They're called premature ventricular contractions, or PVCs for short. For some reason, your heart will "double beat" and then has to pause
and reset its rhythm. Most people have PVCs every now and then, but not everyone can feel them, and for those of us who can, they can be everything from annoying to downright frightening. Sometimes your heart adjusting to gravity will cause the skips while bending over or standing. Don't worry too much. Anxiety
are big contributors to PVCs. If they are particularly bothersome to you, beta blocker therapy
might be worth looking into. Check with your doctor.