A randomized controlled trial of chair interventions on back and hip pain among sewing machine operators: the los angeles garment study

J Occup Environ Med. 2008 Mar;50(3):255-62. doi: 10.1097/JOM.0b013e318163869a.


Objective: Determine whether an adjustable chair with a curved or a flat seat pan improved monthly back and hip pain scores in sewing machine operators.

Methods: This 4-month intervention study randomized 293 sewing machine operators with back and hip pain. The participants in the control group received a placebo intervention, and participants in the intervention groups received the placebo intervention and one of the two intervention chairs.

Results: Compared with the control group, mean pain improvement for the flat chair intervention was 0.43 points (95% CI = 0.34, 0.51) per month, and mean pain improvement for the curved chair intervention was 0.25 points (95% CI = 0.16, 0.34) per month.

Conclusions: A height-adjustable task chair with a swivel function can reduce back and hip pain in sewing machine operators. The findings may be relevant to workers who perform visual- and hand-intensive manufacturing jobs.

Publication types

  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Back Pain / prevention & control
  • Equipment Design
  • Ergonomics / instrumentation*
  • Female
  • Hip Joint*
  • Humans
  • Interior Design and Furnishings / classification*
  • Linear Models
  • Los Angeles
  • Male
  • Middle Aged
  • Occupational Diseases / prevention & control
  • Pain / prevention & control*
  • Pain Measurement
  • Pilot Projects
  • Placebos
  • Surveys and Questionnaires
  • Textile Industry*


  • Placebos