Calculatrice d'Allure de Course

Pace and speed describe the same thing inverted: pace is time per unit distance, speed is distance per unit time. Runners think in pace because it is what a watch shows and what a race plan is written in, and because the arithmetic of converting a target finish time into a pace is the single most common calculation in the sport.

La formule

Pace = total time / distance
Speed = distance / total time
Finish time = pace x distance
Equivalent pace across distances (Riegel): T2 = T1 x (D2 / D1) ^ 1.06

• Pace is conventionally minutes and seconds per kilometre or per mile
• The Riegel exponent of 1.06 reflects the empirical observation that pace slows as distance doubles

Riegel PS, endurance time prediction model. The 1.06 exponent was fitted to race results across distances and is the most widely used equivalence formula.

Race pace targets

The table gives the pace required to hit common finish times. It is the most direct use of the calculator: choose a target, read the pace, and check whether that pace is one you can currently sustain for the distance.

• Race distances are measured along the shortest legal route. Most runners cover slightly more than the official distance, so a watch commonly reads long and the pace it displays is slightly faster than the pace that counts.
• A marathon at the same pace as a half is a much harder effort, which is why equivalence formulas exist.

Predicting across distances

The Riegel formula converts a known race time at one distance into a predicted time at another, using an exponent slightly above 1 to capture the fact that pace degrades as distance grows. It is reasonably good between adjacent distances, for example 10K to half marathon, and progressively less reliable as the gap widens.

The marathon is where it breaks down most. Predicting a marathon from a 5K assumes the runner has the endurance base the formula implicitly expects, and for anyone whose training volume is modest the prediction is optimistic, often substantially. A prediction from a recent half marathon is far more dependable than one from a short race.

• Use the longest recent race you have as the input. Predictions upward from short distances flatter runners with speed but limited endurance.
• Common practice is to add a small margin to a Riegel marathon prediction rather than treating it as a target.

Why most training runs should be slower than race pace

A consistent finding across endurance training research is that the majority of training volume in successful distance runners is performed at low intensity, well below race pace, with a smaller proportion at high intensity. The frequently cited distribution is roughly 80 percent easy and 20 percent hard, and the most common error among recreational runners is compressing everything into a moderate middle that is too hard to recover from and too easy to drive adaptation.

Practically, this means the pace calculated for a race is not the pace for most running. Easy runs should feel conversational, which for most people is a minute or more per kilometre slower than half marathon pace.

Limites

• Equivalence formulas assume adequate endurance training for the target distance. Predicting a marathon from a short race overestimates for runners with low weekly volume.
• Predictions do not account for course profile, altitude, heat, humidity or wind, each of which can change finish time substantially.
• GPS watches accumulate distance error, typically reading long, so displayed pace tends to be slightly optimistic relative to official race distance.
• The formula describes a fresh, rested race effort. It does not predict performance in a training run or on tired legs.
• Individual variation is large. Two runners with identical 10K times can differ considerably over a marathon depending on training history.
• This is a training and pacing tool, not medical advice. Chest pain, unusual breathlessness or dizziness during exercise needs medical assessment.

Questions fréquentes

How do I calculate my running pace?

Divide total time by distance. A 25 minute 5K is 25 divided by 5, giving 5:00 per kilometre, or 8:03 per mile. Speed is the inverse, distance divided by time.

How do I predict my marathon time from a half?

The Riegel formula multiplies the known time by the distance ratio raised to the power 1.06. Predictions from a recent half marathon are reasonably reliable; predictions from a 5K are usually optimistic unless training volume is high.

Why does my watch distance differ from the race distance?

Races are measured along the shortest legal route, while GPS accumulates error and records the path you actually ran, including weaving and corners taken wide. Watches typically read long, which makes displayed pace look slightly faster than the pace that counts.

What pace should my easy runs be?

Conversational, which for most runners is at least a minute per kilometre slower than half marathon pace. The most common training error is running easy days too hard, which compromises both recovery and the quality of hard sessions.

Is pace per km or per mile better?

Neither, they are the same information. Use whichever matches your race distances and your watch. One kilometre is 0.621 miles, so mile pace is roughly 1.61 times kilometre pace.

Références

1. US Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition.
2. MedlinePlus. Exercise and physical fitness.
3. Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology, 2001.
4. MedlinePlus. Sports injuries.