Table 1

Definitions of physical exercise interventions and non-exercise comparators

 StrengtheningExercises to increase the power or endurance of cervical musculature, without a specific focus on deep cervical flexors.
 StretchingStatic or isometric exercises focussed on muscle lengthening, optionally includes passively added (over)pressure.
 Motor controlExercises to increase the control and coordination of deep cervical musculature, specifically flexors. Most commonly achieved with the craniocervical flexion action.
 ProprioceptionExercises to increase the proprioceptive and kinesthetic control of head, neck and eye movements. Examples of proprioceptive training include cervical joint repositioning and gaze direction exercises. While craniocervical flexion exercises also have a proprioceptive component, their primary aim is to improve control of the craniocervical flexion movement and the deep cervical muscles.65 For this reason we opted to keep these as distinct exercise types.
 BalanceExercises aimed at improving postural balance.
 Prescribed physical activityGeneral exercises such as walking, cycling, rowing, aimed at improving overall physical activity.
 Yoga/Pilates/Tai Chi/QigongExercises following traditional principles with a physical component.
 Range of motionExercises aimed at improving range of motion, performed actively without a stretching (static, overpressure) component.
 Strengthening+motor controlA combination of strengthening and motor control exercises as described above.
 Strengthening+stretchingA combination of strengthening and stretching exercises as described above.
 Prescribed physical activity+strengtheningA combination of prescribed physical activity and strengthening exercises as described above.
 MultimodalA combination of three or more of the above-mentioned exercise types.
 No treatment/information/shamNo active treatment, no prescribed physical exercise, no physical/manual therapy. Control interventions may include: information, general advice to stay active (without specific exercise instructions), limited pain education, sham.