Discovered in 1655 by Christian Huygens using pendulums, it is a principle of physics that describes the tendency for two oscillating bodies to vibrate in synchrony. It also refers to phase-locking of two or more rhythmic cycles. Watch race car drivers who drive in the "wake" of cars just ahead of them in the track. The flow "pulls" them along, decreasing the need to exert additional power or force to race ahead or simply stay abreast.  Geese fly 70% more efficiently by entraining to the leader's flight tempo. In humans, biological rhythms are often entrained by external cues. Rhythmical entrainment in group drumming refers to the natural process of assimilating the beat of another. The more relaxed you become, the easier it is.. 

Our health can be viewed as a masterful orchestration of complex rhythms, some of which can be entrained. 

Biological Rhythms are more prevalent than you might imagine: Circadian, Neurotransmitters, Hormones, the Brain, the Heart, and even Breathing, with various practices focusing on breathing to create various altered rhythms to heighten focus and relaxation, are all prevalent in acknowledging the Mind-Body-Spirit Connection and Synchronicity.. when a group is entrained to follow each other's rhythm, you know it and you feel it. Drummers call it "the pocket." The "pocket" exists in life even amidst the challenge of illness. Allowing yourself to see with your understanding and becoming aware of supposed coincidences, through this idea of entrainment to synchronous elements and events, facilitates the personal lock to being "in flow". Evidence based elements of Group Empowerment Drumming include nurturing and support, Camaraderie, self-expression, exercise, guided imagery, spirituality and of course: music-making.