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OBJECTIVE:: To determine and compare the extent of within- and between-laboratory precision in body volume (BV) measurements using air displacement plethysmography (ADP), the BOD POD body composition system, and to interpret any such variability in terms of body composition estimates. DESIGN:: Repeated test procedures of BV assessment using the BOD POD ADP were reproduced at two laboratories for the estimation of precision, both within and between laboratories. SUBJECTS:: In total, 30 healthy adult volunteers, 14 men (age, 19-48?y; body mass index (BMI), 19.7-30.3?kg/m2) and 16 women (age, 19-40?y; BMI, 16.3-35.7?kg/m2), were each subjected to two test procedures at both laboratories. Two additional volunteers were independently subjected to 10 repeated test procedures at both laboratories. MEASUREMENTS:: Repeated measurements of BV, uncorrected for the effects of isothermal air in the lungs and the surface area artifact, were obtained using the BOD POD ADP, with the identical protocol being faithfully applied at both laboratories. Uncorrected BV measurements were adjusted to give estimates of actual BV that were used to calculate body density (body weight (BWt)/actual BV) from which estimates of body composition were derived. The differences between repeated BV measurements or body composition estimates were used to assess within-laboratory precision (repeatability), as standard deviation (SD) and coefficient of variation; the differences between measurements reproduced at each laboratory were used to determine between-laboratory precision (reproducibility), as bias and 95% limits of agreement (from SD of the differences between laboratories). RESULTS:: The extent of within-laboratory methodological precision for BV (uncorrected and actual) was variable according to subject, sample group and laboratory conditions (range of SD, 0.04-0.13?l), and was mostly due to within-individual biological variability (typically 78-99%) rather than to technical imprecision. There was a significant (P<0.05) bias between laboratories for the 10 repeats on the two independent subjects (up to 0.29?l). Although no significant bias (P=0.077) was evident for the sample group of 30 volunteers (-0.05?l), the 95% limits of agreement were considerable (-0.68 to 0.58?l). The effects of this variability in BV on body composition were relatively greater: for example, within-laboratory precision (SD) for body fat as % BWt was between 0.56 and 1.34% depending on the subject and laboratory; the bias (-0.59%) was not significant between laboratories, but there were large 95% limits of agreement (-3.67 to 2.50%). CONCLUSION:: Within-laboratory precision for each BOD POD instrument was reasonably good, but was variable according to the prevailing conditions. Although the bias between the two instruments was not significant for the BV measurements, implying that they can be used interchangeably for groups of similar subjects, the relatively large 95% limits of agreement indicate that greater consideration may be needed for assessing individuals with different ADP instruments. Therefore, use of a single ADP instrument is apparently preferable when assessing individuals on a longitudinal basis.International Journal of Obesity (2004) 28, 80-90. doi:10.1038/sj.ijo.0802466 [ABSTRACT FROM AUTHOR]

The declining salmonid populations reported for many rivers in England and Wales have frequently been attributed to spawning gravel siltation and the need to address this problem through sediment control strategies has been widely recognised. The planning of such sediment control strategies is, however, severely hampered by the lack of reliable information on the source of the fine sediment deposited within spawning gravels. Given the need for information on the source of the fine sediment accumulating in salmonid spawning gravels, a reconnaissance survey, based on the source fingerprinting approach, has been undertaken to establish the source of fine interstitial sediment recovered from spawning gravels in 18 important salmonid rivers in England and Wales. The findings confirm the potential of the fingerprinting approach for establishing the provenance of interstitial fines. More specifically, the results provide useful information on the relative importance of surface and channel/subsurface sources as the source of the interstitial fines collected from the individual study rivers. Significant regional contrasts in the source of this sediment are reported. The findings have important implications for the design and implementation of effective sediment management strategies aimed at protecting salmonid spawning gravels, in terms of both the sources to be targeted and the associated need to adopt different approaches in different rivers. [ABSTRACT FROM AUTHOR]