 According to the Kamsutra, the involuntary shuddering of orgasm is called Samput or the dual case. But it says, no two women make love in quite the same way. So you must orchestrate your rhythms, meaning you're thrusting etc. You must orchestrate your rhythms accordingly to the moods and colors of each lover's melody. You know, not only does every woman feel her orgasm in a different way, but each woman individually also feels her pleasure, her orgasm differently every single day. So don't focus all your attention on trying to get to the orgasm. Don't make that your mission statement. Just focus on your partner's pleasure. Let them decide how they want to use that.