Energy Production Factor

Cellular respiration is the process by which the energy currency of the cell, ATP (adenosine triphosphate), is formed from food. The main energy sources in food are carbohydrates, proteins and fats, and each is broken down through its own complex chemical pathway to release ATP. During exercise the demand for energy rises sharply, so the load on the metabolic system increases many times over.

The three food fuels are not used equally. Carbohydrates provide instant energy compared with fats and proteins, and higher-intensity aerobic activity draws on carbohydrate in the form of glucose and glycogen. Fats, though slower to mobilise, yield a much larger total amount of energy and are relied upon in long-duration exercise. Proteins contribute only a small but still important share of the body's energy needs.

It helps to keep three related terms clear, as they are often tested in CBSE Class 12 Physical Education papers:

• Metabolism — the sum of all the energy transformations taking place in the body.
• Anabolism — the building-up process in which simple molecules are joined to form more complex ones.
• Catabolism — the breaking-down process in which food and stored fuel are split apart to release energy for work.

The body relies on three energy systems to supply ATP, and which one dominates depends on how long, how hard and what type of activity is being performed:

• ATP–CP (creatine phosphate) system — supplies energy for very short, intense efforts lasting under about 10 seconds, such as jumps, throws, sprints, weightlifting and powerlifting.
• Anaerobic system — supplies energy for efforts lasting under about two minutes, such as 200 m and 400 m races. …