Test–retest reliability of physiological parameters in elite junior distance runners following allometric scaling

Abstract

This study aimed to quantify the intra-individual reliability of a number of physiological variables in a group of national and international young distance runners. Sixteen (8 male, 8 female) participants (16.7 ± 1.4 years) performed a submaximal incremental running assessment followed by a maximal running test, on two occasions separated by no more than seven days. Maximal oxygen uptake (V̇O), speed at V̇O (km h), running economy and speed and heart rate (HR) at fixed blood lactate concentrations were determined. V̇O and running economy were scaled for differences in body mass using a power exponent derived from a larger cohort of young runners (n = 42). Running economy was expressed as oxygen cost and energy cost at the speed associated with lactate turnpoint (LTP) and the two speeds prior to LTP. Results of analysis of variance revealed an absence of systematic bias between trials. Reliability indices showed a high level of reproducibility across all parameters (typical error [TE] ≤2%; intra-class correlation coefficient >0.8; effect size <0.6). Expressing running economy as energy cost appears to provide superior reliability than using oxygen cost (TE ∼1.5% vs. ∼2%). Blood lactate and HR were liable to daily fluctuations of 0.14-0.22 mmol L and 4-5 beats min respectively. The minimum detectable change values (95% confidence) for each parameter are also reported. Exercise physiologists can be confident that measurement of important physiological determinants of distance running performance are highly reproducible in elite junior runners.

Effects of Strength Training on Postpubertal Adolescent Distance Runners

“…To calculate appropriate scaling exponents for variables used in the present study, data from a larger cohort of adolescent distance runners (n=42) was log-transformed, and following an analysis of covariance (ANCOVA) comparison for males and females, a common power function was calculated via linear regression. An exponent of two-thirds (95% CI V̇O 2max : 0.34-0.98, V̇O 2 : 0.41-0.90) was previously established for V̇O 2 parameters [22], and applying the same mathematical process in a similar cohort of participants (n=36), values of 0.76 (95% CI: 0.33-1.20) and 0.61 (95% CI: 0.03-1.22) were established for vGRF jump and MVC respectively.…”

“…The linearity of regression lines for participants across both trials was R 2 = 0.981 ±0.02. Prior test-retest reliability work, using a cohort with similar characteristics, demonstrated high inter-session reliability for physiology variables [22].…”

“…Typical error (TE) and minimal detectable change at the 95% confidence level (MDC 95 ) for RE were derived from a previous reliability study in this population [22]. Based upon an anticipated 20% drop-out, 25 participants (13 female, mean ±SD age: 17.2 ±1.2 years, range:…”

“…Testing took place over two days before and after the intervention period, at the same time of day for each participant and under similar laboratory conditions (temperature, 16 The data analysis process used to obtain values for RE and !O 2max has been described previously [22]. Breath-by-breath data were initially filtered to remove any errant breath which did not represent the underlying physiological response [25].…”

“…h -1 ) were used in subsequent analysis. The V̇O 2 value was used with the RER value to quantify the energy cost of running using non-protein quotient equations [26], which is likely to provide a more valid [27] and reliable [22] measure of RE compared to oxygen cost. As sLTP varied across participants, RE was expressed as the energy cost of running per km.…”