title: Identification of serum analytes and metabolites associated with aerobic capacity.
abstract: Studies aimed at identifying serum markers of cellular metabolism (biomarkers) that are associated at baseline with aerobic capacity (VO₂max) in young, healthy individuals have yet to be reported. Therefore, the goal of the present study was to use the standard chemistry screen and untargeted mass spectrometry (MS)-based metabolomic profiling to identify significant associations between baseline levels of serum analytes or metabolites with VO₂max (77 subjects, age range 18-35 years). Use of multivariable linear regression identified three analytes (standard chemistry screen) and twenty-three metabolites (MS-based metabolomics) containing significant, sex-adjusted associations with VO₂max. In addition, fourteen metabolites were found to contain sex-specific associations with aerobic capacity. Subsequent stepwise multivariable linear regression identified the combination of SGOT, 4-ethylphenylsulfate, tryptophan, γ-tocopherol, and α-hydroxyisovalerate as overall, sex-adjusted baseline predictors of VO₂max (adjusted R(2) = 0.66). However, the results of the stepwise model were found to be sensitive to outliers; therefore, random forest (RF) regression was performed. Use of RF regression identified a combination of seven covariates that explained 57.6 % of the variability inherent in VO₂max. Furthermore, inclusion of significant analytes, metabolites and sex-specific metabolites into a stepwise regression model identified the combination of five metabolites in males and seven metabolites in females as being able to explain 80 and 58 % of the variability inherent in VO₂max, respectively. In conclusion, the evidence presented in the current report is the first attempt to identify baseline serum biomarkers that are significantly associated with VO₂max in young, healthy adult humans.
authors.affiliation: Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Lustgarten
authors.forename: Lori Lyn
authors.initials: LL
authors.lastname: Price
authors.forename: Tanya
authors.initials: T
authors.lastname: Logvinenko
authors.forename: Christos
authors.initials: C
authors.lastname: Hatzis
authors.forename: Nandan
authors.initials: N
authors.lastname: Padukone
authors.forename: Nicholas V
authors.initials: NV
authors.lastname: Reo
authors.forename: Edward M
authors.initials: EM
authors.lastname: Phillips
authors.forename: Dylan
authors.initials: D
authors.lastname: Kirn
authors.forename: John
authors.initials: J
authors.lastname: Mills
authors.forename: Roger A
authors.initials: RA
authors.lastname: Fielding
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology*; D001774:Blood Chemical Analysis; D003627:Data Interpretation, Statistical; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D055442:Metabolome; D012737:Sex Factors