“…Among the 27 studies, nine interventions consisted of a low load programme 41,44,53,55,56,58,60,63,66 and eight of a high load programme. 44,50,51,53,56,57,67,74 In 21 interventions, 42–44,46–50,52,54,57–59,61,62,67,74 the cervical extensor muscle exercises were progressive; in 16 interventions, the programme progressed from a low load to a high load programme. 42,43,47–50,52,54,59,61,62,67 In three studies, the intensity of the cervical extensor muscle exercises was unclear.…”