What is a common characteristic of exercise efficiency?

A common characteristic of exercise efficiency is that it declines with high-intensity efforts. As exercise intensity increases, the body's demand for energy rises, which can lead to a greater reliance on anaerobic pathways and the accumulation of metabolic byproducts. This typically results in less efficient use of oxygen, making it harder for the body to sustain prolonged physical activity at high intensities. Thus, individuals may experience higher energy expenditures relative to the work accomplished, indicating a decrease in overall exercise efficiency during high-intensity efforts. This relationship highlights the challenges of maintaining performance as intensity increases, as efficiency is influenced significantly by the balance of energy systems being utilized.