Implementation of specific strength training among industrial laboratory technicians: long-term effects on back, neck and upper extremity pain

Abstract

Background: Previous studies have shown positive effects of physical exercise at the workplace on musculoskeletal disorders. However, long-term adherence remains a challenge. The present study evaluates long-term adherence and effects of a workplace strength training intervention on back, neck and upper extremity pain among laboratory technicians.

Methods: Cluster-randomized controlled trial involving 537 industrial laboratory technicians. Subjects were randomized at the cluster level to one of two groups: training group 1 (TG1, n = 282) performing supervised strength training from February to June 2009 (round one) or training group 2 (TG2, n = 255) performing supervised strength training from August to December 2009 (round two). The outcome measures were changes in self-reported pain intensity (0-9) in the back, neck and upper extremity as well as Disability of the Arm, Shoulder and Hand (DASH, 0-100).

Results: Regular adherence, defined as at least one training session per week, was achieved by around 85% in both groups in the supervised training periods. In the intention-to-treat analyses there were significant group by time effects for pain in the neck, right shoulder, right hand and lower back and DASH-resulting in significant reductions in pain (mean 0.3 to 0.5) and DASH (mean 3.9) in the scheduled training group compared to the reference group. For TG1 there were no significant changes in pain in round two, i.e. they maintained the pain reduction achieved in round one. Subgroup analyses among those with severe pain (> = 3 on a scale of 0-9) showed a significant group by time effect for pain in the neck, right shoulder, upper back and lower back. For these subgroups the pain reduction in response to training ranged from 1.1 to 1.8.

Conclusions: Specific strength training at the workplace can lead to significant long-term reductions in spinal and upper extremity pain and DASH. The pain reductions achieved during the intensive training phase with supervision appears to be maintained a half year later.

Trial registration: ClinicalTrials.gov NCT01071980.

Figure 1

Flow of participants throughout the intervention.

Figure 2

Disability of the Arm, Shoulder and Hand (DASH) at baseline, at 20 weeks follow-up and at one-year follow up. TG1 = first training group; TG2 = second training group. Error bars = SE. * significant time by group effect.

Figure 3

Pain intensity the last 7 days in six regions at baseline, at 20 weeks follow-up and at one-year follow up. TG1 = first training group; TG2 = second training group; a-f = graph number. Error bars = SE. * significant time by group effect.

Figure 4

Cases. Pain intensity the last 7 days in six regions at baseline, at 20 weeks follow-up and at one-year follow up. TG1 = first training group; TG2 = second training group; a-f = graph number. Error bars = SE. * significant time by group effect.

Figure 5

Percentage of subjects with reductions in pain intensity of 2 or more on a 0–9 scale in five different body regions. Intention-to-treat (ITT) analyses among all participants (left column). Participants with pain > = 3 at baseline (right column). On the x-axis 1–2 denotes changes during the first intervention round where the first training group (black bars) performed specific strength training, and 2–3 denotes changes during the second intervention round where the second training group (white columns) performed specific strength training. * significant differences between changes in TG1 and TG2 (chi-square test).