Priming Exercise in Type 1 Diabetes (PET1D)

The Effects of Prior Exercise on Pulmonary Oxygen Uptake Kinetics and the Power-Duration Relationship in Type 1 Diabetes

Critical power is an important threshold in exercise physiology, and is an important determinant of the ability to tolerate high-intensity exercise. The ability to tolerate such exercise is drastically impaired in certain chronic conditions, such as type 1 diabetes. Whilst the most important physiological factors that determine critical power have yet to be determined, previous work from our laboratory suggests that it is related to the speed of oxygen uptake at the onset of exercise. This study will look to utilise "priming" exercise as an intervention to improve the speed of these oxygen uptake "kinetics", and thus critical power and exercise tolerance in individuals with type 1 diabetes. We hypothesize that oxygen uptake kinetics will be faster and critical power will be higher when exercise is performed with compared to without a prior bout of high-intensity priming exercise in a population of individuals with type 1 diabetes.

The ability to tolerate high-intensity exercise, or exercise tolerance, is a key factor that can influence clinical outcomes in a range of conditions. The "critical power" is an important physiological threshold that demarcates exercise intensities that can be sustained for prolonged periods (i.e. below critical power) from intensities that result in exhaustion in a relatively short period of time (i.e. 2-30 minutes, above critical power). Critical power is therefore a key determinant of exercise tolerance. The speed with which oxygen uptake rises at the onset of exercise (i.e. oxygen uptake "kinetics") has been shown by work from our laboratory to be a key determinant of critical power. One intervention that can acutely improve the oxygen uptake kinetics is the performance of a prior bout of high-intensity exercise, known as "priming exercise". Patients with type 1 diabetes have previously been shown to have impaired exercise tolerance compared to healthy controls. The performance of priming exercise therefore represents a potential intervention to acutely improve oxygen uptake kinetics, and therefore critical power and exercise tolerance, in type 1 diabetic individuals. The purpose of this study is therefore to assess the influence of priming exercise on oxygen uptake kinetics and critical power in a population of type 1 diabetic individuals.

Participants will serve as their own controls. Participants will alternate between "primed" (experimental condition) and "non-primed" (control condition) in their visits.

Participants will perform constant power output tests at four separate, fixed intensities to exhaustion on a cycle ergometer on separate days. These exhaustive, constant power tests will be preceded by 3 minutes of light cycling, 6 minutes of high intensity cycling, 7 minutes of rest and 3 minutes of light cycling.

Participants will perform constant power output tests at four separate, fixed intensities to exhaustion on a cycle ergometer on separate days. These exhaustive, constant power tests will be preceded by 3 minutes of light cycling only.

All participants will perform a bout of high-intensity "priming" exercise for 6 minutes, 10 minutes prior to undertaking an exhaustive exercise test on four separate occasions.

All participants will perform 3 minutes of baseline cycling prior to undertaking an exhaustive exercise test on four separate occasions.

The power asymptote of the hyperbolic relationship between power and the tolerable duration of exercise.

Curvature constant of the power-duration relationship. Finite work capacity available above critical power.

Inclusion Criteria: Suffering from Type 1 diabetes with a diagnosed disease duration of 2 - 20 years and no comorbidities. Exclusion Criteria: History of stroke, congestive heart failure, hypertension, or cardiopulmonary disease. Current smoking or have been smoking within the last 12 months Symptomatic autonomic or distal neuropathy HbA1c > 64 mmol/mol Hypoglycaemia unawareness in the last 6 months Taking any medications other than insulin.

Anonymized participant data will be made available to the public in the form of research presentations and a journal article. Anonymized individual participant data not featured in either the journal article or presentations will only be made available upon request to the authors.

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