These are my opinions  based on experience, observations  and influenced by  volumes of readings by mutliple authorities in the health field.

Why hold your breath? Holding your breath causes the body to use up its supply of oxygen. The bodys' monitoring system begins to be concerned about the rising CO2 levels especially with no exchanges. Hence when you exhale the bodys alarm system gets turned off and the whole body gets a repreive. This repreive signals a state of relaxation that affects the sore muscles tremendously. This physiological trick enhances the effectiveness of the technique such that it nearly triples the effect.

Why only 10% push? Getting muscles to relax (which stops the pain bell from ringing) is like a taffy pull. When you pull hard and fast then the taffy will break rather than stretch.  A dozen small efforts is much more productve than a few large efforts. The resulting tears are definitely felt the next day as a healing process must begin. This tearing is what causes inflamation and soreness following a vigorous or deep massage .

The byline of all heath care givers should be to cause no harm.