Timing of Energy Availability on Menstrual Cycle Function (FAST)

Implications for the Timing of Energy Availability on Menstrual Cycle Function

The primary aim of this clinical trial is to evaluate how fasted prolonged exercise may influence circulating reproductive hormones (i.e., estradiol, progesterone, luteinizing hormone) and menstrual cycle length when energy availability is maintained at or above 30 kcal/kg lean body mass/ day among women who regularly do running or cycling exercise. A secondary aim is to determine the effects of fasted prolonged exercise on serum leptin and cortisol.

Participants will be asked to do the following over a ~3 month enrollment period:

• attend a laboratory visit at the beginning of the study to have their resting metabolic rate, aerobic fitness, and body composition tested
• monitor their menstrual cycle length, urine hormones, perceived stress levels, and diet for ~3 months
• complete 3, 90-minute exercise sessions on a stationary bike or treadmill either fed (consuming a carbohydrate meal 1 h prior and 0.7 g carbohydrate/ kg body mass/ h during exercise) or fasted (consuming no meal prior and no carbohydrates during exercise) during month ~3
• saliva samples will be taken prior to and after 90-minute exercise sessions for quantification of leptin and cortisol

Study Overview

• Status: Recruiting
• Conditions: Menstrual Irregularity
• Intervention / Treatment: Dietary supplement: Artificially Sweetened Carbohydrate Beverage; Dietary supplement: Artificially Sweetened Beverage

• Study Type: Interventional
• Enrollment (Estimated): 64
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Marissa Baranauskas, PhD; Phone Number: 719-255-4475; Email: mbaranau@uccs.edu

Study Locations

• United States
  • Colorado
    • Colorado Springs, Colorado, United States, 80918
      • Recruiting
      • William J. Hybl Sports Medicine and Performance Center
      • Contact: Marissa Baranauskas, PhD; Phone Number: 719-255-4475; Email: mbaranau@uccs.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• participates in structured running or cycling exercise for at least 30 minutes on 3 or more days per week
• accustomed to exercising for 90 minutes or more
• has regular periods every 21-35 days
• have not taken hormonal contraceptives for at least the past 6 months
• is not currently or trying to become pregnant or breastfeeding, and has not been pregnant or breastfeeding in the past 12 months
• does not currently have a diagnosis of a major menstrual cycle disorder (i.e., amenorrhea, polycystic ovary syndrome [PCOS], endometriosis, ovarian cancer, ovarian insufficiency, uterine or endometrial cancer)
• does not currently have a metabolic disease (i.e., hypothyroidism, hyperthyroidism, Cushing disease, Addison's disease, diabetes, congenital adrenal hyperplasia)
• does not currently have a major cardiovascular or respiratory disease

Exclusion Criteria:

• miss more than 7 consecutive days of aerobic activity (i.e., running, cycling, cross training)
• demonstrate clinical low energy availability as defined as energy availability <30 kcal/kg fat free mass
• report menstrual cycle lengths <21 or >35 days in the first 2 months of at-home monitoring
• do not demonstrate an anticipated rise in luteinizing hormone and progesterone in the first 2 months of at-home monitoring
• begin taking a hormonal contraceptive
• become pregnant
• are diagnosed with a menstrual cycle disorder (i.e., amenorrhea, polycystic ovary syndrome [PCOS], endometriosis, ovarian cancer, ovarian insufficiency, uterine, or endometrial cancer)
• are diagnosed with a metabolic disease (i.e., hypothyroidism, hyperthyroidism, Cushing disease, Addison's disease, diabetes)
• are diagnosed with a major cardiovascular or respiratory disease
• are unable to follow instructions for any of the procedures

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Fed with Carbohydrates; Participants will complete 3, 90-minute stationary cycle or treadmill exercise sessions 1 h after consuming a meal containing 1 g carbohydrate/ kg body weight. During exercise, they will consume an artificially sweetened beverage containing 0.7 g carbohydrate/ kg body mass/ h as a 2:1 mixture of glucose and fructose.	Dietary supplement: Artificially Sweetened Carbohydrate Beverage; Beverage containing 0.7 g carbohydrate/ kg body mass/ h as a 2:1 mixture of glucose and fructose and artificial sweetener
Placebo Comparator: Fasted without Carbohydrates; Participants will complete 3, 90-minute stationary cycle or treadmill exercise sessions following an overnight fast. During exercise, they will consume an artificially sweetened beverage containing no carbohydrates.	Dietary supplement: Artificially Sweetened Beverage; Beverage containing no carbohydrates or kilocalories and an artificial sweetener

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urinary estrone-3-glucuronide (E3G)	ng/mL	3 months
Urinary pregnanediol glucuronide (PdG)	ug/mL	3 months
Urinary luteinizing hormone (LH)	MIU/mL	3 months
Menstrual cycle length	days	3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Salivary cortisol	ng/mL	3 days
Salivary leptin	ng/mL	3 days

Collaborators and Investigators

• Sponsor: University of Colorado, Colorado Springs

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2024
• Primary Completion (Estimated): August 31, 2027
• Study Completion (Estimated): August 31, 2027

Study Registration Dates

• First Submitted: June 17, 2024
• First Submitted That Met QC Criteria: June 21, 2024
• First Posted (Actual): June 24, 2024

Study Record Updates

• Last Update Posted (Actual): May 1, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: menstrual cycle; functional hypothalamic amenorrhea; female athlete
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Menstruation Disturbances; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Beverages; Artificially Sweetened Beverages
• Other Study ID Numbers: FAST

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No