Motor imagery priming reduces vertical ratio during exhaustive treadmill running
This study demonstrates that a brief motor imagery intervention acutely reduces the vertical ratio during exhaustive treadmill running, suggesting it can serve as an effective neural priming strategy to optimize running mechanics and efficiency.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Running is a rhythm of the body, a continuous cycle of pushing off the ground and landing again. For decades, scientists have known that the way a person moves while running—how high they bounce, how long their feet stay on the ground, and how far they travel with each step—directly affects how much energy they use. A runner who bounces too high wastes energy fighting gravity, while a runner who moves with a flatter, more efficient path can go further or faster with the same effort. While coaches often use physical drills or verbal cues to teach these adjustments, a newer idea suggests that the mind alone might be able to make these changes happen. This concept relies on motor imagery, a mental practice where an athlete vividly simulates a movement without actually moving their muscles. It is a strategy that engages the same brain networks used for real action, and researchers have long wondered if simply thinking about a movement could temporarily "prime" the body to perform it better.
A team of researchers at the University of Genoa set out to test whether this mental rehearsal could instantly change how people run when they are tired. They recruited twenty-six physically active university students, all of whom were familiar with running on a treadmill but were not elite competitive athletes. The study was designed to see if a brief session of mental imagery, performed just before a grueling run, could alter the runner's biomechanics compared to simply reading a text about running. The participants were split into two groups. One group engaged in a guided motor imagery session where they stood on a stationary treadmill with their eyes closed and mentally rehearsed running. They were asked to imagine the sensation of their feet hitting the ground, the forward push of their legs, and specifically to visualize running with a longer stride and less vertical bouncing. The other group, serving as a control, stood in the same position and read a short scientific summary about how running mechanics affect efficiency. Both groups spent roughly the same amount of time on the treadmill before the actual test began.
Immediately after these mental or reading tasks, every participant ran on the treadmill at a speed that was challenging but sustainable, a pace determined beforehand by a separate test that measured their breathing thresholds. They ran until they could no longer continue, a test known as time-to-exhaustion. During this run, the researchers used wearable sensors attached to the runners' shorts and wrists to track every detail of their movement. They measured how fast the runners were going, how many steps they took per minute, how long their feet stayed in contact with the belt, and how much their bodies moved up and down. The key metric the scientists focused on was the vertical ratio, a number that compares how much a runner bounces up and down against how far they move forward. A lower vertical ratio is generally considered a sign of more economical running, meaning the runner is wasting less energy on unnecessary up-and-down motion.
The results showed a clear difference between the two groups, but not in the way one might expect. The time it took for the runners to reach exhaustion was nearly identical for both groups, meaning the mental exercise did not make them last longer or shorter. Similarly, their speed, step length, and the time their feet spent on the ground did not change significantly. However, the group that performed the motor imagery showed a distinct change in their movement pattern. They ran with a significantly lower vertical ratio than the group that simply read the text. This means that the runners who had mentally rehearsed the technique actually bounced less relative to their forward speed. The researchers found that this improvement was consistent regardless of how fast the runners were going; the mental imagery seemed to shift their entire running style to be flatter and more efficient. The control group, despite reading about the importance of reducing vertical bounce, did not show this same shift in their actual movement.
The study suggests that the mind can act as a direct switch for the body's mechanics, even under the stress of exhaustion. The reduction in vertical bouncing observed in the imagery group indicates that the brain, having been primed by the mental simulation, organized the muscles to move more efficiently without the runner needing to consciously think about it during the run. This effect appears to be specific to the act of imagining the movement itself, rather than just knowing about it, since the group that read the information did not achieve the same result. While the study did not find that this mental trick extended the duration of the run, it did demonstrate that a short period of focused imagination could instantly refine the quality of the movement. The findings point to a potential new tool for athletes and coaches: using the power of the mind to fine-tune the body's mechanics right before a demanding physical effort, offering a way to optimize how we move through the world.
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