Self-administered physical exercise training as treatment of neck and shoulder pain among military helicopter pilots and crew: a randomized controlled trial

Background: Neck pain is frequent among military helicopter pilots and crew-members, and pain may influence individual health and work performance. The aim of this study was to examine if an exercise intervention could reduce neck pain among helicopter pilots and crew-members. Methods: Thirty-one pilots and thirty-eight crew-members were randomized to either an exercise-training-group (n = 35) or a reference-group (n = 34). The exercise-training-group received 20-weeks of specific neck/shoulder training. The reference-group received no training. Primary outcome: Intensity of neck pain previous 3-months (scale 0-10). Secondary outcomes: additional neck/shoulder pain intensity variables and pressure-pain-threshold in the trapezius muscle (TRA) and upper-neck-extensor muscles (UNE). Regular training adherence was defined as = 1 training session a week. Statistical analyses performed were intention-to-treat and per-protocol. Students t-test was performed (p < 0.05). Results: Intensity of neck pain previous 3-months at baseline was: 2.2 +/- 1.8 and previous 7-days: 1.0 +/- 1.5, and pressure-pain-threshold in TRA and UNE (right/left) was in kPa: 424 +/- 187 / 434 +/- 188 and 345 +/- 157 / 371 +/- 170 in the exercise-training-group, and 416 +/- 177 / 405 +/- 163 and 334 +/- 147 / 335 +/- 163 in the reference-group, with no differences between groups. Intention-to-treat-analysis revealed no significant between-group-differences in neck pain intensity and pressure-pain- threshold. Between-group-differences, including participants who trained regularly (n = 10) were also non-significant. Within-group-changes were significant among participants with regular training adherence in the exercise-training-group regarding intensity of neck pain previous 3-months (from 2.2 +/- 0.6 to 1.3 +/- 1.3, p = 0.019). Likewise, within the whole exercise-training-group, neck pain previous 7-days decreased (from 1.0 +/- 1.4 to 0.6 +/- 1.1, p = 0.024). Additional within-group-changes regarding pressure-pain- threshold in kPa were for the reference-group a reduction in TRA and UNE (right/left) to: 342 +/- 143 / 332 +/- 154 and 295 +/- 116 / 292 +/- 121 implying increased pain sensitivity, while for the exercise-training-group only a reduction in left TRA was seen: 311 +/- 113. Conclusions: The exercise intervention did not reduce neck pain among helicopter pilots and crew-members as no significant between-group-differences were found. However, some trends were demonstrated as some neck pain intensity and sensitivity improved more within the exercise-training-group but not within the reference-group. The lack of effect may be due to low adherence since only similar to 1/3 of subjects in the exercise-training-group engaged in regular training which may be due to the self-administration of the training.