Describing swimming as ‘slow’ or ‘fast’ is too imprecise to be meaningful. A pace that is slow for 100 meters can be very fast for 1500 meters. A time that is slow for a 25 year old can be world-record pace for a 75 year old. And even for the same swimmer and distance, ‘slow’ or ‘fast’ tells us surprisingly little.
If I swim a series of 100-yard repeats at a pace of 1 minute 24 seconds that would be nothing to write home about if I swam them at a tempo of 1.0 seconds/stroke (which would be 16 strokes per length.) But I’d feel inclined to shout from the rooftops (or at least post on the TI Forum, Facebook and Twitter) if I swam at a tempo of 1.5 seconds/stroke — which would require me to complete each length in 11 strokes.
Drilling much deeper into the slow/fast dichotomy, have you considered that even within the same stroke, some parts should be ‘slow’ while others should be fast. In fact, the ability to do this–called asynchronous timing–is a high level skill that is critical to swimming your best.
The catch (not the entire stroke) should be as slow as possible–all other things being equal. Taking more time on the catch improves streamline by keeping your bodyline extended a bit longer. It also improves propulsion by allowing you to cultivate a firmer grip and keep the water molecules behind your hand and arm quieter.
With a faster catch, you’re liable to move the water more. With a slower catch, you move your body more. The most notorious example is the anchor leg on the Mens 4 x 100 Freestyle Relay at the 2008 Olympics in Beijing. The main Jason Lezak passed Alain Bernard was his dramatically-slower catch–which resulted in him traveling much farther on each stroke.
In contrast, the recovery should be as quick as possible–all other things being equal. This is because the more time your arm is out of the water–where it weighs 10x more– the more ‘stress’ is imposed on your balance and stability. And thus the more chance you’ll use arms and legs to ‘steady’ yourself. Also the more time the recovery arm is out of water, the more time you spend as a ‘shorter vessel.’
But here’s the conundrum. You shouldn’t try to speed up your recovery by moving your arm faster. Instead, strive to (i) travel the shortest distance between exit and entry — a straight line with fingertips barely clearing the water; and (ii) have your hand out of water as briefly as possible.
And here’s one more benefit to practicing a superslow catch: It will improve your Balance and Stability by tuning up spinal-stabilizer muscles.