The Extra Load Index as a method for comparing the relative economy of load carriage systems

Ray Lloyd, Karen Hind, Bridget Parr, Simeon Davies, Carlton Cooke

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The Extra Load Index (ELI) has been proposed as a suitable method of assessing the relative economy of load carriage systems. The purpose of this study was to determine, based on empirical evidence, that the ELI can accommodate variations in both body composition and added load. In total, 30 women walked carrying loads of up to 70% body mass at self-selected walking speeds whilst expired air was collected. In addition, each of the women had body composition assessed via dual energy X-ray absorptiometry. Results show that the ELI is independent of body composition variables, the magnitude of additional loads and the speed of progression. Consequently, it is suggested that it represents an appropriate method of comparing load carriage systems in both scientific and commercial arenas. Statement of Relevance: This paper demonstrates that ELI is independent of body composition, added load and speed and is therefore an appropriate method to generalise comparisons of load carriage systems. It has the advantage of being easily understood by manufacturers and consumers whilst retaining appropriate scientific precision.
Original languageEnglish
Pages (from-to)1500-1504
Number of pages5
Issue number12
Early online date24 Nov 2010
Publication statusPublished - Dec 2010
Externally publishedYes


  • Anthropometry
  • Ergonomics tools and methods
  • Physiology
  • Product design


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