Are You Running Too Slow on Long Runs?

# Are You Running Too Slow on Long Runs?

The conventional wisdom in distance running holds firm: long runs happen at an easy, conversational pace. But emerging evidence suggests many runners misinterpret what "easy" actually means, training slower than necessary and potentially leaving fitness gains on the table.

The confusion stems from terminology. "Easy" in running science doesn't mean barely moving. It means staying in Zone 2, typically 60 to 70 percent of your maximum heart rate, where your body burns fat efficiently and builds aerobic capacity without triggering excessive fatigue. A Runner's World analysis of training data from thousands of distance runners found many perform long runs at paces 30 to 45 seconds per mile slower than their prescribed easy-run zone. This excessive slowness doesn't enhance recovery or adaptation. It simply wastes training time.

Research from the University of Colorado and Koç University shows that long runs produce their greatest aerobic benefit when conducted near the top of the easy zone, around 70 percent of VO2 max. Below that threshold, the adaptations slow considerably. Your mitochondrial density improves less. Capillary development lags. Fat oxidation capacity, the actual goal of long, slow runs, doesn't improve as much.

The practical problem is that runners often confuse "should feel easy" with "should feel very easy." Many aim for a pace where they could carry on a full conversation without any breathing effort. The actual target allows conversation, but with slightly elevated breathing. You can speak in sentences, but not paragraphs.

Elite distance coaches like Renato Canova and Alberto Salazar have long built this into their training structures. Their athletes run long runs at 75 to 80 percent of their lactate threshold pace. For a runner with a lactate threshold of 7 minutes per mile, that means long runs at roughly 8:45 to 9:15 per mile, not 10 or 11 minutes per mile as some recreational runners assume.

The distinction matters across training cycles. During base-building phases, staying at 60 to 65 percent of max heart rate makes sense to build durability without injury risk. But once you've established aerobic fitness, pushing toward 70 percent during long runs produces better results. A 2019 study in the Journal of Sports Sciences tracking marathon finishers found those whose long runs stayed between 68 and 72 percent of max heart rate showed the largest improvements in race pace and VO2 max, compared to those running significantly slower.

Technology helps here. Heart rate monitors and pace-based calculations from training apps now allow precise zone targeting. Know your lactate threshold pace first (via a treadmill test or by running a hard 30-minute effort), then calculate your zones mathematically. This removes guesswork.

The runner who questions whether their easy runs truly feel easy, and who occasionally pushes toward the upper boundary of Zone 2, typically improves faster than the runner who equates easy with glacially slow. You still recover between harder sessions. You still avoid overtraining. But you extract the actual aerobic adaptations your long runs are supposed to provide.