Purpose: The objective of this study is to investigate the effect of three different workplace interventions on long-term compliance, muscle strength gains, and neck/shoulder pain in office workers.
Methods: A 1-yr randomized controlled intervention trial was done with three groups: specific resistance training (SRT, n = 180), all-round physical exercise (APE, n = 187), and reference intervention (REF, n = 182) with general health counseling. Physical tests were performed and questionnaires answered at pre-, mid-, and postintervention. The main outcome measures were compliance, changes in maximal muscle strength, and changes in intensity of neck/shoulder pain (scale 0-9) in those with and without pain at baseline.
Results: Regular participation was achieved by 54%, 31%, and 16% of those of the participants who answered the questionnaire in SRT (78%), APE (81%), and REF (80%), respectively, during the first half of the intervention period, and decreased to 35%, 28% and 9%, respectively, during the second half. Shoulder elevation strength increased 9-11% in SRT and APE (P < 0.0001). Participants with neck pain at baseline decreased the intensity of neck pain through SRT, from 5.0 +/- 0.2 to 3.4 +/- 0.2 (P < 0.0001), and through APE, from 5.0 +/- 0.2 to 3.6 +/- 0.2 (P < 0.001), whereas REF caused no change. For participants without shoulder pain at baseline, there was a significantly greater increase in pain over the 1-yr period in REF compared with SRT and APE (P < 0.01).
Conclusion: Compliance was highest in SRT but generally decreased over time. SRT and APE caused increased shoulder elevation strength, were more effective than REF to decrease neck pain among those with symptoms at baseline, and prevent development of shoulder pain in those without symptoms at baseline.