Ironman Swim - Assessing Race Capabilities

It’s now getting close to your Ironman race and you want to start thinking about how you want to execute a properly paced Ironman swim. Athletes typically have the following questions leading into an Ironman race:

1. How fast should I swim my Ironman?
2. How hard should I swim 2.4 miles?
3. What pacing strategy should I use during the Ironman swim?

Let’s take a step back and go over a few things that should have taken place prior to your race. First, you should have completed a few swim tests using the 1,000 yard or meter time trial testing protocol described in the Swim Assessment and Testing Protocol article. Based on these tests, you should have adjusted your training paces to match your actual swim capabilities. By now you should have logged quite a bit of swim time at T-pace through T-pace +5”.

About 4 weeks prior to your Ironman, you’ll want to complete a very specific long aerobic swim session that consists of 8 X 500 yards or meters. The goal of this session is to hold an EVEN pace for each 500 interval. The rest interval should be 20 seconds (20”). The goal pace should be T-pace +5” to T-pace +7”. If you would honestly assess your skills as weak on long swim endurance, adjust the pace higher to T-pace +5”.

Do NOT warm up. The idea is to replicate the demands of an actual Ironman swim (swim 2.4 miles at an even aerobic pace).

The goals of this session are as follows:

1. To assess if we are swimming the first and second 500 yard/meter interval too FAST. When we start swimming with fresh arms, we tend to swim a LOT faster than we think we are swimming only to find out later that the pace is too fast and we start to slow down (fade). This results in a less than efficient/effective swim since we know that the key to going the fastest speed in the most economical way is to maintain a steady/consistent pace.
2. To assess our overall swim endurance. Do we have the muscular power needed to maintain a certain pace for 2.4 miles? (4,224 yards or 3,862 meters) If we discover that we cannot maintain a consistent pace for 8 X 500, then we know PRIOR to our race that we must slow down throughout the swim.
3. To help us estimate our actual swim time during the race. Athletes constantly over estimate their actual abilities on race day. Not knowing our estimated swim times during a race can impact an athlete in a few different ways. First, they may believe that they can actually swim a speed that is faster than appropriate. During the swim the take it out too hard, go anaerobic, use up their glycogen stores, raise their heart rates and get off to the day in a very inefficient manner. The overly aggressive strategy will eventually catch up to them on the bike or run and they under perform. Second, athletes constantly dream up what they think they will do on race day and these dreams are often faster than their true capabilities. The athlete may actually swim wisely but if their time is slower than what they “imagined” it should be, they feel they have to make up that lost time by going harder on the bike. The result by the run is a nice solid KA-BOOM as they explode about 8 or 10 hours later.

Case Study

An athlete has a T-pace of 1:40 per 100 meters. With NO warm-up, the athlete completes the 8 X 500 workout with the following splits:

#1 – 8:25
#2 – 8:44
#3 – 8:44
#4 – 8:58
#5 – 9:11
#6 – 9:16
#7 – 9:28
#8 – 9:32

What could be learned from a data set that is similar to that above? The athlete should come away with the following learning experiences;

1. Their rate of perceived effort is fooling them which is similar to most athletes on race day when we are rested, tapered, full of adrenaline and a giant cannon goes off with 2,200 people climbing on top of us. What we should see is the athlete completing the first 500 at a pace of T-pace +5” OR SLIGHTLY SLOWER. For this athlete, that would have meant a pace of 1:45 per 100 meters. If we refer to the pace chart and follow the T-pace +5 of 1:45 per 100 across to the 500 meter column, the 500’s should all come in around 8:45 each.
2. The athlete should be able to assess if they had to go anaerobic at any point during the session. We should ask ourselves, “Was my breathing very labored at any point of this session?” It the answer is “yes,” then the athlete should take note and know that they need to slow down and stay aerobic. On race day, you do NOT want to open up your day with a high heart rate, burning glycogen, going anaerobic and wasting energy that could be better utilized during the second half of the marathon (probably 10 hours down the road).
3. The athlete did not hold a consistent and steady pace. With a goal pace of 8:45 per 500, the first three were faster than goal pace and the last five were slower than goal pace. The athlete needs to learn to swim at a smoother pace. This means starting slower and ending faster.
4. If we average out all of the 500’s, we would get an average pace of about 9:02 per 500. Referring back to the pace chart if we locate 9:02 under the 500 meters column we see times for 0:09:00 and 0:09:05. If we move to the right hand Ironman column we will see corresponding times of 1:08:24 and 1:09:02

Note that if the athlete paced themselves a little more smoothly and showed that they were capable of holding 1:45 per 100 pace or 8:45 per 500, the corresponding Ironman swim time would have moved down to 1:06:30. So the athlete may have given up a few minutes just by poor pacing alone.

The athlete should be fully aware that a swim time that is even a few minutes slower than this is fully reasonable on race day. We won’t know if we get boxed in at the first turn buoy. We won’t know if our goggles will get kicked off and have to be reset. We won’t know if there will be a current or chop in the open water. We may not swim perfectly straight in open water conditions, etc. If you get out of the water and see that your swim time is 1:12:32 which is a few minutes slower than your pool simulation, don’t panic. You are right in line with your capabilities if you didn’t go anaerobic during the swim. Get through transition calmly and board your bike.

About 7 to 10 days after the 8 X 500 session, you’ll want to complete a very specific long aerobic swim session that consists of 4 X 1,000 yards or meters. The goal of this session is to hold an EVEN pace for each 1,000 interval. The rest interval should be 20 seconds (20”). The goal pace should be T-pace +5” to T-pace +7”. If you would honestly assess your skills as weak on long swim endurance, adjust the pace higher to T-pace +5”.

Do NOT warm up. The idea is to replicate the demands of an actual Ironman swim (swim 2.4 miles at an even aerobic pace).

The goals of this session are the same as the 8 X 500 session.

Case Study #2

An athlete has a T-pace of 1:40 per 100 meters. With NO warm-up, the athlete completes the 4 X 1,000 workout with the following splits:

#1 – 17:38
#2 – 17:32
#3 – 17:32
#4 – 17:27

What could be learned from a data set that is similar to that above? The athlete should come away with the following learning experiences;

1. Their rate of perceived effort is dialed right in accurately. What we should see is the athlete completing the first 1,000 at a pace of T-pace +5” OR SLIGHTLY SLOWER. For this athlete, that would have meant a pace of 1:45 per 100 meters. If we refer to the pace chart and follow the T-pace +5 of 1:45 per 100 across to the 1,000 meter column, the 1,000’s should all come in around 17:30 each. This athlete did a fantastic job of applying consistent pace. The athlete should have felt that the first 1,000 felt VERY EASY in comparison to the final 1,000 but the final interval was capable of being completed at this pace WITHOUT going anaerobic.
2. The athlete should be able to assess if they had to go anaerobic at any point during the session. We should ask ourselves, “Was my breathing very labored at any point of this session?” It the answer is “yes,” then the athlete should take note and know that they need to slow down and stay aerobic. On race day, you do NOT want to open up your day with a high heart rate, burning glycogen, going anaerobic and wasting energy that could be better utilized during the second half of the marathon (probably 10 hours down the road).
3. The athlete DID hold a consistent and steady pace. With a goal pace of 17:30 per 1,000, all four intervals were in line with goal pace. The athlete has mastered swimming at a smooth and consistent pace and was not fooled by the low level of perceived effort for the first 1,000 interval. This athlete started with an appropriately low rate of perceived effort and ended with an appropriately higher rate of perceived effort on the final interval.
4. If we average out all four of the 1,000’s, we would get an average pace of about 17:32 per 1,000. Referring back to the pace chart if we locate 17:32 under the 1,000 meters column we see times for 0:17:30 and 0:17:40. If we move to the right hand Ironman column we will see corresponding times of 1:06:30 and 1:07:08

Frequently asked questions:

1. How fast should I swim my Ironman swim? A good rule of thumb is to swim as fast as you can aerobically while holding a consistent pace which we learn DOES NOT correlate to perceived efforts in our pool simulation sessions. Going anaerobic within the first 30 minutes of 10+ hour day is probably not going to work out too well for you. Please explain the definition of the term “BONK” to your friends and family that came out to watch and support you race.
2. How hard should I swim 2.4 miles? As we learned from the two pool simulation sessions, it is VERY easy to swim the first few hundred yards/meters too hard when we base things off of perceived effort. We learn through our training that we can easily be fooled and need to have confidence to swim easy enough for the first 5 to 10 minutes until we get into a rhythm during our race. We will be rested, tapered, excited and full of adrenaline at the beginning of an Ironman. Be patient and use your efforts wisely. It’s going to be a long day and even longer if you don’t pace yourself appropriately during the swim.
3. What pacing strategy should I use during the Ironman swim? Use a pacing strategy that you have practiced during your training. You should have logged plenty of laps in that T-pace to T-pace +5” range. Further, you should have a good feel for your capabilities after completing the 8 X 500 simulation session and also the 4 X 1,000 simulation session. Refer to the pace charts to have an idea of a realistic swim time for your Ironman swim.
4. Won’t I automatically be faster on race day in a wetsuit and in the draft of other swimmers? Perhaps but not always. Age-group athletes usually get clobbered during the swim as 2,200 other athletes are all trying to get to and around the same turn buoys in approximately the same time. The majority of Ironman swimmers complete the swim in that 1:08:00 to 1:20:00 time period. Further, there may be a current and/or a chop on the water making it harder to swim or more difficult to sight. You will never swim as straight in an open water environment as you do in a pool with lane lines. It’s very easy to stray off course throughout the swim and even if these off target sections are small to moderate, they add up over 2.4 miles.
5. What if I get out of the water and see that my heart rate is in the stratosphere? You need to slow down and get things back to aerobic as quickly as possible. Don’t let your heart rate escalate even at the mid-point if it is a two lap swim that requires some beach running. Stay calm, stay smooth, stay aerobic.
6. What if I get out of the water and see that I swam a lot slower than I thought I would? No need to panic. Hopefully the reason that you swam slower is because you swam easy and stayed relaxed. This energy reserve may come in handy during the second half of the marathon more than 8 hours down the road. By no means should you attempt to make up the deficit by working harder on the bike. The swim is over, do your best to execute your bike and nutrition strategy to the best of your ability.