Understanding Exercise: Metabolism
Every time you move, your body uses a form of energy to make that happen. Energy originally comes from the food you eat. The two main nutrients we use for energy are carbohydrates and fat. Protein is used to repair and create new muscle tissue rather being used as a form of true energy. Your body breaks down your food into two types of energy: “right now energy” and “save some for later energy.”
- Right now: Glucose
- Save for Later: Glycogen (a long strand of glucose stored in your muscles and liver)
- Right now: Fatty Acids
- Save for Later: Triglycerides (a strand of three fatty acids stored mostly in your fat cells, but also in muscle)
Your body uses different metabolism cycles to break down these energy forms and make them into ATP (the active form of energy). Carbohydrate metabolism works very quickly, but fat metabolism can take awhile to get started. The type and duration of exercise determines what energy form you’ll burn more.
When you first start exercising, your body uses the quickest form of energy – carbohydrates. Glucose and glycogen stores are great for about the first 20 minutes of exercise. After twenty minutes, your glucose starts dwindling and your body needs to tap into a bigger storage of energy on your body: your fat.
Here’s a graph explaining duration of exercise and type of energy metabolism:
This graph would indicate that the longer you exercised (for one bout) the more fat you would burn.
One way to assess your intensity of exercise is by monitoring your breathing. For longer exercise periods, you want to stay at an intensity where you are still able to talk. When you become so out of breath that talking becomes difficult, you’re probably exercising at too high of an intensity. Slow down.
However, if you’re “exercising” and still able to sing a song, then you’re probably not exercising hard enough.
Here’s a graph explaining how exercise intensity affects your fat metabolism…
This graph would indicate that if you exercised at a medium to low intensity, you would burn more calories from fat.
The After Burn
Don’t forget that no matter what type, duration, or intensity of exercise you do, you’ll always have an increased metabolism for about 24 hours afterwards. This increase in your metabolism refills the glycogen and fatty acid stores in all of your muscles that were depleted by the bout of exercise.
Start somewhere reasonable and work your way up to a longer duration. Remember, if you’re wanting to work out aerobically (with air/oxygen) you’ll need to set a pace that you can still talk during exercise.
If you’re wanting to burn more fat with your exercise regimen…
- Any exercise at all will increase your metabolism
- Longer duration (20-120 minutes) gives you the highest fat burn
- Lower intensity (medium to easy) burns more fat than carbohydrates.
Questions? Leave a comment and I’ll try to answer it for you. :)