Short High-Intensity Work vs. Long Moderate-Intensity Work: Which is Better for Running Economy?

Which has more of an effect on running economy: Running fast for a short period of time or running slow for a long period of time? This question has been an ongoing debate in the distance running community for nearly eight decades.

In the 1950’s, when the world’s best mile runners were trying to break the 4-minute mile, this question was hotly debated. Roger Bannister, who broke the 4-minute mile, was described as a minimalist with his training. He averaged only 28 miles per week and was comprised almost entirely of speed interval work.

His competitor, John Landy, on the other hand, would build an aerobic base of 300-miles of low intensity running before starting any specific speed work. He averaged 60 miles per week, which featured a mixture of speed work and easy runs.

After Roger Bannister broke the 4-minute mile in May of 1954, some considered the question answered. Shorter high intensity efforts were better than longer low intensity efforts. Then John Landy became the second man in history to break the 4-minute mile just 1 month later. Thus, the question remained open and countless studies conducted.

A fairly recent study entitled, The Performance and Aerobic Endurance Effects of High-Intensity Versus Moderate-Intensity Continuous Running, can help us understand the question and how to apply it to our training. In the study, the researchers created three groups amongst 20 recreational runners. Group 1 engaged in only high-intensity exercise. Group 2 engaged in only moderate-intensity exercise. Group 3 was the control group and continued their regular exercise regimen.

The researchers found an increase in running economy in both Groups 1 and 2, but the changes were slightly different. Group 1 had an increase in maximal oxygen consumption and velocity at lactate threshold, whereas group 2 had an increase below lactate threshold. In other words, group 1’s increase in running economy was relative to maximal aerobic output for speed, whereas Group 2 had enhanced fat oxidation for fuel efficiency.

So, how can we practically apply this information to our training. Here are two key takeaways:

1.      In the question of which is better at building running economy, the answer is both. Increased aerobic power will help us run strong up hills and make strong moves late in the race. Increased fat oxidation will help our body fuel our muscles efficiently for the demanding workload of an ultramarathon. Both are needed; Therefore, both should be implemented into training.

2.      Our bodies need time to absorb the training. Speed work, or high-intensity workouts, are demanding on the body and take longer from which to recover. Low-intensity work does not break us down the same as high-intensity work, so we are able to engage with low-intensity work more often than high-intensity.