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leg cramps and blood shift

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Jan 21, 2003
I've always had trouble with calf and foot cramps, too skinny for the fins I wear. However its getting worse and I think blood shift is at least partly responsible. I'd appreciate some feedback on what I can do about this.

I dive FRC, which produces a very strong blood shift, subtantially reducing the 02 available to my calf muscles during the dive. I think this is the cause of increasing leg cramps, although age (I'm 68) and not being in great shape are obvious contributers. I get cramps after a while in the water, even when my legs are not working very hard. Pointing my toes to improve streamlining makes it much worse. I take some magnesium before a dive and that helps a lot for body surfing, but is not all that effective for diving.

My question is what to do about this, short of less blood shift? Will simply working on making my legs stronger be all that is needed? Softer fins? Other suppliments?

Thanks in advance
Connor, what fins are you using now? That's probably the problem. Also, how much water do you drink before getting in the water? Oh, and any gently warm-up before the first dive?
Hey Connor,

First off, thanks for getting another FRC specific thread going, you know I'm all in on those :)

I have a very strong bloodshift, especially when I'm in (diving) shape and because of that I get very lactic very fast (especially on Exhale). I've never been prone to cramps and I've also trained quite a bit as a runner (+10km) without bringing water so my muscles may have developed a tolerance to cramping. Although I haven't experienced cramps (repeated exposure to lactic acid might be a culprit) I have worked a little to solve the lactic acid issue I was having.

So theres a few changes that I made to my prep, diving, and equipment set up that helped me with the transition to pure FRC diving.

  1. I'm not using the common negative-after-duck-dive (3m) approach that is usually associated with FRC diving. For a 3mm suit in sea water I would need 2.9kg to achieve that level of buoyancy. This is way too much for me to ascend with unless I wanted to be lactic after 10m. I reduced my freefall depth to around 9-10m with 1.9kg. The reduced weight greatly reduced lactic acid from the get-go. **the reason I'm at 1.9 instead of 2kg is because I made my neck weigh in pounds (2lbs -> 900 grams) and my belt-weights (2 x 0.5) are in kg. I wasn't getting fancy with measuring things to the gram :/ Yes I may have sacrificed the dive response bonuses of the instant freefall but I compensate by maintaining high CO2 during my breathups.
  2. Super soft fins. I had Trygons fins which are really nice (stiffer than average) but the foot pocket is horrible for me. I have a wide foot and I always had foot pain so I decided to finally get a fin that I could put a pathos foot pocket on (alchemy). I bought the softest model which is ridiculously soft. I had to change my finning technique around but so far the lactic acid has been reduced quite a bit and I haven't seen any real loss of power at depth either. I can still do safety really easily and haul up 12kg bottom weights without the support of the buoy.
  3. Over hydrating. I've started drinking almost 1.5l right before getting in the water. Comparing to the days that I forget to bring that much water with me on the walk to the bay in dahab, my blood shift seems stronger (protects lungs better), and I also feel less lactic. Potentially the extra water in the muscles leaves more storage space for waste products and their effect is reduced?? Hydration will also help with cramps in general.. From what I understand though, magnesium+potassium will help reduce cramps but you needs lots of sodium to properly absorb the water as the other 2 minerals don't have the hydrating effect that sodium has.
Thanks guys,

Some thoughts:

I think fin choice is affecting the cramps increasing. Mostly I dive with a Dol-fin and use a style that doesn't undulate much, mostly use ankles and a bit of hip, which probably puts a good bit of strain on my calves. I use a medium Specialfins Kelpie medium blade in Spora pockets for bifins. These were fine for years, but, with increasing age and less use because of the Dolfin, I think they are a bit stiff. Saw some videos of my diving recently and they look stiff. Planning on some very soft blades in future, maybe C4 25s. I would not want to give up the Dolfin, too much fun, so I need some strenthening exercises. Any suggestions?

I don't think that stiffness is the only problem here, some of my diving is mostly pulling up and down a line, and I still get cramps.

I'll try hydration and add potassium before diving.

Warm up?? whats that? Something I need to work on.

Nathan, you are diving deep and need a deeper neutral. Freedive wire has a great artical on most efficient neutral depth and how that at changes wih depth. Check it out if you have not already
Suplementing with D-ribose should help. Seems to work for me and there have been a few clinical trials with cyclists, specifically in relation to ischemia in skeletal muscles.

Sent from my SM-G930T using Tapatalk
Sorry for running into this thread a bit late. Are you still around? Did you fix the problem?

My swim coach recommended calcium supplements for my cramps (it worked).
Nice to see somebody looking at old threads; thanks for the interest. There is a huge amount of knowledge in them.

I've switched to soft fins, Florida Freedivers soft fiberglass in fairly soft pockets. Seems to help. Also recently I've been doing much more weight training to strengthen my calves(among other things) and swimming a lot more laps with body surfing fins. That definitely seems to help. Moved to North Carolina, so not as much diving as previously, so hard to say how I will react to deeper diving.
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