Many runners end up organizing their training around one very practical question: is it better to follow heart rate or pace? It matters more than it may seem. An easy run that feels smooth at 5:10/km on a cool flat morning can feel very different in heat, wind, hills, or accumulated fatigue. At the same time, training by heart rate alone also has limits, especially when the effort changes quickly.
In that context, a study published online on March 24, 2026 by researchers from Rey Juan Carlos University in Madrid compared both methods in recreational distance runners and landed on an interesting conclusion: in the sessions analyzed, heart rate-based prescription kept runners inside their intended intensity zone for more of the workout than race pace-based prescription.
That sounds powerful, but it is worth reading carefully. It does not mean pace is suddenly useless, and it does not mean every runner should rebuild their training tomorrow. What it does offer is a useful clue about when the heart may be a more faithful guide than the watch, and when pace still makes plenty of sense.
What the study actually compared
The study looked at 37 recreational runners with an average age of 38.9 years. They first completed an incremental treadmill test to determine VO2max, ventilatory turn points, and maximal heart rate. They then ran a 5K track race to establish their reference pace.
Using those data, the researchers built two ways to prescribe intensity:
- One based on heart rate, using heart rate ranges linked to ventilatory turn points.
- One based on race pace, using percentages of average 5K pace.
Each participant then completed two individualized session types:
- A 45-minute low-intensity continuous run.
- A 5 x 800-meter high-intensity interval session with 90 seconds of recovery.
The key variable was what the paper calls training execution accuracy, meaning how much time each runner actually spent inside the prescribed intensity zone.
What it really found
In the easy run, the heart rate-based method produced better execution accuracy. On average, runners spent 85% of the session inside the prescribed zone when following heart rate, compared with 69% when following pace.
In the 5 x 800 session, the difference again favored heart rate, but with an important caveat. Execution accuracy was 41% with heart rate-based prescription and 27% with pace-based prescription. In other words, heart rate came out ahead again, but even then both methods showed a fair amount of difficulty keeping runners inside the intended zone during hard efforts.
That detail matters. The study does not say heart rate solves every intensity-control problem. It says something more specific and more useful: under these conditions, it helped runners spend more time near the intended intensity, but the margin of error remained meaningful, especially in harder work.
Why that may happen
What follows is a reasonable interpretation of the study, not a literal statement from the abstract. Pace-based prescription has an obvious advantage: it is easy to understand and maps cleanly onto race goals. The problem is that external pace changes a lot with context. Running 4:50/km on a cool flat day does not cost the same as running 4:50/km in heat, wind, hills, or deep fatigue.
Heart rate, by contrast, tracks the body’s internal response to that context more closely. If the day is harder, heart rate rises even when pace stays the same. That makes it easy to understand why, in an easy run where the true goal is usually controlling effort rather than locking in one exact speed, heart rate can act as a more effective brake.
High-intensity intervals are trickier. Heart rate has a lag when effort rises quickly, so it can also arrive late to the party. The fact that both methods showed fairly low execution accuracy in the 5 x 800 session fits that practical reality quite well.
What this means for recreational runners
The most useful reading is not to pick one side and dismiss the other. It is to understand which tool fits which type of session best.
- For easy runs, controlled long runs, and days with fatigue or heat, heart rate can help keep you from drifting too hard even when pace looks tempting.
- For workouts strongly tied to race goals, such as 5K, 10K, or half marathon pacing, pace still matters because it speaks the real language of racing.
- For demanding interval sessions, a combined approach probably works best: pace, heart rate, and perceived effort together rather than one number expected to do everything.
Put simply, if your habitual mistake is running easy days too fast, this study gives fairly solid support to using heart rate as your main guardrail. If your problem is sharpening race-specific rhythm, pace does not disappear. It just should not be treated as equally reliable in every context.
When pace is more likely to mislead you
There are several situations in which pace-based prescription is likely to lose precision for recreational runners:
- Early heat adaptation, when the same pace carries a higher physiological cost.
- Routes with climbs, descents, or frequent turns, where speed is less stable.
- Days with accumulated fatigue, poor sleep, or incomplete recovery.
- Runners using outdated pace references from a 5K result that no longer reflects current fitness.
In all of those cases, looking only at pace can push you to force the workout more than intended. Heart rate is not perfect either, because it is also affected by temperature, stress, and hydration status, but it does a better job reminding you of the internal cost of the effort.
What the study does not prove
This is the point where it helps to dial back the excitement a bit. The study compared execution accuracy in two sessions, not the results of a full training block lasting weeks or months. By itself, it does not prove that heart rate-based training will improve long-term performance more than pace-based training. It also does not prove that heart rate should always be the default method for every level, distance, or runner profile.
It also looked at a specific group of recreational runners using carefully individualized zones derived from physiological testing. In real life, many runners train with generic formula-based zones or wrist sensors that are not always perfectly accurate. That limits how directly the result can be applied without nuance.
A sensible way to use this information
If you want to apply the idea without overcomplicating things, a practical approach could look like this:
- Use heart rate as the main guardrail in easy runs and controlled long runs where the goal is to accumulate work without drifting too hard.
- Use pace as the main reference when you are rehearsing race-specific rhythm.
- Update your reference zones and paces regularly, because old data can distort either method.
- Do not ignore feel: if the metric says one thing and your body says something very different, the context needs a second look.
For many recreational runners, the best answer is not choosing one metric and marrying it forever. It is learning what question each metric answers. Pace tells you how fast you are moving on the outside. Heart rate gets you closer to how much that pace is costing you on the inside.
Conclusion
The 2026 Spanish study offers a fairly clear message: when the goal is to stay inside a planned intensity zone, heart rate appeared more precise than race pace in these recreational runners, both in an easy run and in intervals. But it also left another lesson that matters just as much: at high intensity, good zone control remains difficult no matter which metric you use.
For everyday runners, the practical takeaway is not to abandon pace but to use it with more context. On easy days, heart rate may protect you better from going too hard. On specific days, pace remains very useful. And when both metrics are understood together, training usually comes out better than when one of them is treated like a complete answer on its own.