Here it goes:

When you clamp down to hold your breath and tighten your trunk muscles, you create a pressure gradient between the inside and the outside.


it means:

When you try to hold your breath[...]

In other words, "when you attempt or make an effort to hold your breath[...]".

The Oxford Learners' Dictionary

to take strict action in order to prevent something, especially crime.

Based on this, I would assume that it roughly means the same thing.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.