Aerobic capacity of women
The maximum amount of oxygen debt is also relatively lower. In the process of individual development, anaerobic abilities develop in girls later than aerobic ones, and decrease in adulthood earlier. Aerobic abilities of women, estimated by the maximum oxygen consumption indicator, are on average 25-30% less than among men. Limited aerobic capabilities with an increase in work power lead to a faster transition of the female body to anaerobic energy production, which indicates a lower threshold for anaerobic metabolism. Up to 10-12 years, the BMD values for boys and girls are almost the same. A particularly rapid increase in the absolute value of BMD in girls is observed at the age of 9-14, further growth can occur only with systematic physical activity. The relative value of the IPC is growing to a lesser extent, and after 14–16 years it can decrease. A feature of the work of women under aerobic conditions is their higher ability to utilize fats in comparison with men. The reserves of fat in the female body are more significant. The total amount of adipose tissue in them is on average about 30% of body weight, and the absolute amount of fat is also greater. As you consume carbohydrate reserves during exercise, women who are engaged in fitness are more likely to switch to utilizing fatty energy sources. However, this means less economical use of oxygen and limits the performance of work related to oxygen deficiency.
Features of the size and composition of the body determine the specific features of the autonomic functions of the female body. Women’s breathing is characterized by lower volumes and lung capacities, higher frequency indicators. Vital lung capacity in women is less than in men by about 1000 ml. The depth of breathing both at rest and during work is less, and the frequency is higher. This determines the lower effectiveness of respiratory function in women. Minute breathing volume in women at rest is about 3-5 l / min., And during work it reaches 100 l / min. and more, accounting for approximately 80% of MOD in men. At the same time, an increase in MOD is achieved by a less favorable ratio of the frequency and depth of breathing and is accompanied by more pronounced fatigue of the respiratory muscles. Men are superior to women in absolute and relative values of maximum pulmonary ventilation. In the process of individual development, from the age of 7–8 years, girls begin the transition from the abdominal type of breathing to the chest type, which is fully formed by the age of 18. In the period from 10 to 14 years, boys begin to surpass girls in terms of growth of VC, MOD and MLV, absolute and relative values of BMD. In girls, the most noticeable increase in these indicators is observed at the age of 11 years. The maximum values are reached at 15 years, and after 35 years, their decline begins.
In the blood system of women, a higher hematopoietic function is noted, which ensures good tolerance to large blood losses and is one of the protective functions of the female body. With the same number of leukocytes and platelets in people of both sexes, the female body is characterized by a reduced number of red blood cells, hemoglobin and myoglobin. Less in women and the volume of circulating blood per 1 kg of body weight. A lower concentration of hemoglobin in the blood causes a lower oxygen capacity of the blood. Every 100 ml of arterial blood in women binds an average of 16.8 ml of oxygen, and in men – 19.5 ml. In this regard, during extreme aerobic exercise in women who are engaged in fitness, less oxygen enters the muscles from arterial blood. Insufficient oxygen supply to the muscles can lead to a pronounced oxidation of blood during work, especially in the submaximal power zone, while the blood pH decreases from 7.34 to 7.11. Such loads are difficult to tolerate by the female body, especially during puberty. The female heart is inferior to the male one in volume and mass. The absolute heart volume in non-fitness women is on average 580 cm, in those involved – 640–790 cm. Smaller volumes of the heart and its ventricles correspond to lower cardiac output. This is offset by a higher heart rate and a higher blood flow velocity. Systolic blood volume at rest is approximately 57 ml in women, and during work it rises to 120 ml or more. In practicing endurance women, the systolic volume is increased, which ensures an increase in the maximum value of cardiac output during work up to 140–160 ml. Minute blood volume in women is about 4 l / min. at rest. Its maximum increase is up to 25 l / min. observed when working in the submaximal and high power zone. A working increase in IOC is achieved in a less efficient way – by increasing the heart rate. The most significant increase in heart rate occurs in young girls. At rest, heart rate in women is about 72–78 beats / min. During endurance training, women developing bradycardia, but more pronounced than men.