Cycling, Podcast, Science and Physiology

James Spragg, PhD | EP#425

 February 12, 2024

By  Bernardo Gonçalves


James Spragg - That Triathlon Show

James Spragg, PhD, is a cycling coach at the Tudor Pro Cycling Team and performance consultant. His PhD research focused on durability, which is the main topic of today's interview. 

In this episode you'll learn about:

  • The concept of durability
  • The relationship between training characteristics and durability in cycling
  • The relationship between physiological measures and durability in cycling
  • The type of intensity, not just the amount of work done, impacts the downward shift in power profile
  • Critical Power (or Critical Speed) is a more comprehensive marker of performance physiology than VO2max
  • Listener questions: how to know when to work on what part of the power-duration curve and more

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James background

02:22 -

  • I hold a PhD in exercise science from the University of Cape Town, specializing in durability, which was the focus of my doctoral studies. 
  • I work as a coach and performance scientist at Tudor Pro Cycling. Additionally, I am part of a performance consultancy company called Intercept Performance Consultancy, where we provide performance services across various sports.
  • Tudor Pro Cycling competes at the professional level, specifically in the middle tier of professional cycling. 
  • As a relatively new team, we're working towards earning points to qualify for the top tier. Our mission is ambitious, and we're dedicated to achieving success.


03:38 -

  • Durability, in essence, refers to the difference in performance capacity between when I'm fresh and when I'm tired within a single session. 
  • A typical starting point for understanding durability is power-duration relationships, which depict the power output achievable for various durations. 
  • A power duration curve is generated by plotting these durations and powers on a graph, indicating performance changes over time.
  • One term frequently mentioned in discussions about durability is the "downward shift" of the power duration relationship. 
  • This shift represents a decrease in performance across all durations. 
  • For example, if I could initially sustain 400 watts for 10 minutes, a downward shift might mean I can only maintain 380 watts for the same duration.
  • In formal testing environments, metrics like critical power (maximal sustainable aerobic power), W prime (capacity for power above critical power), maximum sprint power, and values for specific durations are measured. 
  • However, conducting formal tests isn't feasible in real-world scenarios, such as during races. Instead, we rely on mean maximal power output (MMP) values derived from race data. 
  • These MMP values represent the highest average power sustained over continuous durations during a race, providing insights into an athlete's durability in practical settings.

Training characteristics and durability in professional cyclists across a competitive season

06:31 -

  • When I began my PhD research, I delved into durability in athletic performance. Previous studies hinted at its importance, suggesting that durability, rather than just fresh values, played a significant role in race outcomes. 
  • My primary research focus was determining whether durability is trainable and remains constant throughout the season.
  • Our findings challenged the notion of durability as a fixed component. While fresh power profiles remained relatively consistent across the season, power outputs in a fatigued state showed considerable variability. 
  • Athletes often misinterpreted their form, attributing it to unchanged fresh numbers when, in fact, improvements in fatigue numbers were driving their performances.
  • This discovery led us to explore the trainability of durability. We conducted a study involving under 23 athletes, dividing their season into early, mid, and late phases, each with a targeted goal event. 
  • Performance testing conducted during these phases showed minimal changes in fresh levels. However, when analyzing power outputs at the end of races, we observed a significant drop in fatigue state outputs towards the end of the season.
  • Interestingly, as the season progressed, the gap between fresh and fatigued power outputs widened, indicating a decrease in durability over time. 
  • Conversely, in the middle of the season, the two values became closer, suggesting an improvement in durability. 
  • This fluctuation in durability across the season emphasized its dynamic nature and potential for improvement through targeted training interventions.


09.48 -

  • So alongside analyzing power outputs, we delved into the training data of the athletes during specific periods. 
  • We discovered the correlation between training changes from one period to the next and the resulting change in durability. 
  • It became evident that the overall training load plays a crucial role. When athletes reduced their overall training load, their durability also tended to decrease. 
  • Towards the end of the season, many athletes shifted towards a minimal effective dose of training to maintain their power profile. However, this reduction in volume negatively impacted their durability.
  • Training volume, a significant component of training load in endurance sports, is vital. 
  • Athletes can sustain or slightly increase their volume while incorporating more grey zone training to maintain durability. 
  • This approach helps maintain the overall training load even with a slight reduction in volume. On the other hand, athletes who improved their durability tended to increase their volume and adopt a slightly more polarized training approach. 
  • So, while maintaining durability can involve more heavy-intensity work with reduced volume, improving durability typically requires increasing volume and adopting a more polarized training regimen.

Late season cyclist's fatigue

12:55 -

  • In professional cycling, the mental toll of frequent travel, long days away from home, and time spent in airports adds up over the season. Athletes may experience psychological fatigue, especially towards the end of the season. However, those with specific goals, like the Tour of Lombardie, often maintain their motivation and training volume. Adjustments to training may be necessary throughout the season to accommodate this fatigue.
  • Fatigue is multifaceted, comprising mental, cognitive, and physical components, making it challenging to pinpoint its exact cause. 
  • Nonetheless, understanding the benefits of maintaining training load and increasing durability can motivate athletes, even in the latter part of the season.
  • It's crucial to view seasons not in isolation but as part of a continuum. Loss of durability towards the end of one season means more work to regain it for the next. 
  • Many male cyclists finish the Vuelta with high volume and intensity, take a break, and start the next season strong. This training and recovery cycle is essential for consistent performance over the seasons.

Additional thoughts on this study

15:35 -

  • These general guidelines provide a helpful framework for coaches when prescribing training. Increasing volume often leads to improved durability, but individual responses vary. While it points in a direction for athlete development, it doesn't specify the amount of volume or duration increase. 
  • If such adjustments lead to fatigue, performance may decline. The study aims to clarify whether training should intensify or increase volume to enhance durability, but the application must be personalized for each athlete. 
  • The coach's expertise effectively tailors these findings to individual athletes.

Relationship between physiological characteristics and durability

16:48 -

  • This study is particularly fascinating because it focuses on my PhD research. We aimed to delve into the physiology behind durability, which we know is trainable. 
  • The question was: what physiological changes occur to enhance durability? To answer this, we conducted an extended test protocol with athletes.
  • First, we performed a standard ramp test and steady-state exercises across moderate and heavy-intensity domains to assess exercise efficiency and substrate utilization. Then, athletes underwent a critical power test to determine peak, critical, and W values. 
  • Following this, a fatiguing protocol was implemented before the critical power test was repeated.
  • Our analysis revealed exciting correlations. We found that durability in terms of critical power strongly correlated with various lab measures indicative of aerobic fitness. 
  • Essentially, improving overall fitness led to enhanced critical power durability. However, we observed that W prime (W') didn't correlate significantly with most measures except for substrate utilization. 
  • Athletes who utilized carbohydrates more efficiently during high-intensity efforts tended to maintain their W prime better.
  • Interestingly, we could accurately predict critical power durability using relative VO2 max, LT1, and substrate utilization. 
  • These three measures explained 98% of the variance in critical power or its decline.
  • Other studies attempting similar correlations between lab metrics and performance in fresh and fatigued states yielded inconsistent results. 
  • This discrepancy may stem from inadequate control of fatigue levels between tests and single performance metrics that didn't fully account for critical power and W prime components.

Maintaining W'

21:23 -

  • Finding no correlations between critical power or W prime values in a fresh state and durability was intriguing. I had always assumed that getting fitter or improving critical power would enhance durability. 
  • However, basic aerobic measures like VO2 max, exercise economy, and substrate utilization seem more closely linked to durability.
  • I found it particularly interesting to rank all the variables by the strength of their correlation, measured by the R square value, and discover that VO2 max had the strongest correlation. This goes against the conventional understanding of VO2 max, primarily reflecting performance in short bursts of high intensity.
  • Reflecting on the multiple linear regression results, it became clearer why VO2 max, substrate utilization, and exercise economy emerged as critical factors in durability.
  • VO2 max indicates the size of the aerobic engine, substrate utilization reflects how efficiently fuel is burned and preserved, and exercise economy assesses overall efficiency in converting oxygen intake into pedal power.

Protocol to fatigue athletes

23:37 -

  • Designing fatiguing protocols for scientific studies can be pretty challenging. Intensity levels must be balanced to effectively fatigue athletes while allowing them to complete the protocol multiple times. 
  • The protocol must also reflect real-world scenarios, such as mimicking the demands of a bike race or other relevant activities.
  • When my colleagues and I first attempted the five-by-eight session, we encountered unexpected results. Our initial trial study produced data that contradicted our expectations. 
  • Athletes we thought would be more durable performed worse, while those we perceived as less durable excelled.
  • Upon closer examination of the data, we discovered that athletes who slightly underperformed during the intervals emerged stronger during the final test. 
  • Conversely, those who pushed themselves too hard during each interval struggled more during the subsequent test. 
  • This observation highlighted the importance of controlling the intensity of efforts within a narrow range, typically between 105% and 110% of critical power.
  • Maintaining strict control over these parameters is crucial for minimizing inter-individual variability and ensuring the protocol effectively induces fatigue. 
  • Without such control, the data may be unreliable, undermining the study's validity and usefulness. Therefore, meticulous attention to detail and adherence to predefined controls are essential for obtaining meaningful results from fatiguing protocols in scientific studies.

Takeaways from this study

26:27 -

  • Based on the first two studies we discussed, it's logical to expect that increased training volume would improve exercise economy and substrate utilization, ultimately enhancing durability.
  • In coaching, I would focus on volume if I aim to boost an athlete's exercise economy and optimize their carbohydrate utilization. 
  • This aligns with what we observed in the initial study, where increased volume correlated with enhanced durability. Additionally, the lab study reinforced this connection by demonstrating that the metrics impacted by increased volume also correlated with durability.
  • Athletes with extensive aerobic training experience tend to be the most durable. This observation is evident in cycling, particularly with junior athletes. While juniors may possess impressive physiological metrics like VO2 max and power output, they often lack the endurance developed through years of consistent training volume, limiting their performance in fatigued states.
  • Regarding practical implications, one consideration is whether to utilize lab data to estimate durability or conduct specific durability tests. From my experience, standard step or ramp tests may not capture all relevant data, necessitating additional assessments, such as steady-state exercises in the moderate and heavy intensity domains. 
  • Incorporating these into lab protocols provides more comprehensive insights into an athlete's physiology and can inform durability predictions.
  • In some institutional settings, these extended lab protocols are employed alongside durability predictions to optimize training strategies. While conducting field tests is ideal, constraints such as busy race schedules or limited access to athletes may warrant using lab data as a proxy for durability. Ultimately, it's about leveraging available tools to effectively tailor training approaches.

The impact of intensity in a fatiguing protocol

30:23 -

  • So, not all bike races are created equal. Some can be incredibly intense, while others might be relatively easy, at least in the context of professional cycling. The intensity of a race is closely tied to factors like terrain and course layout. 
  • Based on our pilot testing, it became clear that controlling intensity is crucial when implementing fatiguing protocols for training. 
  • Once we understood the importance of durability and how to train for it physiologically, we began investigating individual differences in intensity response.
  • We utilized the same fatiguing protocol across subjects, involving 105 to 110% of critical power (CP) intervals. 
  • Additionally, participants performed slightly more work at a moderate intensity, typically below 70% of CP. We conducted critical power tests in a fresh state and after each fatiguing protocol to assess changes.
  • Our findings revealed that high-intensity sessions elicited more significant changes than moderate-intensity sessions. Sprint and three-minute power were particularly affected after high-intensity work, indicating a greater impact on shorter-duration efforts. 
  • However, for more extended power outputs such as 12-minute and critical power, the accumulation of work seemed less affected by intensity.
  • At least at a group level, high-intensity work appears to have a more pronounced effect on an athlete's ability to sustain subsequent high-intensity efforts. 
  • These insights shed light on the nuanced relationship between intensity, fatigue, and performance in cycling.
  • I believe glycogen depletion will play a significant role, especially considering the noticeable decrease in W prime following the high-intensity session but not the moderate one. Additionally, there may be some neuromuscular factors at play. 
  • Exceeding critical power likely triggers muscle changes, producing metabolites that negatively impact subsequent power output. 
  • Riding above critical power induces more fatigue-inducing metabolites, which impair the body's ability to generate power afterwards. 
  • This effect is particularly pronounced in shorter efforts, such as three or five minutes, although it also impacts longer durations, such as 10 or 20 minutes.

Why choose the moderate-intensity domain

34:29 -

  • Our study aimed to distinguish between exercise intensity levels, focusing specifically on moderate intensity. 
  • We didn't have the resources to thoroughly explore moderate, heavy, and severe intensities. 
  • Ideally, we would have conducted a more comprehensive study, but time constraints, especially with professional cyclists on tight training schedules, limited our options.
  • Based on the data, heavy intensity appears to represent a slight increase over moderate intensity. 
  • Despite initial testing setbacks, athletes in the heavy-intensity domain didn't exhibit significant fatigue. 
  • This suggests that heavy intensity falls between moderate and severe, leaning more towards the former regarding its effects.
  • Increased glycogen depletion and potential impacts on W prime are likely outcomes of prolonged exposure to heavy intensity. 
  • However, it's essential to note that these findings are based on group-level data, and individual responses vary widely. 
  • Some athletes resisted fatigue, showing minimal changes in power output after moderate and high-intensity sessions. 
  • Others were semi-fatigable, experiencing changes only after high-intensity efforts, while some were categorized as fatigable, showing consistent power profile changes after moderate and high-intensity work.
  • We didn't observe any clear patterns regarding fatigue resistance among cyclists in our data analysis. While some colleagues have linked an athlete's ability to sustain specific power outputs to their speciality, such as sprinters holding sprint power better than others, we didn't find significant differences in more extended power outputs like 20-minute efforts. 
  • Interestingly, we did notice that athletes who could maintain their 15-second power output after high-intensity work tended to be more durable overall. 
  • While this observation might be specific to our cohort, preserving sprint power post-high-intensity efforts could indicate resilience in longer-duration efforts and W' maintenance.
  • For coaches seeking a quick way to gauge an athlete's durability, sprint testing followed by high-intensity work and retesting sprints can provide valuable insights without extensive control measures. 
  • Though not foolproof, this approach offers a convenient alternative to more time-consuming methods.
  • I want to emphasize an important aspect that has become apparent in recent years, particularly in discussions surrounding durability or fatigue resistance. 
  • Many are familiar with fatigue resistance charts, often seen in platforms like WKO, which illustrate power output over time, typically after a certain amount of work, like 2000 kilojoules.
  • Initially, the focus was on how much power an athlete could maintain after a set workload. 
  • However, your work has illuminated another crucial factor: how the work is done significantly impacts fatigue resistance. 
  • It's not solely about the quantity of work but also the quality, particularly relevant for disciplines like cycling and shorter distance triathlons.
  • While total work done may serve as a reliable proxy for long-distance triathletes consistently operating in the moderate to heavy domain, it's insufficient for disciplines requiring varied intensity levels. 
  • Thus, incorporating intensity metrics alongside work done is essential for a more comprehensive understanding of fatigue resistance.

Applications for amateur cyclists

40:57 -

  • So, based on my experience working with continental-level cyclists, who are essentially third-tier professional cyclists, and even some second-tier athletes, I've noticed that when it comes to world-class cyclists, everything needs to be taken up a notch. 
  • You'll likely need to increase the total work to induce the same downward shift in the power-duration relationship. 
  • For instance, instead of aiming for 2500 kilojoules, you might need to target around 3500 kilojoules before seeing significant differences.
  • Conversely, with amateur cyclists, it's a bit different. The downward shift may still occur, but it could happen more rapidly and to a greater extent, mainly depending on the individual athlete's level of performance. 
  • You might start noticing these differences when the total workload for amateur cyclists is lower, perhaps around 1500 to 2000 kilojoules.

How to improve durability

42:23 -

  • Throughout the study, we consistently provided high fuel levels, using a 1:0.8 glucose-fructose carbohydrate ratio and around 90 grams of carbohydrates to simulate race conditions. 
  • However, neglecting proper fueling can lead to more significant glycogen depletion and hinder performance. This is evident in professional cycling, where high carbohydrate intake is emphasized.
  • Additionally, it is crucial to prioritize good, controlled, and sensible training. Athletes perform best when they strike a balance between feeling fresh and fit. 
  • Focusing on training basics, including adequate volume without overdoing it, fosters durability and optimal performance.
  • Furthermore, fresh values play a vital role in setting performance ceilings. 
  • It's essential to ensure that fresh values are sufficiently high and that athletes can maintain performance even when tired. Athletes can maximize their performance potential and durability by considering fueling and training principles.

Fatigued intervals

44:33 -

  • I don't typically use fatigue resistance training to enhance durability, especially with athletes focused on improving endurance. 
  • Instead, I emphasize volume for building durability, keeping high-intensity sessions separate and focused on intensity. 
  • Fatigue resistance training can boost athletes' confidence before essential race blocks. 
  • Improved performance under fatigue conditions can enhance their confidence for race day. 
  • However, I don't rely on it as the primary tool for durability improvement.
  • My approach to training aligns with traditional principles that have stood the test of time. 
  • Durability has always been a critical aspect of training, and while modern methodologies may offer more systematic insights, the basic concept remains unchanged. 
  • Coaches from past generations also recognized the importance of ensuring athletes perform well at the end of races, highlighting that this aspect of training has long been considered in athletic preparation.

VO2max as a marker of the level of the athletes

46:12 -

  • So, when it comes to classifying athletes based on VO2 max, it's become a bit of a misleading practice. In many intervention studies, participants are often labelled "elite" if their VO2 max exceeds 75. 
  • But having a high VO2 max doesn't necessarily equate to elite performance. When you look at other factors like sustainable power outputs and actual performance numbers, many of these so-called "elite" athletes fall short.
  • I believe we need to shift our focus away from solely relying on VO2 max as the gold standard for athlete classification. Instead, we should consider using critical power, speed, or pace metrics. 
  • These measures provide a more comprehensive understanding of an athlete's capabilities in the lab and real-world scenarios.
  • Critical power, for example, reflects aerobic capacity and factors in training volume and competition level. This approach offers a more nuanced and accurate assessment of an athlete's true performance potential. 
  • Plus, it's practical – you don't always need a lab to measure critical power, making it more accessible for field testing.
  • By adopting critical power as an alternative metric, we can better identify athletes' actual performance levels and make more informed decisions in research and training settings. 
  • It's time to move beyond the narrow focus on VO2 max and embrace a more holistic approach to athlete classification.

Should amateurs look at these metrics?

49:10 -

  • Absolutely. Transitioning to using critical power has been incredibly beneficial for me. Compared to other metrics, it provides a clearer understanding of performance and physiology. When you estimate critical power, you also get a W prime estimate, which helps derive a power duration relationship. 
  • This depth of information is invaluable for both athletes and coaches. It simplifies training control and allows for effective retesting to gauge progress. 
  • I always advocate for critical power, critical pace, or critical speed because of its efficiency in providing comprehensive insights quickly.

Testing protocols for critical power

50:23 -

  • The critical power model is most relevant to severe exercise intensity, which includes intensities from critical power upwards until reaching VO2 max before exhaustion. 
  • For most athletes, this typically occurs around the two-minute mark of maximal effort. Testing within this range is crucial for accurate, critical power estimation.
  • The literature suggests testing durations between three and 15 minutes, with professionals possibly extending to 20 minutes due to their higher fitness levels. 
  • Ideally, conducting three tests within this range provides the most reliable data. 
  • Any error can significantly impact results with two tests, hence the recommendation for three tests.
  • Regarding timing, conducting tests on one day reduces daily variation but may introduce fatigue between efforts. 
  • Spreading tests over multiple days helps mitigate this but introduces the risk of having a bad day affecting one of the tests. 
  • To balance these factors, I typically conduct two tests on the same day with a 40-minute break in between for maximal values. 
  • Then, on another day, I conduct a third test, usually a five-minute effort, to enhance the robustness of the critical power and W prime estimate.

Downsides of using a 20min test

54:41 -

  • When choosing the duration of performance tests, I've found that there aren't too many downsides. Due to abundant historical data, I often use 20-minute tests with professional road athletes. 
  • However, some logistical issues are worth considering, such as finding a suitable 20-minute section of the road without interruptions like traffic lights or descents.
  • For amateur athletes, I typically opt for shorter test durations, such as 12 minutes, which still provide valuable insights into performance. 
  • If athletes have experience with specific training efforts, like 15-minute intervals, I may use durations closer to what they're accustomed to. 
  • The key is to choose a duration that allows athletes to perform maximally without veering into submaximal efforts.
  • While some may advocate for longer test durations, such as one-hour powers, these can skew the results and fall outside the model's zone of validity. 
  • Professional athletes may sustain critical power for around 40 minutes, making 20-minute tests suitable for assessing performance. 
  • However, to maintain accuracy and reliability, it is essential to ensure that test durations remain at least 105% of the critical power.

Using the power profile to determine what areas to work on

58:02 -

  • I'm a big fan of Skiba's model, often called the house model, which involves plotting physiological thresholds such as LT1 (or VT1), critical power, and power at VO2 max. While measuring VO2 max power can be somewhat questionable, the model still provides valuable insights. 
  • Skiba elaborated on this model in his recent book, clearly understanding an athlete's strengths and weaknesses. 
  • For instance, if LT1 is 95% of critical power, it won't improve until critical power increases beyond it. This approach helps determine training priorities based on the relationship between physiological thresholds. Of course, it's essential to consider the specific event an athlete is training for; improving overall fitness must align with improved race performance.

Limiter Benchmarks

1:00:21 -

  • The benchmarks are a bit unclear to me, but anything above 85% of LT1 to CP seems high. 
  • To increase it further, you might need to prioritize raising critical power first. 
  • However, suppose critical power is already high as a percentage of your five-minute power output. In that case, you may need to boost your aerobic capacity to elevate the lower end.
  • Considering historical training is crucial, too. If you've completed a substantial volume block but haven't seen much improvement in LT1 to CP, perhaps it's time to change the stimulus. 
  • Sometimes, focusing on another training component can indirectly affect LT1.
  • I often use a simple Excel sheet to visually represent this concept to athletes, showing it as a filled-in "house" graph. 
  • Then, we analyze it in the context of their training data over the past six or twelve months. 
  • If they've logged high volumes, we discuss realistic expectations for improvement and how it might translate to race performance.
  • Another thing to consider is the benchmark for critical power relative to five minutes or power at VO2 max. When determining how close critical power is to its limit without improving VO2 max, I focus on the ratio of critical power to W prime rather than just the five-minute power. 
  • This ratio helps gauge the potential benefit of increasing critical power for race performance.
  • For instance, if you're an Ironman triathlete with a W prime of 25 kilojoules, increasing it to 30 might not be beneficial since you're unlikely to use it in your race. 
  • However, such an increase could be highly advantageous for a punchy road cyclist, especially during uphill finishes.
  • I've analyzed data comparing three-minute and 12-minute power, particularly among triathletes, in my database. 
  • On average, 12-minute power tends to be around 80 to 81% of three-minute power for intermediate to advanced age group triathletes. However, this percentage can vary, ranging from 70 to 88%.
  • Typically, if you're around 80%, there's still room for improvement in your 12-minute power compared to three minutes. But as you approach 85% or higher, you're nearing the limit based on my collected data.
  • While some may compare three-minute to 12-minute power directly, I find the critical power ratio to W prime more insightful. It's an aspect I've personally focused on in my analysis.

Flatten the power curve

1:04:23 -

  • Rather than solely focusing on reducing sprint power, I suggest shifting your focus towards enhancing your aerobic capacity. While reducing sprint power may naturally occur with increased aerobic training, the primary goal should be to elevate your lactate threshold (LT1) and critical power (CP) levels.
  • Considering your already high sprint capacity, incorporating a significant training volume would be beneficial. Additionally, you might explore incorporating sweet spot training into your regimen. 
  • Given your ample room for improvement in aerobic capacity, sweet spot work could effectively target the development of both endurance and high-end aerobic capabilities.

Manipulate intensity for different types of athletes

1:06:03 -

  • Especially in road cycling, we're keen on preserving sprint capacity, even in endurance athletes. Regarding endurance work, particularly for sprinter-type athletes, we're cautious with intensity to minimize any negative impact on their sprint power. 
  • For climbers, it's amusing to see them sprint, as they often generate high power outputs. We can afford to push intensity a bit more with climbers since they're accustomed to heavy work during climbs.
  • Slow-twitch athletes respond well to increased volume. Conversely, fast-twitch dominant athletes may be more prone to overreaching. I've found that keeping endurance training easier for fast-twitch athletes helps prevent overreaching or overtraining.
  • Anecdotal evidence holds value in training prescription, complementing research findings. 
  • While research provides broad guidelines, applying them to individual athletes requires considering various factors and feedback. Incorporating anecdotal evidence and athlete feedback is essential for developing effective training strategies.

Take home messages

1:09:11 -

  • I believe there's been a significant focus on single-session durability in research. Still, day-to-day durability remains largely unexplored, particularly in road cycling, where multi-week races are expected. 
  • Investigating training methods and interventions to enhance day-to-day durability could be a fascinating avenue for future research. 
  • I hope someone else will pick up this topic for their PhD and delve deeper into understanding and improving day-to-day durability in cycling.

Mikael thoughts

1:11:00 -

  • First, the importance of training volume and durability hit home. There are simply no shortcuts when it comes to building endurance and resilience. 
  • While promising, fresh power numbers might impress at the start of a race, the consistent, hard work pays off in the long run, ensuring strong performance not just at the beginning but also at the end.
  • Secondly, discussing physiological markers and their relationship with durability was eye-opening. 
  • VO2 max, growth efficiency, and substrate utilization emerged as critical factors in explaining durability. 
  • This underscores the importance of training holistically, targeting different aspects of physiology to enhance durability.
  • Finally, the conversation on critical power and speed resonated strongly with me. Seeing these concepts underappreciated in mainstream media and training practices is disheartening. 
  • While VO2 max has long been hailed as a performance marker, critical power and speed offer a more comprehensive understanding of an athlete's capabilities, especially in endurance sports like triathlon.
  • I firmly believe that triathletes, in particular, would benefit immensely from shifting their focus to critical power and critical speed. 
  • Unlike cyclists, who may glean valuable data from racing efforts, triathletes rarely engage in maximal efforts during races. Therefore, formal testing and profiling using critical power become essential tools for understanding performance across different durations.
  • In essence, critical power or speed should be embraced as athletes' primary threshold marker and profiling tool. 
  • It offers a more nuanced and comprehensive assessment of an athlete's capabilities, paving the way for more effective training strategies and improved performance outcomes.


Bernardo Gonçalves

Bernardo is a Portuguese elite cyclist and co-founder of SpeedEdge Performance, a company focused on optimising cycling and triathlon performance. He writes the shownotes for That Triathlon Show, and also produces social media content for each new episode.

  • I was interested to hear you support the position that CP is a better indication of physiology especially for triathletes who essentially target steady efforts. I focus on mountain sportive, where the steady efforts are broken by regular descents. Do you believe the same would be true for such athletes?

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