The
Monod Critical Power
Model is a great way to estimate a cyclists functional threshold (1 hour) power output and the power he could
maintain for other periods of time using short power field tests but it says nothing about speed or pace unless used in conjunction
with a power-speed model. The objective of this Triathlon Bike Pace model is to put the two together and provide estimates of a riders
speed and finishing time applicable to standard distance triathlon events, again using only short field tests or previously achieve even
pace as performance estimators.
In fact, since relatively less triathletes than cyclists are presently using power meters, we have designed the estimators for this
model to be specified in terms of average speeds instead of power outputs. We have to assume these average speeds were achieved on a
flat course on a windless day (a key consideration when collecting input data) and then compute the equivalent power corresponding with
the weight and aerodynamic drag estimations also required.
Based on these “power inputs” we then estimate performance at a range of important durations and event distances, using either the
Monod Model or, as an alternative, the Fatigue Curve Model of Riegel.
The Critical Power Curve (Monod)
You can see estimated power for ride durations of 1,3,5,10,15,30,45 & 60 minutes. We have also solved for the power output that,
consistent with the curve, would be maintainable for the standard distance triathlon events. Instead of power outputs for all of the above you can alternatively
select to view the corresponding average speed (given the assumptions, weight and aerodynamic drag inputs mentioned above) or the projected finish time for the specific events.
The Fatigue Curve (Riegel)
The Fatigue Curve Model of
Riegel
has much in common with the Critical Power Curve in that it is designed to model the time dependency of an athlete’s fatigue or endurance, opposite sides of the same coin.
Riegel’s model however is not dependent on power, it is a simple “log-log” relationship between pace and distance which has been shown to fit the decay in an athlete’s pace
extraordinarily well.
As with the Monod option you can select to view estimated power outputs and average speeds for all durations and events, as well as
estimated finishing times for the specific events.
We would suggest that the Fatigue Curve model may be more suitable than the Monod model for estimation of performance and pace at
event durations exceeding 1 hour when anaerobic capacity is less relevant (there is evidence to suggest that it works very well in
the 1-4 hour window) and for this reason we are increasingly used it in endurance Event Modelling.
Sub-FTP Pacing in Multi-Sport
The nature of multi-sport events dictates that athletes invariably choose not to perform at their maximum pace as may be predicted by a model
which considers only the single disciplines in isolation, especially in the longer events. We are aware of some consensus that
triathletes, depending on ability and training status, tend to ride at “85-95% FTP in the HIM bike leg and “75-85%” FTP for the IM
bike leg. For this reason we also provide power, pace and time estimates for these events at these percentages of FTP, an estimate
which you can elect to base on ether the CP or FC model.
Training Zones
A natural extension of all of the above is to quote the training zones implied by the FTP estimates either from one of the above models.
We calculate a popular schema of power training zones then convert them to pace zones given the same assumptions mentioned above.
Inputs – Physical Parameters
- Height (cm). Input rider height in cm. This value is used to estimate the swimmers body surface area (BSA) relevant to swim power calculation.
- Weight (kg). Input rider weight in kg. This value is used to estimate the swimmers body surface area (BSA) relevant to swim power calculation.
Inputs – Test Performances
Input times for 2 or 3 recent performances at available distances.
Outputs – Model Prediction
- VDOT. Predicted pace or event time using the VDOT Model.
- FC. Predicted pace or event time using the Fatigue Curve Model.
- CP. Predicted pace or event time using the Run Power & Critical Power Model
Outputs – @ % FT (1 hour pace) Using Model
Sub-FTP pace or event times for longer triathlon events. Specify the model you would prefer to use as the source of the FTP.