JEPonline Biological Variability in Submaximal Parameters of Performance and Strain

Marschall F, Ferger K, Mueller H. Biological Variability in Submaximal Parameters of Performance and Strain. JEPonline 2014;17(4):102-112. The use of performance and strain parameters to evaluate training effects depends on the assessment of biological day-to-day variability. Without control of this variability, exerciseinduced effects cannot be separated and/or adequately interpreted. In five studies within this study, the variability of the performance parameter ‘physical work capacity’ (PWC150/170) and two strain parameters [heart rate (HR) and oxygen uptake (VO2) at submaximal loads] were determined. Sixty subjects completed 6 consecutive submaximal bicycle ergometric tests during which HR, PWC, and VO2 were recorded. The within-subject coefficient of variation (CV) was determined on the individual average, relativized to the individual standard deviation. The CV of PWC, HR, and VO2 range between 2.35% (CI95 % = 1.22/3.48) for the HR at a 5-min continuous exposure and 4.84% (CI95 % = 4.21/5.46) for the PWC measured with a step protocol. The results indicate that the biological variability is taken into account when interpreting changes in performance. A post hoc analysis using principal component analysis (PCA) makes it clear that a distinction between measurement error and biological variability should be made for further interpretation of the CV.