Effects of menstrual cycle on vagal reactivation in post-exercise recovery among young black African women

A Systematic Review and Meta-Analysis of Within-Person Changes in Cardiac Vagal Activity across the Menstrual Cycle: Implications for Female Health and Future Studies

“…A total of 45 studies published between the year 1995 and October 2018 were included in the systematic review [40,42,43,44,45,49,50,51,52,53,54,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90]. Only one of the 45 studies was published in Russian [43]; all others were written in English.…”

“…In case authors reported (V) multiple experimental conditions in which they investigated within-person changes of CVA, baseline results (i.e., no intervention) were extracted by default. In the five cases where no such baseline was reported, the following decisions were made: Balayssac-Siransy et al [40] asked their participants to perform an exercise test and measured heart rate recovery in absolute value for six minutes. In line with standard procedure (e.g., [41]), we retrieved the data from the third recovery minute for the present meta-analysis.…”

Menstrual Cycle Changes in Vagally-Mediated Heart Rate Variability Are Associated with Progesterone: Evidence from Two Within-Person Studies

“…To date, only seven studies (of roughly 49 currently available studies on cardiac vagal activity across the menstrual cycle as suggested by our meta-analysis [28] and a recent review [30]) have reported associations between ovarian hormone levels and cardiac vagal activity, with mixed results [27,[31][32][33][34][35][36]. However, four major methodological and statistical limitations in these studies prevent clear conclusions.…”

“…However, four major methodological and statistical limitations in these studies prevent clear conclusions. First, many of these studies correlate absolute hormone levels with absolute cardiac vagal activity (using the full repeated-measures dataset), which fails to isolate a within-person variance in ovarian hormones as the critical predictor (by "person-centering" the repeated hormonal predictors [37]); instead, using a variable that dilutes the within-person variance in hormone levels across the cycle with the between-person (or, more probably, between-cycle) variance in hormone levels [31][32][33]35]. Second, the use of a repeated-measures dataset in a simple correlation analysis violates the statistical assumption that observations are independent from one another (since repeated observations are nested within participants).…”

“…Third, some studies appear to subset their repeated measures datasets by cycle phase, then perform correlations between absolute hormone levels and cardiac vagal activity (in a between-person manner); this fails to capture the predictor variance of interest, which is that of within-person changes in hormones across the cycle [27,34]. Finally, each of these studies appeared to examine E2 and P4 as predictors of cardiac vagal activity in separate models, which fails to test both the unique effects of changes in each hormone and the potential interactive effects of these hormones [27,[31][32][33][34][35][36].…”