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How do you compare swimming and running speeds? For example, is swimming 100m in 60s comparable to running 1 km in four minutes in terms of effort or in terms the times in races (e.g. map percentiles of finish times).

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This is like comparing apples and oranges for me; the only thing you can compare is calories burned. – Baarn Oct 6 '12 at 16:26
This is related to this question. – R. Chung Oct 6 '12 at 17:38
Or slightly easier to measure, try to swim at the same heart rate you run at. – Ivo Flipse Oct 7 '12 at 9:10
I don't understand the difficulty in comparing speeds? Is it difficult to measure swimming speed? Are you trying to account for swimming upstream vs downstream? In a still body of water, you should be able to simply use the distance travelled / time to calculate the speed just like you would for a runner. – powerpack Oct 8 '12 at 22:12
If you're talking about comparing times, I've found that running is roughly 4x faster than swimming. That is, a top runner runs 400m in ~50s while a top swimmer swims 100m in ~50s. In the same amount of time, the runner covers 4x the distance. This is useful for comparing running times if you're a swimmer or swimming times if you're a runner. – Hartley Brody Apr 28 '13 at 21:10

2 Answers 2

up vote 7 down vote accepted

A similar question was asked here.

That question included data from the 2009 Ironman Triathlon Championship in Kona, Hawaii. As you may know, the race consists of a 2.4-mile open water swim, a 112-mile bicycle ride, and a 26.2-mile marathon. A version of the scatterplot matrix from that question is shown here.

2009 Kona Ironman swim, bike, and run times

The scatterplot matrix above plots the swim, bike, run, and overall times (in hours) for each finisher. Although not shown on the plot, the correlation between swim and run times is .588, which indicates that there is a moderately strong positive relationship between swim and run performance across individuals (though not as strong as the correlation between bike and run times). The plot shows that "good" runners can be mediocre swimmers, and vice versa.

However, if one is interested in the question "what are equivalent run and swim paces for those who both swim and run?" one way to examine the data is to ask "how does the median run pace compare to the median swim pace?" Similarly, you could ask "how does the 90th percentile run pace compare to the 90th percentile swim pace?", how does the 75th percentile run pace compare to the 75th percentile swim pace?" and so on, comparing each percentile to each percentile. This is what the plot below does. It shows a quantile-quantile comparison of run and swim paces, normalized to minutes per mile for running and minutes per 100 yards for swimming. The dotted red lines show the 2nd, 10th, 25th, median, 75th, 90th, and 98th percentile times for run and swim pace.

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Note the linearity of the relationship between run and swim pacing. In fact, between about the 2nd percentile and the 98th percentile, the correlation coefficient between the two is above .99. The solid red line shows the regression of swim pace on run pace, and the equation for the regression line is given. As a reminder, this shows the quantile-quantile pacing for multisport athletes who are trying to complete an Ironman, so the pacing will be slower than for single-sport athletes in standalone events.

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great, two questions 1) what is the metric formula? 2) how does the Ironman race compare to the results from Ryan? – FredrikD Oct 8 '12 at 19:10
1) Well, if you were interested in, say 10k pace, you could convert from min/10k to min/mile, then use the regression line to get the swim pace, then convert that to, say, pace per 100 meters. 2) This is for multisport athletes and covers a wider range of abilities, so you might think of it as the "equivalent running and swimming pace for someone who does both sports." Ryan was looking at comparing record times for single-sport athletes. And 3) you'll find a slightly different relationship if you had used 2010 data, or a shorter race. I was just showing how one might address the problem. – R. Chung Oct 11 '12 at 18:16
This is the best conversion I have seen, but many triathletes are swimmers as an afterthought so comparing a dedicated swimmer with a dedicated runner might bring a different result. Also, a 100m comparison, with water resistance at speed, won't compare closely to distance. – Peter DeWeese Oct 14 '12 at 22:31
@PeterDeWeese Agreed, and even doing this for a sprint triathlon might give different results than for an Ironman. Note also that if we looked at the run-swim times rather than the quantiles, the correlation is .588, which indicates that swim time explains about 35% of the variance in run time. But this analysis still gives a way to think about how to answer a question like this. – R. Chung Oct 15 '12 at 2:05
@R.Chung Great answer and approach! Did you do a weighted regression or a simple linear regression (SLR). For run vs swim it looks like the homoscedastic assumption of an SLR was violated, this will give too much statistical weight to slower individuals. The individuals who were espeically slow swimmers likely have too much leverage on the regression line. – Rider_X Jan 7 at 22:56

If you start with the world records in a 1500m swim and 10km run you get these times for 100m and 1km

approx 26min 10km --> 2:36min/km approx 14:30 1500m --> :58s/100m

:58 vs 2:36 World record level

1:04 vs 2:51* % increase in the swim time based on the European Masters Record 1500m 35-39.

1:10 vs 3:00* based on a recent swedish swimmer 35-39 time for the 1500m, and that I know several 40+ runners that run under 35. Also a % increase.

**Masters ER 1500m men's 35-39 is 16:00 (1:04). This weekend one of Swedens swimmers swam 1500m in 17:54 (1:11.6). I think these two levels are possible. Not everyone can swim at those speeds, so its not expected that everyone could run at that speed. Maybe we can call this group the amatuerelite. People who train and race for fun, but are not professional athletes.

1:33 vs 4:00 might be a big jump, but this is based on a year OW river race 3km, and a series of 10km races in Sweden. Roughly 7% of those who swim the river race manage a time under 46:30 in 2012. The 10km races had less than 2% under 40min. But this difference could be explained that swimming in 16C water is not for everyone, and in the higher number of participants in a 10km might walk parts, effecting the faster times percentages poorly.

1:55 vs 5:00 (approx 28% of race finishers in the 3km river race "Vansbro" vs 20% 10km)

2:20 vs 6:00 (approx 63% Vansbro vs approx 60% 10km)

so sure one can say it's like comparing apples to oranges, but if you scale the results from enough swimming events and running events, I am sure you will find these values to be relative close.

Open water races in warmer water will produce a higher precentage of breaststrokers that float through the race, were as warm flat races will also attrack more and more "run/walkers". so maybe one could start by removing the last 5-10% of the finishers time?!?

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The formating of this post confuses me, I tried editing, but I failed. – Baarn Oct 8 '12 at 16:51

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