Every individual who initiates a cardiovascular or aerobic exercise program can expect a number of physiological adaptation that result from training. Among the benefits are:
1. An increase in the oxygen carrying capacity of the blood. As a result of training, there is an increase in the red blood cell count. Red blood cells contain hemoglobin, which transports oxygen in the blood.
2. A higher maximal oxygen uptake (max Vo2). The amount of oxygen the body is able to use during physical activity significantly increases. This allows the individual to exercise longer and at a higher rate before becoming fatigued. Depending on the initial fitness level, Max Vo2 may increase as much as 30 percent, although higher increases have been reported in people with very low initial levels of fitness.
3. A decrease in resting heart rate and an intense in cardiac muscle strength. During resting conditions, the heart ejects between five and six liters of blood per minute ( a liter is slightly larger than a quart). This amount of blood, also referred to as cardiac output meets the energy demands in the resting state. Like any other muscle, the heart responds to training by increasing in strength and size. As the heart gets stronger, the muscle can produce a more forceful contraction, which causes a greater ejection of blood with each beat (stroke volume), yielding a decreased heart rate. This reduction in heart rate also allows the heart to rest longer between beats.
Resting heart rates are frequently decreased by 10 to 20 beats per minute (bpm) after only six to eight weeks of training. A reduction of 20 bpm saves the heart about 10,483,200 beats per year. The average heart beats between 70 and 80 bpm. A highly trained athlete can have a resting heart rate of 45 bpm.
4. A lower heart rate at given works load. When compared with untrained individuals a trained person has a lower response to a given task. This is due to the increased efficiency of the cardiovascular system. Individuals are also surprised to find that following several weeks of training, a given workload (let’s say a 10-minute mile) elicits a much lower heart rate response as compared to the response when training first started.
5. An increase in the number and size of the mitochondria. All energy necessary for cell function is produced in the mitochondria. As the size and number, so does the potential to produce energy for muscular work.
to be continued…
Daryl Conant, M.Ed