physiology Q1> why am i tired after diving ?

[Storker]

Nitrogen bubbles. Try extending your safety stop and going r-e-a-l-l-y slow from there to the surface. When I started shooting a dSMB and going slowly enough to be able to wind the line back on the spool, two things happened:

1. I didn't feel as tired after diving
2: I quit seeing "fast ascent" warnings for that ascent after downloading my profile to the PC.

Granted that correlation doesn't equal causation, I believe there's a connection. Read up on micro-bubbles and asymptomatic DCS.

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[TMHeimer]

There are some good theories so far. For me, "tired" and "sleepy" are two different things. I'm tired after almost any dive, especially if a long walk before and after occurs, obviously. Tanks are heavy. And how much area I cover during the dive. "Sleepy" depends on the person. I need to average 8 hours a night. 10 one day and 6 the next is OK. Everybody is different regarding sleep. I don't feel any more sleepy after a dive than before. I'm kind of sleepy all the time.

 

[Subcooled]

It is obvious that when you spend a lot of time in water, your body looses a lot of heat. Producing more heat is tiring.

Also, when you get nitrogen bubbles in your blood stream then your immune system reacts to these strange new things - the bubbles. Fighting the bubbles makes you tired just like flu does. You could avoid ALL the bubbles but you would get horribly bored and cold instead.

Using a heating vest, nitrox and a zero bubble ascent profile might help. Personally I feel less tired after mentally relaxing dives with extremely slow final ascent and nitrox and not feeling cold.

 

[scagrotto]

I tend to get cold on weeklong dive trips in the Caribbean.

I've figured for a long time that most people who do a lot of diving over consecutive days probably end up with a chronic, but minor, case of hypothermia. My body temperature is an awful lot closer to 100º than it is even very warm 85º Caribbean water. I've also been in a portable hot tub that was only about 95 to 96º, and after 15 or 20 minutes it felt downright chilly.

A diveskin or 3mm farmer john wetsuit may be enough to keep you feeling comfortable in the Caribbean, but it's definitely not enough to prevent heat loss.

 

[ironandchrome]

Toasty SI's...mmm. think I'm getting sleepy just reading this. Puget Sound has 55 degree water. Even with a dry suit/ undergarment I'd really enjoy Caribbean temps!

But yes, after a two dive day I'm ready for a nap when I get home. My physical fitness is pretty wimpy right now. I think if I did some sort of exercise (daily 30 min) my post dive exhaustion would be really minimal. The more I do during a dive - fight current, help watch students, task load, etc. the more tired I feel.

 

[dumpsterDiver]

I've figured for a long time that most people who do a lot of diving over consecutive days probably end up with a chronic, but minor, case of hypothermia. My body temperature is an awful lot closer to 100º than it is even very warm 85º Caribbean water. I've also been in a portable hot tub that was only about 95 to 96º, and after 15 or 20 minutes it felt downright chilly.

A diveskin or 3mm farmer john wetsuit may be enough to keep you feeling comfortable in the Caribbean, but it's definitely not enough to prevent heat loss.

The Caribbean can get VERY warm in the summer. A 3 mm suit may be too warm for many people, especially with a hood. If the water temperature is below your core temperature then you will lose heat to the water. However, the diver may generate MORE heat than is lost to the water. Many times I have been too warm in the water and have had to remove the hood while diving, unzip etc.

If your argument is that diving makes you tired because you are always losing heat.. That just doesn't fly. I have done commercial diving in relatively cold water with high levels of exertion (in shallow water) 4-5 hrs per day in water and it does not make you tired like doing several deep dives.

 

[TSandM]

I am definitely more tired after diving cold water than warm, but cold water is not only cold, it involves a lot more weight to move around, so it's more work. I can do a max of 3 dives in 45 degree water in a day, and I am very tired at night. I can do four and sometimes five in warmer water.

However, the big differences for me in post-dive fatigue came with two things. One was getting fitter, so the gear moving was less stressful. The other was changing my ascent strategy, so that the closer I get to the surface, the slower I am going up. In GUE's DVD, "The Mysterious Malady", which is a series of interviews with researchers into DCS, David Doolette says he is convinced that fatigue is a form of subclinical DCS, and I agree with him. The standard, relatively rapid ascent to a safety stop, followed by what is often a VERY rapid ascent to the surface, is a recipe for fatigue. Slowing the ascent, and in particular taking several MINUTES to get from 20 feet to the surface, changed my post-dive fatigue a bunch.

 

[Imla]

I agree with TSandM. I used to get tired after dives, but after changing ascent strategies (and choice of gas) I rarely feel fatigued after diving. Especially in warmer waters.

My recipe... 3m/min from 15m up to 3m. 1m/min from 3m and up (Or from 6m and up...)
I also exclusively dive 32% for rec diving.

 

[KeithG]

Heat loss and physical exertion are my votes.

Get a better fitting wetsuit and stop kicking so much.

 

[Pedro Burrito]

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