Study suggests runners should ‘lean into it’ — but not too much

As the Summer Olympics approach, some fans of the Games may be inspired to start running.

A new study by Daniel Aslan, PhD student in integrative and evolutionary biology at the USC Dornsife College of Letters, Arts and Sciences, and researchers at California State Polytechnic University, Humboldt sheds light on the optimal degree of forward lean for runners who want to save energy.

The study looked at recreational runners who ran with different levels of forward lean, from a nearly upright posture to a maximum lean of 8 degrees. Findings suggest that running with a slight forward lean of 2 to 4 degrees results in less energy demand compared to a maximum lean.

In fact, runners using a slight forward lean, similar to that typically preferred by most runners, were 8 percent more energy efficient.

The study was published May 29 online in PLOS ONE.

In the study, participants were asked to run on a treadmill at a speed of 8 miles per hour using three levels of forward postural lean (upright, maximum lean, and 50% of maximum lean) while researchers measured their oxygen consumption and carbon dioxide production to calculate the amount of energy being expended.

Overall, runners were 7% to 9% less energy efficient when running with their maximum forward lean than when running with a moderate lean or running upright.

“Surprisingly, our results show that running with a maximum lean increases the energy cost of running in a way that is similar to adding 1 kilogram (2.2 pounds) of weight to your lower legs,” said Justus Ortega, kinesiology professor at Cal Poly Humboldt and director of the Biomechanics Lab there.

The study also hints that the energy savings from moderate leaning could be linked to less demand on the hip muscles, particularly the gluteus maximus, which is more active when running with a large lean and likely requires more energy consumption.

“Improving running techniques that save energy is important when it comes to maximizing performance. But perhaps more importantly, people are more inclined to stick with physical activity that requires less energy. So, results like these may be important for both improving athletic performance and promoting consistent engagement in recreational running,” said study co-author Aslan, who is a member of the Evolutionary Biology of Physical Activity Lab headed by David Raichlen, professor of biological sciences and anthropology at USC Dornsife. Aslan worked on the study while a master’s degree student at Cal Poly Humboldt.