What is the Origin of Exercise-Induced Thermogenesis?

The concept is a core element of bioenergetics and exercise physiology, derived from the first law of thermodynamics applied to the human body, where chemical energy is converted into mechanical work and heat. The term specifically isolates the thermal effect of exercise from other thermogenic factors like diet or environmental temperature. It is a critical metric for understanding the caloric cost and metabolic impact of physical training.

What is the Mechanism of Exercise-Induced Thermogenesis?

The primary mechanism involves the inefficiency of ATP production and utilization in muscle cells, where a portion of the chemical energy is inevitably lost as heat. Hormones such as epinephrine and norepinephrine further contribute by stimulating lipolysis and increasing metabolic rate in various tissues, including brown adipose tissue. This hormonal surge amplifies the heat production, contributing to the overall thermogenic effect that persists into the post-exercise recovery period.

Exercise-Induced Thermogenesis

Meaning

Exercise-Induced Thermogenesis (EIT) is the measurable increase in the body’s core temperature and energy expenditure that occurs as a direct result of physical activity. This physiological process represents the energy liberated as heat during and immediately following muscular contraction and the subsequent metabolic recovery phase. EIT is a key component of total daily energy expenditure and plays a significant role in body composition regulation and metabolic health.