Last Updated on by Eat Better Move More


Exercise involves physical activity that helps you improve your health and maintain fitness. Exercising daily is very good for your physical and mental wellbeing. Exercise helps reduce the risk of cardiovascular diseases, it helps you to reduce and maintain weight, and it also helps to improve your mood. It is recommended to exercise at least 20 minutes every day.

For the body to function, it needs energy. When you exercise, you sweat, your heart beats faster and your breathing increases. All these processes take up energy. You often wonder why experts advise you to eat healthy when you’re exercising. Your body needs fuel to do its work. Exercise makes everything in the body work faster than normal. This means that more energy is required than what the body normally uses for its daily activities. What is the thermic effect of exercise? How much impact does exercise make on your body?


The thermic effect of any physical activity is the amount of energy that the body utilizes when moving. When you exercise, the amount of energy used up can be monitored. The thermic effect of physical activity involves any moment from simply walking to something as intense as running. Energy is the ability to do work; exercise is work.

The muscles store little amount of ATP, and when the energy is used up, energy is then produced through other means; either through aerobic or anaerobic metabolism. Energy is generated from three systems; the phosphagen system, the glycolytic system and the oxidative system. They are all involved in the production of ATP. Adenosine Triphosphate (ATP) is gotten from food (fats, carbohydrates, proteins); it is involved in muscle contraction. These systems are always involved when you exercise. Each system of energy generation is influenced by the duration and the intensity of the particular exercise you are performing.


Phosphagen system of energy generation is the fastest means of energy generation. Energy is provided for vigorous activities that don’t last beyond 30 seconds; exercises like jumping, throwing a ball, or sprinting don’t exceed 10 to 30 seconds and they utilize phosphagen system of energy generation. In the phosphagen system of energy generation, ATP (Adenosine Triphosphate) is generated through creatine phosphate. It is a form of anaerobic metabolism. When your exercise exceeds 30 seconds, your body system begins to generate energy from the glycolytic system.


The glycolytic system is mostly an anaerobic form of metabolism. It produces ATP from carbohydrates. When you are involved in light or moderate exercises, glucose is broken down to form pyruvate through aerobic processes, yielding a small amount of energy. This process is called “slow glycolysis”. However, when the energy available is not sufficient for the body’s need i.e. oxygen present is not enough for muscle contraction, pyruvate is converted to lactate. This type of glycolytic system is called an anaerobic form of glycolysis. It is involved in energy production for intense exercise that lasts for about 30 seconds to 3 minutes. This system of energy provision is also fast but not as fast as the phosphagen system.


Oxidative system of energy generation is an aerobic system. It makes use of oxygen for energy production. While glycolytic system of energy generation makes use of carbohydrates to produce energy, the oxidative system utilizes not only carbohydrates but also other macromolecules; proteins and fats (majorly fat). This system is involved when you are performing light to moderate exercises. The oxidative system is able to provide energy for a long period of time.

It is worthy of note that the three systems of energy production work together. The intensity and the time taken during exercise determines which system is more involved. Take an obstacle course race for example. For the jumps you’ll make over hurdles, you have to tap into the phosphagen system, to climb steep hills, the glycolytic system is activated and for the entire duration of the race, the oxidative system is involved.



The thermic effect of exercise or in a more definitive term, the thermic effect of activity varies from individual to individual depending on the physical activity such individual is involved in.

To monitor the energy activity your body is making use of during exercise, you can take note of your heart rate. A change in the intensity of your heart beat would show if you’re making use of aerobic or anaerobic form of energy generation.

Increase in heart rate, change in breathing pattern and your muscle fatigue can help you determine which system of energy you are using. Anaerobic exercise cannot exceed 3 minutes. Once you realize that the intensity of your workout is reducing because you’re getting tired, you can deduce that you are making use of an anaerobic form of energy generation.

On the other hand, if you notice that the intensity of your exercise does not reduce and you can still go on with your workout for more than three minutes, you are exercising aerobically.

Aerobic exercise involves walking, jogging, swimming or cycling. It is a great way to burn calories but not as much as people think. Fat is the primary source of energy during aerobic exercise. If you exercise with the aim of burning significant amount of calories, you have to engage in more intense forms of exercise and this involves anaerobic metabolism.


The non-exercise activity thermogenesis is the amount of energy we use up through normal activities we perform daily; activities like taking a walk to see a friend, walking up the stairs, cleaning the house, moving furniture, working in a factory. Non-exercise activity thermogenesis can help burn additional calories without you even putting too much effort.

Thermic Effect of Exercise Summary

What is the thermic effect of exercise? It is the amount of energy you burn when you exercise. Energy is produced during exercise through aerobic and anaerobic metabolism. Three systems of energy generation are responsible for the production of ATP; the phosphagen system, the glycolytic system and the oxidative system. Aerobic metabolism utilizes oxygen to produce energy from fats and carbohydrates for exercise that lasts over a period of time. Anaerobic metabolism produces ATP from carbohydrates. It is utilized when energy is needed quickly.


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