There’s a steep hill near my house that accounts for a portion of my usual running loop. It’s also a part of our local marathon, and a spot you see many runners doing trips up and down for their intense training days. Hills are always one of the hardest segments of a running route, but some studies have questioned their usefulness as a training tool. To expand our understanding, researchers recently compared incline running to level-grade running in a study published in the Journal of Strength and Conditioning Research.


The researchers focused on three major measures of running performance. The first was VO2 max, which is the body’s maximum ability to utilize oxygen. VO2 max is an important factor in aerobic exercise, since more oxygen means more energy.


The second variable the researchers considered was blood lactate level. Blood lactate level is a measurement of the byproduct of anaerobic metabolism. For endurance performance, depending too much on the anaerobic systems will result in fatigue. A related score is the lactate threshold, also called the anaerobic threshold, which is the point at which your muscles produce more lactate than your body can remove. It’s also the point at which your ability to maintain a pace takes a steep nosedive.


Breaking Muscle Shop

The final focus of this study was running economy, which measures how much oxygen is required at a given running speed. Some people believe running economy is one of the most important variables to examine when looking at changes to running performance caused by training. Much like a campfire, the body needs oxygen for its aerobic energy processes. When oxygen consumption in the body is high, it’s because our energy expenditure is elevated as well. Although increasing VO2max is important, since it represents the greatest degree the body can consume oxygen, having better running economy by reducing the oxygen required at race pace is probably even more critical.


Separate tests of strength and power were also taken for good measure. All of these variables were studied on a group of 32 experienced runners over six weeks of training. The study participants were broken into three groups. The runners in the control group kept doing the training they had been doing prior to the study. Another group ran at an incline on a treadmill for both intervals and steady state. The rest of the runners ran on a flat treadmill surface for the same relative intensities as the hill group.


The researchers discovered that incline running did indeed improve performance, but it did so at about the same rate as the level-grade running. So when it comes to hills versus flat running for performance, there doesn’t seem to be a major difference over six weeks. Interestingly, the control group improved too, although not as much in running economy. This is probably because none of the participants had been doing intervals prior to this test. These results suggest it was the intervals, not the incline level, that made a difference in the two test groups.


It’s important to note the intensities were the same between the two treadmill test groups. What this means is that if you aren’t doing hills or intervals now, the extra intensity could be beneficial to your training if added in for a few runs a week. The researchers noted that none of the protocols replace weight training as a running aid, so stay in the gym as well.



1. Derek D. Ferley, et. al., “The Effects of Incline and Level-Grade High-Intensity Interval Treadmill Training on Running Economy and Muscle Power in Well-Trained Distance Runners,Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000274


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