Muscles and joints have very specific actions; a muscle fires and its associated joint moves. It would be very jerky if it were not for the connective tissue sheaths that run around groups of muscle fibres, joints and through our entire bodies. This fascia has elastic and recoil properties, and mediates the total movement of multiple joints to produce smooth, controlled results like walking, writing, dancing, Yoga…
Connective tissue fibres live in a protein solution called a “colloid”. This solution becomes more gel-like in lower temperatures, and more liquid in higher temperatures. Hence practicing in warm environments induces greater ease of movement.
Note that stiffness can be caused by an undelying constriction in the tissues leading to decreased circulation and lower local temperatures. This needs a long term fix. Practicing in the warmth might be enough to free it up; it might also need physio (or similar) intervention.
As an aside: how does fascia provide an elastic recoil within the body? It’s made of collagen, which is not elastic, but fibres are coiled and this patterning allows for springiness. If the fibres becomes dense, matted or not aligned in the direction of movement then the elastic quality is lost and restriction of movement follows.
Yoga has tremendous power to heal, renew and rebuild. It’s important for us to know this is based not in tradition handed down from the Guru but in one’s own practice and self enquiry, today, now. That’s not to say that the Guru can’t help – rather that the Guru probably did it all for him or herself by independent hard work, and we can probably do it to.