Pace, race prediction, heart-rate zones and VO2 max.
Smart training is measured training. Pace, heart rate and aerobic capacity turn vague effort into numbers you can plan around. This guide explains the key running and fitness metrics and links to the calculator for each.
Pace — minutes per mile or kilometer — is the language of running. Once you know your pace at one distance, you can estimate it at another. The Race Time Predictor uses Riegel's formula to predict your 5K, 10K, half or marathon time from a recent race, and the Treadmill Pace Calculator converts a treadmill's speed into pace and a finish time. For race day, the Marathon Pace Calculator turns a goal time into the exact splits you need to hit.
Training by heart rate keeps easy days easy and hard days hard. Your maximum heart rate is roughly 220 minus your age, and the range between rest and max splits into five zones. Most training should sit in Zone 2 (easy aerobic) to build a base, with smaller doses of higher zones for fitness. The Heart Rate Zone Calculator maps your zones, and entering a resting heart rate switches it to the more personal Karvonen method.
VO2 max is the maximum oxygen your body can use — the best single number for aerobic fitness. The Cooper 12-minute run test estimates it from how far you run all-out in 12 minutes. The VO2 Max Calculator does the conversion and rates your level. Improving it takes consistent aerobic volume plus occasional hard intervals.
Running burns calories largely in proportion to your body weight and the distance covered — roughly 100 calories per mile for a 150-pound runner. The Running Calorie Calculator estimates your burn from weight, distance and effort. Remember that distance, not speed, drives most of the total.
Three ideas underpin almost every successful plan: build mileage gradually (the classic guidance is to avoid large weekly jumps), run most miles easy and a few hard, and recover deliberately. Metrics make these concrete — they tell you when easy is truly easy and whether your fitness is trending up. Use them to guide effort, not to turn every run into a test.
From a recent race using Riegel's formula — the race-time predictor does it for any distance.
Mostly Zone 2 (easy aerobic) to build a base, with smaller amounts of higher zones.
It varies by age and sex, but 45+ is generally good for adults.
Distance dominates; effort and incline add a bit.
Gradually — large weekly jumps raise injury risk.