Thank you for your query. The cardiovascular system (heart and the blood vessels) is a highly dynamic one supported by the rest of the systems (nervous, renal and endocrine) in the body. Normally the heart and vessels are capable of functioning under stress and at different levels of demand from the body. When there is no disease, this adjustment goes unnoticed. However , as we age, personal habits, lifestyle, stress, environmental and genetic factor work together to create hurdles for the cardiovascular system(CVS) to function normally. When you exercise or are dehydrated/hungry , your body s demand on the CVS increases and this can lead to delayed or defective adjustments which maybe exacerbated by diabetes, hypertension and heart disease. For instance, when you exercise, blood flow to all the vital organs, brain, kidneys gets compromised slightly due to the increased demand to your muscles and lungs to provide oxygen. In healthy individuals, this compromise is neutralised by changes triggered locally . These changes or adjustment s are reduced in the above mentioned disorders as they damage the vessels . Benign causes could be inner ear disturbances that affect your sense of balance. This can be diagnosed clinically. Any breathing difficulty, especially associated with dizziness, chest pain should be checked out immediately. Do not strain yourself and see your doctor to check your vital functions. If you cannot meet them, go to the ER If caught early and appropriately treated, the damage to the organs can be reduced or even stopped. Every second counts. Please avoid driving and strenuous activity until cleared by your physician. Hope this helps. Please write to us if you need further clarification. Wish you good health