The Compex Wireless, the world's first wireless muscle electro-stimulator, which is used by HTC-Highroad, the cycling team of Mark Cavendish, the 2011 Tour de France sprint champion and recently crowned 2011 World Road Race Champion, employs Nordic Semiconductor’s Nordic nRF24LE1 proprietary 2.4 GHz System-on-Chips.

Targeting professional athletes and serious consumer sports and fitness enthusiasts such as marathon runners and keen cyclists, the Compex Wireless employs mechanical biofeedback ('mi-SCAN') technology to automatically and safely adjust the stimulation settings to the specificities of each muscle.

Electro muscle stimulation has long been used by elite professional athletes both during training and between training sessions and competitive events but the Compex Wireless is the first electro-stimulator to offer the convenience of wireless to maximize application freedom and comfort without the risk of users getting tangled up in trailing cables. It also gives non-professional users the ability to access the benefits of muscle stimulation on a regular basis.

In operation, a Nordic nRF24LE1 2.4 GHz SoC with on-board microcontroller running a Compex-developed wireless networking protocol is located in each of up to four compact wireless circular stimulators (5.5 cm diameter, 1.8 cm thick and 50 g in weight). These communicate with another nRF24LE1 located within a wireless controller featuring a 6.1 cm color LCD screen and simple user interface used to set up and control the Compex Wireless.

Each stimulator can operate for an entire day between recharges from a built-in 450 mAH lithium-ion polymer rechargeable battery under highly demanding (two training programs at high power and three recovery programs) usage conditions.

"When we began development of this project we weren't RF specialists so we decided to recruit an experienced RF engineer and discuss what we were trying to do with a number of local independent wireless design and development labs," said Nicolas Fontaine, R&D Team Manager & Senior Firmware Engineer at Compex Médical in Switzerland (a division of DJO Global) that developed the Compex Wireless. "They all recommended Nordic Semiconductor because of the technical capability of its solutions, quality of service and support, competitive pricing, and operational reliability."