Aerobic (cardiovascular) fitness is one of the most important components of physical fitness.The other components are muscular strength and endurance, and flexibility and low-back function. Cardiovascular fitness is measured as the amount of oxygen transported in the blood and pumped by the heart to the working muscles and as the efficiency of the muscles to use that oxygen. Increasing cardiovascular fitness means increasing the capability of the heart and the rest of the cardiovascular system in their most important task, to supply oxygen and energy to your body.
Having good cardiovascular fitness has many health benefits. For example, it decreases your risk of cardiovascular diseases, stroke, high blood pressure, diabetes and other diseases.
Cardiovascular fitness is best improved by activities, which employ large muscle groups working dynamically. Such activities include walking, jogging, running, swimming, skating, cycling, stair climbing and cross-country skiing.
The heart is like any other muscle - it becomes stronger and more efficient after practice. Heart rate is a quantitative measure of heart's work. At rest a healthy heart of an average individual beats approximately 70 beats per minute. A conditioned heart beats much less at rest, only 40 to 50 beats per minute or even less. Heart rate variability is a quality measure of heart's work. The lower the resting heart rate the higher the heart rate variability, and thus the better the quality of heart's functions.
Cardiovascular fitness is related to age, gender, exercise habits, heredity and cardiovascular clinical status. Maximum values occur between ages 15 and 30 years, decreasing progressively with age. At the age of 60, the mean maximal aerobic power in men is approximately three fourths of that at the age of 20. With sedentary lifestyle, there is a 10 % reduction in the mean maximal aerobic power per decade, the reduction with an active lifestyle being less than 5 %.