A simple client-side running calculator that estimates training paces and predicts race times based on a recent race result. There is a track calculator for working out splits on a 400m track as well.
The calculator is written in javascript so no server required.
These calculations provide a good ballpark but do not factor in variables such as training volume, experience, age, D' or multiple distance race results so will have limited accuracy, particularly in the longer distances >30km.
Race times are predicted using the formula by Peter Riegel:
T2 = T1 x (D2/D1)^1.06
Where:
- T1 is the time achieved for D1.
- T2 is the time predicted for D2.
- D1 is the distance over which the initial time is achieved.
- D2 is the distance for which the time is to be predicted.
Training Paces are estimated using percentages of Critical Speed as determined by Dr Philip Skiba in his book, Scientific Training For Endurance Athletes (2022).
Critical Speed (and D') cannot be determined from a single race result and should be calculated mathematically from test data using the model proposed by Skiba in the above literature. This calculator estimates a CS range by predicting 30 to 40 minute race pace by rearranging Peter Riegel's formula:
pace = T2/D2 = T2/(D1 x (T2/T1)^0.943)
A good technical description of the power-duration asymptote (Critical Power, CP), work above CP (W'), the equivalent speed-duration asymptote (Critical Speed, CS) and distance above CS (D') and why they are useful can be found in the 2017 paper Critical Power: An Important Fatigue Threshold in Exercise Physiology by Prof Andy Jones et al.