The most common cause of vascular obstruction is a blood clot, also known as a DVT. This type of vascular problem usually occurs in one leg (not both), and leads to swelling of the soft tissues throughout the foot and ankle. The swelling can also extend further up the leg.
The hypothalamus is a part of your brain that controls body temperature. When you exercise, your body temperature increases, causing the hypothalamus to signal the brainstem to further increase your heart rate.
Oxygen levels increase during exercise due to a physiological response controlled by the brain. The medulla controls respiration rate during many activities, including sleeping, exercise and eating. During exercise, the cells burn oxygen more quickly than they do while at rest.