Effects of Different ''Exercise Snacking'' Modalities on Glycemic Control in Patients With Type 2 Diabetes

Patients with type 2 diabetes (T2DM) face an increased risk of obesity, hypertension, and hyperglycemia, attributed to impaired cardiorespiratory fitness, elevated Hb1AC levels, and impaired lipid status. Therefore, effective prevention of complications and T2DM-related diseases is crucial for increasing the life expectancy of T2DM patients. Regular exercise plays a crucial role in the prevention and management of diabetes and its associated complications. However, most T2DM patients are not engaged in exercise. The most common causes are a lack of time, monotonous training patterns, and the severe exhaustion patients experience after recently developed and effective HIIT and SIT programs. Therefore, recent studies have explored the concept of "exercise snacking" (brief isolated bouts (\< 1 min) of intense exercise spread throughout the day

) as a promising strategy to improve glycemic control, functional capacity, and cardiometabolic health among clinical and healthy populations. However, the type, intensity, and volume of exercise bouts that result in the best improvement are unknown. Therefore, we hypothesize that these exercise modalities may also acutely improve glycaemic control in sedentary overweight patients with T2DM.

1. This study will examine the acute impact of two modalities of ''Exercise Snacking'', compared with a no-exercise control (CON), on glycemic control and blood pressure
2. Compare the acute effects of two ''Exercise Snacking'' modalities
3. Collect data on individuals' perceptions of each workout mode using measures of Rate of Perceived Exertion (RPE), enjoyment, affect, and adverse events

A randomized crossover design will be used for the acute effects study.

Prior to the experimental protocols, participants will be asked to come to the lab on four separate days, which will be scheduled to meet individual schedules.

Day one An electrocardiography stress test (ECG) test will be performed to assess if participants could enroll in the study. The test will be conducted, monitored, and reviewed by a Cardiologist and written approval will be necessary for further inclusion in the study. Moreover, during the first visit a continuous glucose monitoring (iCGM) device - will be inserted on the participant's non-dominant upper arm according to the manual guidelines. The accuracy of the iCGM devices will be validated using capillary vs interstitial iCGM measurements.

Day two The participants will be tested for anthropometric characteristics (height), and body composition. This procedure is necessary to determine the BMI most validly. All tests will be conducted in the laboratory of the Faculty of Sports and Physical Education.

Day three The maximal incremental test on the cycle ergometer will be used to determine the cardiorespiratory fitness level (VO2max, VO2peak) as well as the resting heart rate (HRrest), maximum HR (HRmax), and HR recovery (HRRTEST). These parameters, primarily HRmax will be crucial when implementing the intensity of the session which will not be done in an ''all effort'' manner. Participants will be familiarized with wearing the heart rate monitors and using the rating of perceived exertion scale (RPE) too. Briefly, after a 5-minute warm-up at 50 W, the intensity will be increased by 15 W/min until the tempo can no longer be maintained at 50 rpm. Cardiorespiratory fitness will be measured using an online gas analysis system (Cosmed Quark; CPET, Rome, Italy), VO2peak will be determined as the highest ten-breath rolling average and accepted if two or more of the following criteria were met: (1) voluntary exhaustion, (2) a plateau in VO2 despite increasing intensity; (3) maximal heart rate within 10 beats of the age-predicted maximum. This protocol already has been used in patients with T2DM.

Day four On the fourth day, the familiarization process will be conducted. Briefly, participants will be given the opportunity to try on the exercise sessions that we will use in the main protocols.

Main experimental protocols Before each trial participants will be asked to avoid any strenuous exercise at least for 72 hours. After 7 days of baseline assessment, participants will come to the laboratory. Each of these trials will be separated by at least 5-7 days. Before and after each protocol blood glucose levels (SBP and DPB) will be measured, as well as RPE, enjoyment, affect, and adverse events using the standardized questionaries and rating scales. Moreover, HR will be measured continuously during each exercise session.

1. Participants will come to the laboratory three times a day and the protocols will not last longer than half an hour. Therefore, after a short-term warm-up on the cycle ergometer (5 minutes, the intensity was determined by the participants themselves), short-term, intense bouts of cycling 6x1 minute at 90% HR max with a minute of active break between bouts will be performed (at 50 W). Recovery will last 3 minutes, also at the self-paced. The whole process will be repeated two more times during the day with intervals of 1-4 hours
2. For the SS group, training will consist of three separate sprints on the cycle ergometer separated by 1-4 h. The SS exercise bouts will consist of a 2-minute warm-up followed by a 20-s sprint and then a 1-minute cooldown (three separate workout sessions each lasting 3 min 20 s). The warm-up, cooldown, and recovery periods will all be performed at 50 W. Each sprint will be performed at a resistance of 0.21 N m/kg and include a 10-s period when participants will be advised to accelerate the number of rpm as fast as possible.
3. Control - During CON, participants will come to the lab and remain sedentary throughout this entire period.

Eligibility Criteria:
Inclusion Criteria:

* 18-45 years old patients who have been diagnosed with Type 2 diabetes at least 3 months prior to the start of the study according to standard criteria
* BMI between 25 and 35 kg/m2 Inactive patients according to the International Physical Activity Questionnaire
* patients receiving medical therapy (no more than two medications) and not undergoing exogenous insulin therapy
* patients free of injuries and without any contraindications to exercise or chronic diseases that might be disruptive with vigorous activity
* patients should be stable on their current diabetes medications, with no recent changes in their treatment regimen

Exclusion Criteria:

* patients undergoing exogenous insulin therapy or/and receiving more than two glucose-lowering medicaments
* highly physically active on the International Physical Activity Questionnaire (IPAQ)
* patients suffering from any of the ''end-stage'' chronic diseases including: renal disease, liver disease, neuropathy, cardiovascular diseases uncontrolled hypertension
* patients who are strictly prohibited by medical professionals from engaging in vigorous exercise