Height and length of arms together with proportion vary from one
individual to the next. Placing both hands in front of the abdomen may
not necessarily work for all. A practitioner with shorter arms if required
to place hands in front of the abdomen, for instance, needs to have
back bent and shoulders strained, even suffering in the end from
breathing reversed and subdued.
According to records from the sutras, the Buddha' s arms being
long enough to touch his knees was one of his 32 physical marks.
In assuming the lotus position, length of the Buddha' s arms enabled
him to place—lightly and easily—hands atop each other in front of the
abdomen whilst, in absolute independence, sitting up straight. So, it is
wonderful for meditators to competently emulate the postures of the
Buddha images and it is passable, too, for those with shorter arms to
simply place hands on thighs next to knees, sit up, hold abdomen,
keep waist straight, and hence assume comfort.