I have been helping many of my swim students recognize the critical role that a firm core muscles (think spine held firm like an arrow, from tail bone to crown of your head) play in holding balance in the water. How can I, the teacher, hold Skate Position (rotated to about 30 degrees) indefinitely without moving my limbs to support it, while my student next to me immediately falls back to flat.
The difference is that my core muscles are trained to hold this position. Once my body line is held rigid by those muscles in the abs and back, surrounding the spine, like a submarine is held rigid by it’s internal frame, I can subtly adjust my ‘ballast’ (my head and arms) to balance my legs/hip weight against my head/arms, over the pivot point of my floating chest, without moving the limbs for any propulsion (yes, I have to apply the most gentle toe flick to stay near the surface- I am a sinker- read about dealing with this in my forum essay).
So once students discover their desperate need for these under-developed core muscles, they ask how they could strengthen these on dry-land to help them in the water, and often specifically ask about yoga.
My wife does yoga and it really helps her. I would definitely recommend yoga-like exercises to tap into those core muscles, wake them up, and learn to use them. Dry-land work will certainly build those muscles.
However, Balance on Land does not translate into Balance in Water necessarily. On land you are learning how to Balance by pushing back against gravity pulling down on your body. While in the water you are learning to REST between gravity pushing down and water buoyancy pushing you up. So being skillful in yoga-pose Balance on land, will not instantly make you good at yoga-like control in the water. It will make more in-tune with using those muscles, but you still have to practice in the water to get skills that work in the water.
This is because Balance is not a ‘strength’ skill, it is a neuro-muscular skill. It is your brain that controls the position and tension in those muscles, and it is precision and repetition that builds such strong neurological connections that you will be able to hold superior Balance position while swimming under all sorts of conditions. Holding superior position really does not take enormous strength, just precisely applied strength. This is one of the reasons elite swimmers (or any elite physical performer) look almost relaxed in their peak effort, because they really are applying less force (and less struggle) than the rest of us. By simply waving the magic wand of ‘practice-practice-practice’ just like they did, you and I too can swim effortless-like.
When we prefect Balance, we remove struggle from our movements. When we perfect Streamline, we remove water resistance working against us. When we perfect Efficient Propulsion, we move forward faster with less effort. Balance sets the stage for Streamline, and Streamline sets the stage for Propulsion. Without good Balance, you get inferior propulsion. Balance is 60% of the skill behind fast, efficient, effortless swimming. You cannot over-train your Balance skills.
So, by all means, enjoy some dry-land yoga, or other core-strengthening exercises. But remember that only in the water will you learn to use them to hold superior Balance position for swimming.