Fast Skins and Shaving Don’t Mix

For decades, swimmers have shaved every hair off their bodies before big swim meets.  My own competitive swimming days were in the late 1980s and early 1990s, which were just before the advent of full bodied swimsuits.  Back then, a faster suit was always a smaller one.  The more you left exposed, the better (for swimming speed anyways).  And you shaved everything that couldn’t be covered by that tiny suit or a swim cap. 

I began shaving down for big meets at age 14 because everyone did, no matter if you were follically deficient or Chewbacca.  It wouldn’t be just the legs and arms.  Chest, back and even armpits were fair game.  We even shaved the palms of our hands and the bottoms of our feet!  The timing of shaving was critical too.  Swimmers would not shave all season long (even the women), just so that come race morning you would feel unexpectedly fast.  Most shaved the night before, but others would wait until race morning. 

Things have changed in the swimming world in the past 10 years.  A 180 pound man fitting into a size 4 g-string isn’t a symbol of manliness anymore.  Suits are now meant to cover more of the body, not less.  So an enduring question remains.  How important is shaving with these new full bodied swim suits?  To answer this question, I put together a simple experiment.  Wearing a fast-skin, I swam a bunch of sprints one day, shaved down, and re-did the same sprint set the next.  If shaving helps, it should register as faster times.

The set was 8 x 25 yards, as fast as I could go.  I took 4 minutes minimum rest between each repeat.  Starts were in-water, and repeats were timed by stopwatch with 1/100 second resolution.  Freestyle was the stroke used throughout the test.  The swimsuit used was a Speedo Fast-Skin II single piece triathlon model.  A picture is shown below.  This suit covers the torso, waist and top half of the quadriceps.  However, the arms, shoulders and legs below the knee are exposed. 

The first set (without shaving) was completed on Saturday, Sep 20, 2008.  I then shaved the arms and legs that weren’t covered by the swimsuit.  The second set (shaved) was completed on Sunday Sep 21, 2008.  The same pool (and same lane) was used for both days.  Each repeat was swum in the same pool direction in order to minimize any effects of pool jets/current. 

After all of my years of swimming and shaving down, I was expecting to go faster on Sunday.  My actual results after shaving were exactly the same as without shaving!  I was unable to characterize a benefit to shaving, even though my experiment had a 95% confidence interval of plus/minus 0.1 seconds (or 1% of total time).  Thus, if the performance improvements of shaving were greater than 1%, I should have found a difference.  Performances on a repeat by repeat basis are shown below.

Click here for a larger image.

A paired comparison was used on a repeat by repeat basis in order to calculate the p-value and confidence intervals.  Thus, [no shave] – [shave] was calculated separately for repeat 1, repeat 2 and so on.  The average and standard deviation of the differential was then statistically analyzed.  But you don’t have to be a statistician to see the results.  The graph clearly shows that the “no shave” and the “shave” data look very similar.

So, what can you take away from this data?  If you shave religiously before every big swimming/triathlon race (like I do), have you been wasting your time?  The only conclusion I can make is that I was unable to characterize an improvement associated with shaving when you are already wearing a full bodied swimsuit.  I can say that the chance of shaving benefit being greater than 1% of total time is unlikely.  However, I cannot tell if shaving has no benefit or a slight benefit that is less than 1%.

A benefit of less than 1% would be a very small amount of time in any triathlon swim.  For example, if it takes you 25 minutes to do a 1.5km swim (as in an Olympic distance triathlon), a 1% improvement would represent just 15seconds.  If the benefit is only 0.5%, then the benefit is only 7 seconds.  In other words, even if there is a slight benefit in shaving for triathlon swimming, it is not enough to give you a significant advantage over your competitors.  Conversely, a 1% improvement (or even a 0.5% improvement) can make a HUGE difference in competitive swimming, especially in sprints where every hundredth of a second counts.  For example, the difference from first place to last place of the men’s 50 meter freestyle final at the 2008 Olympic Games was only 1.9% (or 0.42 seconds).   

I have been scrambling to understand why shaving didn’t help me swim faster with a full bodied swimsuit.  After all, I have read many studies which show that shaving in general does make you swim faster.  So why didn’t it show up in this experiment?  Possibly, the benefits of shaving are negated the moment you put on a fast-skin.  After all, wearing a fast-skin and shaving are both ways to reduce your friction and drag with the water.  Perhaps a full body swimsuit alters the flow of water over your entire body such that it becomes irrelevant if any exposed skin has hair or not.

It is also possible that experimental limitations affected results.  Data from only one athlete (myself) was presented.  And I have to admit, I was not Chewbacca before I shaved down.  Maybe the number of repeats was too low (8 is a small number for statistical analysis).  Maybe if I had more hair to shave the results would have been different.  Maybe the benefit to shaving allows you to swim at the same speed more efficiently, but doesn’t improve your maximum speed.  These are all possibilities.  I suppose a larger study will be done some day to find out for certain.

Should you shave everything exposed for a triathlon swim?  Though many triathletes shave their legs on a regular basis, few shave their arms.  This experiment says that is ok.  However, if shaving down is part of your pre-race ritual, I would continue to do so.  I intend to keep shaving my arms for every big triathlon race.  I may know in the back of my head that it is probably not helping.  But after so many years of shaving down, it would feel like I’m not prepared to race without a shave.  And feeling like you are not ready to race is often worse than actually not being ready to race.  Until next time, happy training!