What physiological feature increases due to high-intensity exercise?

Maximal oxygen uptake, also known as VO2 max, refers to the maximum rate at which an individual can take in and utilize oxygen during intense exercise. High-intensity exercise increases the physiological demands on the body, resulting in adaptations that enhance the efficiency of the cardiovascular and respiratory systems. These adaptations include increased cardiac output, improved pulmonary function, and greater muscle oxidative capacity, all of which contribute to a higher VO2 max.

Engaging in high-intensity workouts stresses the body in a manageable way, prompting it to adapt by improving its oxygen delivery and utilization capabilities. As athletes train consistently at high intensities, their bodies become more proficient at handling oxygen, leading to higher VO2 max values over time.

Other options such as blood glucose levels and joint instability do not necessarily reflect a positive adaptation to high-intensity exercise; instead, blood glucose levels may fluctuate based on various factors including nutrition and exercise duration, while joint instability can result from poor form or overtraining. Body temperature regulation is critical during intense exercise but doesn't fundamentally increase in a way that reflects a key physical adaptation like maximal oxygen uptake. Thus, the enhancement of VO2 max is a hallmark response to high-intensity training, making it the correct choice.