Is it normal to have a mild headache after exercising? i don't have any condition that i know of, i'm obese, is not too much exercise , just beginner's exercise with personal trainer. 30 minutes 5 days a week?

Have you ever checked your blood pressure before, during & after exercise? Most of the time a rise in BP isn't the cause of these headaches. They are often dull rather than pounding and are caused by straining affecting forehead muscles during isometric workouts. However severe throbbing headaches with and after exercise would be worrisome. Check your BP at least before& after the workout.

There could be several reasons for headache associated with one's exercising. High Blood Pressure is top on the list. Have BP checked before and after exercising to note the trend and have it corrected if not in the normal ranges. Is one well hydrated? Are the Eyes, Ears, Sinuses,... functioning normally? In other words, has one seen the PCP for Comprehensive Baseline Medical Evaluation?

Your headache could be triggered by dehydration, and best to have adequate fluid intake prior to exercise. Some folks with migraine can have headaches triggered by exercise. Certainly check your blood pressure levels, and assess if any medications you are taking currently may be underlying cause.