Sports
Exercise Physiology and Athletic Performance
Quick fact
Elite endurance athletes can have a VO2 max (a measure of oxygen utilization) over double that of a sedentary person, sometimes exceeding 80 mL/kg/min.
Why this is interesting
Have you ever wondered why some athletes can run faster or lift heavier than others, even with similar training? The answer lies in how their bodies harness energy and adapt to stress.
Read the full explanation
Understanding Exercise Physiology and Athletic Performance
Think of the body like a hybrid engine. It has three energy systems: an immediate 'sprint' system (ATP-PC), a short-burst 'glycolytic' system, and a long-haul 'oxidative' system. During exercise, these systems blend to produce movement. As you train, your heart becomes a stronger pump, your lungs more efficient gas exchangers, and your muscles build more mitochondria (the power plants). Your blood vessels grow denser, delivering more oxygen. This is why a trained athlete can perform at higher intensities for longer than an untrained person.
A deeper explanation
Exercise physiology explains these adaptations at the cellular and systemic level. Training stimulates the production of enzymes that break down fuel faster, increases the number and size of mitochondria, and improves the efficiency of the electron transport chain. The cardiovascular system responds with increased stroke volume, capillary density, and blood volume, enhancing oxygen delivery. The lactate threshold—the point at which lactate accumulates faster than it can be cleared—rises with training, allowing sustained high-intensity effort. These mechanisms are why periodized training, with stress and recovery cycles, maximizes performance. Understanding them allows athletes to target specific energy systems, avoid overtraining, and design workouts that elicit desired adaptations.