Who volunteers to have sex in a laboratory?
I was struck by this question when reading about an experimental study of ideal sexual positions for men with back pain.
For the purpose of the research, couples were filmed using motion capture and infra-red technology while they had sex.
The researchers were in a separate booth where they could hear, but not see, the participants. Electrodes were used to record muscle activity in certain parts of the body, to get an idea of force.