Fueling the Female Athlete: Auditing Her Representation in Studies of Acute Carbohydrate Intake for Exercise

Abstract

Purpose: The aim of this audit was to assess the representation of female athletes within the literature that has led to current guidelines for carbohydrate (CHO) intake in the acute periods surrounding exercise and the quality of this research.

Methods: We conducted a standardized audit of research assessing CHO loading protocols, CHO mouth rinse, and CHO intake before, during, and after exercise.

Results: A total of 937 studies were identified in this audit. There were a total of 11,202 participants across these studies, with only ~11% being women. Most studies involved male-only cohorts (~79%), with a mere 38 studies (~4%) involving female-only cohorts and 14 studies (~2%) including a methodological design for comparison of sex-based responses. The frequent use of incorrect terminology surrounding menstrual status and the failure of most studies (~69%) to provide sufficient information on the menstrual status of participants suggests incomplete understanding and concern for female-specific considerations among researchers. Of the 197 studies that included women, only 13 (~7%) provided evidence of acceptable methodological control of ovarian hormones, and no study met all best-practice recommendations. Of these 13 studies, only half also provided sufficient information regarding the athletic caliber of participants. The topics that received such scrutiny were CHO loading protocols and CHO intake during exercise.

Conclusions: The literature that underpins the current guidelines for CHO intake in the acute periods around exercise is lacking in high-quality research that can contribute knowledge specific to the female athlete and sex-based differences. New research that considers ovarian hormones and sex-based differences is needed to ensure that the recommendations for acute CHO fueling provided to female athletes are evidence based.

FIGURE 1

Flowchart demonstrating the screening process to identify articles examining acute CHO fueling strategies, and the number of individual studies included for each of the five acute CHO fueling strategies. MR, mouth rinse.

FIGURE 2

The total number of male and female participants (A) and total number of studies with at least one male or one female participant (B) for each of the acute CHO fueling strategies. MR, mouth rinse.

FIGURE 3

Frequency of study population for each acute CHO fueling strategy, with the number of studies indicated within the legend (A) and the median number of male and female participants within each study population (B). *Significantly different median number of male vs female participants. MR, mouth rinse.

FIGURE 4

Proportion of studies examining performance, health or indirect themes (A) and proportion of participants within each athlete tier: Tier 0 (sedentary), Tier 1 (recreationally active), Tier 2 (trained/developmental), Tier 3 (highly trained/national), Tier 4 (elite/international), and Tier 5 (world-class) for each of the acute CHO fueling strategies (B). C, Histogram of yearly publication rate for male-only studies and female-only studies for all acute CHO fueling strategies combined. MR, mouth rinse.

FIGURE 5

Proportion of studies of female participants classified according to methodology around menstrual status: Gold standard (best-practice methodologies followed), Silver/Bronze standard (some best-practice methodologies followed), ungraded (menstrual status defined but insufficient information on methodological control of ovarian hormonal profiles), and unclassified (insufficient information to define menstrual status) for each acute CHO fueling strategy. Number of studies within each menstrual classification indicated on legend. MR, mouth rinse.

FIGURE 6

Flowchart of studies that provided adequate methodological control of ovarian hormonal profiles (Bronze standard or above) that assessed a performance outcome (A) or an indirect theme (B) with corresponding acute CHO fueling strategy, menstrual status, menstrual cycle/HC phase, and caliber of female participants in each study. MC, menstrual cycle.