Have you ever felt like you're giving your all in your running training, yet not making the progress you expect? You might be putting in countless hours, focusing on heart rate or mileage, and still not seeing significant improvement. What if there was a smarter way to train, a method that lets you measure and enhance your performance more effectively? Enter the concept of running power.
Power-based training is revolutionising how athletes train, and it isn't just for elite runners. It provides meaningful data that helps you - whether you're a beginner or experienced runner - improve your performance and efficiency. In this blog, you'll discover what running power is, how it works, and how you can use it to become a stronger, faster, and smarter runner. In addition, you will also learn how different power zones work, and how to apply them effectively to your training. We'll discuss key metrics that create a continuous feedback loop, helping you make improvements over time.
Power, in simple terms, is the rate at which work is done. In running, it's a measure of how quickly you're using energy to propel yourself forward.
\(P=\frac{W}{t}\)
The equation shows that power depends both on work and time. For instance if you run faster (less time) uphill, your power will be higher. The nominator of the equation (work) depends again on multiple parameters such as air resistance, inclination, and the athlete's weight. The absolute power of a heavier athlete for instance is higher for the same pace due to the additional weight to be lifted. so if you would like to compare athlete performance across weight categories, you can use the relative performance metric.
\(Prel=\frac{P}{weight}\)
One of the most popular device for measuring running power is the Stryd foot pod, although other tools are available. These devices capture data about your runs, including the power you are generating and the efficiency of your running. It tells you how effectively you're managing your effort, which can be particularly useful in races where pacing is critical. By monitoring power, you can stay within an optimal effort range, ensuring you don't burn out before the finish line which is particularly helpful for long-distance runs.
What is the power of top athletes?
Sprinting: In a 100-meter sprint, athletes like Usain Bolt can generate approximately 2,500 to 3,000 watts at the start due to explosive power. The average power output during the full sprint is lower as peak power declines after the initial burst.
Long-Distance Running: Marathoners produce less power compared to sprinters, with an average of around 300 to 400 watts, depending on speed, efficiency, and body weight. This corresponds to roughly 5-6 W per kilogram, maintaining a speed of over 20 km per hour. Beginners typically produce around 150-200 watts, or 2-3 W per kilogram.
Running economy also influences how much power is needed at a given speed. Efficient runners require less power because they waste less energy through vertical movement or ineffective foot strikes.
To incorporate power into your workouts, start by setting power targets for each training session, depending on your goals. For instance, during endurance runs, aim to maintain power output within a lower zone, where aerobic capacity is emphasised. On the other hand, if you're focusing on increasing speed and strength, integrate short intervals that push above Critical Power (CP), which relies on anaerobic capacity. Please note that we will discuss the concepts around different zones and critical power in the following chapters.
Aerobic Capacity Relates primarily to heart efficiency and muscle oxygen use. It relies on oxygen to produce energy, using fat and glycogen as primary fuel sources. Aerobic capacity dominates in sustained, long-duration activities like long-distance running. Training for aerobic capacity improves endurance and energy efficiency, enabling you to perform longer without fatigue.
Anaerobic Capacity: Relates to muscle strength, power, and biochemical efficiency. It does not require oxygen and instead relies on glycogen for rapid energy production. Anaerobic capacity is crucial for short bursts of high-intensity efforts, such as sprints or weightlifting. Training for anaerobic capacity enhances power, speed, and the ability to tolerate lactate buildup, allowing for stronger, faster performance over shorter durations.
Utilising power in your training gives you insights into how well your body is handling different energy systems, allowing you to optimise workouts for both endurance and peak performance.
While power itself is valuable, combining it with other metrics can provide an even clearer picture of your progress. Key metrics like Functional Threshold Power (FTP) and Critical Power (CP) are essential for setting benchmarks and measuring improvement.
Table: Comparison and use of FTP and CP
| Metric | Definition | Test Method | Usefulness |
|---|---|---|---|
| FTP | Maximum power sustainable for 1 hour | 20-minute test with 0.9..0.93 factor | Good estimate of anaerobic threshold |
| CP | Highest power that can be consistently sustained (critical threshold) | Several intervals of 3, 5, 7, 12, 20 minutes | Accurate boundary for aerobic vs. anaerobic load |
Critical Power Evaluation
The Critical Power (CP) Curve is derived by plotting the relationship between power output and time-to-exhaustion (TTE) for a range of all-out efforts at different durations. This curve provides insights into your aerobic and anaerobic energy systems. To obtain the power curve, perform several maximal efforts of varying durations (e.g. 3 minutes, 5 minutes, 12 minutes, 20 minutes) to exhaustion. For each effort, record the average power output.
Ensure Sufficient Recovery: Allow enough recovery between efforts to avoid fatigue affecting your results.
Plot the Data: Plot power output on the y-axis and duration (time-to-exhaustion) on the x-axis. The result is a hyperbolic curve.
Power-Time Model:
\(P(t) = CP + \frac{W'}{t} \qquad whereby \quad t >= 5s \)
Alternatively, the relationship can be linearised by transforming time or power:
\(f(t) = P \cdot t = W' + CP \cdot t \)
Determine CP and W' using regression filling in above values:
i.e. for a 3min, 5min and 20 min all-out effort:
\(180s \cdot 360 W/s = 64'800 W = CP \cdot 360 + W'\)
\(300s \cdot 350 W/s = 105'000 W = CP \cdot 350 + W' \)
\(1200s \cdot 345 W/s = 408'000 W = CP \cdot 345 + W' \)
Using linear regression, find the values of CP and W' that best fit the curve and then insert them in the power time model to draw the hyperbolic curve.
Note: From a conceptual standpoint, the CP model balances anaerobic and aerobic contributions:
Higher short-duration power implies a larger anaerobic capacity (W'), which means that CP - the steady aerobic threshold - becomes less prominent in defining your overall performance. The model assumes your total capacity is distributed between W' (anaerobic) and CP (aerobic), so increasing W' reallocates energy emphasis away from CP.
FTP: Functional Threshold Power Evaluation
Higher FTP usually indicates a well-developed aerobic system, essential for endurance events. It means the runner can work at higher intensities aerobically, with less reliance on the anaerobic system, which fatigues faster. To calculate your FTP, perform an all-out, maximum effort for one hour and record your average power.
As a shortcut to above approach, perform a 20-minute time trial at your maximum sustainable effort and apply the formula by Riedel to calculate the FTP:
The Riedel formula is an empirical formula used to estimate Functional Threshold Power (FTP) over different time durations. It assumes that the power-duration relationship follows a predictable curve based on the athlete's power over shorter efforts.
The formula is expressed as:
\( P_t = P_{t1} \cdot \left( \frac{t_1}{t} \right)^x\)
where:
Depending on the fatigue factor, the measured Power value for a 20 min run will be multiplied by a factor of 0.90 up to 0.93 to obtain the FTP.
\( FTP = P20min * 0.93 = 345 * 0.93 = 321W \)
Having calculated both FTP and CP. we can now apply them to evaluate the training zones for the different training types.
| Zone | Zone Definition (Extended) | FTP Percentage | Critical Power Percentage | Heart Rate Percentage |
|---|---|---|---|---|
| Zone 1 | Very easy effort used for active recovery sessions to promote blood flow and facilitate recovery. | < 55% | < 50% | 50-60% |
| Zone 2 | Long-duration, steady efforts that build aerobic capacity, increase fat utilisation, and improve endurance. | 55-75% | 50-85% | 60-70% |
| Zone 3 | Moderate intensity, just below threshold, which helps improve muscular endurance and lactate clearance. | 76-90% | 86-100% | 70-80% |
| Zone 4 | At or near FTP; helps increase lactate threshold and sustain high intensity over a longer period. | 91-105% | 101-120% | 80-90% |
| Zone 5 | High intensity efforts used to increase aerobic power and VO2 max. | 106-120% | > 120% | 90-100% |
| Zone 6 | Short, very intense intervals used to build anaerobic energy systems and muscular power. | 121-150% | - | - |
| Zone 7 | Maximum power output efforts, used to improve explosive strength and neuromuscular coordination. | > 150% | - | - |
Zones 1-4 emphasise aerobic development, with Zones 2 and 4 being particularly important for endurance. Zones 5-7 focus on anaerobic and power development, crucial for short, high-intensity efforts or finishing strong in races.
The idea behind using different training zones - whether it's power (FTP or CP) or heart rate (MHR) is to target different energy systems and physiological adaptations:
These zones help guide training plans to ensure balanced development. Most endurance athletes spend a significant amount of time in Zones 1-2, with targeted intervals in Zones 3-5 to maximise performance.
What do I gain with these calculations? Power-based training offers numerous benefits over traditional heart rate-based approaches by providing immediate and precise feedback on effort levels. Here's how it applies to different types of training:
| Training Type | Advantage |
|---|---|
| Aerobic Base Runs | Power provides a consistent measure of effort, unaffected by external variables like stress, temperature, or hydration. This ensures you stay within the intended lower intensity range to effectively build your aerobic base. |
| Tempo Runs & Intervals | Power responds instantly to changes in effort, unlike heart rate, which lags behind. This allows for precise targeting of the intensity zone needed to improve lactate threshold and muscular endurance. |
| Recovery Runs | Power ensures you stay in the true recovery zone, avoiding unintended overexertion caused by heart rate fluctuations from fatigue or dehydration. |
Here is a sample training plan for one week that includes power-based running sessions and strength training:
You can enhance your running efforts analysis by a set of additional metrics which help you monitoring your progress towards your goals:
Indicates how efficiently your body is working at a given exertion level. A lower heart rate for a given power output shows improved efficiency and endurance.
Helps evaluate your running economy. Better running economy means reaching higher speed with the same power output.
Long-term changes in power, speed, and heart rate can indicate whether your training is effective and your performance is improving.
An increase in heart rate at the same power and speed can be a sign of fatigue, dehydration, or overtraining.
Incorporating power-based training into your weekly plan can significantly enhance your running performance by providing more precise control over intensity and effort. Unlike heart rate-based training, power metrics give immediate feedback, allowing you to optimise your workouts regardless of external factors like temperature, stress, or fatigue. By understanding the different types of training sessions and using power-based metrics, you can ensure that each workout has a specific purpose, whether it's building endurance, increasing speed, or promoting recovery.
By following these steps and paying attention to your power metrics, you can make your training more efficient, reduce the risk of injury, and achieve your running goals more effectively.
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Author
Alberto Desiderio is deeply passionate about data analytics, particularly in the contexts of financial investment, sports, and geospatial data. He thrives on projects that blend these domains, uncovering insights that drive smarter financial decisions, optimise athletic performance, or reveal geographic trends.