Exercise Frequency During Endurance Training: Cardiorespiratory, Hematological, and Muscle Oxidative Adaptations
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- University of Calgary
- Enrollment
- 30
- Locations
- 1
- Primary Endpoint
- Change from baseline maximal oxygen uptake (VO2max) after 8 weeks of training
Study Overview
Brief Summary
The goal of this interventional study is to compare training for different numbers of days each week in healthy, young individuals. The main questions it aims to answer are:
- Does exercising less often improve endurance fitness as much as exercising more often?
- Are endurance fitness improvements caused by improvements in the muscle and blood?
Participants will train on a stationary bike for eight weeks. Researchers will measure the participants endurance fitness, as well as muscle and blood characteristics, before and after training to look for improvements from the training protocols.
Researchers will compare low-frequency exercise (two times per week) and high-frequency exercise (four times per week) to see if they each improve endurance fitness.
Detailed Description
Questions and Hypotheses:
The primary research question of this study is "Does exercising less frequently lead to improvements in aerobic fitness that are not worse than the improvements from exercising more frequently, when total exercise volume and exercise intensity are matched?" The secondary research questions of this study are: "Does exercising less frequently lead to similar improvements in hemoglobin mass, neuromuscular fatigue resistance, and skeletal muscle oxidative capacity compared to exercising more frequently, when total exercise volume and exercise intensity are matched?" The investigators hypothesize that the "weekend warrior" training program will induce improvements in cardiorespiratory fitness that are not worse than the improvements elicited by the standard training protocol. The investigators hypothesize that these improvements will be driven by similar improvements in markers of skeletal muscle mitochondrial content, and hemoglobin mass, and neuromuscular fatigue resistance between both training protocols.
Study Design and Methods:
32 participants total (16 female, 16 male; 8 per sex per group) will be randomized to either the low- or high-frequency training groups and will undergo physiological testing at baseline, after 4 weeks, and after 8 weeks of training. The sample size of 32 was calculated based on an alpha of 0.05, a power of 0.90, a group allocation ratio of 1:1, and a dropout rate of 20%. As this study is using non-inferiority testing, the investigators also set the allowable difference to 0 (the null hypothesis), the standard deviation for change in the primary outcome to 3 (based on data from a recently completed study), and the non-inferiority margin to 3.5 mL/kg/min, which is equivalent to 1 metabolic equivalent of task unit (MET), a standard unit for assessing cardiorespiratory fitness that is often considered to have clinical significance.
The low- and high-frequency groups will perform exercise two or four days per week, respectively. The intensity and duration of training sessions will increase throughout the study to ensure the training stimulus is maintained as participants become fitter. Training intensities will be individualized based on exercise testing.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Basic Science
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 40 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •provide written informed consent
- •complete and pass the Get Active Questionnaire (GAQ), a physical activity readiness screening tool
Exclusion Criteria
- •classified as obese (BMI > 30 kg/m^2)
- •taking medications that are known to affect cardiovascular and/or metabolic responses to exercise (including but not limited to beta-blockers, anti-inflammatories, anti-coagulants, insulin, etc.)
- •dieting for weight loss or following a low carbohydrate diet
- •smoking or using tobacco products within the previous year
- •consuming excessive amounts of alcohol (>21 units/week)
- •having known health problems such as renal or gastrointestinal disorders, metabolic disease, heart disease, vascular disease, arthritis, diabetes, respiratory disease, uncontrolled blood pressure, dizziness, thyroid problems, or any other health conditions that may confound results
- •having orthopedic issues that limit exercise performance
- •using an investigational drug product within the last 30 days
- •are pregnant
- •have donated blood in the previous 90 days
- •being highly trained or engaging in training more than 4 times per week
- •do not understand English
Arms & Interventions
Low-Frequency Training
Exercise performed on a stationary bike two times per week. Total weekly exercise volume (the product of intensity, duration, and frequency) will be matched between groups. Intensity will be the same, so the low-frequency group will perform double the duration of exercise in each session compared to the high-frequency group.
Intervention: Low Frequency Exercise Training (Other)
High-Frequency Training
Exercise performed on a stationary bike four times per week. Total weekly exercise volume (the product of intensity, duration, and frequency) will be matched between groups. Intensity will be the same, so the high-frequency group will perform half the duration of exercise in each session compared to the low-frequency group.
Intervention: High Frequency Exercise Training (Other)
Outcomes
Primary Outcomes
Change from baseline maximal oxygen uptake (VO2max) after 8 weeks of training
Time Frame: 8 weeks
Change in maximal oxygen uptake determined using an incremental exercise test on a cycle ergometer, measured after 8 weeks of training relative to baseline
Secondary Outcomes
- Change from baseline near-infrared spectroscopy (NIRS)-derived oxidative capacity of the vastus lateralis muscle after 8 weeks of training(8 weeks)
- Change in quadriceps maximal voluntary contraction (MVC) force decline in response to the same absolute exercise task, after 8 weeks of training(8 weeks)
- Change in quadriceps maximal voluntary contraction (MVC) force decline in response to the same relative exercise task, after 8 weeks of training(8 weeks)
- Change from baseline hemoglobin mass after 8 weeks of training(8 weeks)
- Change from baseline peak power output after 8 weeks of training(8 weeks)
- Change from baseline gas exchange threshold after 8 weeks of training(8 weeks)
- Change from baseline respiratory compensation point after 8 weeks of training(8 weeks)
- Change in time to task failure after 8 weeks of training(8 weeks)
Investigators
Tom Tripp
Principal Investigator
University of Calgary