Early morning is the best time for a furtive swim--so early that this swimmer was still wearing his evening shirt.

I no longer have easy access to a swimming pool, so when on holiday and one is suddenly available at all hours, I take full advantage. A hard swim raises the heart rate and taxes the muscles, but, unlike running or skipping rope, I never emerge in desperate search of a shower. I know of no other exercise that is so rigorous and so refreshing. I disappear several times each vacation day, before meals and between engagements, returning a little out of breath but otherwise ready for whatever is scheduled.

Maybe my definition of swimming for exercise differs from most. I often see other swimmers plodding away, rhythmically putting length after length behind them. I have neither the patience (nor, likely, that sort of endurance) to spend an hour in the pool. So I sprint. Down-and-back, rest, down-and-back, rest and so on. I’m not opposed to slower, longer swims; I just prefer the thrill and efficiency of half-a dozen sprints.

The crawl is the classic fast swim. It works the shoulders, torso and back, but I always find it lacking for the legs. Strangely, the breast stroke, which is slower and more methodical, is a greater challenge when executed at speed. I think this has something to do with drag; the crawl forces a long, elegant line through the water, whereas the body is square during a breast stroke, ploughing through the chop like a slow but capable tug boat.

A brisk breast stroke also seems to work the chest in a different way to the pushup. It’s a spreading versus a pressing motion, and the muscle fibers quickly make themselves known by a deep and unfamiliar ache. The same is true for the legs; squats might strengthen the thighs, but the frog kick required during the breast stroke forces a pulling and pushing that becomes apparent by sprint number two. And whether it is realized or not, none of these motions are possible without tightening the abdomen. The chest, thighs, abdomen—these areas are precisely what a man should keep an eye on as he ages if he wishes to fill his jackets and avoid letting out his trousers.

Like my other preferred forms of fitness, no gear is necessary. I see others with goggles and noseclips, earplugs and swim caps. I’m sure they provide benefits for the dedicated, but I find sauntering into the pool area, cranking out a dozen sprints before cooling off in the shallow end is about as efficient and carefree as exercise gets. One minor word of caution though: as you become faster in the water, and the waist inevitably slims, you will be tempted to vault yourself from the water at the pool's edge. Do make sure your trunks have a good drawstring.

Ready, steady, swim... (followed immediately by cocktail hour).