Tri Talk Triathlon Podcast, Episode 63

How your swim pacing affects the rest of your race, specific performance gains from swim apparel, and is it ever too warm to wear a wetsuit? It’s a swim special edition, today on Tri Talk.

Welcome to Tri Talk your podcast source for triathlon tips, training, news and more. New listeners since episode 62 hail from Kansas and Moscow, Russia. In Kansas, my guess is the increase in listeners comes from the upcoming 70.3 Ironman event less than a week away, best of luck to you at that event. When I saw my download stats I did a double-take assuming that Moscow meant Moscow, Idaho. But no, there are really new listeners from Russia, where I spent 6 unforgettable weeks in my youth. My goal at Tri Talk is to help you swim, bike, and run faster, to meet your personal triathlon goals. Whether you are an elite or amateur triathlete, we cover sprint distance to Ironman distance. I’m your host, David Warden, and this is Tri Talk Episode 63. 


I know that the last thing that those of you from the Midwest United States want to hear about right now is more water. If you are from that area and were caught in the middle of that terrible flooding, I wish you a quick recovery. Bear with me as we spend this episode exclusively on swim-related topics, that have, however, a direct impact on your bike and run as well. For example, in our lead topic we’ll find out if swim pacing has a much larger influence on your overall triathlon performance that you may have previously thought. We’ll also look at a study that places a specific time savings on wearing a speedsuit in the water, and the implications for wearing one out of the water. Finally, we’ll briefly look at some numbers around wearing a wetsuit in warm water, and if that leads to the risk of overheating.

In triathlon news, I’m guessing that the increase in listeners from Russia had something to do with the drama surrounding which country would end up with 3 Olympic slots rather than two, with a virtual tie between the US, Russia, and Australia going into the final race to determine those slots. The dramatic ending to the men’s Olympic triathlon qualifying slots took place at the ITU World’s at Vancouver this past week-end. Congratulations to both Russia and the US for their strong finish, and squeaking in enough points to qualify 3 men for this summer’s Olympics. If you would have told me last year that Australia would only qualify 2 men’s slots into Beijing, I would have never believed you.

Episode 61 introduced Joe Friel’s decoupling protocol, and the feedback from that episode was significant. There are 2 particular comments on decoupling that came in I’d like to review. First, from Roger Behle of Anaheim Hills, California who writes:

“When testing for decoupling, what period of time should be allotted for warm-up? I raise this question because I have personally noticed a gradually increasing heart rate – sometimes lasting up to 30 minutes – before leveling off at a steady pace (running). I assume you would not want to include increases in heart rate attributable to warm-up when assessing decoupling.”

Roger brings up an excellent point, because since the decoupling protocol is based on the changing delta between Zone 2 HR and power output. An unusually high upward drift in HR during the first 30 minutes of warmup could artificially indicate high decoupling, when in fact it was only due to the time it took for the athlete to even initially reach Zone 2. There is a significant variation in the amount of time it takes an athlete to warmup. Some can do it in 10 minutes and some, like Roger take 30.

For athletes performing a 3-4 hour decoupling test, I would suggest very little warmup for 3 reasons. First, the test is so long that any front-loaded HR data will have minimal effect on the overall results. Second, performing a long warmup places the athlete at risk of fading too early in the protocol. A solid 30-minute warmup followed by a 4-hour ride could cause the rider to not be able to sustain as much power at the end of the test, and have artificially low power at the end. Third, dehydration is a large factor in cardiac drift, and that extra 30 minutes places you in a position to potentially be more dehydrated at the end of the test, elevating the HR.

For short decoupling tests of 1-2 hours, I don’t see a consequence of a Zone 1 warmup helping the athlete achieve high Zone 1 or low Zone 2 before officially starting the test. Particularly doing a warmup on the bike before performing the run. Great question, Roger.

Another comment came from my friend and former USAT Head Coach, Marc Evans who lists a few other snags with decoupling:

1) Heart rate is NOT an absolute indicator of intensity. How, are athlete’s determining  one 2? That’s a very difficult number to determine.

2) Dehydration during the second half of the test will affect Hrate.

3) Muscle glycogen at start

4) Sleep and rest before the test

5) Temperature and other environmental considerations such as humidity, pollution, inclement weather

6) Improvement or decreases in mobility, flexibility and core strength (those glutes we’ve talked about…)

7) Rest between workouts and pre-testing protocol so the results can be more consistent

8) Motivation

I respect the science and find it very interesting, but there are of course, many variables at play. Triathlete’s often hope for that “little blinking number” to tell them they’re on track with training.”

Thanks, Marc for your expertise and input. And by the way, the next time I have you assess my strength and mobility, you’re going to be amazed at my gluteus medius. My gluteus medius will become legendary within the medical community. In fact, I have already submitted a proposal to the American Medical Association to have the gluteus medias renamed to gluteus Warden-ius.

Also, I should point out that Roger Behle, who asked about decoupling and warm up, also pointed out that dehydration could skew the test in his e-mail to me.

Let’s get on to the good stuff, shall we? I’m going to relate a quick story of why I chose to research this next topic, and how it really hit home for me. I participated in a sprint triathlon this past week. I came into it with high expectations of finishing near the very top of the event. The course played to my strengths with a challenging canyon bike course, and a slightly shorter swim course than a typical sprint distance event.

However, the morning of the race, the weather was in the 40s and raining at the race. The race director’s decided, justifiably, to cancel the bike portion and make it just a swim-run. This was pretty devastating to me, because my swim is still my weakest sport, and I count on the bike to get myself back into position in the race. I had been popping off all week about how well I was going to finish the race, my 2 brothers had come to watch me race, one all the way from Hong Kong. Those of you with brothers know exactly how competitive that can be. I was determined to finish as strong as I had predicted.

So, I decided I had to go all out on the swim, holding nothing back. The result was excellent, a full minute faster than I had done in the past at that same distance. However, when I hit the run, everything fell apart. And we are only talking about a 5k run here. The whole race took less than 30 minutes, but I literally bonked on the run. So what happened?

Well, lot’s of things could have happened, but the following is a fascinating study on how swim intensity affects your overall triathlon performance.

A study by the University of Western Australia  had 9 skilled triathletes perform a 750-meter swim time trial to establish their fastest swim pace for that distance. That 750-meters is, of course, the typical true sprint-distance swim length. Having established their swim time trial at that distance, the triathletes performed 3 sprint-distance triathlons in a controlled environment, but with varying swim pacing before the 3 triathlons. The 3 paces were at 80-85% of the time trial velocity, 90-95% of the time trial velocity, and 98-102% of the time trial velocity. We’ll refer to them as S80, S90, and S100.

The times for S80, S90, and S100 were 734, 673, and 619 seconds respectively. S80 was a full 114 seconds slower than S100, and over a minute slower than S90. Initially, you might be thinking what I am thinking, “hey, I can be a full 2 minutes faster if I lay it all out on the swim!”

But, the subsequent cycle times were very interesting. S80, S90, and S100 were 1654, 1682, and 1808 seconds respectively. Meaning, the cycling time after the 80% swim effort was 154 seconds faster than the cycle time after the S100 effort on the swim. The S90 was 126 seconds faster than the S100. The researchers concluded that the difference between the S80 and S90 cycling efforts was not statistically significant, but that the difference between either the S80 or the S90 and the S100 was statistically significant.

So, at this point we might be saying, since both the S80 and S90 are statistically the same result on the bike, the S90 should be the best swim effort because it had a one-minute advantage over the S80 on the swim. We’ll come back to that.

Let’s add the run onto these sprint tests. There was a difference in run performance, again with the faster run times occurring after the slower swim efforts. But, the difference in run times between the 3 trials was not statistically significant, and the researchers rightfully concluded that the run was unaffected by the swim intensity.

However, when it came to the mean overall triathlon times for S80, S90, and S100 there is where the real good stuff is. The times were 3658, 3681, and 3763 seconds  respectively. The S80 was a full 105 seconds faster for the overall event than the S100. Even though the S100 was almost 2 minutes faster than the S80 on the swim, those 2 minutes were easily gobbled up by the decreased performance on the combined bike and run. Again, while there was not enough of a delta on the run between the 3 swim intensities, there was enough of a statistical difference on the combined bike and run for the researchers to conclude that the S80 swim intensity was significantly higher than the S100. Also the researchers noted that overall triathlon time of the S90 was faster than the S100, it was not enough of a difference, and therefore the only statistical improvement in performance came from the S80 swim effort.

How do we apply this to our training? First of all, I think that this means we need to practice swimming at 85% of our time-trial effort for sprint-distance racing, and to do that, we need to test a 750-meter time-trial frequently to know what 85% of that is.

One of the theories from these same researchers was that going beyond a lactic threshold too early, even only for a short period of time, places the athlete at a serious disadvantage for the remainder of the race. The researches noted another study which had shown that intense arm exercise that raises circulating lactate concentrations can impair subsequent leg exercise, and this is one of the primary reasons for the case of the negative split. Going out too hard early taxes your system too high, and it can’t recover. To review really quick, a negative split refers to finishing the second half of a steady-state endurance event faster than the first half.

But this study makes me think of a negative split not just in terms of a negative split for a single discipline, but a negative split strategy for the entire race. Meaning, maybe we should not be looking to negative split the swim, and then negative split the bike, and then negative splint the run, but rather look at your entire race as one big negative split. Treat the swim and first half of the bike as one lap, and the remainder of the bike and run as the second half of that negative split. I have not specific research on this, but I would imagine that even swimming the second half of the swim at high levels of lactic concentrations could result in similar consequences on the overall race to what we saw with the entire swim at high intensity.

Does this apply to longer swim distances? Does this mean 85% intensity is the optimal swim intensity for all distances? Probably not. Although this is good evidence for sprint distance events, 90% effort of a 1,500-meter time trial pace is going to be much less than 90% of a 750-meter time trial pace. Or, on the extreme, 90% of your Ironman swim pace is probably well below lactic threshold, whereas 90% of 750-meter pace is probably at or above your threshold. I feel like it is safer to push the percentage higher of your time trial pace for the longer swim events. The key is to find a pace that is below your lactate threshold. For sprint distance, I’m liking this 85% number.

One last thing on this study. The overall power outputs on the bike for S80, S90, and S100 were 304, 298, and then it dropped all the way down to 278 watts for the S100.

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I have two more quick swim studies I wanted to share with you. This first one is sort of a followup from last week, where I discussed the interesting wind tunnel test from one athlete who shaved 80 seconds off of his 40K time trial just by switching from a two-piece tri top and bottom to a one-piece suit. Yes, all of the speed-suit manufacturers claim that their suit will make you faster on the swim. There is also a ton of interest in the Speedo skin suits because some swimmers are complaining to FINA, the world governing body for swimming, that the suits are so fast that they introduce an unfair advantage.

It was nice to find a study that actually looked at the performance of a skin suit to contemporary race apparel on the swim. In this study, published just last year in the Journal of Science and Medicine in Sport, researchers took 8 triatheltes and compared a swim brief, basically a Speedo, to a modern speed suit. Again, just like the last study, this was done over a 750-meter time trial. The speed suit was 19 seconds faster than the racing brief. Not a huge difference, but considering it costs about $200 for a decent speed suit, that is only about $5 per seconds saved if we can assume 38 seconds over a 1,500 meter time trial. But, only for indoor or warm water swims when you don’t have a wetsuit.

I keep coming back to the notion that although the speed suits were designed for increased speed in the water, can I assume at least some improvement on the bike wearing the speed suit? The only concrete data I have is from that one wind-tunnel test on one athlete, but the concept makes sense. Yes, water has much more drag than air, but did you know that because you are going so much faster on the bike and exposing so much more surface area due to positioning than on the swim, that the drag co-efficient for a swimmer and cyclist are almost the same? Drag plays every bit as much a role in cycling as swimming, and again I can’t help but think that the design for decreased drag in the water translates onto the bike.

Let’s look at it this way. If you save 19 seconds over 750 meters of swimming as this last study proved, let’s assume 19 seconds for every 15 minutes of swimming, which is 76 seconds per hour.

Now, how much did the athlete save over an hour time trial in the wind tunnel from wearing a one piece? 80 seconds, or 20 seconds per 15 minutes. At the very least, that is a curious coincidence.

By the way, I need to thank Tri Talk listener Martin Thow from Australia for sending me this study.

All right, one more swim study. I decided to research this study because of some concern that swimming with a wetsuit in relatively warm water put the athlete in danger of overheating, either on the swim or with overheating consequences later on the bike or run. Some athletes were choosing to not wear a wetsuit in water that was below the legal wetsuit temperature threshold of 78 degrees F.

It is likely that if you are swimming in water that is let’s say, 77 degrees F, that the ambient temperature that you will be cycling and running in is probably going to be much higher than 77 degrees at some point during the race, so I can see why this would be a concern.

A study published in Medicine and Science in Sports and Exercise took 5 male triatheltes and had them perform two Olympic-distance triathlons in a controlled environment. For both swims, the triathletes swam in 25.4 degrees C, which is just below 78 degrees F, for 30 minutes in a flume. One swim was performed with a neoprene wetsuit, and the other a regular swim suit. The bike and run portion of the race were performed in a hot and humid environment at 89.6 degrees, just below 90 degrees F with 65% relative humidity, which is pretty dang humid. It’s pretty rare that an athlete will come out of the water and immediately start racing at 90 degrees.

During the entire triathlon, core body temperature did not differ between the wetsuit and swimsuit tests. However, skin temperature was higher during the swim portion of the test when wearing the wetsuit by about 4 degrees C. But, by 15 minutes into the bike this temperature difference had dissipated, and temperatures stayed the same for the duration of the race for both the wetsuit and swimsuit tests. More importantly, there were no differences in VO2, heart rate, or rating of perceived exertion between the wetsuit and swimsuit tests. Additionally, no significant differences were found in cycling, running, or total triathlon times.

At least for Olympic distance racing or shorter, there appears to be very little risk of wearing a wetsuit in any temperature under that 78 degree limit. Even for half-Ironman racing, these athletes swam for 30 minutes, which is about the time it takes for a good swimmer to finish the 1.2 mile half-Ironman swim. My guess is that even for full Ironman racing, any overheating is also likely to be gone within 15 minutes on the bike. Unless you just hate wearing wetsuits in general, it looks like you are safe from overheating in wetsuit legal water temperature.