Min strokes per length != max efficiency?

The efficiency of a swimming stroke is dependent upon many variables but some of the biggest variables are these: 1. Body size, height, weight, strength. The height of the person dictates the number of strokes they need to take to attain the same speed of someone taller (everything else being equal). The weight in proportion to the height takes on the same consequence (more rotund = more strokes). 2. Efficiency of the stroke itself. If the stroke pattern is efficient less strokes are needed to maintain the same speed (everything else being equal) and vice versa. 3. I do agree that some swimmers need to take more strokes to make up for other deficiencies. When everything is equal stroke efficiency is the trump card differentiating the best in the world from the rest of the world.

I guess that the interesting point for me was that, as you say, a more efficient stroke will result in fewer strokes per length but at the same time fewer strokes per length is not necessarily more efficient in terms of effort. I wonder if some people are physiologically better able to use a stroke with a higher turnover in the same way that I would expect that a lower gear would work better for one person where someone else would do better one gear up in cycling.

Efficiency is the least amount of energy expended for a given speed over a given distance. The idea that there is a one-size-fits-all technique for all people for all distances and efforts is a bizarre notion that swimming just can't seem to shake. Even racewalking left that idea behind almost 40 years ago. The laws of physics are the same for everyone; the optimal application of same is different for everyone. -LBJ

. The idea that there is a one-size-fits-all technique for all people for all distances and efforts is a bizarre notion that swimming just can't seem to shake. Even racewalking left that idea behind almost 40 years ago. . -LBJ One of the most sensible things I have read on this forum.

One of the most sensible things I have read on this forum. I agree that each person will have their own optimal stroke count. We're all built differently and will have somewhat different mechanics. Physiologically different people might also be able to sustain a higher turnover or higher power output than average. I'd maintain that the basic mechanical motions will still be the same, though, and that the key ideas are minimize drag, maximize propulsion. Stroke length will differ, some people have shorter arms and may be able to sustain a higher turnover without increasing drag, but a nearly optimal basic swimming stroke will be similar with most people.

Kicking seems to be a big part of it. Manaudou and Evans both used light two-beat kicks. Swimmers who appear to glide more are actually coasting on a powerful kick. Ian Thorpe is a good example.

So how does one measure efficiency? Fewest strokes, fastest time for a given distance-- like swim golf? It it 1. or 2. below? 1. If it takes me 80 seconds and 50 strokes to swim 100 yards, it is more efficient if I take 48 strokes and still maintain that 80 second pace? 2. Or is it more efficient if I take 50 strokes and improve my time to 78 seconds for 100 yards? We're talking about whether increased SPL with all other factors equal necessarily means more efficiency. There is a possibility that few swimmers or coaches ever consider: neither #1 nor #2 which you listed is right. In both cases, you could be getting less efficient. In an absolute sense, #2 is definitely a decrease in efficiency, since faster swimming is almost always less efficient due to drag. Especially if you get to this point by trying to stretch your stroke, or by kicking harder. Relative to speed, you might be increasing your efficiency in scenario #1 or #2, but the whole point of this thread is that SPL can increase via methods other than efficiency.

So how does one measure efficiency? Fewest strokes, fastest time for a given distance-- like swim golf? It it 1. or 2. below? 1. If it takes me 80 seconds and 50 strokes to swim 100 yards, it is more efficient if I take 48 strokes and still maintain that 80 second pace? 2. Or is it more efficient if I take 50 strokes and improve my time to 78 seconds for 100 yards? Neither. The only way to measure true efficiency is via testing oxygen/energy usage at a given speed for a given distance. Examples (non-exhaustive) of why each of the above can be misleading: 1. I can swim 25 yards in 14 strokes pretty readily for most paces. I could also do that 25 yards with 11 strokes at most of those speeds if I really concentrate. However, it takes me more energy/effort to do so. Therefore, I am less efficient at 11 strokes since it took me the same amount of time but more energy/effort. 2. You may be able to hold the same stroke count and drop time by maintaining the same effort with the arms, but adding a stronger kick. (I can't - my kick is worthless.) The energy used for the arms is the same, but you've also added energy with a more vigorous kick and so calling it more efficient is misleading. My own rule-of-thumb for efficiency is that if I can cover a given distance at a given pace with less fatigue than I have previously, then I have become either biomechanically or biochemically more "efficient." -LBJ

one can get technical efficiency = useful power output divided by total power input ie, what are you getting for what you are putting in question is, what's your measure.....strokes per length, distance per stroke, or speed or time to the finish? hard to pin down things that are changing, particularly regarding input power/energy perhaps time to get to finish with an all out swim may be the most meaningful estimate of efficiency (power = work divided by time) (work = force times distance traveled)

one can get technical efficiency = useful power output divided by total power input ie, what are you getting for what you are putting in question is, what's your measure.....strokes per length, distance per stroke, or speed or time to the finish? hard to pin down things that are changing, particularly regarding input power/energy perhaps time to get to finish with an all out swim may be the most meaningful estimate of efficiency (power = work divided by time) (work = force times distance traveled) I think the point here is that, as you say, efficiency is measured in terms of energy expended, and none of strokes per length, distance per stroke, or time for distance measure energy expended directly. The problem is that it is hard to measure energy output directly. I think your assumption is that in two all out swim of a given distance by a single person the total energy expended by an individual will be the same so the faster time will indicate greater efficiency. This would imply that instead of counting strokes in an effort to get more efficient that we should track our interval times instead. Alternately one could test the duration for which one could maintain a given pace using two stroke variations, and the greater the duration the more efficient that stroke variation must be. That brings up the question of the relative advantages of stroke counting versus monitoring speed or duration...