pretty geeky evening. However, upon checking my emails I was relieved to discover that at least one other person was engaged in an equally geeky activity. Tim had lent me his heart rate monitor during our last DNF training session and on Sunday evening I received an email attaching the graphs he’d created on his computer.
If you read the previous post, you’ll know that last week at London Freedivers I joined Tim and Nick in their punishing (at least for me) DNF training. The graph below shows my heart rate over the first exercise, which involved 10 repeats of 33m DNF, leaving every 1min 30seconds. This means that the slower you swim the length (helping you to relax and conserve energy) the less time you have to recover before the next length.
Graph 1 - CO2 DNF Table
The next graph is a DNF swim of about 50m, which I did with at the start of the session. I had contractions quite early and came up 4 strokes after the first contraction.
Graph 2 - 50m DNF
Unfortunately, I don’t know the exact time I started and ended the dive, so it’s a little bit difficult to draw conclusions. Bearing this in mind, I find the following points most interesting:
1. As you can see, my heart rate drops by 70bpm during the dive! It’s very cool to be able to see the effect of the dive reflex in pictorial form. If I remember correctly, I had a 3 minute breathe-up before the dive.
2. The graph shows that my heart rate is lower at the beginning of the breathe-up than it is at the end! This is at odds with what I would expect; I’d expect a gradual lowering of heart rate during the breathe-up and then a slight peak caused by stress immediately before immersion. It looks like I need to review what I’m doing for my breathe-up.
3. My heart-rate is elevated before the breathe-up even begins. I just measured my resting heart rate on the inside of my wrist sitting in the café and its 69bpm. Even this seems a bit high – I’m going to blame it on my lack of aerobic fitness (or on the hottie sitting at the next table reading Hemingway). Assuming immersion occurs just before 03:20, my heart rate is nearing 90bpm at the start of the breathe-up and it rises to 115bpm immediately prior to immersion.
4. Assuming (again) that I end the dive at approximately 03:21:20, there is a subsequent leap in heart-rate within a very short space of time – surely this can’t be good for you?!
OK, I have to rush off to training at London Freediving now! Harry's down in London doing a placement at the London Diving Centre and will be training with us tonight :). If anyone has any comments on the graphs, I would love to hear them...
Heart rate higher at end of breath than at beginning means ur over breathing a bit (hyperventilating)rather than being stressed out pre dive. 3 mins is a long breath up unless its mainly relaxation? quite sure most of us do it to some degree aware of it or not.
ReplyDeleteApparently high-HR due to pre-dive stress helps have a good DR during the dive, leading to O2 conservation (I remember reading somewhere that Seb Murat used to change his routine to ensure that he had adequate pre-dive stress).
ReplyDeleteNot sure to what degree this is true, but it doesn't seem to be necessarily true that a low pre-dive HR leads to better results...
S
This comment has been removed by the author.
ReplyDeleteAbove removed due to typo!
ReplyDeleteAnonymous - Most of the 3 minutes is just sitting in the pool quietly. Breathe-up in the sense I think you mean it is no longer than 1 minute 30 sec. I agree that over breathing is something we all do to some extent, though.
S - Ooh, interesting! I've heard a bit about this, although nowhere near enough to feel like I understand it. Any references/links you can point me to?
Hi Grace,
ReplyDeleteThe first graph is also interesting, as you notice your graph is getting a lot! smoother during the CO2 table.
"Breathing up" usually means over breathing for most. Hence the higher rate and deeper breathing causes higher HR, and some stress in itself. But the most negative effect is the loss of CO2. Next time experiment with minimalistic slow shallow breathing, and see how that works for you. Last exhale can bee deeper, and try not to stretch on inhale too much. Start your dive slow and smoothly glide into a nice rhythm.
Upon surfacing, inhale slowly, hold. I've never heard of any difficulty with the HR rise upon surfacing. Personally my HR goes in static from ~ 33 -> 100 ish coming up from a 2'45" + - just after my HR hit it's lowest point (33).
Anyway it's just a number. What really counts is blood flow. Something to be done either by more HR OR more Volume per beat...
A good condition and stamina help the efficiency. I think Freediving is great for the body because of the wide range of HR. Much more flexible then the cyclist hovering most of the time within a narrow HR range.
Love, Courage and Water,
Kars