Molecular Signature of Inactivity Induced Exercise Responsiveness

Overview

Fitness is one of the best predictors for heart and brain disease. To increase ones fitness, the American Heart Association (AHA) says to exercise at least 150 minutes per week or 75 minutes per week if really hard. These exercise guides are pretty effective, however not everyone will get the same results. What individuals do outside of the exercise bout can influence the effectiveness of exercise. One of these factors is our time sitting, which has caused the phrase "sitting is the new smoking". Other studies have said that the metabolic benefits of exercise are decreased when you exercise after a few days of low activity (less than 5,000 steps per day). This is important in that exercise may not be able to fully offset these times of inactivity. However, these studies were only looking at different fats in the blood. As exercise increases fat burn up to 10 times in the muscle, more research is needed to understand how inactivity affects the muscle during exercise and after exercise. This study will help answer two questions: 1) How does a day of sitting a lot affect the muscle's ability to respond to exercise? and 2) How does a day of sitting a lot affect carbohydrate and fat burn during and after a bout of exercise? The investigators will answer these questions by having people complete one day of inactivity (less than 5,000 steps) or normal activity (more than 8,500 steps). Subjects will then come in the next day to bike somewhat hard for 1 hour. The investigators will take blood samples before, during, and after exercise to measure energy sources. The investigators will also collect pieces of skeletal muscle before and after exercise to see how the muscle responded to exercise. This study is significant for the publication of exercise guidelines to minimize risk of heart and metabolic diseases.