Mechanical scale and load cell underwater weighing: Acomparison of simultaneous measurements and the reliability of methods

Jordan R. Moon, Jeffrey R. Stout, Ashley A. Walter, Abbie E. Smith, Matt S. Stock, Trent J. Herda, Vanessa D. Sherk, Kaelin C. Young, Christopher M. Lockwood, Kristina L. Kendall, David H. Fukuda, Jennifer L. Graef, Joel T. Cramer, Travis W. Beck, Enrico N. Esposito

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Both load cell and mechanical scale-based hydrostatic weighing (HW) systems are used for the measurement of underwater weight. However, there has been no direct comparison of the 2 methods. The purpose of the current investigation was to simultaneously compare a load cell and mechanical scale for use in HW. Twenty-seven men and women (mean ± SD, age: 22 ± 2 years) participated in the 2-day investigation. Each subject completed 2 HW assessments 24 hours apart. Singleday comparisons of all trials for both days revealed no significant difference between the mechanical scale and the load cell (mean difference <0.016 kg, p >0.05). True underwater weight values were not significantly different between methods for either days (mean difference <0.014 kg, p >0.05) and accounted for a mean difference in percent fat (%FAT) of <0.108%. The 95% limits of agreement indicated a maximum difference between methods of 0.53% FAT. Both methods produced similar reliability SEM values (mechanical SEM <0.72%FAT, load cell SEM <0.75%FAT). In conclusion, there was no difference between mechanical scale and load cell measurements of underwater weights and the added precision of the load cell only marginally (<0.16%FAT) improved day-to-day reliability. Either a mechanical scale or load cell can be used for HW with similar accuracy and reliability in young adults with a body mass index of 18.7-34.4 (5-25%FAT).

Original languageEnglish (US)
Pages (from-to)652-661
Number of pages10
JournalJournal of strength and conditioning research
Issue number3
StatePublished - Mar 2011
Externally publishedYes


  • Body composition
  • Hydrodensitometry
  • Hydrostatic weighing
  • Reproducibility

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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