improve down time

Aerobic fitness, relaxation and lots of practice are the key points.  Comfort so your mind can relax.  Anxiety burns lots of O2.  Slow the heart rate down.  Take long slow deep breaths at the surface.  Take plenty of time between dives.  Get into a rhythem.  1 minute down, 2 minutes up on the surface.  Don't overextend your bottomtime.  It makes it harder to recover and make another dive.  Pace yourself.  Just my 2 cents.
Dave

Oh yeah, one more thing:  The importance of the Pike Dive on the surface with being properly weighted.  I like being just a touch positively buoyant.  Then when you kick your feet up into the air for your pike dive the weight of your legs in the air will push you down into the neutral to negative zone - without kicking much or at all.

The perfect free dive would be one where you don't kick at all on the way down, just free-falling to the bottom.  Save your kicks for the way back up.  Those leg muscles use a lot of juice.

Merv, I slacked off on the diving last year, but this year I'm gonna go for it again.  So yeah, let's go for it.  If you pick up the freediving as fast as you did the yak-fishing, you'll be great in no time.  Wear your scope -patch!  If you think yak-fishing makes you sick, free-diving is worse.   I've seen guys blow chunks out through their snorkel - yuck.

If you're no good at water ballet just stick one leg up in the air, it works about the same

Hyperventilating is a problem because it reduces CO2 in your blood faster than it replenishes oxygen and our urge to breathe is based on CO2 concentration, not O2 deficiency.  Thus if you hold your breath to deplete O2, hyperventilate briefly then hold your breath again you may run out of oxygen and black out before you feel a particularly strong urge to breathe. 

At home I have a chest freezer that I modified to be temperature controlled beer fermenter, the fermentation produces CO2 and escaping gasses also let you smell the beer to see how it's coming.  The first batch I did in the freezer I took a big whiff of nearly pure CO2, I was instantly hit with an urge to breathe stronger than I've ever experienced.  I'd been concerned I might reach down inside to lift out a bottle, breathe too much CO2 accidentally, black out fall in and suffocate, but after getting a hit of the CO2 there's no danger of breathing the stuff and not noticing.  It's about as noticeable as tear gas.

A couple years ago, I decided I wanted to improve my bottom time.  After reading up on training methods, I figured the easiest way to work on it was to hold my breath while walking down the hallways at work.  It seemed to work as I found I could walk farther on a single breath as time went on.  My goal was always to make it from my office to the bathroom on one breath.  I tried and tried, but always came up short...   

One day I felt really relaxed.  I knew this was the day I'd make it.  Took a few deep breaths and off I headed to the throne room.  Completely focused, I side-stepped a co-worker, tried to relax my mind, and paced my steps diligently.  As I rounded the last corner, I could see the bathroom door.  The urge to breathe was overwhelming, but I fought it off.  My pace quickened as I was determined to make it!   

Pride overwhelmed me as I burst through the door in victory, gasping for air!  Then... something else overwhelmed me... the horid smell I can only surmise originated in the bowels of unnamed employee in stall #2.  The relief of that first gasp of air was replaced by suffocating nausea as I stumbled out the door, coughing and hacking like I'd just been hit with mustard gas.  As I sat there on the ground, trying not to throw up... I decided that was the end of my freedive training.   

Let me know what your doctor friend says.

Hi Divers:

   Lots of good tips. I would also make sure to dive straight down and, not at a angle. 
   The proper Gear like, the Picasso Freediving Fins help but at a steep price . $$150.0
                   Sea-ya at VanDamme
                   Ernie

Picasso Freediving Fins Intel:
http://shop.bbprodive.com/category.sc;jsessionid=48A57A3A835DC40454BADC85A7A8BB09.qscstrfrnt01?categoryId=10
       

On the physiology thing I'd be skeptical about breath-training techniques, breath hold tables etc  Breath techniques of yoga is a different matter

The amount of O2 you can "store" is pretty much set, hemoglobin saturation is already close to 100% in normal circumstances

CO2 receptors in smokers are muted from having chronically high pCO2 and it's possible that happens in freedivers who are essentially athletes who retain CO2 while they're working out instead of blowing it off at a steady rate

Not sure about O2 receptors

I think the largest benefit of the tables is that they get people to practice holding their breath in an orderly manner and in a controlled environment.  The tables help one become comfortable with the urge to breath (whether oxygen debt or co2 build up) and understand one's physiological & mental limits better.

90% of diving is mental.  Many people panic when the urge to breathe comes.  This might not be signaled by traditional panic signs, but as simple as mind racing, tensing of muscles, and/or increased heart rates - all of which will burn O2 at a higher rate.  A large part of successful breath-holding is learning to calm oneself at will and curb anxiety.  That mental aspect combined with the discipline to properly breathe up prior to the dive, focus on form, and control movements are almost unilaterally more important than physical prowess.  A lot of training is mental, some is physiological.  The tables help with both.



Your comments about CO2 build up have been incorporated into many breathe up routines.  While the body may feel ready to dive and at 100% a minute after the previous dive, tests have shown that it takes longer for O2 saturation to return to full strength.  That's the #1 reason I wear a dive watch - not to see how deep/long I can dive, but the surface timer lets me know that even if I feel fine, I need to stay on the surface a bit more.  If I keep diving without proper surface intervals, it'll catch up to me later in the day as the oxygen debt accrues.


As you said, there's a human physical limit on a lot of this.  Understanding how to take ful advantage of what you have... is the true goal of training. 

..... 

90% of diving is mental.  .......................

Very true!  Comming from a xxxl diver whom has been diving for over 20 year. Since 12yo.

Over all fantastic thread with great info being shared.

I run stairs on the hill across my street. The other day I tried running a few sets while holding my breath. It wasn't easy and left me gasping but I'm going to keep at it and see if I notice results.

Never mind...I tried it again today. It's painful, and I don't think it can be good for the heart.

I've gone through most of the threads in the diving and spearfishing forum and this by far the most useful thread I've found.  In my younger days I was able to stay underwater for 2 minutes. 

I attribute it to a video I had seen about this guy who had just set the free diving underwater record for depth.  Most of you guys have echoed what he said about staying calm underwater. 

I'm currently looking for a pool in the oakland berkeley area to go swim with my wetsuit and fins.  My belief here is that holding your breath changes when encumbered with weight, fins and 7mm 2 piece wetsuit. 

Also, has anyone here any experience diving with a tooth ache?  Also, diving with type 1 diabetes?

JTF

Are you talking about a tooth ache or tooth Squeez?  One is just general pain constant when in or out of the water the other is caused by a bubble of air trapped inside a tooth under a crown or somthing like that.

I hate tooth aches go get it fixed it could be an infection of the root of the tooth.  Squeez is usualy a problem for scuba divers but I guess it could be a problem for freedivers to a lesser extent you might try grinding your teeth togateher to releave the pressure. 

I read the Terry Maas book on spearfishing and now I'm reading the Manual on freediving by Palazari. The manual is very technical but I can't say enough about the helpful info. I was much more comfortable diving last week and did a 3 minute breath hold Monday (dry).

I bought a Picasso open cell wetsuit and it was a huge difference from my regular 7mm. The open cell is lighter, more flexible and warmer. I haven't used my freedive fins yet but I'm going back up for 4 or 5 days the weekend of 5-2 and will use them. It's time for me to get down to some depth.

My belief here is that holding your breath changes when encumbered with weight, fins and 7mm 2 piece wetsuit.  JTF

I went freediving in Cozumel with only a mask, snorkel and cheap fins and hit 55 feet deep which is an out of my skull depth for me.
Diving sans weightbelt and wetsuit, diving in warm water and having 100 foot viz DEFINITELY makes a difference.