Wearable Muscle fatigue sensor could help athletes avoid injury

A wearable device that senses how close muscles are to fatigue could help athletes train harder while avoiding injury.

A Prototype system has been devised by Mohamed Al Mulla, in PhD research at Essex University’s School of Computer Science and Electronic Engineering.

Athletes generally have to rely on their own perception of muscle fatigue – clinically defined as a reduction of the ability of a muscle to contract and exert force. Localised muscle fatigue can be beneficial in promoting muscle growth or potentially harmful. Often it’s a fine line and timing is crucial, Al-Mulla said.

“What I want to do is build a bridge between the brain and the muscle,” he added.

To acquire input data, the system uses surface-electromyography electrodes to detect electrical signals as muscles contract and a goniometer to measure kinematics as muscle fatigue can manifest itself as small oscillations or vibrations. Signals from the muscles are then amplified and converted from an analogue to a digital stream.

In order to test and calibrate the system, Al-Mulla and his team asked five male gym users to perform a resistance exercise while hooked up to the sensors and amplifier. They were then asked to exert force for as long as possible.

Analysing data, the team found that the onset of fatigue occurred in several distinct phases – what Al-Mulla calls “transition to fatigue”.

“Once you detect the onset of a transition to fatigue then you can calibrate it with a timer, so I can tell the user, for example, “in 30 seconds you will stop”.”

The nest stage will be to make the components more discrete and portable.

Sourced from "the Engineer" magazine 

BY ANDREW CZYZEWSKI