Some people are more flexible than others: the ligaments around their joints are looser and permit a greater range of motion – hyperflexibility is an inherited body type. Joints are the pivots for movements in the body, supported by strong ligaments and according to a study of flexibility, the importance of these different factors are:
- Joints and ligaments 47%
- Muscles 41%
- Tendons 10%
- Skin 2%
Women are generally more flexible than men, because of higher levels of female hormones that make the ligaments looser but also make women more prone to instability in their joints. Men have higher levels of testosterone which supports muscle growth and their joints are generally more stable but less flexible.
Yoga asanas extend the range of motion of joints by stretching muscles and this can be highly problematic if the focus is only on stretching muscles and not strengthening them. Strong muscles don’t cause inflexibility, but enhance it, by supporting and protecting joints. Strength only leads to inflexibility if
- people never stretch their muscles
- people develop muscle imbalance from
- Unbalanced exercise routines
- Alignment problems caused by injuries or incorrect movement habits.
Although yoga is mostly about stretching, some people remain relatively inflexible because of inhibition of stabiliser muscles around the joint via reciprocal inhibition. This can occur when yoga sequences focus on strengthening using particular types of asanas – please refer to Reciprocal Inhibition and Hips. Strengthening the stabiliser muscles with the right exercises can improve a stiff person’s flexibility much more than continuous stretching will.
Flexibility is neurological – nerve responses to changes in a joint inhibits muscles if joint safety is compromised. Joint ranges of motion can be extended by stretching muscles, which effectively resets the neurological response but if motion goes too far ligament damage and permanent instability results.
Hot yoga can be very helpful for healing muscle injury because blood flow to the muscles increases in the heat and speeds up healing processes but there is a danger of damaging joint structures with heat-induced flexibility: it’s possible to extend a joint’s range of motion, making it hyper flexible, but a yogi may lack the strength to support extreme ranges of motion and can injure themselves this way.
Tight muscles cause uneven pressure on joint surfaces and incorrect movement at the joint. Some joints have many pain receptors and incorrect functioning will cause pain, but in other cases, only a grinding or creaking is felt at the joint – especially at the knees. When joints malfunction the stabiliser muscles around the joint will go into spasm to inhibit movement to protect the joint from further damage – causing pain at the joint.
It is possible to be unaware that a muscle has gone into spasm because some of the hip*, shoulder and chest muscles** are supplied with motor nerves only, and don’t have sensory nerves. There are pain receptors in these muscles and their attachment points, but no sensory input to the brain about their movements. This is why muscle imbalance in the shoulder is mostly felt in the Deltoids, which do have sensory nerves, and why hip muscle dysfunctions are felt as Sacroiliac and lower back pain, Piriformis pain, bursitis of the hip or knee problems.
A correctly functioning joint is never painful. Some joint pain is related to arthritis, but a lot of joint pain disappears if a joint is mobilised and balance is restored in the surrounding muscles. It is important to remember that a malfunctioning joint can develop arthritis in the long term because uneven pressures on joint surfaces causes wearing of cartilage and damage to ligaments.
A stiff joint causes hypermobility in joints around it, especially in the spine and sacroiliac joints. If a joint becomes stiff, it needs to be mobilised with specific stretching exercises prescribed by an experienced professional before doing any kind of exercise or yoga classes. Stretching in a yoga class may be exactly what a particular joint needs, or it may be precisely the wrong kind of stretching for that joint. Exercising with stiff joints is counterproductive because inhibition of muscles by malfunctioning joints develops compensatory movement habits.
*Gluteus- Maximus, Medius and Minimus and Tensor Fascia Latae
** Sternocleomastoid, Trapezius, Levator Scapulae, Rhomboids, Serratus Anterior, Latissimus Dorsi, Teres Major, Subclavius, Pectoralis Major and Minor, all rotator cuff muscles except Teres Minor
Source: Kendall, McCreary, Provance, 1993, Muscles: Testing and Function pp378-9
Kim, 2004, Ultimate Flexibility
DeFranca, 1996, Pelvic Locomotor Dysfunction
Kendall, McCreary, Provance, 1993, Muscles: Testing and Function
Cook, 2003, Athletic body in Balance