Speeding up at the end of a Dynamic

[BennyB]

Hi all,

I'm sure this has been discussed a couple of times before but I can't find anything in a search.

I find i'm hitting a hypoxic limit in my dynamics lately - when I come up I feel like any further and i'd be risking BO, yet a minute or so afterwards i'm not lactic at all which makes me think that it's more of a mental barrier. Though at the time it certainly feels like i'm pushing as far as I can go.

With this in mind I decided to change my style a bit. Before, I used to have a slower monofinning kick (2 kicks and a glide). Last night I did my usual style up to the point of real discomfort (well after the contractions had started), about 15m away from my PB, at which point I ramped up the speed and going quite quickly managed an extra 5m before surfacing.

Is this a normal technique? Is there any science to it? My reasoning was that at the point of real discomfort I felt I had only a certain time (not distance) left in me. Eg. at that point I felt I only had 15 seconds or so left. So by speeding up, it actually felt a bit better mentally, I had no change in lactic load or perceived hypoxia.

Just wondering if anyone else does the same and have noticed an improvement in distance without sacrificing their safety (ie. being closer to blackout). Interestingly, I still didn't feel that lactic afterwards.

Cheers,
Ben

[DiverTodd]

Speeding up to get in that "one last push" during a dynamic is pretty common; it's also a way to shift thoughts away from the discomfort that's going on in your lungs! But, it also uses oxygen more quickly, so it's best to STAY at your normal pace and NOT speed up (this advice came from a VERY high source!). As usual, the BEST way to increase your distance is practice, practice, practice.

Todd

[TRITON]

I didn't get any benefit from speeding up at the end of my dynamic,besides a good chance to end up with LMC or a blackout.I think speeding up is a result of a lack of self-control.It's especially "dangerous" to speed up in DNF,because whenever I was close to my PB(100m) and accelerated at the end ,I didn't come up "clean" or even had an LCM.

[pat fish]

In general what you want for a long dynamic is vasoconstriction under the effect of high PCO2, acidosis and glycolysis. Speeding up at the end of a dynamic seems to go against the concept of vasoconstriction - it increases muscular blood circulation again. It increases muscular tonus, blood pressure and it increases the level of activity in your central nervous system. The drop in blood pressure that you have anyway after resurfacing is more severe. You are more likely to suffer LMC or blackout. Just some thoughts...
Pat

[turtle]

what if you are working anaerobically when at the end of a dive and heavily hypoxic? then you could speed up all you want, lactic acid allowing, and cover more distance than maintaining a slow pace to the end. Doing apnea walks i found that once a dive response had been established, the intensity (speed) of the following walk was neither here nor there to the total time until breaking off. but maybe during a full lung dynamic, you're not allowing a dive response to establish properly anyway, so this is all irrelevant.

a really simple way to look further into the question would be to measure heart rate throughout a dynamic with a 'sprint' at the end and see if your cardiac rate does go up again in response, or if it just keeps dropping steadily until you surface.

as the french say: bof?

f

[pat fish]

I was thinking of the very same while writing the first post: once vasoconstriction is established an increase in power/speed could even be benefitial? But for a long dynamic a speedup at the end seems to increase tension only and to induce stress. Let's say for a 100m dynamic you will feel the elevated PCO2/ intensivating of divereflex at around 50m. Then the phase of diving under acidotic conditions is still very long - and a speedup at 90m doesn't seem to make a difference for the distance. But it might increase the chance for LMC/BO.
Pat

[turtle]

well, to look at it the other way round then - if you're beginning to feel a strong DR at the half way mark of a dynamic, and therefore a long way from the end of that dive, maybe the focus shouldn't be on speeding up at the end but about slowing down the first part of the dive, i.e. while you're still using your resources very inefficiently?

f

[Walrus]

There is an old thread on this, at least 2-3 years back. Can't find it at the momen't will have a look. As for advice that "comes from a very high source" not to speed up I say what is the logic behind it ?
Towards the end of a dynamic with a higher state of hypoxia your heart-rate will be lower as the dive reflex/survival respsonse increases and your muscles work more aenerobicaly. A higher kick rate may not cause as much of an increase in hearate as you think. Like turtle said a really good way to test this may be using a heartrate monitor and actually try it out. I've done plenty of 180m+ dynamics where I have increased speed at the end. I have done longer distances since then ie 200m+ where I haven't increased speed at the end but it's more due to lactic build up then choice, it just becomes damn hard to move your legs.
On the flipside if you are already going at a high speed then speeding up may not be efficient as drag greatly increases with speed. I think there may be something gained from trying different speeds and even changing speed on a max dynamic. You never know until you try.

Cheers,
Wal

[DiverTodd]

I don't know the technical reasoning or logic behind it (I'm not that up on my biology...heh heh), but that advice came from a certain freediver who was a monofin swimmer in his younger years, and currently holds two (and until last month, 3) freediving world records.

Todd

[BennyB]

Thanks for your replies everyone. I was thinking in terms of the anaerobic workload as Turtle pointed out, but i'm thinking now that seeing as i'm not getting lactic in my dives (funny - when I started, a big dynamic would leave me almost unable to walk afterwards) i'm probably not getting a big dive response to begin with.

The heart rate monitor is an interesting idea - I have a Polar one but the sample rate is probably too long to effectively record, and I doubt i'd be able to do a max dynamic and check my heart rate at the same time. Of course there's always apnea walking but I don't get too much of a chance of that anymore now that the days are getting shorter.

I've only tried it once so I will experiment a bit more. I've only done 2 max attempts with the slower style. When I say I speed up at the end, I mean that I incorporate a glide in my slow pace, and in the faster pace I don't wait for the glide. I think with my new fin everything's a bit quicker anyway. Like Wal said, experiment around and try and glean a bit more info based on the experiences of some of the top guns.

Cheers,
Ben

[DeepThought]

Originally Posted by BennyB

The heart rate monitor is an interesting idea - I have a Polar one but the sample rate is probably too long to effectively record, and I doubt i'd be able to do a max dynamic and check my heart rate at the same time.

Maybe your buddy can swim near you with the watch and check your HR, I'm not sure how much range these polars have.

[pat fish]

Shouldn't the question rather be "is going slowly at the beginning of a dynamic beneficial" than "is speeding up beneficial at the end of dynamic" ?
Under the aspect of letting set in the dive reflex and with the logic that this is happening strongly after the first urge to breath, moving slowly at the first part of a dynamic might be the way to go.
Pat

[DiverTodd]

During my last dynamic (with fins) I noticed that I was actually pretty comfortable during the first 25m. It was during the return trip to 50m that I started getting uncomfortable, but I resisted the urge to speed up, and I still managed to make it to 50m. The next goal is 75m; ACK!

Todd

[naiad]

Maybe it works differently for different people. Those who are good at static but get tired easily may be better at going slowly for dynamic. Those who are not so good at static but have good general fitness may be better at going fast.

I start off slowly and either go slow the whole way, or speed up at the end, but that's more due to lack of self-control.

Lucia

[DiverTodd]

Originally Posted by naiad

but that's more due to lack of self-control.

Lucia

(Todd envisions Lucia going full speed, losing control, then having a spectacular underwater crash into the pool wall....)

Todd