Well, that last post was really more about how breathing is not taught in Shintaido than about how it is. So let's get down to the nitty-gritty.
Shintaido jumping exercises (shin shin kaihatsu taiso 身心開発体操) were discussed in an earlier post from the point of view of getting in touch with our instinctive intentionality. If we look at these techniques from the point of view of breathing, a few things become clear:
1. They are generally very physically demanding aerobic exercises, typically involving elevated heart rate and breathing (maybe a little sweating as well).
2. Opening movements of the hips, waist, chest and abdomen are emphasized.
3. Many of these exercises also involve serious challenges to our balance. That is, movements where we deliberately transgress the boundaries of the the zone within which we can easily maintain physical balance activate reflex arcs (discussed in this post), which are mechanisms by which the body instinctively recovers its stability.
4. The combination of 1, 2 and 3 means that the abdomen, ribcage, diaphragm, spine, hips and pelvis — composing the core or trunk of the body — are being intensively exercised in several different ways simultaneously. Heavy demands are placed on the body core in regarding mechanics of physical movement, maintenance of stability and of breathing or oxygen intake all at the same time.
5. Obviously there is a profound connection between emotional states and breathing. Emotions such as fear, anger, joy (including laughter), etc. affect our breathing patterns. At the same time, the features of the shin shin kaihatsu taiso movements mentioned in 1-3 (intense physical exercise, opening the most vulnerable parts of the body, and being off-balance) have a potentially dramatic influence on our emotional condition. In combination, it's clear that these movements can directly affect our breathing patterns, and also impact our emotional condition, which then affects our breathing.
The above may explain why even people who are "in good shape" can quickly feel exhausted when introduced to these exercises for the first time. Furthermore, as mentioned earlier, breathing lies at the cusp of the autonomic and consciously-controlled functions of the body. Likewise, we might also say that it lies at the cusp of our physical and emotional or spiritual lives. This is probably key to the meaning of the name shin shin kaihatsu taiso — "mind/heart* and body opening exercises." (* "Mind" and "heart" are the same word in Japanese).
To sum up, the practice of Shintaido shin shin kaihatsu taiso exercises is clearly a method that has potentially profound impact on our way of breathing, even if nothing is explicitly said about "breathing" in the teaching and learning process.
This may also have important practical implications for the future development of the Shintaido curriculum, as many instructors are involved in bringing modified versions of Shintaido to communities with special needs (for example elderly people). Obviously, very few elderly people should be encouraged to do classical shin shin kaihatsu taiso exercises. However, as we develop modified versions of many Shintaido movements suitable for specialized audiences, I believe that identifying and maintaining the underlying principles of the movements will help us stick close to the essence of what Shintaido is about, even as the specific movements may be presented in modified form.