What is a consequence of not including a cool-down in an exercise routine?

Not including a cool-down in an exercise routine can lead to a higher risk for cardiac complications. During exercise, the body undergoes various physiological changes, including increased heart rate, blood pressure, and blood flow to the muscles. A cool-down period allows for a gradual transition back to a resting state. This transition helps to slowly lower the heart rate and blood pressure, thus preventing immediate changes that could stress the cardiovascular system. Without a proper cool-down, abrupt cessation of activity can lead to issues such as dizziness, fainting, or more severe cardiac complications, especially in individuals with pre-existing health concerns.

The other consequences mentioned in the options either do not accurately represent the effects of omitting a cool-down or describe positive outcomes that would not arise from such a practice. For instance, increased muscle flexibility and improved recovery generally come from properly managed warm-ups and cool-downs, while enhanced athletic performance is a result of a well-rounded training regimen rather than the absence of post-exercise recovery measures.