question for ya'll

a breath-hold is usually divided into a comfortable part (no urge to breath, very relaxing) and the uncomfortable part (urge to breath, contractions, not very relaxing).
contractions are involuntary muscle contractions of your chest and ab muscles. contractions start when a high amount of co2 has accumulated in your body (o2 decreases). the frequency of contractions varies depending on people, some even don't get any at all. but that is rather rare. early contractions will be rather easy to hold but longer you hold your breath the quicker and more violent they will be. one thing to train here is the ability to hold a longer time of contractions which can be a bit demanding.
the intensity of your breathing will also influence greatly when you get contractions. hyperventilation will delay them but it is not a recommended technique. search here for 'hyperventilation', 'shallow water blackout' and 'bohr-effect'. there will be a lot more explanations. also search for threads discussing the risks and dangers of apnea! do this before any training in water!

enjoy

roland