Dive Reflex

[hogphish]

It baffles me why the elements of my dive reflex are so variable in onset. When I do hypoxic cardio such as breathholds while stationary biking I can't seem to accurately predict how many periods of breathold it takes to kick in my bradycardia. When I am on my game I go from 120 BPM doing cardio at a 400 cal burn rate to 60 bpm with in 20 seconds of my breathold while still maintaning the same degree of energy expenditure. However some exercise sessions take two breatholds or so to kick in the reflex while others take 5 or 6. Does any one else share this experience and is there an accepted explaination for it. I have a pretty good grasp of physiology but I know there are some great minds on this board. If I knew the factors that govern the onset of my MDR I could better control it in the water.

 

[patbrassil]

I was taught in FII lvl 2 about several different triggers for your reflex. The first is exposure, which is just getting your face wet. The body senses the face in the water and that helps the reflex kick in. The next is pressure, the body senses the atmospheric pressure change (you could probably simulate this on dry land by doing diaphragm inflections.) And the third is a breathhold, i believe it is the urge to breath that sets it off but i'd need to check my notes.

So basically my warmup for a free dive is a mask free breathup, followed by dives to 10m, 20m, then 30m and waiting for the urge to breath at each depth. And finally a negative pressure dive or two. (I hate negative pressure dives so ussually just one)

For dry statics maybe try: A breathup with a wet towel over face, diaphragm inflections, and finally a warmup breathhold or two?

 

[watts]

Forth might be stress (anticipation of a big dive) and fifth not training your Dive response out. Keep your training specific. If you want to swim a long way does swimming medium distances often realy help you on max attempts?

 

[Siku]

Watts can you expand on that please. I don't really understand how you would train your dive reponse out, unless you mean that increasing other abilities (e.g. efficient finning, CO2 tolerance) might mean that, for a given depth/time/distance, the dive response doesn't "bother" to kick in as hard.

Is that what you mean?

 

[hogphish]

I can predictably drop my heart rate into the low thirties with an FRC breathold and I have no problem getting bradycardic at 30 meters. My issue is why in my training program I can't predictably tap into the bradycardic portion of my MDR while doing exertional apnea (dry land). I'm a safety supervisor and have a pretty good grasp of freediving physiology.

 

[watts]

Is it important or wanted to get a strong dr on land?

 

[hogphish]

Is it important or wanted to get a strong dr on land?

I can't always train in the water so I am trying to maximise my dry land training. I just find it interesting physiologically that I can't predictably induce bradycardia on land with exertional breath holds. Of course everyone in the gym thinks freedive training is crazy.

 

[trux]

Try putting a wet towel or a bag with ice cubes over your face, if you really, for some reason, need bradycardia for your dry training.

 

[Siku]

Isn't it more likey the DR will show itself as vasoconstriction during dry training. Surely the bradycardia will be limited by the intensity of the exercise?

 

[hogphish]

The issue is Trux..that I view my ability to induce bradycardia during dry land exertional apnea as an indication of my freedive fitness level. But because of the unpredictability of this guage (induced bradycardia) perhaps I can't use it as a paramater. As I stated, some days I can all out bust my ass on the stationary bike and cut my heart rate in half with a 30 second breathold and then under the same conditions 2 days later struggle with it. @ SIKU..I can't easily measure peripheral vasoconstriction but heart rate is easily monitored.

 

[trux]

You cannot really use bradycardia as an indicator of your fitness level. It is dependent on far too many factors - overall body temperature, temperature of extremitites, the difference of the temperatures before and during the dive, especially on the face, level of CO2 (disputed by some studies to be relevant, but experience at most freedivers tells it is), level of hypoxia, stress, awareness of holding the breath, depth/pressure, mental state, previous and present exercion, type of exercise, and some others,...

And the bradycardia is also less important than you think for the freediving performance. So focus more on the training BH times or distances, than on the bradycardia at your dry training, or measure your hypoxic levels with an oximeter instead, and you'll be fine.