With muscle control, you create sensations that you can focus on feeling.
Focusing on the sensations created while turning muscles on and off enables you to be mindful. It allows you to be present in your own body.
The more you practice noticing what is going on inside your body, the easier it can become to notice changes that occur outside of your body, when they happen. Rather than just learning to turn muscles on and off at will, mindful muscle control makes it easier to apply mindfullness to anything that you do.
Muscle activation allows us to feel our body. However, to become aware of our body initially, it helps to practice turning our muscles on and off.
Once we've got a feel for our muscles in general, we can then use that awareness to improve our ability to sense our body in general.
Muscle activation at the back of the thigh and hip in a standing forward bend can give us a feel for our thigh and hip bone. As well as the muscle belly creating a sensation because it is active, it creates a pull on the ischial tuberosity and the PSIC helping us to feel those points of the hip bone.
If both the inner and outer hamstrings are active, they will create tension at the back of the knee along both the inner and outer aspects, helping us to become more aware of our knee. And if the deep fibers of the gluteus maximus are active we'll get a sense of the back of the upper part of the femur.
If the biceps femoris short head is active then it will give us a sense of the remaining length of the back of the femur.
Muscle activation isn't an isolated event. It creates tension in connective tissue and that is something else that can give us a feel for our body.
In a standing or seated forward bend with the hamstrings relaxed, there will be a lengthening sensation at the back of the legs. If, while in a forward bend, you turn the hamstrings and/or glutes back on, the sensation can become slightly different.
Activating a muscle while it is lengthened "dampens" the muscle activation signal. And if a muscle is in stretch then this signal can become intertwined with the stretch signal. Both sensations can give you a sense of your body (and what is happening to it).
Exert hip flexors and hip extensors against each other, (and include other muscles of the hip joint as required) and you can get a sense of your hip joint.
Do the same thing in a forward bend or back bending hip position and you can feel you hip joint in those two configurations.
Likewise with the knee joint. Activate quadriceps, hamstrings, the long hip muscles, and the gastrocnemius and you can get a fairly solid feel for your knee whether it is bent or straight.
Some people think that just because a knee is straight the muscles of the knee joint are relaxed. Or if the hip joint isn't flexed then the hip flexors are relaxed.
If you learn to activate these muscles at will, you can experience all of this for yourself.
Practicing muscle control gives you an understanding of your muscles that extends far beyond just knowing the names of muscles and their supposed function. It helps you to understand that muscles can work in a variety of joint positions, no matter what their name.
You gain this understanding by learning to experience the muscles in your own body.
That in turn requires you to be mindful.
To make it easy to be mindful, you can repeatedly turn muscles on and off with a slow and smooth rhythm. The changes in sensation that muscles generate when they are turned on and off then give you something to focus on.
Muscles don't work in isolation. They have to work against an opposing force in order to activate.
Because muscles can work against each other, you have a guaranteed mechanism for turning muscles on. Simply use them against each other.
Apart from then enabling you to feel your body this also stabilizes whatever joint those muscles both work on.
People who find muscle control difficult tend to be people who are floppy. They can drop into the splits or do a forward bend easily. However, they can't control their body as they move into either of these positions.
These are the types of people I tend to have the most trouble teaching muscle control too because they can't feel their body. A lot of my teaching techniques have evolved from trying to effectively teach muscle control to floppy people.
In this case, being tight can be an advantage because you have something that someone who can easily do the splits (but can't control themselves as they go down) hasn't. You have a feel for your body.
This makes it easier for you to be mindful.
If you want to get more flexible, mindful muscle control is one way of working towards it.
With muscle control, the door is opened to a wider variety of stretching techniques. With muscle control it is easier to do both active stretching and relaxed stretching. You have flexibility of choice because you can feel when your muscles are active or relaxed.
How does muscle control lead to better balance?
Muscle control helps you to stabilize your feet (or your hands or whatever other part of the body is serving as your foundation). That in turn gives your foundation rigidity and sensitivity, allowing you to feel pressure gradients and control them.
Without muscle control you'd be a bag of bones and organs spread out on the floor like a loosely filled sandbag or waterbed mattress. With muscle control you can make your body stable in the places you choose.
If you stabilize the parts of your body in contact with the ground, that stability, provided it is not excessive, can allow you to feel differences in how your skin is pressed between bone and floor.
Differences in sensation throughout your point of contact with the floor tells you where your center of gravity is in relation to your foundation.
Through your point of contact you can also control your center when it wanders.
Even in non balancing poses skin contact can tell you when you are lightly touching the floor and can help you feel when a limb or part of the body has completely left the floor.
Hair can also be used as a sensor in this regard, particularly when dealing with light or gentle contact. pHowever, to move mindfully between "light" skin contact and lifting or between light skin contact and pressing, you need muscle control.
For simple exercises and routines for learning mindful muscle control check out the Smart yogi muscle control and proprioception.
Each workshop focuses on a single technique (and practicing it in a variety of poses) so that you can build the understanding of the technique into your body.
If you are a beginner, then you might find Smart yogi 5 beginner yoga routines more appropriate.