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Completed

NCT Number: NCT06074003

Does Biological Sex Influence Insulin Sensitivity and Muscle Metabolism Following High-intensity Interval Exercise?

High-intensity interval exercise (HIIE) is a type of exercise that involves alternating periods of intense exercise with periods of rest. HIIE has been shown to improve many aspects of cardiovascular and metabolic health in a time-efficient manner (e.g., only 20 minutes per exercise session). An important health benefit of exercise is improved blood sugar control, which can help reduce the risk of metabolic diseases like type 2 diabetes. A single session of HIIE has been shown to improve blood sugar in males, but it is unknown if females achieve the same health benefit. It is also not fully understood how exercise improves blood sugar in males and females. Therefore, the purpose of this project is 1) to determine if a single session of HIIE improves blood sugar control in males and females, and 2) to evaluate if changes in skeletal muscle can explain the beneficial effects of HIIE on blood sugar.

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Key information

Conditions

Exercise Behavior Motor Activity

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Goldring Centre for High Performance Sport

Toronto, Ontario, M5S2C9, Canada

About this study

The primary purpose of this study is to determine if biological sex influences the effects of high-intensity interval exercise (HIIE) on insulin sensitivity and muscle mechanisms. The investigators will measure insulin sensitivity and muscle outcomes of participants on two separate occasions: 1) Following 30 minutes of sitting in the lab; and 2) Following a single session of HIIE on a stationary bike. Insulin sensitivity will be measured by taking blood samples after participants consume a sugary drink. Muscle outcomes will be measured by taking a small amount of muscle from the vastus lateralis (thigh) muscle. Groups of male and female participants will be recruited and tested using best practice guidelines for sex-based comparisons of exercise responses.

The study will advance knowledge regarding the potential for biological sex to influence the metabolic responses high-intensity exercise.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 18-35 yrs
  • VO2peak considered recreationally active as defined as 'fair' or 'good' (males: 41.6- 50.5ml/kg/min; females: 35-41.9 ml/kg/min) based on Canadian Society for Exercise Physiology (CSEP) normative fitness values.
  • BMI between 18-27 kg/m2
  • 1-3 structured exercise sessions/week, and not training for any specific sport
  • Weight stable (within ± 2kg for at least 6 months)
  • Eumenorrheic (female only), defined as menstrual cycle lengths ≥ 21 days and ≤ 35 days resulting in 9 or more consecutive periods per year)
  • Non-smoker

Exclusion criteria

  • Diagnosed with cardiovascular or metabolic disease, hyper- or hypogonadism, and/or polycystic ovarian syndrome (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 (<21 days or >35 days)
  • Pregnant, lactating, or menopausal
  • Recreational smoking of any kind
  • 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)

Treatment and study plan

Seated Rest (Non-exercise control)

Other

Sitting for 30 minutes

High-Intensity Interval Exercise

Other

Performing a single session of high-intensity interval exercise on a cycle ergometer

Primary outcomes

  1. Insulin area under the curve

    Time frame: 3 hours

    Insulin area under the curve measured during glucose tolerance test

Secondary outcomes

  1. Glucose area under the curve

    Time frame: 3 hours

    Glucose area under the curve measured during glucose tolerance test

  2. Mean insulin concentration

    Time frame: 3 hours

    Mean insulin concentration measured during glucose tolerance test

  3. Mean glucose concentration

    Time frame: 3 hours

    Mean glucose concentration measured during glucose tolerance test

  4. Peak insulin concentration

    Time frame: 3 hours

    Peak insulin concentration measured during the glucose tolerance test

  5. Peak glucose concentration

    Time frame: 3 hours

    Peak insulin concentration measured during the glucose tolerance test

  6. Insulin:glucose ratio

    Time frame: 3 hours

    Insulin to glucose ration measured during the glucose tolerance test

  7. Postprandial glucose oxidation

    Time frame: 3 hours

    Postprandial glucose oxidation measured with a metabolic tracer

  8. Skeletal muscle glycogen content

    Time frame: immediately before and after exercise

    Muscle glycogen use during exercise

  9. Skeletal muscle contractile signaling protein content

    Time frame: immediately before and after exercise

    Measured via western blotting

  10. Skeletal muscle insulin signaling

    Time frame: 1hr into glucose tolerance test

    Measured via western blotting

  11. Mitochondrial gene expression

    Time frame: Change from pre-exercise to 3hr post-exercise

    Measured via Reverse transcription polymerase chain reaction

  12. Muscle protein synthesis rates

    Time frame: 3hr post-exercise

    Muscle protein synthesis rates assessed by incorporation of oral stable isotope tracer following exercise

  13. Local muscle oxygenation

    Time frame: During exercise

    Muscle oxygenation (vastus lateralis) assessed with near-infrared spectroscopy (NIRS)

  14. Local muscle oxygenation

    Time frame: Pre-exercise, immediately post-exercise and 2 hrs post-exercise

    Muscle oxygenation (vastus lateralis) assessed with NIRS during and following thigh cuff inflation

Sponsors and collaborators

Lead sponsor

University of Toronto

Other

Registry information

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Oct 10, 2023
Registry last updated
Aug 19, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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