Some people say to me they aren’t flexible enough to do yoga. This is the equivalent of saying “I’m too dirty to take a bath”. When people think about yoga, one of the first things that comes to mind is being able to stretch your body into all different kinds of pretzel like shapes. Although the ability to touch your head to your toes may look incredible, it’s not really what yoga is all about. One of the goals of asana (posture) practice is to create balance between strength and flexibility in your body. Every time you practice yoga you get closer to balancing out your own body. Whether you as an individual are flexible or not, you will gain endless benefits just from trying; weak muscles will strengthen while tight muscles will lengthen. Let’s take a closer look at the composition of muscles, how they contract and how they stretch. Muscles, your hamstrings for example, are separated into tissue sections called fascicles. These are the strands that you can actually see when you cut into red meat or poultry. Each fascicle is made up of bundles of muscle fibers (cells), which are further broken down into tens of thousands of thread like myofibrils: the contractile element of skeletal muscle. The amount of myofibrils present in each muscle fiber determines the size of the whole muscle. Each myofibril is composed of two types of even smaller structures called filaments. These thick and thin filaments are arranged into millions of compartments called sarcomeres. The capacity for muscles to stretch and contract originates at this microscopic level. Muscles are connected to the spinal cord by nerves, this is where the communication takes place. When a muscle contracts, a signal is transmitted from the brain or spinal cord deep into the muscle fibers. This connection site is called the neuromuscular junction. The signal stimulates the release of calcium which causes the thick and thin filaments to slide across one another, which, in turn causes the sarcomere to shorten. When a large collection of sarcomeres shorten, a muscle contraction occurs. Muscle stretching is essentially the opposite of muscle contraction. When a muscle stretches, the overlapping filaments decrease causing the sarcomeres to stretch, allowing the muscle fibers to lengthen. This elongation realigns muscle tissue on the smallest level. This is why stretching muscle tissue is equally important as it is to strengthen it. When stretching is neglected the thick and thin filaments stay in a shortened state, which can lead to chronically tight muscles or even muscle contractures (permanent tightening), both of which will limit your range of motion and your flexibility. Most people think about stretching after a workout, but are ignorant to the fact that every time you use your body, muscle contractions are taking place, therefore there is a need for stretching to maintain a healthy balanced state. Other factors that contribute to short and tight muscles are injuries, both traumatic or repetitive. When you strain a muscle your body produces mechanisms that protect the initial injury. However, if throughout the healing process stretching is overlooked scar tissue will set in, again affecting range of motion and the overall health of those tissues. The average person spends a significant amount of time sitting; this can be looked at as a repetitive injury. In the seated position muscles are held in a shortened state for an extended amount of time having the same effect as continuous muscle contractions.
As mentioned earlier yoga helps you to create balance in your body, it allows you to strengthen and stretch your muscles at the same time. One of the ways this is achieved is through reciprocal inhibition. This is a neuromuscular reflex that inhibits opposing muscles during movement. When you contract the agonist (prime mover) the neural drive increases in that muscle and signals are sent to decrease the neural drive in the antagonist (opposing muscle). This causes the antagonist muscle to relax. It is much easier to stretch a muscle in its relaxed state rather than when it is contracted. As shown in figure 2(a) Janu Sirsasana, the hamstrings (agonist) are contracted, this inhibits the quadriceps (antagonist) allowing them to stretch. In figure 2(b) Paschimottanasana, the opposite is happening, the quadriceps are now contracting, which reciprocally inhibits the hamstrings. Typically agonist and antagonist muscles are located on opposite sides of a joint as they create opposite movements on said joint.
You can find reciprocal inhibition in almost every yoga posture. The easiest way to apply the benefits of this reflex in your yoga practice is to get familiar with the muscles you feel stretching in each posture. Remember that contracting the muscles on the opposite side to which you feel the stretch will initiate reciprocal inhibition, helping to relax or inhibit the muscles you are in fact trying to stretch. The next time you find yourself folding forward into Uttanasana, use your abdominal muscles to pull your upper body closer to your legs. Observe the subtle changes this causes throughout the back of the body. As your body begins to rebalance while you continue to experiment with these sensations, you will start to find greater ease in postures you may have previously avoided. Through the practice of yoga you will discover a beautiful way to counterbalance the physical asymmetries we generate in our bodies day to day.