Improving Individual Glycemic Response With Exercise Intensity (INTENSITY)

Large interindividual variability exists in the glycemic response to exercise program, resulting in a subset of individuals known as exercise non-responders (NRs). Increasing the intensity of an exercise intervention has been proposed as one method for rescuing NRs by producing beneficial changes. However, this theory has not been tested on NRs classified using glycemic outcomes. This study will evaluate if increasing the intensity of an exercise intervention will elicit a response within previous exercise NRs.

Exercise can effectively slow the progression towards Type 2 diabetes (T2D). However, data suggest large interindividual variability exists in glycemic response to exercise, resulting in a subset of individuals known as exercise non-responders (NRs). Emerging research proposes that altering the parameters of an exercise intervention to provide a sufficient stimulus can elicit a response in those previously identified as NRs. To date, no research has attempted to rescue previously classified NRs based on glycemic outcomes by altering the parameters of an exercise intervention. This study will implement an exercise program targeted at achieving the Canadian Physical Activity Guidelines, and calculate the number of NRs. We will then evaluate if increasing the intensity of exercise will elicit response to the treatment in the NRs. Sixty adults living with prediabetes or T2D will be recruited into one of a control group, or an exercise group. The exercising participants will begin a 16-week exercise intervention, targeted at achieving 150 minutes of moderate to vigorous intensity (equating to 4.5 METs) aerobic physical activity per week. Following the 16-week exercise program, participants will be randomized into two groups, each completing an additional 12 weeks of exercise. The first will maintain the same time and intensity, while the other will complete the 150 minutes per week at an intensity equal to 6.0 METs. Randomization will occur in blocks in order to ensure an equal number of NRs in each group.

Participants will first be randomized as controls or exercisers. All exercisers will complete a 16 week exercise program, then be randomized into two groups. The first group will increase the exercise intensity and conduct another 12 week program. The second group will continue the original program for an additional 12 weeks.

The primary purpose of the control participants are to provide a measure of variability. They will be used in our calculations of typical error to classify participants as responders or non-responders, and to quantify inter-individual variability.

The maintained exercise group will complete the original 16-week exercise intervention at an intensity of 4.5 metabolic equivalents (METs), and repeat the intervention for another 12-weeks following its completion.

The increased intensity exercise group will complete the original 16-week exercise intervention, followed by an additional 12 week intervention completed at an intensity of 6.0 METs.

Complete 28 weeks of aerobic exercise, with one week (following week 16) for testing. Week 1 - 16 Intensity: 4.5 metabolic equivalents (METs). Duration: Week 1: 80 minutes Week 2: 100 minutes Week 3: 120 minutes Week 4: 135 minutes Week 5 - 16: 150 minutes/week Week 17: Physiological Testing Week 18 - 29 Intensity: 4.5 METs Duration: 150 minutes/week All exercise must be completed across a minimum of two sessions per week. Sub-maximal exercise tests will be completed every 4 weeks to adjust intensity.

Complete 28 weeks of aerobic exercise, with one week (following week 16) for testing. Week 1 - 16 Intensity: 4.5 metabolic equivalents (METs). Duration: Week 1: 80 minutes Week 2: 100 minutes Week 3: 120 minutes Week 4: 135 minutes Week 5 - 16: 150 minutes/week Week 17: Physiological Testing Week 18 - 29 Intensity: 6.0 METs Duration: 150 minutes/week All exercise must be completed across a minimum of two sessions per week. Sub-maximal exercise tests will be completed every 4 weeks to adjust intensity.

The number of responders to the original 16-week exercise program, based on improvement in glycated hemoglobin

The number of responders following the additional 12-week exercise program, based on improvement in glycated hemoglobin

Weight (kilograms) and height (measured in centimetres and converted to metres) will be combined to report body mass index in kg/m^2

Inclusion criteria: Community-dwelling adults aged 19 years or older. Currently living with prediabetes or T2DM as diagnosed by a physician and confirmed by an HbA1c value of 5.7% or above, as verified by duplicate testing. Not currently partaking in a self-reported regular physical activity regimen, defined as consistent participation in running or jogging activity, attending physical activity or exercise classes on a weekly basis, or averaging 10,000 steps per day or more over the course of 7 days. Exclusion criteria: Self reported as currently diagnosed as having, or being treated for, low iron concentrations or anemia. Diagnosed with any red blood cell altering condition. Currently living with any cardiovascular disease which would impact the ability to safely participate in exercise training. Currently prescribed any medication which would impact the ability to use a heart rate monitor to accurately track exercise intensity.

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