When we exercise, especially when we want to lose weight, we make good use of the calories from food and grow stronger in the process. Without exercise, or living a sedentary lifestyle, those pesky energy units are stored away as extras in fat cells to be used as needed. Pesky? Definitely, if we fail to balance calorie intake with expenditure.
You see, our body remembers a time far away from modern life. When people went on foot or hunted with the wolves. Obesity wasn’t a problem then as it is today and energy storage was vital for the survival of early humans.
But even when we are eating healthy foods, our body more often than not has calories to spare as we don’t move as much or do physically demanding work.
Simply put, if we are not exercising, even healthy eating plus office work can lead to excessive body fat.
Knowing how your body utilizes energy can help you understand different activities and exercise routines.
Three different fuel sources the body uses for energy
The Immediate Energy System:
- Breaks down ATP (adenosine triphosphate) already stored in cells and uses CP (creatine phosphate) to quickly make more [tag]ATP if needed. CP is available only for a few seconds.
- Feeds energy to muscles rapidly, lasting about 10 seconds
- Exercise: lifting a heavy weight, getting up off a chair, jump aside, picking up a child
- Oxygen: Not used during activity
The Anaerobic (Nonoxidative) Energy System
- Makes a great amount of ATP (adenosine triphosphate) by breaking down glucose, a simple sugar, and glycogen, a complex carbohydrate, stored in the liver or skeletal muscles
- Feeds energy to muscles rapidly
- High intensity activity, lasting about 10 seconds to 2 minutes
- Exercise: Fast, short run up the hill, running up flights of stairs, 400 meter sprint
- Oxygen: Not used during activity
The Aerobic (Oxidative) Energy System
- Needs oxygen to make ATP (adenosine triphosphate) and takes place in cellular structure, the mitochondria. It uses body stored glucose, glycogen, fat and protein
- Feeds energy slowly to muscles over longer periods of time
- Low to moderately high intensity, activity lasting more than 2 minutes
- Exercise: long 30 minute walk, 2 mile run, bike riding, swimming
- Oxygen: Yes
- Fuel consumption depends on the intensity of the workout and how fit a person is
Conclusion: When we exercise, we are likely to use all three energy systems. Which system kicks in depends on the intensity and length of time you exercise. Good example would be interval training. You start running slowly, then run as fast as you can for up to 10 seconds to 2 minutes up a hill, then the immediate and nonoxidative system takes over because the oxidative system can’t supply fuel to the muscles fast enough.
Technorati Tags: calories, exercise routines, Anaerobic, Aerobic
