Why does a brief jog leave some people winded while others seem to glide along with ease?

Training, fitness level, and muscle strength clearly matter. But researchers are finding that the brain also has a powerful influence, especially in how hard physical effort feels.

Why effort feels different from person to person

Effort refers to the energy we use to perform activities like running, cycling, or lifting weights. While this energy use can be measured physically, the experience of effort is not purely mechanical. It is also shaped by perception, which can differ widely from one individual to another.

That perception plays a major role in whether people stick with exercise. When a workout feels overwhelming, people are more likely to stop or avoid it altogether. When the same activity feels manageable, it becomes more enjoyable and easier to continue over time.

This raises an intriguing question. 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 in the School of Kinesiology and Physical Activity Sciences at Université de Montréal, is investigating that idea alongside three researchers from Université Savoie Mont Blanc in France as part of an international research project.

Testing vibration during cycling

In a recent study, the research team examined whether vibrating specific tendons could lower the perceived effort of cycling. They used a wearable vibrating device designed to stimulate tendons before exercise.

Volunteers took part in laboratory tests on a stationary bicycle. Each participant completed two conditions: one session after tendon vibration and another 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. After that, participants cycled for three minutes at a pace they perceived as either moderate or intense, adjusting their effort to match the target level.

The outcome was striking. After tendon vibration, participants produced more power and showed higher heart rates compared with sessions without vibration. Even though their bodies were working harder, their sense of effort did not increase.

How vibration may alter brain signals

The researchers are now trying to understand how tendon vibration changes the brain's interpretation of effort. While the precise biological mechanisms are still being studied, Pageaux has proposed several possible explanations.

"Depending on the amplitude and frequency of the vibration, we can either excite or inhibit neurons in the spinal cord," he said. "Also, prolonged vibration changes the reactivity of the neuromuscular spindles and alters the signal sent to the brain."