Does Estrogen Blunt the Effects of Exercise Training on Glycemic Control

Previous research has found that males and females respond differently to exercise training, particularly with respect to improvements in blood sugar control and immune system health. This is crucial since insulin resistance, which can lead to type 2 diabetes and other health problems, affects millions of Canadians. People with insulin resistance often have higher inflammation. Exercise is known to improve insulin resistance and reduce inflammation, but females seem to benefit less from exercise compared to men. The investigators believe this difference might be due to estrogen, a hormone that helps regulate blood sugar (in non-exercising conditions) and reduce inflammation. Females have higher estrogen levels, which might explain their ability to regulate resting blood sugar control and also immune function at rest. Our research will investigate how estrogen influences the acute and chronic effects of exercise males. The investigators will study how estrogen influence's the body's response to exercise, particularly in terms of reducing inflammation and improving blood sugar levels as well as immune function. Overweight and obese males will undergo 2 weeks of high intensity interval training while taking either an estrogen supplement or placebo. Prior to and following training males will undergo an assessment of maximal fitness (VO2max test) and an oral glucose tolerance test. Prior to and following the acute exercise test blood samples will be taken to determine the acute effects of exercise on immune cell function and inflammation. Prior to and during the oral glucose tolerance test participants will have blood samples taken to determine glucose handling and insulin sensitivity. They will also have a muscle biopsy taken prior to and 1h into the oral glucose tolerance test to determine the effects of estrogen supplementation on insulin signaling, mitochondrial content and function, fat metabolism and fat storage in skeletal muscle.