Effects of backpack load on critical changes of trunk muscle activation and lumbar spine loading during walking

Ergonomics. 2018 Apr;61(4):553-565. doi: 10.1080/00140139.2017.1365950. Epub 2017 Aug 23.

Abstract

This study investigated the effects of carrying a backpack while walking. Critical changes featuring the disproportionality of increases in trunk muscle activation and lumbar joint loading between light and heavy backpack carriage weight may reveal the load-bearing strategy (LBS) of the lumbar spine. This was investigated using an integrated system equipped with a motion analysis, a force platform and a wireless surface electromyography (EMG) system to measure the trunk muscle EMG amplitudes and lumbar joint component forces. A predictive goal programming model was developed to determine the most critical changes in trunk muscle activation and lumbar joint loading. Results suggested that lightweight backpack carriage at approximately 3% of body weight (BW) might reduce the peak lumbosacral compression force by 3% during walking compared with no load condition. The most critical changes in both trunk muscle activation and lumbosacral joint loading were found at a backpack load of 10% of BW. Practitioner Summary: This study investigated the effects of backpack load on the LBS of lumbar spine while walking. A backpack load of 3% of BW might reduce the peak lumbosacral compression force by 3 and 10% of BW induced the most critical changes in LBS of lumbar spine.

Keywords: Trunk muscle activation; backpack carriage; goal programming; load-bearing strategy; lumbar joint loading.

MeSH terms

  • Abdominal Oblique Muscles / physiology
  • Adult
  • Electromyography
  • Humans
  • Lifting*
  • Lumbar Vertebrae
  • Male
  • Muscle, Skeletal / physiology*
  • Paraspinal Muscles / physiology
  • Rectus Abdominis / physiology
  • Superficial Back Muscles / physiology
  • Walking / physiology*
  • Weight-Bearing / physiology*
  • Young Adult
  • Zygapophyseal Joint / physiology*