How Does An Ergometer Work?

The Process

An ergometer is a computing device used to measure work exerted during physical activity. This broad definition includes everything from a pedometer to cardiac stress test equipment. More commonly, ergometers simulate sport specific activities while collecting and computing the user's physical exertion. Popular ergometer modalities include the treadmill, bike, and rower. These classic cardiovascular exercise machines are fitted with sensors to capture speeds, loads and power output. Often the user is also fitted with sensors to measure physiological responses to exercise such as heart rate, oxygen consumption and body temperature. A computer processes this data to provide the measures of work relevant to the modality and purpose of use. Each ergometer modality has its own mechanism for presenting the workload against which the user's work capacity is measured.

Mechanism

The treadmill provides a varied workload by changing the speed and inclination of a large belt used for walking or running. Sensors in the machine track the speed and inclination, while a heart rate monitor or electrocardiogram can track the user's cardiovascular response to the workload. A computer provides instant and continuous feedback from the sensors and calculations related to power output, calorie consumption and work capacity.

The bicycle ergometer and arm ergometer place much of the user's body weight into a seat allowing greater control of the workload. The work load is varied by mechanical friction, electrical conduction, air resistance or fluid resistance. It is solely the user's responsibility to maintain selected speed. Sensors on the machine track the speed and resistance; a computer combines this with the user's vitals to provide relevant measures of cycling work capacity.

The rowing ergometer takes competitive rowing on land to provide a controlled simulation of racing across a river. The workload is varied by changing the drag coefficient on a flywheel being driven by chain connected to the rowing handle (oar). Sensors on the machine track the speed, frequency, and force on the flywheel; a computer combines this with the user's vitals to provide relevant measures of rowing work capacity.

Considerations

Every ergometer modality has pros and cons. The treadmill involves an activity everyone is familiar with so the learning curve is diminished; this is beneficial in non-sport specific applications. However, since the workload is related to body weight, this is not a consistent measure for users with changes in body weight. Also it is difficult to collect blood pressure readings, blood samples and muscle biopsies during use. The bicycle and arm ergometers are more difficult for users not familiar with these modalities increasing the learning curve effect. Most of the user's body is supported and immobilized by the seat making it easier to get blood pressure readings and blood samples during use. This also makes them more consistent for measuring users with changes in body weight. The rowing ergometer, while very specialized and sport specific, provides a lot of quantifiable data in an efficient simple device.