[Potential reversal/amplitude analysis: problems of normal value determination].

Turn/amplitude-analysis was applied to the right m. biceps brachii and the right m. rectus femoris of 30 healthy women aged 19 to 39 years. Interference patterns were recorded at 20, 40 and 60% of the individual maximum force of both muscles. We evaluated the turns/s, the amplitude/turn and the ratios amplitude/turns:turns/s and turns/s:amplitude/turn. Normal values of the turn/amplitude-parameter were calculated as means +/- 2 SD at defined levels of force (table 1 and fig. 2) and in form of clouds (fig. 3). Our clouds were clearly different from those of Stalberg. Since normal values of our and other studies were inconsistent we believe that every laboratory has to elaborate its own normal values. Turns/s, amplitude/turn and the ratio turns/s:amplitude/turn increased and the ratio amplitude/turns/s decreased with increasing force (fig. 6 and 7). Turn/amplitude-parameters were partly significantly higher or lower in the m. biceps brachii than in the m. rectus femoris (fig. 8.).