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DeepSeaExplorer

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The primary reason for the frog kick is that it doesn't stir up the bottom. It can also be more efficient because there can be a glide or coast between kicks when not at full speed or swimming into current. It's easier to adjust swimming speed by adjusting the number of kicks per minute (duty cycle) or the amount of thrust of each kick. When swimming slower, it can conserve air by reducing the duty cycle to less than 100% and/or adjusting the thrust.

The flutter kick is good for a burst of speed, but there's no glide and the duty cycle is 100%. It also sends fin wash downward and will stir up the bottom.
 

TSandM

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The long-leg, full flutter kick generates continuous propulsion through the entire kick cycle, but uses short muscles with little mechanical advantage, so it's fatiguing.

The modified flutter, done from the knees with a flat body, uses a much more mechanically efficient technique. It minimizes downward water deflection. It is extremely useful when swimming into flow or current.

The frog kick directs water backwards. It uses efficient muscles and involves a rest period during each kick cycle. This also allows the diver, particularly the novice diver, to get a brief buoyancy check, because if they sink or rise during the glide phase, they realize they are not truly neutral. The frog kick is also the basis for the helicopter turn and back kick, both of which are useful for precise positioning for observing marine life, or taking photographs.
 

mruseless

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Before learning and really getting comfortable with the frog kick, I used the flutter and that sort of sideways half flutter you often see tropical divemasters using. I always had sore ankles after a few days of diving on a liveaboard, and sometimes outright pain at the top of my ankles during the first few dives. As I've learned to use the frog and modified frog, I've found it to be an extremely comfortable kick. The only time I do a full leg flutter now is when I really need a short burst of power, like going into current.

---------- Post added November 16th, 2014 at 12:20 PM ----------

I should also add that I had recontructive knee surgery in May, and had a big dive vacation in September. While flutter kicking was fairly stressful on the knee, I had no problems at all frog kicking.
 

Sandie7

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The long-leg, full flutter kick generates continuous propulsion through the entire kick cycle, but uses short muscles with little mechanical advantage, so it's fatiguing.

The modified flutter, done from the knees with a flat body, uses a much more mechanically efficient technique. It minimizes downward water deflection. It is extremely useful when swimming into flow or current.

The frog kick directs water backwards. It uses efficient muscles and involves a rest period during each kick cycle. This also allows the diver, particularly the novice diver, to get a brief buoyancy check, because if they sink or rise during the glide phase, they realize they are not truly neutral. The frog kick is also the basis for the helicopter turn and back kick, both of which are useful for precise positioning for observing marine life, or taking photographs.

I do not understand how the modified flutter works ... it looks like the water is being moved downwards ... obviously it is not, but I would need to try it to understand.

I've also watched the "helicopter turn" and the "back kick" and it was fascinating - however I felt better practise what I am being taught right now ... amazing skills, don't think I will ever do something like that :)
 

drbill

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I've never mastered the frog kick... my knock knees make it more difficult for me and it seems to irritate my hips. When I dive, I don't generally try to cover too much "ground" since I'm looking for critters to film. Therefore the flutter kick I use doesn't tire me out, at least when I'm using my Apollo BioFins. Back when I used Jet Fins it was a different story. Your mileage may vary.

Also, some of the fins favored by the frog kickers are pretty heavy and not good for travel given airline weight restrictions. When I travel, I don't take my BioFins for that reason but use my ancient US Divers (now Aqualung) Blades which are lightweight.
 

RJP

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The other downside to the standard flutter-kick - which is obviated by the frog kick - is that the flutter kick has the unfortunate side effect of having you roll slightly to the left... and then slightly to your right during each kick cycle. This will have a tendency - especially with newer divers - to exagerate any balance issues related to swimming around with a heavy tank and a bunch of lead on your back.

Frog kick is not only more efficient from a propulsion standpoint... it's also "roll neutral" if you will.

---------- Post added November 17th, 2014 at 11:59 AM ----------

I do not understand how the modified flutter works ... it looks like the water is being moved downwards ... obviously it is not, but I would need to try it to understand.

You're right. The water is moving downward in a modified flutter. However, there is much less water moving per kick, it's not moving as forcefully, it's not moving as far, and - depending on how long your legs are - it's being moved downward from an additional two feet or so above anything you don't want to expose to downward moving water.
 

Sandie7

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You're right. The water is moving downward in a modified flutter. However, there is much less water moving per kick, it's not moving as forcefully, it's not moving as far, and - depending on how long your legs are - it's being moved downward from an additional two feet or so above anything you don't want to expose to downward moving water.

Ok, makes more sense now, thank you !
 
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PatW

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A flutter kick is pretty easy. As noted, it can easily stir up the bottom and mess up the visibility.

The frog kick does not stir up the bottom as easily and when using it, you are less likely to kick the reef. For this reason, most dive masters use the frog kick.

The frog kick also gives the diver more positional control. You can use a modified frog kick to brake, pivot and even go in reverse. When I dive with my camera, I use the frog kick most of the time.
 

Akimbo

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…Frog kick is not only more efficient from a propulsion standpoint... it's also "roll neutral" if you will...

What? If the frog kick were more efficient than it would be used by world-class freedivers who use the flutter or dolphin kick with monofins. The times for world records in the breast stroke would also be faster instead of slower than the freestyle. The flutter kick is biomechanically far more efficient, just look at the size of muscles in your legs and how the joints function.
 
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