Specific strength training is shown to relieve neck pain in office workers. The purpose of this study is to evaluate the effectiveness of specific strength training in women with severe neck pain and to analyze the dose-response relationship between training adherence and pain reduction. One hundred eighteen untrained women with severe neck pain (>30 mm VAS pain) were included from a larger study, in which the subjects were randomized to 20-week specific strength training for the neck/shoulders or to a control group. In the intention-to-treat analysis, the training group experienced greater pain relief than the control group (p < 0.01). Participants who adhered "per protocol" decreased pain by 35 mm VAS (95% confidence interval: -26 to -44) from baseline to follow-up corresponding to a 70% reduction. In the dose-response analyses, participants with medium and high training adherence showed better pain relief than the control group and those with low adherence (p < 0.0001). The decrease from baseline in the medium and high adherence groups was 37 mm VAS (28-46 mm) and 33 mm VAS (24-43 mm), respectively. Specific strength training reduces pain intensity in women with severe neck pain, and 1-2 training sessions per week for 20 weeks (∼30 training sessions) seems sufficient for optimal pain relief.