Why does a short jog leave some people breathless while others seem to move effortlessly?
Training, fitness level, and muscle strength clearly play a role. But researchers are increasingly finding that the brain also plays a powerful role—especially in how hard physical effort feels.
Why Effort Feels Different From Person to Person
Effort is the energy we use to perform activities such as running, cycling, or lifting weights. While that energy use can be measured in the body, the sensation of effort is not purely mechanical. It is also shaped by perception, and that perception can vary widely between individuals.
This matters because perceived effort strongly affects whether people keep exercising. When a workout feels overwhelming, people are more likely to stop early or avoid activity altogether. When the same workout feels manageable, it becomes easier to repeat and maintain over time.
That leads to an intriguing possibility: what if the feeling of effort itself could be reduced, helping people push past the sense that exercise is simply too hard?
Benjamin Pageaux, a professor at the School of Kinesiology and Physical Activity Sciences at the Université de Montréal, is exploring that idea with colleagues from Université Savoie Mont Blanc in France as part of an international research project.
Testing Tendon Vibration During Cycling
In a recent study, the team investigated whether vibrating specific tendons could reduce how hard cycling feels. They used a wearable vibrating device designed to stimulate tendons before exercise.
Volunteers completed laboratory sessions on a stationary bike under two conditions: one after tendon vibration and one without any vibration beforehand.
For the vibration condition, the device was strapped to the Achilles and knee tendons and activated for 10 minutes before cycling began. Participants then cycled for three minutes at a pace they rated as either moderate or intense, adjusting their output to match the target level.
The results were striking. After tendon vibration, participants generated more power and had higher heart rates than they did without vibration. Even though their bodies were working harder, their perceived effort did not increase.
How Vibration May Change Brain Signals
The researchers are now working to understand how tendon vibration alters the brain’s interpretation of effort. While the exact biological mechanisms are still being studied, Pageaux has suggested several possible explanations.
Depending on the vibration’s amplitude and frequency, stimulation may either excite or inhibit neurons in the spinal cord. Prolonged vibration may also change how neuromuscular spindles respond, altering the signals sent from the muscles to the brain.
By changing the information traveling from the body to the brain, vibration may reshape how exertion is perceived. In other words, exercise can feel easier even while the muscles are producing more force.
Could This Help People Stay Active?
Although the findings are promising, the research is still at an early stage. So far, the tests have focused on short cycling bouts under controlled conditions.
Pageaux noted that it has not been tested in endurance events like a marathon—only in a brief, three-minute cycling effort. Still, the study provides early evidence that this approach can work in this type of exercise.
Next, the team plans to study brain activity during exertion more directly, using tools such as electroencephalography and magnetic resonance imaging to see how tendon vibration affects neural activity while people exercise.
The researchers are also examining the opposite process: how pain and fatigue can amplify the sensation of effort and make physical activity feel harder than it otherwise would.
Ultimately, the goal is to develop strategies to lower perceived effort and help more people become physically active, especially those who are currently sedentary.
