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How to Use TSS to Prepare for an Ironman

For many athletes, the very idea of racing an IRONMAN is daunting. The distances involved are so great that most athletes are overwhelmed and, as a result, tend to approach training with a very narrow focus (volume) while ignoring other important aspects of training.

Where to start? How rapidly should I progress? How much volume is enough? What intensities should I target? These are all questions that need to be addressed prior to creating an IRONMAN training plan, if one is to achieve success.

While focusing on being able to complete the distance may be appealing, it is only addressing one factor in the racing equation while ignoring perhaps the biggest contributor to IRONMAN racing success—intensity. If an athlete, or coach, truly wants to plan for a successful IRONMAN race, they will need to look beyond the volume approach.

Identify Your Sport-Specific TSS to Determine Your Goal CTL

This is where athletes can take their training to the next level by planning with Training Stress Score (TSS). TSS is calculated by combining the duration of a workout with its Intensity Factor® (IF), how hard the athlete worked compared to his/her functional threshold, or the maximum intensity that can be sustained for approximately one hour.

TSS allows an athlete or coach to compare the imparted training stress of workouts of different types, and even disciplines, on an “apples to apples” comparison. In this manner, overall training stress can be precisely controlled and allocated to areas that are most in need to elicit the biggest improvements in performance, without overreaching the athlete and risking illness or injury.

Because TSS is data driven, it is critically important to start off with complete and accurate data for Functional Threshold Power (FTP) or pace, as well as heart rate (HR) for each discipline (HR for swimming is not currently viable), and to test regularly to make sure your Training Stress Scores are accurate for the workouts throughout the training cycle.

Once you have reliable data to calculate TSS for your workouts you can start planning your training. The first step to successful planning of any kind is to identify both where you currently are and where you want to be at the conclusion.

I believe you should start your planning by having a target fitness level for race day. When using the Performance Management Chart (PMC), Chronic Training Load (CTL) is the measure of fitness you accumulated through your training—the six-week exponentially weighted average of your daily TSS.

You can look at past seasons and identify the CTL you achieved prior to a successful race to set a target, or, if this is your first IRONMAN race or you want to set a PR or take your racing to the next level, you can rely on general season targets that work for most, although not all, athletes (Figure 1).

These averages are sport-specific CTL targets, and are based on your cycling FTP for your bike CTL, and your running FTP (in kph) for your run CTL.

Swimming TSS is a more nebulous entity due to the variety introduced not only by technique, but also by the different conditions encountered in training – different pools, open water, temperature, drills, kicking etc., and should be determined in a more athlete-specific manner. Collecting and analyzing enough pace data from comparable pool training sets or open water swims will provide the best estimation of race day performance, CTL target and TSS for the swim.

Figure 1 Peak CTL guidelines for athletes depending on their goal (rFTPa in kph)

Athlete Bike CTL Run CTL (in kph)
Ironman Finisher/Midpacker 15-25% of bFTP (1.5-3) x rFTPa
Kona Age Group Qualifier 20-30% of bFTP (2-5) x rFTPa

Credit: Triathlon 2.0 by Jim Vance

Determine Your Goal Race-Day CTL to Plan Your Training

Once you have your race day CTL Target, subtract your current CTL from it to identify your required CTL gain, then divide that number by the number of weeks to race day to determine your weekly CTL gain.

You now have overall and sport-specific weekly TSS targets to structure your training. At this time, you will also get your first important feedback in the form of the answer to the question, “Is my goal reasonable given my current fitness and the amount of time I have available to prepare?”

If your weekly CTL increase (known as your ramp rate) is within the accepted norms (Figure 2), then it is fair to say you can expect to achieve your goal with minimal risk of illness or injury from overdoing it. If it is far above that, then you will have to re-evaluate your CTL goal.

Ramp rates are individualized and dependent on past training, athlete level and goals as well as injury proclivity, although I’ve found that rates of 5 to 8 per week work for most athletes. Below that and your training is probably lacking structure and focus. Much above that and you risk injury.

Figure 2 CTL Ramp Rate guidelines based on risk of injury.

Weekly CTL Ramp Rates
CTL <45 CTL >70
Low Risk 4 6
Moderate Risk 6 8
High Risk 8+ 10+

Credit: Triathlon 2.0 by Jim Vance

Using TSS/CTL Targets To Plan Specificity IRONMAN Training

Once you have calculated your CTL gain and weekly TSS targets, it’s time to start planning the specifics of your training. Depending on an athlete’s starting point, it may become apparent that one sport might need more focus than another, allowing for a very precise and efficient TSS allocation to achieve the required fitness gains without overloading the athlete and risking injury.

You should consider that 1 point of CTL is not equal among the three disciplines. Due to the weight bearing nature of running, running CTL is harder on the body than an equal amount of Cycling CTL, which is more impactful than a comparable Swim CTL. As a result, ramp rates may vary greatly among the three disciplines.

It is a good idea to incorporate race specific stress in training early on, provided the athlete has the fitness to handle the training load. TSS allows you to impart that specific stress rather than focusing on much less precise time or distance measures.

The bike leg is the longest segment by far and it will also greatly impact your ability to run well in the marathon. As a result, preparing your body to handle the rigors of the specific effort should be a priority.

An IRONMAN bike leg will usually record approx. 250 to 300 TSS (you can approximate yours by using your FTP, IF and estimated finish time), giving you a target for a specific training stimulus to plan for. Initially this can be a low intensity long duration ride, and evolve to more closely mimic race intensity and duration as the training progresses.

Swim race TSS values are much lower given the shorter duration of an IRONMAN swim leg and can therefore be more easily achieved in training, allowing you to develop the tolerance required on race day. I would not recommend reproducing race day run TSS in training, given the increased risk of injury.

IRONMAN run TSS projections can be made based on training metrics such as Intensity Factor, Functional Threshold Pace, and the Mean Maximal Pace Curve after a race TSS ride. On average an IRONMAN run will vary between 190 and 250 TSS, depending on the athlete, while IF ranges are between 0.7-0.85. With this information, you can determine the appropriate IF, and thus pace or power, you or your athlete can hold off the bike and train to achieve that goal.

Adjust Your Plan as Needed Along the Way

This approach will quickly provide answers to some important questions. Is your target run pace too aggressive for you to sustain off the bike? Can you tolerate your bike race TSS after a race equivalent swim TSS? Is your nutrition plan sufficient for the projected race day TSS? Can your body absorb the nutrition under the specific stress? You will then be able to adjust your plan, as needed, well in advance of race day giving you the confidence that you have a solid and executable race plan.

Training for an IRONMAN is daunting, but the planning does not need to be. Planning using TSS based on your individual data will eliminate guess work, simplify your training and greatly improve the probability of reaching the start line with the fitness and confidence to have your best performance.


This article was written for and published in the blog.

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Get Stronger and more Resilient in the Off Season!

The Off Season is the perfect time to introduce some focused Strength Training

By this time of the year a lot of triathletes in the northern hemisphere are nearing the end of their competitive season and are ready to transition into their off season. For many, this means no more structured training, a general loss of fitness and the need to build it all back up in the early spring. But what if you could give your body and mind the break they need while still laying the foundation for the upcoming season? For the past several months, training has meant long hours building the aerobic engine we value so much as endurance athletes. At a certain point the gains become smaller and smaller and harder to come by. The longer we stress our body in a singular manner, the less responsive it becomes to that stimulus. The off season is the perfect time to introduce some focused strength training – the different stimulus that will elicit several greatly beneficial adaptations for the upcoming season.

Correct Imbalances

Every athlete has muscular imbalances resulting from ingrained movement patterns. These imbalances are not only a prime cause of inefficiency in sport specific movement as well as loss of power generation, but can lead to injury that can sideline you for weeks or months. By taking the time to address these imbalances in the off season, an athlete can make the return to aerobic training more focused and productive by reducing the chances of an injury. After all, a stronger muscle is a more injury resistant muscle. Hamstring injuries, for example, are an all too common occurrence, often requiring a long recovery and rehabilitation period. However, it has been shown that eccentric strength exercises dramatically reduce the risk of acute hamstring injury (3,4). Who wouldn’t want to lower their risk of injury?

Improve Economy

As an endurance athlete you want to ensure you are expending the least amount of energy to cover a given distance at a specific speed. After all, we only have so much energy on race day, and how we expend it can mean the difference between a great race and a poor one. Running, being the last leg of a triathlon, is probably the most impacted by poor economy and the place where the biggest improvements (or losses) in performance can be gained. Even an efficient and economical runner can become inefficient when fatigued, and a weak runner will fatigue sooner than a strong one. In a Triathlon, especially a long course one, the fact is exacerbated by the bike leg preceding the run. It becomes doubly important to develop strength and power to allow your body to maintain form and efficiency throughout the entire race.

Strength training has been shown to improve running economy in runners by 3 % over a 12-week period when added to their regular training versus no improvement for runners who did not (6). I realize that doesn’t sound like much, but for a 3:30 Ironman marathoner that is a 6 minute and 20 second improvement. Now keep in mind that improvement came not through extra aerobic training, higher fitness or more work on race day –  that improvement came from being able to move your body forward at a faster pace using the same effort through making your muscles and movement pattern more efficient. Now imagine also being less likely to get injured, and being able to recover faster due to the improved ability of your body to tolerate your training. You can truly take your training to the next level and those time gains can increase significantly!

Increase Strength and Power

Strength training will also significantly affect your swim by increasing the power of your pull by strengthening specific musculature as well as creating a stronger kinetic chain to stabilize your whole body during your stroke. This will lead you to swim faster while using less of your total available energy and power, leaving you more rested as you exit the water.

On the bike increased strength is a huge asset. Power is defined as Torque x Circumferential Pedal Velocity (Cadence). Strength training increases neural drive and thus the ability of our muscles to contract with speed and coordination, leading to improved Cadence. Strength is defined as the ability to increase a muscles’ capacity to exert force, on the bike this translates to the ability to generate greater Torque. The net result of a well-designed and integrated strength training program for a cyclist or triathlete can be summarized as the ability to push the pedals harder while maintaining cadence – more Watts! Who doesn’t want that?


The Hormonal benefits of Strength Training

Perhaps even more important for Masters athletes are the hormonal adaptations that strength training elicits. We all know that as we age our bodies got through changes that are not optimal for performance. Muscle mass, strength and power all tend to decrease and our ability to recover from training is reduced as well. A lot of this decline is rooted in hormonal changes that happen as we age. Resistance training has been shown to stimulate the production of hormones that increase strength, resiliency and performance of our musculature (7). As a result, recovery will be enhanced alongside power and lean body mass. These will combine to maintain speed and performance for the athlete who, in the absence of resistance training, would have experienced a gradual but significant decrease over time. It’s like turning the clock back, or perhaps slowing it down a few notches!

What about bulking up too much?

There is a widespread belief that strength training is incongruous with endurance athletes. It is often thought that since increased muscle weight is a performance detractor it should be avoided by endurance athletes, who should therefore eschew strength training altogether. While it is true that gaining too much muscle weight would hinder performance, it is very unlikely that an endurance athlete would achieve such hypertrophy. First of all, a properly structured strength training program for an endurance athlete should not be solely focused on hypertrophy, it should be tailored to strength and power gains and periodized as a companion to regular endurance exercise. Secondly, there is an antagonistic relationship between aerobic/endurance and strength training that detracts from the growth of muscle fibers versus strength training alone (5). As far as the belief that strength training will decrease aerobic capacity, research indicates that heavy resistance training has very limited, if any, negative effects on aerobic power (1), and it can actually enhance performance in endurance sports (2).


By working on strength development, especially sport specific strength, you are upgrading the available horsepower of your engine. When you return to full endurance training, while maintaining some in season strength work, you will be able to significantly improve your performance come race day.

If you would like to learn more or have questions feel free reach out to me. I’m always happy to talk training!










  1. Wilson, JR, Marin, PJ, Rhea, MR, Wilson, SM, Loenneke, JP and Anderson, JC. Concurrent Training: A meta-analysis examining interference of aerobic and resistance exercises. J Strength Cond Res 26:2293-2307, 2012..
  2. Sedano, S, Marin, PJ, Cuadrado, G and Redondo, JC. Concurrent training in elite male runners: The influence of strength versus endurance training on performance outcomes. J Strength Cond Res 27:2433-2443, 2013
  3. Nichols, AW. Does eccentric training of hamstring muscle reduce acute injury in soccer? Clin J Sports Med 40:2256-2263, 2012.
  4. Petersen, J, Thorborg, K, Nielsen, MB, Budtz-Jorgensen, E, and Homlich,P. Preventive effect of eccentric training on acute hamstring injuries in men’s soccer: A Cluster-randomized controlled trial. Am J Sports Med 39:2296-2303, 2011.
  5. Kramer, WJ, Patton, J, Gordon, SE, Harman, EA, Deshenes, MR, Reynold, K, Newton, RU, Trilet, NT, and Dziados, JE. Compatibility of high intensity strength and endurance training on hormonal and skeletal muscle adaptations. J Appl Physiol 78:976-989, 1995.
  6. Yamamoto, LM, Lopez, RM, Kalu, JF, Casa, DJ, Kraemer, WJ, and Maresh, CM. The effects of resistance training on endurance distance running performance among highly trained runners. A systematic review. J Strength Cond Res 22:2036-2044, 2008
  7. Kraemer, WJ. Hormonal mechanisms related to the expression of strength and power. The Encyclopaedia of Sports Medicine: Strength and Power in Sport. Komi, PV, ed. Oxford: Blackwell Scientific, 291-304, 1992.
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Meet the Coach

I am passionate about sports and physical activity. I grew up as a soccer player in Italy, playing for my hometown’s professional team. After moving to San Diego with my family I started training and competing in Multisport events and have completed numerous Triathlons, from Sprint to Ironman. I believe One on One coaching provides the best pathway to Optimal Performance on race day. Every athlete is different in their physiology, strengths, weaknesses and response to training. In my opinion, a tailored and personalized approach is the only way to achieve optimal results.

“What gets measured gets improved!”

My coaching and training approach is predicated on the belief that quantitatively driven training provides the most likely path to success. This process is based on creating an unbiased and objective assessment of an athlete, their strengths and weaknesses measured against goals and objectives. Only once this is done can a training plan truly be designed that will be both tailored to the athlete and focused on their goals.