Timing of Energy Availability on Menstrual Cycle Function

NCT06471582 | Recruiting

• 1 other identifier: FAST
• Study Type: interventional
• Target: 64
• Locations: 1 country
• Sites: 1

Brief Summary

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

Conditions

Menstrual Irregularity

Keywords

functional hypothalamic amenorrhea; menstrual cycle; female athlete

Outcome Measures

Primary Outcomes (4)

• 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 Outcomes (2)

• Salivary cortisol

  3 days

• Salivary leptin

  3 days

Study Arms (2)

Fed with Carbohydrates

EXPERIMENTAL

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

Fasted without Carbohydrates

PLACEBO COMPARATOR

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

Interventions

Artificially Sweetened Carbohydrate Beverage DIETARY_SUPPLEMENT

Beverage containing 0.7 g carbohydrate/ kg body mass/ h as a 2:1 mixture of glucose and fructose and artificial sweetener

Fed with Carbohydrates

Artificially Sweetened Beverage DIETARY_SUPPLEMENT

Beverage containing no carbohydrates or kilocalories and an artificial sweetener

Fasted without Carbohydrates

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• University of Colorado, Colorado Springs: lead

Study Sites (1)

William J. Hybl Sports Medicine and Performance Center

Colorado Springs, Colorado, 80918, United States

RECRUITING

MeSH Terms

Conditions

Menstruation Disturbances

Interventions

Artificially Sweetened Beverages

Condition Hierarchy (Ancestors)

Pathologic Processes; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Beverages; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages

Central Study Contacts

Marissa Baranauskas, PhD

CONTACT

719-255-4475; mbaranau@uccs.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: June 17, 2024
• First Posted: June 24, 2024
• Study Start: August 1, 2024
• Primary Completion (Estimated): August 31, 2027
• Study Completion (Estimated): August 31, 2027
• Last Updated: May 1, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)