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Beware this is REALLY nerdy Ever wondered what you are really buying in time savings when spending four hundred plus dollars on a brand new wetsuit just because it has arms and your old one doesn’t? The answer to this question is contained in this article, in seconds per 100 meters gained! Our conclusions are based on data we gathered in a controlled experiment. Results and method will be detailed. The experiment involves two elite amateur triathletes (Curt & Duane), a 50m pool and four different swim suits: a full sleeve wetsuit, a sleeveless wetsuit, a fast-skin swimsuit and a training swimsuit. Laps were swum using the suits at varied speeds. For each lap, heart rate was recorded. A relationship between Heart Rate vs. Time was created for each swimsuit and swimmer. Using this relationship, we obtained the performance benefits of each suit compared to a training swimsuit. See Figure 1.
Figure 1 – Comparison Results At a set Heart Rate approximating race pace, results are estimated and shown in Figure 2. A near identical improvement (over training suit) between swimmers was observed using the full wetsuit (7.9%) and fast-skin swimsuit (1.5%). The results between swimmers differ on the sleeveless wetsuit (6.8% for Duane vs. 3.3% for Curt). The results indicate that the sleeves on a wetsuit do improve swim times. They also indicate that a sleeveless wetsuit helps but not as much as a full wetsuit. For non-wetsuit triathlons, the results indicate a fast-skin offers some benefit but not as much as a wetsuit.
Figure 2: Improvement
Figure 3 – Suits used The times were selected such that the fast target (32 seconds) was approximately at the aerobic threshold of both swimmers. This reduced the likelihood of time order biasing in the results. The 4 seconds between targets was meant to be significant but not so large that the high target (40 seconds) was unreasonable. The runs were completed in a randomized order, again to reduce any bias effect by the swimmers.
The swimmers were communicated on a lap-by lap basis the suit required and the goal time to hit. They would always wear the training suit as a base layer, and add or remove the other suits as required. There was no restriction of rest between intervals. The swimmers were started whenever they were suited up and ready.
Figure 5 – Measuring Heart Rate
Figure 6 – Residuals plots
Figure 7 – Normal probability plot & histogram An analysis was also performed to estimate the repeatability of the swimmers to hit the various target times. The results are shown in Figure 8.
Figure 8 The two middle charts of Figure 8 are important because they show that the swimmers average swim to target did not change with suit type. In other words, there was no suit type that was swum consistently above or below the target in relation to any other suit. The top right box-plot is interesting. Note that the 40 second box is larger than either the 32 or 36 second box. This means that the swimmers had largest variation when hitting the 40 second target. The bottom left chart shows the variation of target times (4 seconds) in relation to the swimmer’s ability to hit the target (at about plus/minus 0.8 seconds). Obviously, the swimmer’s ability to hit target will be less than 1 second because any greater result was repeated.
Figure 9 plots the analysis of all contributors to heart rate. This includes the swimmers involved, the goal times, and the suit type. The top left of Figure 9 shows the average heart rate reading sorted by swim suit type. The top right displays the average heart rate by swim time. It is of note that there is a larger jump in heart rate between 32 and 36 seconds compared to 36 and 40 seconds. The chart on the lower left shows that Curt had a lower heart rate than Duane throughout the experiment. The equations of Heart Rate vs. Time that are plotted in Figure 1 were used to calculate the results shown in Figure 2. All lines were established using a least squares best fit linear relation. The equations of each are shown in Figure 10. A target heart rate was selected by us that approximated a race pace effort. For Duane, this was estimated as 47 and Curt as 47. Setting these values for Heart Rate in the equations shown in Figure 10, the resulting time differentials were obtained as plotted in Figure 2. A crucial assumption in this whole experiment was the use of a heart rate response variable to predict swim time improvement. We are assuming that an equal heart rate can be attained with equal effort regardless of the swim suit worn. Also, the conclusions become less applicable the further one swims away from the times we tested. For example, world class swimmers go faster than our testing times, so they may not get the same benefit as these results suggest. Also, the conclusions may be less applicable to weaker swimmers because they are slower than our testing times. An observation of Figure 1 is that with one exception, the best fit lines are all roughly parallel to each other. In other words, the benefit of each suit did not change much with swim speed. This challenges any notion that wetsuits are more or less beneficial depending on how fast you swim. For swimmer Duane, the Fast Skin and trainer suit became equal at the slowest speed (40 seconds), suggesting that Fast Skins have less benefit at slower speeds. However, this result was not duplicated with swimmer Curt. Another observation of Figure 1 is that the sleeveless wetsuit results between Curt (3.3%) and Duane (6.8%) were different. Since the swimmers never traded wetsuits during the experiment, it is impossible to tell if this difference is due to swimmer technique, wetsuit design or something else. The similar results of both swimmers with the Full Suit (7.9%) suggest that the performance difference between the Full Suit designs is negligible.
Overall, the experiment was successful in estimating the performance of different swimsuits. The Full Suit was superior to the sleeveless wetsuit. In an Olympic distance triathlon, a Full Suit improves your time by a huge 1 minute 23 seconds. The benefit for a Fast Skin is 16 seconds for the same distance. These times may be small or large depending on your level of competitiveness in the sport. If your full suit costs $400 dollars, you are looking at $5 dollars for every second you gain. If your Fast Skin costs $250, you are spending $16 dollars per second. Now the next time you are in the market to buy racing gear, you will know exactly where your money is going.
Curt & Duane Curt Wood and Duane Dobko are elite amateur triathletes who reside in Minneapolis, MN. Both began racing triathlon after successful collegiate swimming careers and now race for the Gear West Elite Team out of Long Lake, MN.
Comments Add a Comment You make me feel a lot better about my recent purchase. Textbook study work here - well done. Thanks! posted by P Tango on 8/27/2009 Add a Comment |
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The swimmers were always started together and finished at the same time (see Figure 4). In order for the data to count, both swimmers had to hit the target time to plus/minus 1 second, as recorded by stopwatch timing. When the target was missed, the lap was repeated. For successful laps, the swimmers counted their heart rate over a 20 second interval immediately following the lap (see Figure 5). The lap time and heart rates was recorded.
