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The primary aim of this study is to compare the acute glycemic effects of two novel, alternative physical activity (PA) strategies (dispersed post-meal PA, PA snacks) to a no PA condition and to exercise sessions representing the PA guidelines (standard 30-minute walking bout performed under fasting and under postprandial conditions and a standard 30-minute resistance training session) among sedentary breast cancer survivors who are currently receiving hormone therapies and age- and BMI-matched postmenopausal women without a history of cancer. The secondary aim is to determine whether the alternative PA strategies are acceptable and feasible in the free-living setting. An exploratory aim is to determine whether the outcomes differ between women with and without a history of breast cancer and use of aromatase inhibitors.
The investigators hypothesize that:
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Standard Physical Activity - Fasted | Experimental | Participants will perform 30 minutes of walking at a self-selected pace 15 minutes prior to consumption of first meal in the morning (including cream/sugar/milk in coffee or tea). |
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| Standard Physical Activity - Post-Meal | Experimental | Participants will perform 30 minutes of walking at a self-selected pace 30 minutes after the start of the first meal in the morning. |
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| Dispersed Physical Activity | Experimental | Participants will perform 10 minutes of walking at a self-selected pace 30 minutes after the start of each main meal throughout the day (i.e., three bouts total). |
|
| Physical Activity Snacks | Experimental | Participants will perform 2 minutes of walking or marching on the spot at a self-selected pace every 30 minutes throughout the day for 7.5 waking hours. |
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| Muscle Strengthening | Experimental | Participants will perform 30 minutes of muscle strengthening exercises targeting the major muscle groups of the whole body performed by following along with a video, to start 30 minutes after the start of the first meal in the morning. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Standard Physical Activity - Fasted | Behavioral | 30 minutes of walking at a self-selected pace that they must have completed 15 minutes prior to consumption of first meal in the morning. |
| Measure | Description | Time Frame |
|---|---|---|
| 24-hour glucose incremental area under the curve (iAUC) | Assessed for each single-day intervention using a continuous glucose monitor from 8:00 am to the intervention day to 8:00 am the following morning. | Baseline, 24 hours of each intervention day |
| Measure | Description | Time Frame |
|---|---|---|
| 24-hour mean glucose | Assessed for each single-day intervention using a continuous glucose monitor from 8:00 am to the intervention day to 8:00 am the following morning. | Baseline, 24 hours of each intervention day |
| Postprandial iAUC |
| Measure | Description | Time Frame |
|---|---|---|
| Physical activity | Participants will be asked to wear a Garmin smartwatch for the duration of the study to track completion of physical activity bouts and heart rate during each bout for each single-day intervention | 24 hours of each intervention day |
| Systolic and Diastolic Blood Pressure |
Inclusion Criteria:
Postmenopausal biological females diagnosed with stage I, II, or III breast cancer and currently using aromatase inhibitors (AI) for at least 3 months prior to start of study participation
All participants must meet the following criteria:
Exclusion Criteria:
If unable or unwilling to receive medical clearance by a physician after being screened for major signs or symptoms of cardiovascular diseases, diabetes, or renal disease and safety to initiate exercise.
Using drugs for diabetes management (e.g., exogenous insulin, Ozempic, metformin, etc.) or actively losing weight (i.e., >5 kg weight loss in past 3 months) from drugs or other reasons
Report any injury or other reason for not feeling capable of completing a 30 minute continuous walk or muscle strengthening exercise
Unable to access an Ontario Lifelabs location for an overnight fasted blood draw
Do not have a smartphone compatible with the applications required to collect data.
Cannot read and understand the consent form or communicate in English.
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Amy A Kirkham, PhD | Contact | 416-946-4069 | amy.kirkham@utoronto.ca | |
| Jenna B Gillen, PhD | Contact | 416-978-3244 | jenna.gillen@utoronto.ca |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Remote Ontario-wide | Recruiting | Toronto | Ontario | Canada |
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5-arm randomized crossover trial
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| Standard Physical Activity - Post-Meal | Behavioral | 30 minutes of walking at a self-selected pace to start 30 minutes after the start of the first meal in the morning. |
|
| Dispersed Physical Activity | Behavioral | 10 minutes of walking at a self-selected pace to start 30 minutes after the start of each main meal throughout the day (i.e., three bouts total). |
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| Physical Activity Snacks | Behavioral | 2 minutes of walking or marching on the spot at a self-selected pace every 30 minutes throughout the day for 7.5 waking hours. |
|
| Muscle Strengthening | Behavioral | 30 minutes of muscle strengthening exercises targeting the major muscle groups of the whole body, to start 30 minutes after the start of the first meal in the morning. |
|
Assessed for each single-day intervention using a continuous glucose monitor for two hours following each meal.
| Baseline, 24 hours of each intervention day |
| Peak postprandial glucose | Assessed as the highest glucose concentration during the 2 hours following each meal using a continuous glucose monitor. | Baseline, 24 hours of each intervention day |
| Daytime glucose concentration | Assessed for each single-day intervention using a continuous glucose monitor from 6:00 am to 12:00 am on the intervention day. | Baseline, 24 hours of each intervention day |
| Nocturnal glucose concentration | Assessed for each single-day intervention using a continuous glucose monitor from 12:00 am to 6:00 am on the intervention day. | Baseline, 24 hours of each intervention day |
| Time in hypoglycemia | Assessed as the number of hours with glucose less than 3.9 mmol/L using a continuous glucose monitor. | Baseline, 24 hours of each intervention day |
| Time in hyperglycemia | Assessed as the number of hours with glucose greater than 10 mmol/L using a continuous glucose monitor. | Baseline, 24 hours of each intervention day |
| Indices of glycemic variability | Indices include standard deviation, coefficient of variation, mean amplitude of glycemic excursion, and continuous overall net glycemic action | Baseline, 24 hours of each intervention day |
| Participant acceptability | Acceptability related to participants' experience with each single-day intervention will be assessed using a researcher-developed questionnaire at the end of each intervention day. Seven items use a 5-point Likert scale with responses ranging from "Strongly Disagree" to "Strongly Agree", while four items ask about participant confidence with responses ranging from 0 ("Not Confident") to 10 ("Very Confident). A higher total score indicates the intervention is more acceptable to the participant. | 24 hours of each intervention day |
| Participant enjoyment | Enjoyment related to participants' experience with each single-day intervention will be assessed using the short form of the Physical Activity Enjoyment Scale at the end of each intervention day, consisting of 8 items each scored on a 7-point Likert scale, with the total score ranging from 8 to 56, and a higher total score indicating greater enjoyment. | 24 hours of each intervention day |
Measured as the average of the last 5 of 6 systolic and diastolic blood pressure measurements using an automatic blood pressure device. |
| Baseline |
| Waist circumference | Circumference of the waist measured using an inelastic tape | Baseline |
| Body mass index (BMI) | Calculated using self-reported body weight and height. | Baseline |
| Fasting glucose | Analyzed from fasted (overnight, 12 hours) venipuncture performed and processed at any Lifelabs location of participant's choice. | Baseline |
| Fasting insulin | Analyzed from fasted (overnight, 12 hours) venipuncture performed and processed at any Lifelabs location of participant's choice. | Baseline |
| Lipid profile: HDL, LDL, total cholesterol, triglycerides | Analyzed from fasted (overnight, 12 hours) venipuncture performed and processed at any Lifelabs location of participant's choice. | Baseline |
| Hemoglobin A1c | Analyzed from fasted (overnight, 12 hours) venipuncture performed and processed at any Lifelabs location of participant's choice. | Baseline |
| Metabolic syndrome | Determined based on standardized criteria using previously specified outcomes. | Baseline |
| Framingham 10-year cardiovascular disease risk score | Calculated via a standardized scoring algorithm using previously specified outcomes, with total scores ranging from less than -3 (indicating <1% 10-year risk of cardiovascular disease) to more than 21 (indicating >30% 10-year risk of cardiovascular disease). | Baseline |
| Dietary intake | Various components of dietary intake including macronutrients and micronutrients will be assessed through 1-day food record on a weekday collected using ASA-24 online system. | Baseline |
| Perceived stress | Assessed using a researcher-developed visual analog scale (0-100, with a higher value indicating greater perceived stress) at the start of each intervention day. | Prior to start of each intervention |
| Muscle soreness | Assessed using a researcher-developed visual analog scale (0-100, with a higher value indicating greater muscle soreness) at the start of each intervention day. | Prior to start of each intervention |
| Sleep quantity and quality | Measured via Garmin smartwatch for the total sleep duration and efficiency. | Baseline, 24 hours of each intervention day |
| ID | Term |
|---|---|
| D001943 | Breast Neoplasms |
| D007333 | Insulin Resistance |
| D009043 | Motor Activity |
| ID | Term |
|---|---|
| D009371 | Neoplasms by Site |
| D009369 | Neoplasms |
| D001941 | Breast Diseases |
| D012871 | Skin Diseases |
| D017437 | Skin and Connective Tissue Diseases |
| D006946 | Hyperinsulinism |
| D044882 | Glucose Metabolism Disorders |
| D008659 | Metabolic Diseases |
| D009750 | Nutritional and Metabolic Diseases |
| D001519 | Behavior |
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