title: Contribution to the diagnostic reliability of the combined stimulation myographic/mechanographic method applied to the musculus quadriceps femoris.
abstract: The left and right quadriceps femoris muscle (QFM) of 11 to 13-years old children and of 10 adult sportmen was stimulated supramaximally by a single shock. Simultaneously the muscle action potential (MAP) and the mechanogramm (MG) was recorded. In the MG of both groups several maxima appeared with averaged contraction times (CT) between 43-47 ms, 80-86 ms and 115-126 ms in the left as well as right position. In some cases maxima of approximately 65 ms and between 140-160 ms were found. The CT from test to retest varied about 1-7% and the amplitude about 7, 5% and 4%. The maxima of the left QFM having a CT of about 47 ms and 84 ms were significantly higher than on the right one. At the left muscle an aerobic load of 1 W/kg body mass elicited a significant reduction of the maximum by 84 ms. The remaining difference to the right muscle is 10-15%. It was concluded, that the maxima of the mean CT of 43-47 ms and 80-86 ms are those of the FTF- and STF-populations. The maxima of 65 ms should be due to the FTO-fibres and the maxima higher than 100 ms must be explained by evoked responses of the motoneurones. The reaction of the ST-amplitudes is due to extensibility changes and the remained difference shows the higher potential strength of the STF at the left muscle. Within the potentiation of the formerly recruited FTF.
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D005071:Evoked Potentials; D006801:Humans; D007866:Leg; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D009135:Muscular Diseases / Q000175:diagnosis*