Beginning an exercise program can be daunting, especially when the routine of exercise is new to you. Not only does regular exercise take time out of your day, but the fatigue and muscle burn you feel during exercise and the soreness afterward can be hard to handle at first. Many times, the tough experience of a new exercise program may tempt you to give up. However, if you know what is really happening in your body, you may want to hang in there a bit longer. Exercise can change your body for the better, at the cellular level, and that can eventually affect your appearance and the way you feel.
Muscular Adaptations
During cardiovascular and resistance exercise, your muscles are put under stress, especially if your body is performing activities it does not normally do. Your muscles adapt to the exercises you perform to become stronger, enabling them to handle heavier work and perform at a higher level. People who have more fast-twitch fibers tend to gain strength faster, and should see a quick increase in muscle size and strength. Those who have more slow-twitch fibers, which give them a tendency for developing endurance, should see an improvement in their stamina during cardiovascular exercise. These changes are aided by the presence of mitochondria, organelles that generate energy for your cells.
Cardiovascular and Respiratory Adaptations
When you exercise, your heart beats faster and you breathe harder. This is the body's normal way to get oxygen to the working muscles and to bring unwanted carbon dioxide back to the lungs for exhalation. If you begin exercising regularly, there are a few things that will become more efficient. Your stroke volume, or the amount of blood that is pumped out of your heart during one beat, will increase. This is a result of your heart's becoming stronger. Additionally, the number of red blood cells in your body increases, which improves your body's ability to transport oxygen to your working muscles and cells. The efficiency of the exchange of oxygen for carbon dioxide waste will increase at the cellular level. With these gained efficiencies, your resting heart rate will slow and your heart will not have to work as hard.
Neural Adaptations
If you have just begun an exercise program, you may have encountered an increase in strength without seeing any change in your muscular structure. This is because your nervous system has a lot to do with your initial increase in strength. This occurs because exercise increases the efficiency of messages traveling from your central nervous system to your muscle and joint fibers, called neural drive. This can make movement more efficient and help prevent injury.
Metabolic Adaptations
When you begin exercise, your metabolic rate rises to keep up with your pace. After exercise, your metabolism falls back to its original point slowly, helping you to burn extra calories even after you stop exercising. Your resting metabolism will stay elevated above its resting rate for about 12 to 24 hours, if your exercise is prolonged and at a high-intensity level. Even if you are just starting out, you will experience small residual increases in your metabolism after exercise that can aid in weight loss. Adding muscle mass will also increase your metabolism, as lean muscle mass keeps burning fat all day.
References
- Encyclopedia of Sports Medicine and Science; "Adaptation to Exercise: Progressive Resistance Exercise"; Thomas Fahey; 1998
- Centers for Disease Control and Prevention; "Physical Activity and Health: A Report of the Surgeon General"; 1999
- TeachPE: Long-Term Effects of Exercise
- Sports Medicine; "Neural Adaptations to Resistive Exercise: Mechanisms and Recommendations for Training Practices"; D.A. Gabriel et. al.; 2006.
