Timing of exercise can affect results

By Brian Attebery

Published: September 23, 2008

It has been said that "timing is everything.” That statement applies to fitness in a major way.

Making time for exercise is the first example. Research indicates you are 90 percent more likely to complete your workout if you do it first thing in the morning. Makes sense, doesn't it? The alarm is the only thing between you and the gym. Otherwise, those late meetings and soccer practices eat up the rest of the day.

The morning crew at my fitness center is a lot more consistent than my evening crew. I can almost always count on the same people to arrive at the same time. My evening people have a greater swing in the times they show up.

Timing of exercise affects efficiency of exercise, too. Exercising first thing in the morning can kick-start your metabolism. If your primary goal is weight loss, try performing your aerobic exercise on an empty stomach. You will burn much more fat.

Let me explain. When we sleep, we fast. Our bodies will release hormones such as human growth hormone and glucagon. Although it is an important partner with insulin function, glucagon is basically the opposite of insulin in terms of function. Insulin is a storage hormone, involved with storing carbohydrates in the cells and liver as glycogen. Insulin also inhibits the release of fatty acids; in other words, it slows down fat burning.

Glucagon, on the other hand, helps the body make up fuel usage in the form of fatty acids as plasma levels of glucose drop. Insulin levels drop as plasma glucose drops, while glucagon elevates as plasma glucose levels drop. This increase in glucagon will cause the body to start using fat for energy as well as pull remaining carbs out of the liver for energy.

In other words, your body is already burning fat when you sleep due to running out of stored carbohydrates. So, this is the perfect time to pour gasoline on the fire by performing aerobic exercise. The body will use up stored carbohydrates in the form of glycogen when we first start our treadmill or other forms of aerobic activity. As time goes on, more and more fat cells will be called upon as the body runs out of glycogen. There is an inverse relationship. Imagine one tank goes down, while another one kicks in to make up for the loss of fuel. The body is going to burn more fat in the morning due to the state of fasting and the hormonal environment that is in effect.

In the evening, your body must burn through those carbohydrate stores first. Since you have been eating throughout the day, there is more to burn. Another train of thought is to exercise in the evening to help make up for the natural metabolism slowdown that occurs at night. I would agree with that theory, as well. The reality is that you can justify the timing of your exercise in many ways.

An addendum to the fasting exercise routine is to emphasize that I was talking about aerobic activity, not weight training. I don't recommend fasting before lifting weights. I also want to emphasize that this timing issue is geared toward fat burning, not sports performance, which is another topic. Most people who go to the gym go to lose fat and get into better shape. Breaking the land speed record is not the goal for most treadmill walkers. Most hope to burn fat and inches while they strengthen their cardiovascular system.

If you are stuck on your weight loss routine or hope to see it speed up, try a brisk walk or bike ride before breakfast three or four days a week and watch that fat melt off.

Remember that your diet the rest of the day is just as important to make the most of those early exercise bouts.

In other words, eating a doughnut after your exercise is not going to keep that fat-burning machine of yours busy burning fat. We only wish it were that easy.

Brian Attebery is a degreed and certified trainer. He owns and operates Results Fitness and Nutrition Center in Edmond. His Web site is www.resultsfitnessusa.com.

Comments