Relaxation and sports performance training
Sports performance relaxation training surfaced as long ago as the 1930's as researchers and coaches held the belief that relaxation was a key to peak performance. A study carried out in 1936 by Jacobson set out to test whether college athletes had superior relaxation skills due to their advanced level of muscle control compared with the general population. He used needle electrodes in the bicep muscles to measure the electromygraphic (EMG) sginals as muscles contract and relax. This early work was a bit inconclusive. Most athletes were found to relax well but not all. Im not sure whether this was anything to do with using needle electrodes to monitor EMG.
Basmajian's work in the 1960's really raised the level of interest in EMG and sports. He was able to show, with the improved technplogy of the time, that it was possible to train a person to control muscle movement to a very fine degree - to the level in which a single muscle fibre could be activated. As sport is one way or another about using muscle efficiently and effectively the interest in EMG and sport was assured.
These days it seems unlikely that learning to relax one set of muscles using EMG biofeedback would improve overall sports performance. However, during the 1970's and 80's a number of studies looked at the effect of relaxing various muscle groups on overall sports performance.
Rather obviously in hindsight better results were produced when muscles that were central to a particular sport were targeted. For example, the hamstring muscles of gymnasts and of sprinters were successfully targeted with EMG biofeedback to bring about improved flexibility.
More recently, Porge's Polyvagal theory of the autonomic nervous system has noted that there is indeed interaction of the muscles and especially of the face and head with the state of the brain and heart. Perhaps the researchers of the 1930's were onto something but did not manage to demonstrate it through limitations of technology and methodology. Today some coaches would utilise biofeedback relaxation of the facial and trapezius muscles as this has a powerful effect on overall relaxation - and in addition target specific muscles based on the needs of a particular sport.
Modern equipment such as the NeXus 10 lends itself very well to EMG sports performance training. The equipment is light and portable and can record to an SD card or via Bluetooth to your computer. A number of EMG channels can be monitored along with other relevant signals as dictated by the sport (ECG, respiration etc). Typical muscles for relaxation purposes would be the frontalis muscles of the face and the trapezius muscles. Appropriate feedback can be provided in training based on the athlete lowering the level of muscle activation below some threshold level. Over a number of sessions the athlete learns to perform this type of relaxation on cue without the need for the instrumentation.
To learn more about biofeedback and the NeXus hardware explore the systems and links on this site.