Healthy
Conditions
Keywords
exercise, women
Brief summary
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. We will also determine how these responses differ from males.
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. We will also determine if these responses differ from males. Female 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 and sex influences adaptations to training.
Interventions
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
Sponsors
University of Toronto
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
No
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 for females and greater than 39ml/kg/min for males) * 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 * Females only: 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)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Endurance performance | Before and after 2 weeks of exercise training | Time to completion and average power output during a 250kJ time trial |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Skeletal muscle mitochondrial content | Before and after 2 weeks of exercise training | Measured via Western blotting |
| Skeletal muscle mitochondrial enzyme activity | Before and after 2 weeks of exercise training | Measured via enzyme activity assays |
| Skeletal muscle capillarization | Before and after 2 weeks of exercise training | Measured via immunofluorescence |
| Skeletal muscle lipid content | Before and after 2 weeks of exercise training | Measured via immunofluorescence |
| Skeletal muscle protein synthesis | Before and after 2 weeks of exercise training | Measured via the incorporation of a stable isotope tracer during the 2 weeks of training |
| Cardiorespiratory fitness | Before and after 2 weeks of exercise training | Measured via a maximal exercise test on a cycle ergometer |
| Anaerobic exercise performance | Before and after 2 weeks of exercise training | Power output during a Wingate anaerobic test |
| Skeletal muscle carbohydrate and fat metabolism | Before and after training 2 weeks of training | measured via Western blotting |
| Fasting Insulin Resistance | Before and after 2 weeks of training | Measured via homoestatic model assessment (HOMA-IR) |
| Fasting plasma insulin | Before and after 2 weeks of training | measured via ELISA |
| Fasting plasma glucose | Before and after 2 weeks of training | measured via blood assay |
| Sex hormones (estrogen, progesterone, testosterone) | Before and after 2 weeks of training | measured via plasma assay |
Countries
Canada
Outcome results
None listed