How to split a race

Recently I had a boring day at work, so I decided to nerd out a little bit. Ok a lotta bit. I wanted to know the relationship between different splits in a race. For example...if Swimmer A is swimming a 100 freestyle, what percentage of their race is spent swimming the first 50, and what percentage of the race is spent swimming the second 50. In a perfect world, it would be 50% for each. But when you factor in the start, and the extra energy the swimmer has at the beginning of the race things get a little more complex.

Before I dive in, you might be thinking, "Why in the world would you want to know this information?" It can come in very useful in practice and in meet situations. Say I have a swimmer (we'll call her Erin) that wants to qualify for the state meet in the 100 breaststroke. Erin needs to swim a 1:10 to have a good shot at qualifying. As her coach, I can use the data I found and have Erin practice swimming the pace she needs to go to get her goal time. In a meet, I can look at her first split and know if she is on track, below her pace, or going to slow to get her goal time.

So in my initial research, I found someone had done this sort of thing for NCAA swimmers. This gave me a good start, but I wanted to know how splits were related in high school swimmers being that high school swimmers are generally less physically mature and less experienced. So to expand on this research, I recorded splits of high school swimmers at the Iowa High School State Championship meet from 2009-2012. Here is a sample of the data from the girls 100 breaststroke:

Total Time          First 50 (%)          Second 50 (%) 
1:01.18              28.59 (46.7)           32.59 (53.3)
1:04.97              30.99 (47.7)           33.98 (52.3)
1:05.30              31.00 (47.5)           34.30 (52.5)

I did this for four years of times totaling 96 different times. I took the average percentages found each year and compared them. Here is what the averages look like:

Year     1st 50 %          2nd 50 %
2009      46.6                 53.4
2010      46.6                 53.4
2011      46.7                 53.3
2012      46.5                 53.5

I was taken aback by how similar these averages were! So I had to test them out for myself. I took the split percentages and applied them to several of the 100 breaststroke races I have coached over the last couple years. Almost every swim was dead on these same split percentages! I decided that this is no coincidence. 

From this data, I have created split cards for my swimmers. That way if they have a goal time, they know what they need to swim for a split from a start and from a push to achieve that goal.

Every event has different percentages for different reasons. It seems that breaststroke has the highest drop off from the first to the second 50. This could be because the start plays a bigger factor, or that breaststroke requires a large amount of power and wears the athlete out more than other strokes.  Backstroke has the smallest drop off from first to second split for the simple fact that the swimmer is not diving from the blocks for the first split.

Here are the breakdowns for percent of time spent on each split for different races. This data was compiled from NCAA athletes by Doug Huestis (the head coach for the Bay Masters program) and then added to by myself featuring Iowa high school athletes.

Event          Men          Women
50 Free       .4791         .4807
                   .5209         .5193

100 Free     .4715         .4752
                   .5285         .5248

200 Free     .2328        .2387
                   .2535        .2542
                   .2584        .2567
                   .2553        .2504

100 Back    .4831        .4834
                   .5169        .5166

100 Breast .4659        .4666
                   .5341       .5334

100 Fly       .4698       .4756
                   .5302       .5244
    
If you take these decimals and multiply by 100 you will get the percentage of time ideally spent on each split for any particular races. I stuck to these times because these are the races we see in a high school meet and races that are most common. The 50 percentages are per 25.

Hopefully this concept makes sense. If you understand it, it can be extremely useful in practicing at race pace and training for a specific goal. Keep in mind that the splits taken in a race in backstroke and freestyle were taken when the feet hit the wall on the turn. So if you are comparing times, that is something you might want to think about.