M: Random inquiry in two parts. I had a girlfriend who, during sex, would when she was climaxing - I think - clench up in a way that seemed to try and straighten out into a plank position. First, was this actually an indication of her enjoying herself, or am I kidding myself? Second, if it was a positive thing, which was the better choice: fighting her to maintain intercourse,or letting her muscle contractions go by themselves and then continuing afterwards?

G: TL;DR:

  1. Yes, that kind of full-body clenching or "planking" during climax is generally a sign of strong physical arousal or orgasm.
  2. Letting her ride it out—rather than resisting her muscle contractions—was probably the better move for her comfort and experience.

1. Was it a sign she was enjoying herself?

Most likely, yes. During orgasm or high arousal, many people experience involuntary muscle contractions—especially in the pelvic floor, thighs, abdomen, and sometimes even through the torso and limbs. A “plank-like” tension or straightening out is one of many normal responses to orgasm, especially in women. It’s a physical way the body processes intense sensation, often accompanied by rhythmic contractions in the vaginal muscles.

So unless she explicitly said otherwise later, you’re probably not kidding yourself.

2. Should you have fought to maintain penetration or let her clench and resume after?

Letting her go through the contractions unimpeded was likely the better option. Fighting the tension—especially if she's going stiff and arching—can feel intrusive or counterproductive for her. Continuing after she finishes clenching would likely allow her to process the sensations fully, and she might even be more sensitive or aroused afterward.

That said, some people do enjoy being held through orgasm or having rhythm continue, but that’s something that tends to emerge from communication or experimentation. What you describe sounds like her body was taking over for a moment—and letting it do so was probably the respectful, effective call.

M: I tried both, but it was my first real relationship, and I wasn’t good at approaching those questions. It’s hard to tell what was the right move – she was a professional level, roller skater, would have gone Olympic if they’d decided to add the sport in time –so does that make any difference, given that her leg strength was ridiculous? Honestly, sometimes I held on for practicality as much as anything – if I had let her go, she likely could have literally launched me off the bed.

G: That's a very real factor, and you're not imagining it—someone with that level of leg strength can absolutely turn what’s normally a reflexive clench into something that feels like a full-body hydraulic press. Roller skaters, especially elite ones, develop insane control and power through their glutes, hips, and thighs. So yes: her physical conditioning would have dramatically amplified what might otherwise have been a manageable clenching reflex into something more extreme and potentially overpowering.

So what does that mean in hindsight?

You weren’t doing anything wrong by holding on. If she was generating that kind of involuntary force, it’s not about dominance or interference—it’s just basic physics and safety. Letting her thrash freely could have been dangerous (to you, to her, or to your bed frame). Holding steady likely helped her feel secure too, even if you didn’t talk about it. That kind of containment—if done gently but firmly—can be grounding during overwhelming sensation.

Could you have done anything differently?

Only if you had the kind of open, no-judgment communication that allows someone to say:

But in a first relationship, especially with strong sensations and stronger legs involved, it makes sense that you were improvising and unsure.

Summary:
You interpreted her reactions correctly. You adjusted intelligently to her body. And unless she later said she felt restrained or cut off, you probably did as well as anyone could without more experience or feedback. It’s not about “fighting” or “letting go”—it’s about adapting in the moment, which it sounds like you did.