Influence of Menstrual Cycle Phase on Adaptations to Sprint Interval Training

Influence of Menstrual Cycle Phase on Metabolic and Performance Adaptations to Sprint Interval Training

Sprint interval training improves endurance performance and induces metabolic adaptations in muscle. Most research demonstrating these responses has been conducted in males, with limited studies evaluating changes to endurance performance and skeletal muscle oxidative capacity in females. Moreover, it is currently unknown if training in specific phases of the menstrual cycle influences adaptations to training. Thus, the purpose of the present study is to compare adaptations to 2 weeks of sprint interval training performed in the follicular vs. luteal phase of the menstrual cycle in healthy, eumenorrheic women.

Study Overview

• Status: Recruiting
• Conditions: Healthy
• Intervention / Treatment: Other: Sprint Interval Training

Detailed Description

The primary purpose of the present study is to determine if menstrual cycle phase influences adaptations to 2 weeks of sprint interval training. Participants will be randomized to perform 6 sessions of sprint interval training over 2 weeks in either the Follicular Phase or Luteal Phase of their individual menstrual cycle. Blood and urine sampling will be used to confirm menstrual cycle phases. Training will involve 4-6 x 30-second Wingate sprints with 4 minutes of rest in between (~14-28 min per session). Before and after the training intervention, investigators will measure participant's aerobic and anaerobic performance, cardiorespiratory fitness and skeletal muscle outcomes. Performance and fitness measures are performed on on a stationary bike, and muscle outcomes are measured by taking a small amount of muscle from the vastus lateralis (thigh) muscle.

This study will advance knowledge on how the menstrual cycle influences adaptations to training in females

• Study Type: Interventional
• Enrollment (Estimated): 24
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jenna Gillen Assistant Professor, PhD; Phone Number: 4169783244; Email: jenna.gillen@utoronto.ca

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5S 2C9
      • Recruiting
      • Goldring Centre for High Performance Sport
      • Contact: Jenna Gillen; Phone Number: 4169783244; Email: jenna.gillen@utoronto.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Participating in 150 min of moderate-vigorous physical activity/week
• VO2peak of 'good' or above based on American College of Sport Medicine (ACSM) normative values(greater than 35.0ml/kg/min)
• Body mass index (BMI) between 18-27 kg/m2
• Performing 2-4 structured exercise sessions/week.
• Weight stable (within ± 2kg for at least 6 months)
• Non-smoker
• Menstrual cycle length of 27-35 days
• Minimal menstrual cycle length variability (less than 3 days)
• Ovulating monthly evidenced by a positive urinary luteinizing hormone surge
• Blood progesterone concentration greater than 16 nmol/L.

Exclusion Criteria:

• Hormonal contraceptive use within the last 3 months
• Polycystic ovarian syndrome (PCOS) or endometriosis
• Failure to meet MC verification criteria.
• Diagnosed with cardiovascular or metabolic disease, hyper- or hypogonadism, and/or PCOS
• The use of medication for managing blood glucose or lipid metabolism
• Current use of oral contraceptives or use within the last 3 months
• Irregular menstrual cycles (<27 days or >35 days)
• Pregnant or post-partum in the last 12 months, lactating or breast feeding within 3 months of the start of study, or menopausal
• Recreational smoking tobacco
• Inability to perform the study exercise protocols or follow the pre-trial dietary or physical activity controls
• Taking medications affecting substrate metabolism (corticosteroids or nSAIDs)
• Actively engaging in a low-carbohydrate diet (e.g., ketogenic, Atkins)

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
Active Comparator: Follicular Phase Training; Exercise training in the follicular phase (~days 1-14) of the participant's menstrual cycle	Other: Sprint Interval Training; 6 sessions of sprint interval training over 2 weeks. Each session involves 4-6 x 30 second Wingate sprints with 4 minutes of recovery in between on a stationary bike
Experimental: Luteal Phase Training; Exercise training in the luteal phase (~days 15-28) of the participant's menstrual cycle	Other: Sprint Interval Training; 6 sessions of sprint interval training over 2 weeks. Each session involves 4-6 x 30 second Wingate sprints with 4 minutes of recovery in between on a stationary bike

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Endurance performance	Time to completion and average power output during a 250kJ time trial	Before and after 2 weeks of exercise training

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Skeletal muscle mitochondrial content	Measured via Western blotting	Before and after 2 weeks of exercise training
Skeletal muscle mitochondrial enzyme activity	Measured via enzyme activity assays	Before and after 2 weeks of exercise training
Skeletal muscle capillarization	Measured via immunofluorescence	Before and after 2 weeks of exercise training
Skeletal muscle lipid content	Measured via immunofluorescence	Before and after 2 weeks of exercise training
Skeletal muscle protein synthesis	Measured via the incorporation of a stable isotope tracer during the 2 weeks of training	Before and after 2 weeks of exercise training
Cardiorespiratory fitness	Measured via a maximal exercise test on a cycle ergometer	Before and after 2 weeks of exercise training
Anaerobic exercise performance	Power output during a Wingate anaerobic test	Before and after 2 weeks of exercise training

Collaborators and Investigators

• Sponsor: University of Toronto

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2025
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026

Study Registration Dates

• First Submitted: December 16, 2024
• First Submitted That Met QC Criteria: December 16, 2024
• First Posted (Actual): December 20, 2024

Study Record Updates

• Last Update Posted (Actual): April 29, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: exercise; women
• Additional Relevant MeSH Terms: Behavior; Motor Activity; Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Physical Conditioning, Human; Exercise; High-Intensity Interval Training
• Other Study ID Numbers: HSREB50581

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