Comparing two 10 km runs: pace, heart rate and recovery context
A worked example of comparing similar-distance runs while accounting for route, intensity, meal timing and missing wearable data.
The scenario: the second 10 km is slower
Two runs cover roughly the same distance, but the second has a slower pace. Start by checking whether both were intended as the same kind of session. An easy run and a hard effort answer different questions even when the distance matches.
Look at route, elevation, stops and conditions in your own records. Similar-distance matching is a useful starting point, not a guarantee that the sessions are equivalent.
Use heart rate only when it is available
Review average heart rate, intensity information and splits where the provider supplies them. Missing samples can limit comparisons. Do not reconstruct a detailed heart-rate profile from a single average.
Next, inspect the surrounding sleep, logged food and recent training. If nutrition is incomplete, keep that limitation visible rather than interpreting an apparent deficit as a measured cause.
Build a personal baseline
A first eligible run may become the baseline when there is no comparable history. That is different from being ranked against other runners or judged against an ideal performance.
As compatible sessions accumulate, look for recurring associations. A better run following better sleep is worth exploring, but one pair cannot separate sleep from pacing, weather or fitness changes. Use the comparison to choose what to record consistently next time.