Classic BIVA Differences by Position and Rugby-Specific Tolerance Ellipses in Collegiate Male Rugby Athletes

Authors

Christian Rivera, Sam Houston Station UniversityFollow
Hayden Johnson, Sam Houston State UniversityFollow
Stephanie Hansford, Sam Houston State UniversityFollow
Regan Renfro, Sam Houston State UniversityFollow
Dalton Prye, Sam Houston State UniversityFollow
Matthew Poole, Sam Houston State UniversityFollow
Saheed Jaiyeola, Sam Houston State UniversityFollow
Sage A. Newman, Sam Houston State UniversityFollow
Adesiji Adetona, Sam Houston State UniversityFollow
Oscar Woodside, Sam Houston State UniversityFollow
Jmya Hughes, Sam Houston State UniversityFollow
Preston James, Sam Houston State UniversityFollow
Kelly Hines, University at BuffaloFollow
Jade Simon, Sam Houston State UniversityFollow
Drew E. GonzalezFollow
Christopher D. GreenleafFollow
Micheil Spillane, Sam Houston State UniversityFollow

Abstract

Bioelectrical impedance vector analysis (BIVA) supports interpretation of hydration and soft-tissue status, yet population reference ellipses may not reflect rugby union athletes. PURPOSE: Compare classic BIVA between forwards and backs and derive rugby-specific tolerance ellipses. METHODS: Twenty-one collegiate male rugby athletes (forwards n=15; backs n=6) completed standing multifrequency BIA (seca mBCA 514) in the morning after an overnight fast (≥12 h) and ≥24 h exercise abstention. Hydration was assessed via urine specific gravity (USG; CLINITEK Status+; Multistix 10 SG). Whole-body 50 kHz resistance (R) and reactance (Xc) were averaged bilaterally; |Xc| was used, values were normalized to height (R/H, Xc/H), and phase angle was calculated (arctan[Xc/R]·180/π). Groups were compared with Welch t-tests and mean vector displacement with Hotelling’s T² (α=0.05). Rugby-specific 50/75/95% tolerance ellipses were derived from the mean vector and covariance matrix. RESULTS: USG indicated 18/21 athletes were >1.020 and 14/21 were recorded as ≥1.030. Overall, R/H and Xc/H were 287.2 ± 42.5 and 33.4 ± 4.8 Ω/m, and phase angle was 6.7 ± 0.6°. Backs had higher R/H (331.7 ± 22.0 vs 269.4 ± 34.8 Ω/m, p<0.001, g=1.87) and Xc/H (37.4 ± 2.5 vs 31.8 ± 4.5 Ω/m, p=0.002, g=1.32) than forwards; phase angle did not differ (6.5 ± 0.5 vs 6.7 ± 0.6°, p=0.320, g=-0.33). Mean vectors differed (Hotelling’s T²=16.2, p=0.004). CONCLUSION: Classic BIVA differentiates rugby position groups; preliminary rugby-specific tolerance ellipses may improve athlete-contextualized interpretation of vector displacement, with replication in larger cohorts (especially backs) warranted.

Recommended Citation

Rivera, Christian; Johnson, Hayden; Hansford, Stephanie; Renfro, Regan; Prye, Dalton; Poole, Matthew; Jaiyeola, Saheed; Newman, Sage A.; Adetona, Adesiji; Woodside, Oscar; Hughes, Jmya; James, Preston; Hines, Kelly; Simon, Jade; Gonzalez, Drew E.; Greenleaf, Christopher D.; and Spillane, Micheil (2026) "Classic BIVA Differences by Position and Rugby-Specific Tolerance Ellipses in Collegiate Male Rugby Athletes," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 18, Article 240.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss18/240