Built-in exercise monitor predicts fitness

Dec 20 2007

We all hold the secret to getting fit, according to researchers from the University of Exeter. The research team has shown that we each have a built-in ability to judge how hard our bodies are working, often with remarkable precision.

A series of studies over the last two years, culminating in three academic papers in the past two months, has shown a consistently close correlation between actual and perceived exertion in people of all levels of fitness. The team has found that an individual's own sense of how hard he or she is working corresponds exactly with actual level of exertion, measured by heart-rate and oxygen uptake.

The experiments involved people being asked to exercise at various levels of intensity on a scale of six to 20, with six being completely inactive and 20 being on the verge of exhaustion. The amount of exertion was determined purely by the individual, who made a judgement on how hard to work based on his or her interpretation of the scale. The researchers simultaneously monitored the person's heart-rate and oxygen uptake, which are the most widely-used measures of physical exertion. In almost all cases the results matched exactly the levels that would be predicted for each specific number on the six to 20 scale. This demonstrates our ability to judge precisely how hard our bodies are working.

Professor Roger Eston, Head of the University of Exeter's School of Sport and Health Sciences says: “We have worked with over 300 individuals in the last two years and now have a body of evidence to show that we each have a highly accurate built-in exercise monitor. We have found that people's sense of how hard they are working matches what fitness testing equipment tells us, in some cases to the heartbeat.”

The research could lead to a more personalised approach to exercise, with personal trainers and gym instructors putting the onus on their clients to judge their own appropriate level of exercise intensity. Professor Eston continued: “I would recommend exercising between 12 and 15 on the scale to achieve fitness benefits without over-straining. As an individual becomes fitter, he or she will be able to run, swim or cycle faster without increasing his or her perception of exertion, so what feels like a 15 will change.”

This approach could help keen gym-users to hone their fitness and make their exercise regimes more effective, but the research team believes the main benefit could be on those who are new to exercise. Professor Eston explains: “People are often nervous of going to gyms for the first time because they think they will be unable to perform the exercises that their instructor asks them to do. Taking this new approach, a gym instructor would ask a customer to exercise at a particular level of perceived exertion rather than, for example, requesting ten minutes running at 10km an hour.”