Go down to the article on fitness and diving:
https://www.dhmjournal.com/images/37/DHM_Vol37_No3.pdf
Sample sizes are not large but interesting:
From the article:
"The basis for this was US Navy research indicating that the maximum speed a fully equipped diver could attain was 1.3 knots (1.8 km.h-1) at a work rate of approximately 13 MET. Realistically, this is a demanding standard given the normal level of effort involved with diving. Swimming at a more typical speed of 0.5 knots required an effort of only 3 MET in the same equipment. While emergent conditions may produce a transient demand for great power output, it is unclear if a capacity of 13 MET is a reasonable threshold."
I think very few divers could meet the 13 MET threshold and that such a requirement for recreational diving including technical diving is too high. MET is taken from VO2 max divided by 3.5 and for women 3.2 since VO2 accounts for body weight in the calculation. More or less, something like that.
The VO2 max declines with age, for sedentary folks after age 30 there is typically a decline of 10% per decade. For physically fit and active persons who continue to train the reduction is about 5% per decade. I would like to see that bar chart if age taken into account. Body weight (excessive) coupled with declining VO2 max and low fitness might equal a cardiac event? You/me are not what we used to be, period!
I know that the BMI chart is not popular with some folks and that it has some flaws and that only serious athletes have ever had a VO2 maximum test (I have had three but I was kinda serious) but can it really be argued that keeping body weight under control as we age is not important to diving and life quality in general?
My observation of divers as a lifelong endurance type athlete (well, athlete now might be accurate
) and 50 plus years as an active diver is that a high level of fitness is not required for most SCUBA diving activities but is beneficial. If as you board the boat the boat tilts to your side and there are ten folks on the other side, you might want to look into Weight Watchers first and then a fitness program second.
It is not possible to exercise off caloric intake. The most important aspect of general fitness is food intake IMO. You could never step into a gym or spend an hour in the saddle but get on BMI (by controlling your calorie intake) and do wonders for your general health. But coupled with a fitness regimen, you are golden. Body weight/mass is the enemy. People tend to gain 10 plus pounds per decade and your maximum heart rate also declines along with VO2 max. The less of you there is for your heart to pump blood to and through and the less of you there is for your lungs to oxengenate, the better (IMO) for SCUBA diving. And the older we get, the more important it becomes to control weight.
Weight generally goes up as we age for most people (and more of that weight is fat rather than muscle), VO2 max and maximum heart rate decline as we age for everybody, there is a crossing point and you do not want to be there when SCUBA diving lest one become an entry in that bar chart.
I guess my point is that we can talk about fitness programs but the real enemy is body weight/mass. Especially as we age.
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