Training for endurance needs more than a good FTP
In this blog I'll highlight the need to build resistance to fatigue into your training strategy, and how this fits in with the prevalent desire to focus on building FTP as the primary performance metric.
Fatigue resistance, is a crucial aspect of endurance cycling performance, enabling us to maintain a desired or required level of performance for the period of the ride. This is important for endurance events, such as Sportives, Gran Fondos and multi-day tours as they generally expect participants to have the appropriate level of performance required to complete the ride within a set time limit. It is also important for our social rides to keep up with the group, so we need to be able to maintain the set pace.
To illustrate that, the post’s title image shows how a cyclist’s sustainable power reduces over duration of a ride. You can see the point at 20 minutes where the cyclist can maintain 352 watts (FTP of 314 watts), and how this reduces by 10% if it is undertaken after expending 1,000kJoules of energy, We can also see the decline for longer rides, and armed with this holistic view of our power and the impact of fatigue, allows us to direct our training efforts towards our goals more accurately.
However, with the advent of indoor training Apps and online fitness platforms, we can be easily seduced to train ourselves using workouts that do little to build this resistance to fatigue.
A prime example is FTP (Functional Threshold Power). This metric measures our maximum sustainable power output for a one-hour effort (usually tested using average power over a 20 minute period x 0.95). It has gained so much popularity as it hits our short term gratification needs perfectly; it can be improved relatively quickly, and who doesn’t like that feeling when you hit a new FTP Threshold ?
As a result, FTP is seen in many circles as the primary metric for performance, with the resultant abundance of “FTP builder” programmes on your favourite indoor ride App. However this over-emphasis on FTP can be misleading and can hamper our ability to perform in endurance rides.
Taking a step back, the prime reason we should be measuring FTP is that not only does it can give us a performance benchmark, but perhaps more importantly helps us identify our lactate threshold, the tipping point towards exhaustion, and hence is essential in the setting of our training schedules to maximise strengths and minimise performance limiters.
So while FTP is an extremely important metric, it doesn't necessarily indicate our ability to maintain performance over a longer ride; at or below FTP levels, fatigue significantly impacts performance. For example the typical social cyclist is able to ride slightly above FTP for about 40 minutes, called Time To Exhaustion, after which, the tank will be empty; we’ve probably all been there.
This can be illustrated with a few examples as follows:
In this example the cyclist is capable of a mean maximum power of 203 watts for 20 minutes, which would drop by 38% to 127 watts if measured after expending 1,000 kJoules of energy. After 3 hours there is a steep decline in sustainable power and in this instance the cyclist would only be able to maintain 25watts, a drop of 77%. We would consider this cyclist to be requiring training rides that build their resistance to fatigue as a priority, ie long low intensity endurance rides.
In the second example, the cyclist has a similar mean maximum power for 20 minutes, though in this case the reduction is about 12% to 178 watts. You can see that this athlete does long endurance rides, and experiences a decline of 35% in mean maximum power power at 8 hours. In this instance the priorities could be shifted more towards moving the overall power curve up, though if depends if this cyclist was training for an event such as the Mallorca 312, in which case we’d tip the balance towards building endurance.
Without building long, low intensity workout (ie high zone 2 endurance) into our schedule, we will not obtain the physiological adaptions required to maintain our performance on longer rides, ie resistance to fatigue.
Whether you are new to cycling as a sport/leisure activity or are a seasoned cyclist, and are training for a specific event or challenge, the first priority (see caveat) must be to build base aerobic fitness (ie move the power distribution curve to the right).
How do we know when we’ve done enough ? Metrics we use to measure fatigue resistance include Efficiency Factor, measuring what you get out (normalised power) versus the effort (heart rate), the degrees of aerobic decoupling, ie how your power/pace changes over time in relation to your heart rate, and the percentage of power reduction over time in relation to energy expenditure (KJoules). Note that this does not mean that we do not need to include lactate threshold and aerobic capacity workouts, but these have a lower priority.
Once you have the base aerobic fitness and resistance to fatigue established (a coach can help identify the correct inflection point), only it is then appropriate to shift the emphasis to other limiters such as threshold (FTP) and aerobic capacity, effectively moving the entire power distribution curve upwards.
Following this strategy will help you obtain and maintain higher performance for longer periods, ie power and fatigue resistance.
In conclusion, building resistance to fatigue is essential in endurance sports. It enables the maintaining a consistent performance for a given effort throughout the chosen event or challenge. While FTP is a useful metric but does not necessarily reflect our ability to perform over a prolonged period.
caveat - reverse periodisation may be appropriate in certain circumstances.