Using a new method of measuring passive-mechanical tonus-parameters of muscle tissue in situ ("Myomechanographie, MMG") we evaluated in 12 healthy men reactive changes of the muscle tonus immediate after one middle-frequent Electromyostimulations (EMS)-period (duration: 15 min). With the MMG was proved, that the applied EMS cause an organic effectiveness; the muscle in situ is more "elastic". This showes especially the increase of the single parameters 'elastic retraction' and 'total compressibility'. In the comparison group (n = 12) we obtained contrary after relaxly steady position (duration: 15 min.) clear reduced single parameters. The muscle is reactive less "elastic".