Calcium channel blockers are used to aggressively treat blood pressure disorders. This class of medication inhibits the movement of calcium into electrically excitable tissue, including cardiac and vascular smooth muscle cells. When you exercise, your body calls on the heart to increase its cardiac output as well as the pressure of blood being pumped. If you are taking a calcium channel blocker, talk to your doctor about how limited your cardiovascular exercise routine should be.
Heart Physiology
The heart is a homeostatic organ; it is able to adapt to the requirements of the body, though sometimes these changes can be pathologic. For instance, in the case of hypertension, or high blood pressure, the body is signaling to the heart that it requires more blood pumped to it at higher pressures. The heart responds by increasing the strength and volume of its contractions.
Electrical Activity of the Heart
Heart muscle cells, also known as cardiomyocytes, are inherently electrical tissues capable of generating action potentials, much like nerve cells in the brain. In the case of cardiomyocytes, however, the goal of generating an electrical impulse is to generate a contraction in the muscle fiber. One of the ions that your body has evolved to manipulate during cardiac contraction is calcium. Commonly represented as Ca++, calcium is a common ionic element in excitable, electrical tissues throughout the body. In the case of the heart, the movement of Ca++ ions is responsible for initiating the crosslinking and contraction of actin and myosin fibers -- the proteins that make your muscles move -- inside the cardiac muscle cell.
Effects of Calcium Channel Blockers
Calcium channel blockers primarily affect the function of cardiomyocytes and smooth muscle cells surrounding arteries. By blocking the influx of calcium into these two types of muscle, the drug decreases the pressure within your vascular system by relaxing the muscle cells in a process that is analogous to relaxing the walls of a pump and its pipes.
Applications in Elevated Heart Rate Exercise
It is important to understand that while taking calcium channel blockers, you have essentially placed a restriction on the ability of your heart and circulatory system to increase the pressure within your network of veins. If you exercise, it may be necessary for your body to increase its blood pressure in response in order to keep your cells properly supplied with energy and oxygen; however, while you are on the medication your heart will be restricted in its ability to respond and rise to the aerobic challenge.
References
- "Pathophysiology of Heart Disease"; Leonard Lilly; 2007
- MayoClinic.com: Calcium Channel Blockers
