Measurement error of self-paced exercise performance in athletic women is not affected by ovulatory status or ambient environment

Abstract

Measurement error(s) of exercise tests for women are severely lacking in the literature. The purpose of this investigation was to 1) determine whether ovulatory status or ambient environment were moderating variables when completing a 30-min self-paced work trial, and 2) provide test-retest norms specific to athletic women. A retrospective analysis of three heat stress studies was completed using 33 female participants (31±9 y, 54±10 mL min-1 kg-1) that yielded 130 separate trials. Participants were classified as ovulatory (n=19), anovulatory and/or luteal phase-deficient (n=4) and oral contraceptive pill users (n=10). Participants completed trials ~2 weeks apart in their (quasi-) early follicular and mid-luteal phases in two of moderate (1.3±0.1 kPa, 20.5±0.5 °C, 18 trials), warm-dry (2.2±0.2 kPa, 34.1±0.2 °C, 46 trials) or warm-humid (3.4±0.1 kPa, 30.2±1.1 °C, 66 trials) environments. We quantified reliability using limits of agreement, intraclass correlation coefficient (ICC), Pearson's correlation coefficient (r), standard error of measurement (SEM) and coefficient of variation (CV). Test-retest reliability was high, clinically-valid (ICC=0.90, r=0.83, both p<0.01) and acceptable with a mean CV of 4.7%, SEM of 3.8 kJ (2.1 W) and reliable bias of -2.1 kJ (-1.2 W). The various ovulatory status and contrasting ambient conditions had no appreciable effect on reliability. These results indicate that athletic women can perform 30-min self-paced work trials ~2 weeks apart with an acceptable and low variability irrespective of their hormonal status or heat-stressful environments.

Do E2 and P4 contribute to the explained variance in core temperature response for trained women during exertional heat stress when metabolic rates are very high?

“…Women remain underrepresented in the exercise thermoregulation literature and > 70% of studies still do not report ovulatory status or menstrual phase (Hutchins et al 2021). Ovulatory status should not inhibit inclusion into this research topic (Schaumberg et al 2017;Zheng et al 2021b) although, importantly, the current results support calls for future measurement and consideration of ovarian hormone concentrations being standard (Elliott-Sale et al 2021). Individualization of human thermoregulation models improves the prediction of heat strain, largely through an increase in the number of input parameters (Havenith 2001).…”

“…Results reported in the current study were those for which a maximal number of measures were recorded for the n = 36. For interested readers, other physiological (i.e., thermoregulatory, cardiovascular, inflammatory) and reliability measurements were performed during these trials and can be found in our separate studies (Lei et al 2017 , 2019 ; Zheng et al 2021a , 2021b ).…”

“…The purpose of the current paper was to determine the relative contribution of the E 2 and P 4 alongside other morphological, physiological, functional and environmental factors in explaining the individual variation in trained women when considering the core temperature response (peak T core , [ T peak ]) and work output (mean power output) with very high metabolic rates. To achieve this, we retrospectively analyzed results from 36 trained women completing a self-paced 30-min work trial that has been shown to be unaffected by ovulatory status, ambient environment and pre-load/warm-up duration (Zheng et al 2021b ). Participants were distinguished by intra-participant (i.e., early follicular and mid-luteal phases) or inter-participant (i.e., ovulatory vs. anovulatory vs. oral contraceptive pill [OCP] user) differences in their endogenous E 2 and P 4 concentrations.…”

Reliability of a 60-min treadmill running protocol in the heat: The journal Temperature toolbox

“…For example, we have previously demonstrated when using a similar protocol that a dietary intervention resulted in an attenuated T core response of 0.2 ± 0.5°C during the 45 min fixed-intensity pre-load [ 23 ]. Based on the current results ( Table 2 and Figure 4 ) we can interpret this finding as not only statistically valid but greater than the measurement error; in other words, we can be confident of the true effect of the intervention based on the signal-to-noise ratio [ 24 ]. Secondly, future studies investigating interventions or comparing different populations now have a known measurement error for ΔT core during exercise that can inform sample size justification [ 16 ].…”

“…Small data sets (e.g. <40) are more sensitive to heterogeneity [ 12 , 24 ]. Therefore, we caution interpretation of the current results without confirmatory research using larger data sets.…”