awenborn wrote:
I suspect there's a number of reasons why HR drops so rapidly in swim rest periods compared to runnning or cycling: (1) The cooling effect of the water - you're going to dissipate all that excess heat from working out much more quickly if you're submerged in water than, for example standing around in still air on a running track.
(2) Physiology - swimming is largely an upper body activity (arms/shoulders/back) and the time required to supply-and-return blood from the heart and lungs to those muscles is much shorter than your leg muscles, ergo you can reasonably expect to recover quicker.
(3) Oxygen debt - your heart rate is likely elevated because of the oxygen debt from restricted breathing rather than overloading the cardiovascular system; reverting to a limitless supply of oxygen during rests helps rapidly correct this. i.e. the limiting factor in swimming is your pulmonary system (and utilisation thereof) rather than your cardiovascular system. N.B. I'm not sure if this is backed up by any evidence, but that's certainly how I feel during swim sets.
Your #1 is true if you're swimming in a 78-79* pool, but many pools that I swim in are more like 86* which would actually have the opposite effect, espec if compared to running at 60* or cycling at any temp below 78*. In fact, cycling prob has much more cooling than swimming in general, if all seasons of the year are considered.
Your #2 prob has validity and I had forgotten this angle. :)
Your #3 is highly, highly dependent on conditioning. I feel I can get just as totally gasping from running or cycling as from swimming.
In any case, this is an interesting discussion. :)
"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."