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Faster Ironman Run Splits

You’re a good swimmer and excellent cyclist. But running is standing between you and a trip to Kona, or a higher step on the podium. What can you do about it? What will make you a faster runner? After all, it isn’t like cycling where you can “buy” a faster time with more aerodynamic equipment. In the final analysis, if you want to run faster, you simply have to run faster. There are no shortcuts.

There are many possible obstacles to running faster in an Ironman. These may be a poor diet, injuries, inadequate race-day nutrition, side stitches, cramps, and heat. We can’t address all of these here. Let’s explore the process for developing a faster Ironman run split by starting with “periodization.” This is simply a way of expressing training with a timeline. We’re going to take about six months to make you a faster Ironman runner. Here’s how.


Periodization and Running

In the following I’ve divided the year into three distinct periods—Base, Build, and Peak. Each of these periods has a purpose. The Base period is a time of general training that typically lasts about 12 weeks for the Ironman. The workouts are “general” in that they are not exactly what you will experience in the race. Training at this time focuses on the three primary abilities—endurance, force, and speed skill.

Following the Base period is the Build period that also lasts about 12 weeks for an Ironman build-up. At this time the workouts increasingly take on the characteristics of the Ironman, meaning that the intensities and durations of the training become more race-like.

The last period—Peak—is the culmination of all of the preceding training. It’s the time when training consolidates all of the previous fitness gains by allowing for recuperation through tapering of volume while intensity remains race-like. This is a two-week period followed by the race week.

Throughout this 27-week process the triathlete’s purpose must always be to keep his or her race limiter in mind. If hills are a personal weakness and the race course will be hilly, then this limiter must be emphasized in training whenever possible. The same goes for force, speed skills and the other abilities described below. Always focus your training resources primarily on your limiters.

How many runs and how many running hours or miles should an Ironman triathlete do each week? I’m sorry, but I can’t answer those questions here. There are simply too many individual variables for me to give a blanket answer or even a rule of thumb. But I can tell you this: The more of a limiter that the run is for your Ironman race performance, then the more time you must devote to it. A very good runner may well be able to get by with three weekly runs whereas a running-limited triathlete may need to run five times a week. Few, if any, will need to run six or seven days a week.

Now let’s examine the training details for becoming a faster runner for each of these periods of the season.


Let me ask you a question: What’s most important for an endurance athlete—endurance, speed, or strength? No, it’s not a trick question; the answer is “endurance.” If you can’t run 26.2 miles you can’t finish the race. Therefore, LSD (long, slow distance) is the heart of training for an Ironman. The Base period is the time to develop this endurance for going the distance, without concern for pace. Just run long and slow—if you’re really running it can’t be too slow.

How long should the LSD run be? I like to see Ironman triathletes build up to two-and-a-half to three hours in a single session regardless of how long they anticipate being on the run course. Beyond two-and-a-half hours there is really not much happening physiologically that makes any difference to your ultimate Ironman run fitness. But the risk of injury increases dramatically after three hours.

Be careful with these runs. Allow plenty of time to build from your current, longest duration to the goal duration. Most athletes need 12 weeks to do this safely. Increase the duration of the once weekly long run by 15 to 20 minutes for two or three weeks before taking a rest and test week (more on this below).

Also pay close attention to shoe breakdown during this period. Make sure you start with a pair that is right for you and then stick with the same model for the entire Ironman training period replacing them before wear is evident. This may only be 200 miles for a bigger runner while smaller runners’ shoes may go 500 miles before buying new shoes. Heavy-duty shoes will also last longer than a lightweight pair.

Let’s now consider what will eventually make you faster. The starting point for this is “force”—the ability to drive the body forward powerfully with each foot plant. To get faster you must be able to apply muscular force to the ground.

How is force developed? If you’ve ever lifted weights, you already know the answer—resistance. If the running muscles are frequently required to overcome increased resistance they will grow stronger. Initially, this force building may be done with weights.

The step-up exercise is one of my favorites for the endurance runner who needs more force. With a dumbbell in each hand, step on to a box or platform that is just high enough to put your thigh at parallel to the ground or slightly lower—never higher. This will probably be in the range of 12 to 16 inches, depending on your leg length. (The details—days per week, sets, reps, and loads—is beyond the scope of this article. See The Triathlete’s Training Bible for more on weight training.)

Once weight room strength is well-developed, the next step in creating greater leg force is to run hills. This doesn’t have to be anything complicated in the Base period. Just run on a hilly course once a week for one of your non-LSD runs. Practice good form on the uphills, which brings us to the next ability.

“Speed skill” is without doubt the most neglected aspect of running fitness for endurance athletes, especially Ironman triathletes. Speed skill is the ability to run economically when at race pace. It’s easy to spot uneconomical runners—they have a lot of vertical oscillation. The more you bounce up and down the more energy you will squander. Energy expended vertically is wasted energy because it moves you no closer to the finish line—which is in a horizontal direction.

Do you bounce when you run? If your cadence is less than about 84 rpm you are bouncing. Count your right foot strikes for one minute to determine cadence. Then check what the elites do. Their cadence is above 90 rpm. The Kenyans, even near the end of a marathon, are running at about 96 rpm.

So how do you increase cadence? Let’s look at just one way as there are many. The starting point is to have little concern for stride length, at least for now. Check cadence every time you run—at the start, in the middle, and again near the end. Try to increase it. If you’re now running at 78 rpm, hold 80 rpm for a few minutes several times in a run. Then go to 82. Eventually it will rise and you’ll run faster with no apparent increase in effort. Don’t expect this to happen overnight. It will take weeks, months, and years to approach your optimum cadence.


Now that your endurance, force, and speed skills are well-honed from several weeks of working strictly on these abilities, it’s time to go to work on the ability that will ultimately result in faster Ironman run splits—muscular endurance.

Muscular endurance (ME) is the ability to apply a fairly high amount of force to the ground for a fairly long time. It’s the combination of the force and endurance abilities you built in the Base period. Now all we’re doing is bringing them together into a race-specific form of fitness.

ME workouts at this time of year are either interval or tempo sessions. The effort is not high, but kind of high for such a duration. It is typically right at or somewhat below your lactate threshold (LT) heart rate or pace.

So what is your LT heart rate and pace? One way to find LT heart rate is to simply run a 30-minute time trial on a flat course in cool weather. Your average heart rate for the last 20 minutes of this run is a close approximation of your LT heart rate. LT pace is about 10 seconds per mile slower than your current, non-triathlon, 10k-race time.

The accompanying sidebar (“ME Workouts”) provides a few examples of this type of training.

As mentioned above, the purpose of the Build period is to prepare you for the stresses anticipated in the race. One of the best workouts for this is the “brick”—as used here, a combined bike and run workout. Such a weekly workout will help you prepare to run at race pace on the rubber legs that come after a 112-mile ride.

The biggest mistake Ironman triathletes make with bricks is to run too long. This is not an LSD workout, but more of an ME session. All you really need the run portion for is to get used to coming off of the bike and settling into your running race pace—one that is eventually going to be maintainable for your goal time. LSD runs for a brick are not necessary to achieve this. In fact, they may very well be counterproductive. By putting you on tired legs and then requiring that you run goal pace for something approaching goal duration is a sure way to 1) cause an injury, 2) create so much fatigue that you can’t come out of it in 72 hours, or 3) become chronically overtrained.

These runs need not be longer than about 90 minutes. And, in fact, only one or two need be that long in the Build period. Start with 30 to 45 minutes after a long ride (which also includes some race efforts) and add 10 to 15 minutes each week. Do a brick in each of two consecutive weeks and then skip it during your rest and test week.

In the Build period you will also need to maintain your endurance, force, and speed skills developed in the previous period. This is easy since it takes less effort to maintain an ability than it does to create it.

Your weekly brick should have a bike portion long enough to maintain bike endurance. If the course you’re training for is hilly, do the bricks on similar terrain to maintain force.

Continuing to periodically check cadence during different types of runs, but especially when at goal pace, will keep your speed skills improving.


This is a two-week period when you back off from the higher volumes of the Base and Build periods. The weekly hours now get considerably shorter each week, by about 20 to 30 percent, to allow your body to “catch up” with the training stresses of the previous weeks and bring the body and mind to a physical peak. This tapering of volume varies by sport. Realize that the Peak period is preceded by a rest and test week so that you go into fairly well rested. Starting the Peak period tired is counterproductive.

Due in part to the high orthopedic stress to the lower body, running requires the longest taper. Cycling volume may remain constant until two weeks before the race. But, again, if recovery seems slow err on the side of a longer taper for bike training. Start the swim taper from 10 to 14 days before the race. The orthopedic stress placed on the body by swimming is minimal compared with running and recovery is therefore considerably faster.

During the Peak period do a muscular-endurance workout every 72-96 hours until the last week. The volume of each workout is reduced as this period progresses, but the intensity remains constant. Don’t make the common mistake of trying to run faster at this time. You should have already established the proper pace for each workout in the previous periods. The only reason to speed up now is if your fitness has measurably improved as determined by testing—the ultimate test.

Rest and Test Weeks

Ironman triathletes are among the most self-motivated of all athletes. It takes a special perseverance to prepare for such an event. Unfortunately, that same perseverance that makes finishing the race possible has a darker side—obsessive compulsion. Those who train for the Ironman are driven to workout it seems, even at the expense of their own health and well-being. Frequent and extensive recovery periods must be built into the schedule if the athlete is to remain healthy and continue to positively adapt to training.

In the Base period such a recovery period is needed every three to four weeks depending on how the athlete is handling the volume. In the Build period the recovery periods are no less than every third week just to remain on the safe side. For those who recover more quickly, reducing the rest and test weeks to five days duration will still allow for recovery without overdoing it.

After four to six days of greatly reduced volume—perhaps half of what has been typical—self-testing is done to gauge progress. For the run, a simple but effective test is a three- to five-mile time trial on a track at a heart rate that is 12 to 14 beats per minute below LT heart rate. Warm-up before the time trial elevating heart rate to the test zone before starting. Be sure to keep as many variables as possible the same from one test period to the next. This includes state of recovery, time of day, pre-run food, shoes, course, and warm-up. As fitness improves over several weeks, the run time should get faster.

At the end of the Base period and again at the end of the Build period it’s a good idea to confirm LT heart rate with a 30-minute time trial as described above.


Running a faster split in an Ironman takes more than training. It also takes believing. If you don’t think it’s possible then it won’t happen. The workouts described here are not only intended to improve your fitness, but also to improve your confidence. A faster run split is possible if you concentrate on it.


Joe Friel is the author of The Triathlete’s Training Bible. He has self-coaching software, based on his book, posted on line at www.trainingbible.com.




ME Workouts

Build and Peak periods

Do one of the following weekly except in rest and test weeks.

Cruise Intervals

Structure: Run work intervals that are 6 to 12 minutes long.


Intensity: 1-6 bpm below LT heart rate or 1-10 seconds/mile slower than LT pace.


Recovery: Jog easily for 1/4th the duration of the previous work interval.


Volume: Accumulate 20-40 minutes of work interval time in one weekly workout. Add a bit each time.


Course: May be done on a hill, flat road, or track.


Tempo Finish

Structure: At the end of an LSD run or after a bike ride (brick) increase the intensity for a set number of minutes.


Intensity: 7-14 bpm below LT heart rate or 11-20 seconds/mile slower than LT pace.


Volume: Start with 30 minutes of tempo and add 10 minutes weekly until 70-90 minutes is reached. (Total run time if combined with LSD is no longer than 3 hours.)


Course: Simulate the Ironman run course if possible.