The Impact of Tune Up Races on Ironman Performance

Joshua Gordon, PhD

Objective: This study investigates the optimal timing and intensity of tune-up races—specifically, Ironman 70.3 events—as preparation for full Ironman 140.6 races and examines whether such races are necessary for peak performance.

Methods: Using a dataset of 100,000s of finishers, we analyzed performance outcomes across various intervals between tune-up races and main events, the intensity of effort in tune-up races, and the impact of the number of tune-up races on performance in subsequent full Ironman events.

Results: Our findings challenge traditional strategies, suggesting a potentially optimal 14-week interval between a 70.3 tune-up race and a full Ironman for improved personal best (PB) odds. Athletes demonstrating peak performance in tune-up races tend to replicate success in main events, underscoring the importance of intensity. However, the necessity of tune-up races is nuanced; while a single 70.3 race within 180 days prior to a full Ironman marginally improves PB likelihood, multiple tune-up events may hinder performance due to inadequate recovery and training disruptions.

Conclusions: The study underscores the value of personalized training and racing strategies, encouraging athletes to consider longer lead times for tune-up events, approach these races with competitive effort, and balance the number of tune-up races to avoid potential negative impacts on Ironman performance.


  • Timing of Tune-Up Races: Traditional strategy suggests scheduling a 70.3 tune-up race 4-6 weeks before a full Ironman. However, data shows a potential PB boost with a longer lead time of around 14 weeks.

  • Intensity of Tune-Up Races: Athletes tend to perform best when giving their best effort in tune-up races, with peak performance indicating success in the main event.

  • Necessity of Tune-Up Races: While completing a 70.3 race before a full Ironman may improve PB odds marginally, excessive races can hinder performance due to recovery and training disruptions.

Section 1:  The Power of Tune-Up Races

Ironman 140.6 training plans are often seen as a one-time blueprint—execute the plan, and that's it. But, as an experienced athlete with eight Ironman's and multiple World Championship qualifications under my belt, I'm here to share that tune-up races are an invaluable tool on the Ironman journey. Let's dive into what they are and why they're crucial to reaching peak Ironman performance.

What and Why: Tune-Up Races Explained

Tune-up races are shorter events strategically scheduled into your Ironman training. Their objective is to simulate race-day conditions, allowing you to test your fitness, refine your race-day strategies, and build mental resilience. Think of them as dress rehearsals for the main event.

The Benefits: Beyond Just a Training Day

Tune-up races offer a multitude of advantages:

  • Dialing In Race Logistics: Nutrition, pacing, transitions, and gear choices—experiment in a lower-stakes environment before a full Ironman.

  • Confidence Boost: Strong performances in tune-up races reinforce your training and provide that crucial mental edge.

  • Identifying Weaknesses: Expose areas needing improvement to address them with laser focus before race day.

Now that we've explored the significance of tune-up races and why they're pivotal in Ironman training, let's look into strategic approaches to maximize their effectiveness. In the next section, we'll discuss optimal timing, selection criteria, and even consider the debate surrounding cross-discipline tune-up races like marathons. By fine-tuning our strategies, we can elevate our preparation and performance for the ultimate goal: conquering the Ironman.

Section 2: Tune-Up Strategies

Timing and Selection Criteria:

The classic Ironman tune-up race is a half Ironman (70.3) scheduled roughly 6-8 weeks before your main event. This distance offers a significant challenge, allowing you to thoroughly assess your endurance, nutrition strategies, and overall readiness for the full distance.  While this timing is based on anecdotal evidence and conventional wisdom in triathlon circles, it's important to consider your individual fitness levels, training plan, and Ironman goals when making this decision.  In future sections, we'll delve into available data to see if it supports this approach or reveals alternative strategies.

While timing is key, your tune-up plan should be tailored to your unique circumstances. A seasoned athlete with a solid fitness base may handle a half Ironman closer to their "A" race, whereas a newer athlete might benefit from more recovery time. Always consider your recovery rate and how tune-ups fit within your overall training load. Your "A" race goals will also play a role –– if your primary focus is simply finishing the Ironman, less demanding tune-up races might be more suitable than a physically taxing half Ironman.

Choosing tune-up races strategically greatly enhances their value. Ideally, look for events that mimic the terrain and climate you'll encounter on Ironman race day. A well-organized event minimizes external stressors, allowing you to fully focus on your performance. And don't forget the practical side: Travel logistics and how the race fits into your training schedule should also factor into your decision to ensure it's a benefit rather than a disruption.

Cross-Discipline Tune-Up Races:

Athletes often consider cross-discipline tune-up races as a valuable addition to their triathlon training for several reasons: 

  • These races offer an opportunity to test fitness levels in a competitive environment, simulating the race-day experience and identifying areas for improvement. 

  • They also help refine race-day logistics, nutrition strategies, and mental preparation. 

  • Additionally, cross-discipline races can break up the monotony of triathlon-specific training, provide a mental boost, and potentially improve performance in specific disciplines, enhancing overall triathlon readiness.

A common question for many endurance athletes is deciding whether to run a marathon before tackling an Ironman, especially from those new to Ironman competitions. The answer isn't straightforward: while running a marathon before an Ironman isn't a necessity, it's an option depending on your goals and training approach.

Training for a marathon and an Ironman differ significantly. Marathon preparation typically involves more frequent runs, including several long runs up to 20 miles at a time. In contrast, Ironman training usually incorporates fewer runs per week, with a long run capped at 2hr. 30min., emphasizing time and quality intervals spent rather than miles covered. This difference in approach reflects the triathlon's multi-sport nature, where swim and bike sessions contribute substantially to cardiovascular and run fitness, unlike marathon training, which focuses almost exclusively on running.

Moreover, the race day experiences between a standalone marathon and an Ironman's marathon leg are distinctly different. A marathon race strategy involves pacing oneself through the early, easier miles, pushing through the middle, and digging deep to maintain pace towards the end. The Ironman marathon; however, is a relentless effort from the start, a direct continuation of the exertion from the bike leg, with no easy miles and a constant mental and physical challenge throughout.

Section 3: Empirical Data Analysis

What do Athletes actually do?

In this section, we determine the most prevalent strategies employed by athletes and how these correlate with achieving personal records in the Ironman 140.6. The initial step involves identifying athletes who have completed both Half Ironman and Full Ironman events. To explore the concept of a tune-up race, we required the interval between these events to be under 365 days. Practically, a gap exceeding 180 days may not be considered relevant, and this criterion might be further refined. The rationale for excluding longer intervals is that races beyond this timeframe do not fall within the same competitive season, thereby warranting separate consideration. Athletes can typically achieve peak performance twice annually (spring and fall) without the recovery from the first event impacting the second.

Therefore, the preliminary analysis focused on calculating the minimal time gap between 70.3 and 140.6 events for each participant, ensuring the 70.3 event preceded the 140.6. To illustrate a simple example below, I used my own race history as an example. In recent years, I completed two 70.3 events closely followed by 140.6 events. The first instance involved IM 70.3 Texas occurring 34 days before the IMWC 140.6 St. George, and the second, IMWC 70.3 St. George, 23 days before Ironman Arizona in 2022. For this analysis, the objective was to select the shortest time interval between a half and a full event to examine how the performance in the immediately following race is influenced by the athlete's chosen preparation period.

Dataset Overview

I sourced the dataset from using a custom Python scraper. (Feel free to contact me for access to the processed data or any additional questions relevant to potential analysis.) Before estimating the time difference between a full Ironman and a half Ironman, I encountered several issues that necessitated data trimming and preprocessing. These included: (a) races lacking a swim segment, (b) races featuring shortened bike or swim sections, (c) races involving downriver swims that distorted the model, and (d) timing chip issues such as missing bike split data despite having total time recorded. Following data trimming, some key summary statistics for the dataset are as follows:

  • Span of Years:

    • From 2015 to 2023

  • Number of Finish Times (703 Events + 1406 Events): 1,040,487

  • Number of Events:

    • 703 Events: 516

    • 1406 Events: 255

  • Number of Distinct Cities:

    • 703 Events: 184 cities

    • 1406 Events: 71 cities

  • Number of Unique Athletes by Continent of Residence/Origin:

    • Africa: 2,088

    • Asia: 6,082

    • Europe: 99,586

    • North America: 138,056

    • Oceania: 2,952

    • South America: 15,376

Image 1: Map of Ironman and Ironman 70.3 Locations

Image 2: Distribution of dataset by Age Groups

To ensure inclusion in the analysis, I specifically chose athletes who completed at least one 703 race and at least two 1406 races. I was uniquely able to identify participants by Age Group, Country, and Name. I devised a dynamic categorization method to accommodate participants transitioning between age groups throughout the 8-year period. For instance, an individual might have finished a 70.3 race in the F25 category and later completed a 140.6 race in the F30 category.

Empirical Data Analysis

Common Questions:

  • Time between half and full Ironman? 

  • Gap between first 70.3 to first 140.6?

  • 70.3 two months before first 140.6?

Questions I will attempt to answer from this real world data:

Question 1: Assuming I am going to do a tune-up race, when should it be? 

Question 2: How hard should I race the tune-up?

Question 3: Is there any tangible benefit to doing a tune-up? (Do I even have to do one?) 

Let’s dive into the data!

Question 1: Assuming I am going to do a tune-up race, when should it be? 

When planning the timing of a tune-up race in preparation for a key event, it's helpful to turn to data to guide decision-making. The distribution in the dataset reveals a noticeable peak around the 4- to 6-week mark, with the most common interval between a 703 race and a 1406 race being approximately 5 weeks. This observation is reflected in the histogram where the mode—or the most frequently occurring time interval—is at about 37.55 days. Such timing aligns well with prevalent training strategies and traditional guidelines within the endurance racing community. Furthermore, examining the median interval shows it to be around 77 days, or approximately 11 weeks, which might suggest a broader range of individual approaches to scheduling tune-up races. 


A pertinent question arises from the observed 4-6 week tune-up range: Is 4-6 weeks truly optimal for performance? To address this, a dual-method analysis was conducted:

(i) I calculated the probability of setting a PB in the 1406 race following a 703 tune-up for each time interval bin identified in the histogram. The analysis revealed the percentage of participants achieving a PB across various tune-up-to-1406 time gaps, averaged across all demographics. Notably, while the majority opt for a tune-up within 4-6 weeks and the median time gap stands at about 10 weeks, the data points to a higher likelihood of setting a PB when the gap extends to approximately 14 weeks. 

Thus, it appears that although significant people do their tune-ups between 4-6 weeks with the median being around 10 weeks, performance in terms of probability of setting a personal best, is closer to 14 weeks (100 days). 

Though there are discernible variances among different age groups—with older athletes generally benefiting from longer intervals between races—the central tendency for most remains around the 100-day mark. Detailing these age-specific nuances one by one is beyond this article's purview, but it merits mention that they do exist and influence performance outcomes. Below we can see from left to right Age Groups 18 to 75, with Female on Top and Male on Bottom. The general trend is for the likelihood of a personal best to increase near 100 days, plateau, and begin to decrease once more. On both the top and bottom we can see a relative but consistent decline in the probability of setting a PB as the age increases (within the 8 years of data available). 

(ii) In a complementary approach, I refined the dataset to encompass athletes with multiple 1406 and 703 race completions, pinpointing each athlete's PB in the 1406 distance. I then evaluated the probability of achieving a PB for each tune-up-to-1406 time window represented in the data. For seasoned athletes, the likelihood of a PB did not exhibit marked fluctuations based on the interval between tune-up and 1406 races. A notable increment in PB probability is observed from day 0 to 77, followed by a gradual decline. However, another peak materializes around the 6-month mark, suggesting that when both the 703 and 1406 events are spaced half a year apart, athletes likely approach both races with equal competitive emphasis, rather than treating the 703 event as merely a tune-up.


Question 2: How vigorous should a 703 race be prior to a 1406 race? 

To explore the potential correlation between the performance in a 703 race and the likelihood of achieving a PB in a subsequent 1406 event, I narrowed the dataset to individuals with multiple entries in both race types. The analysis focused on comparing athletes' relative performances in 703 races during the preparatory period immediately before their best 1406 times. The findings indicate that in 76% of cases, athletes recorded a personal best at the 703 distance when the time interval between their 703 and 1406 races was shortest.

The accompanying plot suggests that most athletes (76%) achieve their peak 703 performance during the tune-up period. It is essential to recognize that this observation is correlational, not necessarily indicative of causation. Peak fitness levels may naturally lead to PBs in both the 703 and the 1406 races. Hence, the critical question of this research is whether the effort put into a 703 race should be maximal. The data supports a clear affirmative: if the 1406 race is a priority ('A race'), and the objective is to peak, then it is advisable to fully exert oneself in the tune-up 703 race, as it is likely to coincide with a PB performance.



Question 3: Do I have to do a tune-up? 

In this section I analyze how athletes who include a 70.3 as a tune-up compare to those whose first event of the year is the Ironman 140.6. To do this, I first filtered out the earliest recorded race of type 1406 for each athlete. This step ensured that an athlete's initial performance in a 1406-type race did not influence the identification of PBs, focusing instead on improvements over time. Subsequently, for each remaining 1406 race, I assessed the athlete's race history to count the number of 703-type races they participated in within the 180 days leading up to that 1406 race. This was done regardless of whether those 703 races were PBs, providing a measure of the athlete's recent race frequency and preparation. Finally, I analyzed how the frequency of participating in 703 races within this 180-day window influenced the likelihood of the subsequent 1406 race being a PB. This approach aimed to quantify the relationship between recent race activity (specifically, participation in 703 races) and performance achievements in 1406 races.

The stacked bar chart illustrates the relationship between participating in 703 races within 180 days before a 1406 race and the likelihood of achieving a personal best in the 1406 race. The data indicates that there is no positive correlation between the number of tune-up 703 races and setting a personal best in a subsequent 1406 event. Interestingly, the trend suggests an inverse relationship: as the number of 703 races increases, the probability of recording a new PB in a 1406 race diminishes. This pattern may suggest that while tune-up races are commonly thought to prepare athletes for upcoming events, they may also lead to less than optimal performance, possibly due to inadequate recovery or accumulated fatigue. This insight could be valuable for athletes and coaches when designing training and race calendars with the goal of peak performance in mind. 

However, it should be noted that the transition from 0 to 1 tune-up 703 race within the 180-day period prior to a 1406 event has been found to be statistically significant in terms of PB odds. Specifically, there is a 1.2% increase in the likelihood of setting a PB in the 1406 race when an athlete participates in one tune-up 703 race compared to none.



Section 4: Practical Advice for Athletes

Based on the empirical analysis conducted, here is a synthesized summary to offer practical advice for athletes preparing for a 1406 distance event:

Timing of Tune-Up Races: The data suggest a common strategy is to schedule a 703 tune-up race around 4-6 weeks prior to a 1406 race, with the mode falling at about 37 days. However, the probability of setting a PB in a 1406 is slightly higher when the interval extends to roughly 14 weeks, diverging from the traditional window. Athletes, particularly older ones, may benefit from experimenting with this longer lead time to optimize performance.

Intensity of Tune-Up Races: Athletes appear to perform best when they approach a tune-up race with full competitive effort. In 76% of cases, a PB at the 703 distance occurred when it was run closest to the 1406 event. This suggests that peak performance in a tune-up can be a good indicator and contributor to success in the main event. Coaches and athletes should consider the intensity of these preparatory races as integral to the overall racing strategy.

Necessity of Tune-Up Races: Although many athletes incorporate a 703 race within 180 days before a 1406 event, this practice is not universally beneficial. The analysis indicates a diminishing likelihood of setting a PB in 1406 with an increasing number of 703 races, possibly due to factors like recovery and training disruption. However, completing at least one tune-up 703 race is associated with a marginal but statistically significant improvement in PB odds for the 1406 race.

Personalization of Training Plans: Given the variability observed across age groups and individual responses to race timing and intensity, athletes should consider personalizing their training and race plans. While aggregate data provides general trends, individual optimization may involve tailoring race schedules and intensity based on personal health, fitness levels, and recovery capacity.