Measurements of Isometric Strength and Electromyography of Elbow Flexors under Active and Passive Conditions

The aim of this study was to measure maximum isometric force under two different conditions: active and passive conditions. The electromyograms (EMGs) were also measured. The elbow exors of healthy subjects were studied. Six healthy subjects took part in this study. The isometric maximum force and the EMGs of the elbow exors were measured under two contrasting conditions. The rst was a standard isometric measurement in which a subject actively pulled a xed wire using their elbow exor at 100% effort (active). In the second case, the subject tried to keep their elbow at 90 degrees of exion for as long as possible against external forces produced by an electric motor (passive). The highest force values were extracted during the isometric phase when the elbow angles were kept constant. Hence, the elbow angles were also monitored by an electric goniometer in the later measurement. The passive condition resulted in higher forces than the active condition in 4 of 6 subjects. For a subject who showed different maximum forces under the two conditions, the mean (standard deviation) measured maximum forces under active and passive conditions were 285.2 (11.0) N and 300.2 (14.1) N, respectively (p < 0.01). For the EMG, there were no signi cant differences between the two conditions. In conclusion, the passive condition used in this study enhanced isometric maximum forces compared to that obtained under standard isometric conditions.