Simplify the following text for a Grade 11 native English-speaking person.
Original: A small study has shown that a test group which only had intercourse experienced , as a whole , lower blood pressure in stressful situations than those who had intercourse but also had masturbated for one or more days .
Simplified: A small study has shown that in one test group , recent full intercourse resulted in the lowest average blood pressure in stressful situations .