what activity increases blood pressure
Blood pressure readings absolutely can effected by exercise, but for how long is a little tougher to answer. Let me explain. During exercise, your heart pumps more blood out to your body per minute, while the blood vessels within the muscles you are using expand. These two countering effects cause a rise in your blood pressure. If you are working one muscle group (i.e. biceps curls), the your blood pressure rises a lot during the exercise. If you are working a large group of muscles (i.e. jogging), then your blood pressure will go up a little.
During upright exercise, the normal blood pressure response is to observe a progressive increase in systolic blood pressure with no change or even a slight decrease in diastolic blood pressure. The slight decrease in diastolic blood pressure is due primarily to the vasodilation of the arteries from the exercise bout.