; no = < 20° and > -5°).
4. The use of breaks and exercise reminder software and the number of breaks will be assessed by questionnaire.
5. Extrinsic effort and reward (esteem reward, status control and monetary gratification) and need for control, assessed by the short version of the Effort-Reward imbalance questionnaire [
31].
6. Decision authority, estimated with the Job Content Questionnaire [
32].
7. Phase of behavioural change with regard to physical activity and work style (1. coping with work-related stress, 2. sufficient breaks, and 3. body posture and workplace adjustment), assessed with a questionnaire based on the Trans Theoretical model [
33] and the Precaution Adoption Process Model [
26].
8. Cardio respiratory fitness, estimated using the validated UKK walk test [
34,
35]. A short medical questionnaire is used in order to exclude participants from the UKK walk test due to medical reasons.
9. Maximum grip strength, measured using the Jamar hand dynamometer [PGB Active Living, 's-Hertogenbosch, the Netherlands] while the participant is standing with the shoulder in 90° flexion and the arm in full extension.
10. Health care use. At baseline participants were asked whether or not they ever sought medical help for neck and upper limb symptoms. In addition, they were asked to indicate which health care provider(s) they visited. At both follow-up measurements participants were asked again whether or not they sought medical help for neck and upper limb symptoms in the past six months and which health care provider(s) they visited.