Which is NOT a potential effect of a decreased pH during intense exercise?

During intense exercise, the body experiences an increase in metabolic activity, leading to the production of lactic acid and a subsequent decrease in blood pH. This drop in pH, known as acidosis, can significantly impact various physiological functions.

Choosing "improved cardiovascular function" as the answer highlights the fact that decreased pH does not enhance cardiovascular function. Instead, acidosis can impair cardiovascular efficiency. As pH declines, the body struggles to maintain optimal cardiovascular responses, which can lead to diminished oxygen delivery to muscles and reduced cardiac output.

In contrast, the other effects mentioned, such as muscle fatigue, inhibition of enzymatic reactions, and altered calcium handling, are directly linked to the consequences of low pH. Muscles may become fatigued due to an accumulation of hydrogen ions that disrupt the muscle's ability to contract efficiently. Enzymatic reactions, crucial for energy production in muscles, can be inhibited due to changes in the enzymatic environment caused by low pH levels. Additionally, alterations in calcium handling can affect muscle contraction and relaxation, further contributing to fatigue and impaired performance.

Therefore, the selection of "improved cardiovascular function" effectively indicates that a decrease in pH is detrimental rather than beneficial to cardiovascular performance during intense exercise.