06/07/2022
Use of Speed and Power Data to Assess Endurance and Durability Among Runners
By Tomer Geminder, EnduCloud
One of the keys for enhancing running performance is a gradual progression in loads along the time axis. The progress in loads is due to progress in training duration, intensity, or a combination of both. The athlete progression and the emphases are individually tailored to the athlete, his/her constraints, his/her intensity-duration curve, the event to which they are training for and the available time.
The intensity-duration curve provides a comprehensive snapshot of the athlete's abilities including the speed or power they can sustain for the various durations, the time to exhaustion with prolonged efforts, and more. Not only does this two-dimensional snapshot provides us with a much more complete picture of the athlete compared to individual thresholds like power or speed at lactate threshold or time to exhaustion, but it also enables us to track the athlete's progress, focus the training on the weaknesses, and predict performance. Furthermore, the duration-intensity curve provides insights into the athlete's aerobic and anaerobic profiles, which are at the basis of his performance.
Some interesting points that can be calculated from the duration-intensity curve include:
- The athlete’s lactate/anaerobic threshold/second respiratory threshold – the threshold that separates heavy intensity from severe intensity domain.
- Critical power/speed – The power / speed that can be held for a long period of time
- "Anaerobic Capacity" (W '/D') – The ability of the athlete to exert effort above critical power/speed. This ability "empties" during intense efforts, and slowly "recharge" with pauses between them.
- Durability (TTE - Time to Exhaustion) – the rate of decay in the athlete’s ability during prolonged efforts
- Stamina – The time current sped or power can be sustained. This value is determined by the combined athlete's aerobic and anaerobic abilities in efforts above the lactate threshold, and by the combined aerobic ability and durability to efforts below the lactate threshold.
- Aerobic threshold/first respiratory threshold – As of now there is no exact tool other than laboratory tests, to calculate this value, so we use only a rough estimate and/or subjective metrics
The duration-intensity curve can be found from a series of dedicated tests of different durations which are usually held over about a week, or be estimated using the athlete's training data. We recommend using initial values derived from tests, and later update the figures using data attained during training, while giving extra weight to tests for different distances which are carried out throughout the season.
A simple example of the benefits of using the intensity-duration curve over discrete thresholds is the ability to obtain better estimations for the anaerobic threshold or the athlete's functional threshold power (FTP). In contrast to the current tools that base the FTP assessment on the assumption that this value is close to the intensity that can be maintained for an hour, or approximate it by shorter tests, in practice we see that these values are obtained in different athletes over a wide range of durations from 30 minutes and up to 70 minutes or more, with correlation to the athlete fitness, which regularly leads to overestimation of the FTP of amateur athletes. The result is that many amateur athletes, mostly riders, perform hard training at disproportionate power to their actual abilities.
Another example is the ability to accurately predict race times in long competitions lasting two hours or more, including the marathon, and the ability to predict the impact of external factors such as heat load, inclines, fatigue, fitness, etc. Furthermore, monitoring the athlete's durability makes it possible to assess the level of readiness for very long events, and accordingly update the training mix in order to utilize the available training time for the competition in the most effective way.
In conclusion, the use of the duration-intensity curve instead of discrete thresholds provides us with new tools for understanding the athlete's abilities and the physiology at their core, adapting the training to the individual athlete, and predict their abilities at different distances enabling better competition planning.
