To build endurance, you don’t have to spend hours of your daily life training and doing intense exercises. HIIT is a great way for building endurance since it focuses on the major endurance-building points in the body.

One of the main elements of endurance is cardiovascular performance. This refers to the way your heart works and the subsequent working of the circulatory system in response to heart’s pumping. The functioning of the heart can be measured by three determinants.

1. Heart Rate
This is the rate of your heart beating per minute. The more your heart beats in a minute, the more blood is pumped to the body and the faster your body moves towards endurance.

2. Stroke Volume
This refers to the blood amount that is pumped every time the heart beats. Since there is a direct relationship between the stroke volume and endurance, a higher stroke volume is beneficial for the body.

3. Contractility
This refers to the force with which your heart pumps blood to the body. The stronger the force, the farther the blood travels. If contractility is higher, an individual has more blood flowing to the exercising muscles. This blood is laden with oxygen and nutrients that are then utilized by the skeletal muscles for strength and repair.

How Is Endurance Built?
Endurance is not only a measurement of how hard your heart is pumping blood. It also refers to the amount of oxygen that can be delivered to your muscles. This variable is called VO2. This variable depends on the factors mentioned above as well as on the amount of oxygen that is extracted from the blood that enters the muscles. Not all the oxygen that is taken to the muscles by the blood is taken by the muscles. The oxygen has to be extracted first and the more oxygen extraction capacity the muscles have, more oxygen they will receive.

Another factor that contributes to endurance is the mitochondrial density. It is common knowledge that mitochondria is the power house of the cell. What this means is that it is involved in the production of energy in the form of ATP. This energy is produced through different cycles that take place in the mitochondria. The higher the mitochondrial density, the more energy is produced for the consumption of the body.

How Does HIIT Build Endurance?
HIIT builds endurance by working on all the variables that are mentioned above. It enhances the stroke volume for ensuring a greater amount of blood flow to the skeletal muscles. Moreover, it also has an effect on contractility and increases the pumping force of the heart.

As far as mitochondrial density is concerned, HIIT is a great alternative to aerobic exercises for increasing your mitochondrial density. If there are more mitochondria is the body, more energy production takes place and that gives the muscles more endurance.

Another way in which HIIT induces endurance is by increasing the number of enzymes present in the mitochondria. As mentioned above, energy is produced in the mitochondria through different cycles. In all the steps of these cycles, different enzymes act on the substrate to form a product. These enzymes have their distinctive activities that are essential for energy production. HIIT leads to an increase in these enzymes and these enzymes then further increase the endurance in skeletal muscles.

When you perform HIIT, it shifts the signalling pathway in the body from a slower to a faster one. For breakdown of nutrients and extraction of energy from them, the mitochondria are activated through a ‘switch’ in the body called PGCa. During high intensity exercises, the signalling pathway for activation of this switch is a lot faster. As a result of that, the enzymes’ activity is enhanced and the mitochondrial density is also increased.