Comparisons as the key for all meaningful interpretation
Due to its relative amplitude character which is influenced
by local detection conditions and the lack of normative
curves or activation levels, the comparison of EMG findings
is the most important strategy to analyze and interpret EMG
data. Whenever you plan an EMG experiment or test, try to
also plan reasonable comparison conditions right from the
beginning. It is especially helpful to compare EMGs from
the same muscle site in different movement phases, portions
of the record or test activities: These analyses don’t
require any amplitude normalization (see Analysis question
level 2: more or less). It is probably the most important
EMG design at all.