Effects of wearing a wetsuit on triathlon swim performance and stroke mechanics

[Sports Science Editor]

Wearing a wetsuit is known to increase your swim performance due mainly to improved buoyancy and given the option, most triathlon competitors would always chose to “suit up” rather than braving the elements in a bathing costume only! Whilst it may not be common in the UK, several races around the globe take place in water which is warm enough for wetsuit use to be banned or optional. In order for you to make an informed decision regarding wetsuit swimming, this article examines the effects of wetsuits upon open water swim performance and also its effects on stroke mechanics.

How was the test conducted?*
A total of 13 triathletes (9 male/4 female) took part in the study which used an endless pool to examine the following factors:

1. Swim VO2 max with and without wetsuit
2. The speed at which VO2 max was reached with and without wetsuit
3. Economy and lactate at both 60% and 80% VO2 max with and without wetsuit
4. Stroke length (distance per stroke) at both 60% and 80% VO2 max with and without wetsuit
5. Stroke rate (strokes per minute) at both 60% and 80% VO2 max with and without wetsuit

The selection of 60% and 80% VO2 max for the sub-maximal swim speeds is based upon the fact that swim speed in triathlon racing tends to be between these rates (Miura et al 1999).

What were the findings?

1. The actual VO2 max did not vary with or without a wetsuit, but the swim speed at which VO2 max was reached was 5.4% faster when wearing a wetsuit compared to wearing a normal swimsuit

2. The energy cost when swimming at 60% VO2 max and wearing a wetsuit was 14.4% lower than when not wearing one

3. The energy cost when swimming at 80% VO2 max and wearing a wetsuit was 7.5% lower than when not wearing one

4. When swimming at both 60% and 80% VO2 max, the swimmers stroke length did not change a great deal when wearing a wetsuit, but there was an increase in stroke rate (the arms were moving faster)

5. Swimming 1,500 metres at 80% VO2 max in a wetsuit would decrease swim time by 70 seconds compared to non-wetsuit swimming, based on the findings of this study

The researchers found an interesting difference between swimming with and without a wetsuit at 60% VO2 max, energy usage being much lower when swimming with a wetsuit. They concluded that when swimming at very slow speeds a swimmers body sinks further into the water causing more drag – hence the buoyancy of a wetsuit is a big help to slower swimmers in particular. When swimming at 80% VO2 max, the faster pace allowed the body to lift in the water which reduced the benefits of the wetsuit.

In addition, the researchers noted (using video footage) that at even faster speeds (above 80% VO2 max) the buoyancy of the wetsuit made even less difference as the high velocities lifted the swimmers even further. We can take from this research that slower swimmers will undoubtedly benefit more from a well fitting wetsuit, and it is also fair to say that the benefits of the wetsuit will be greater for any swimmer as the distance of the event increases. The amount of overall effort (taken as a percentage) is far greater greater at slower speeds than faster speeds if you choose not to use a wetsuit – a “swim costume only” sprint triathlon may be considered a viable option (based on the time savings in transition) but should be avoided at Ironman distance!

The researchers also found that stroke rate increased when wearing a wetsuit but stroke length stayed the same. In simple terms the swimmers covered the same distance each stroke but their arms were moving faster. Due to the fact that their bodies were more buoyant, they were able to pull themselves through the water with greater ease (less drag) and this enabled them to increase stroke rate. Without a wetsuit, the lower body and greater drag slows movement through the water thereby slowing down the arms.

Conclusion
Wearing a wetsuit enables you to swim faster and with less effort and has a proportionately greater impact on slower swimmers and those swimming longer distances. The changes in speed are due to increased buoyancy which reduces drag and allows a greater stroke rate. Swimming regularly in a pool can lead to relatively low stroke rates for age group swimmers (40-50 strokes per minute) and this highlights the importance of training in a wetsuit when possible. One of the primes focuses when wetsuit swimming should be increasing stroke rate (target 60 strokes per minute) without loss of form.

* Taken from Tomikawa et al (200*. Factors related to the advantageous effects of wearing a wetsuit during swimming at different submaximal velocity in triathletes. Journal of Science and Medicine in Sport. 11, 417-423.


About the author of this training article
Marc Laithwaite, is Sports Science & Coaching Director, at The Endurance Coach. Mark has a Bsc (Hons) sports science and is working towards his Phd sports science. He is a member of the British Association of Sports and Exercise Scientists (BASES), a British Cycling Federation Blood Analyst, BTF Level 3 Coach & Coach Educator, UKA Level 3 Coach and ABCC Level 3 Coach.

The Endurance coach, provides sports science and coaching support services for endurance athletes. Their services include VO2 max testing, lactate profiling and metabolic assessment for endurance athletes of all standards in their own sports testing lab. The Endurance Coach also runs a range of training camps throughout the year and offers physiotherapy and rehabilitation services. For more information or if you are looking for world leading coaches to assist you, e-mail The Endurance Coach.

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