Rate-adaptive intra- or epicardialer cardiac stimulator and activity sensor

The invention includes an electrode leadless implantable cardiac stimulator (10) with an acceleration sensor (36) which provides as an output an acceleration signal. Here, the acceleration sensor (36) having a type determining unit (40) which is designed to generate from the acceleration signal an activity signal by the activity determination unit (40) comprises returning to a heart's own motion component of the acceleration signal from the acceleration signal at least partially subtracted.