Dynamic Isometrics
by Nizar Abu-Hamdeh
Dynamic Isometrics are a form of resistance training in which a prolonged stop is maintained at a specific joint angle within the range of motion of an exercise. Very often the movement is stopped in the same position as in a particular portion of a sport event. Usually, the position is held for 2-3 or more seconds followed by an explosive continuation in the concentric phase of the exercise (Weineck, 2004). Weineck suggests 6 sets 6 repetitions using 60-70% of the one repetition maximum, however, the optimal set and rep schemes can't be taken out of context and depend on many factors.
For example, the athlete might descend into a half squat position with a barbell on his shoulders or dumbbells in his hands, pause 2-3 seconds, and then rise up as fast as he can and take off. A method described by Yessis(1987) is the delayed squat, in which even more stops can be done prior to the concentric phase.
To perform the delay squat, slowly bend at the hips and knees until there is a 160° angle in the knee joints. This position is held for three to four seconds. Lower with the same speed until there is a 145° angle in the knee joint and hold again for three to four seconds. Again lower to 115°, hold three to four seconds, and then finally to 90° and hold again. Rise up in a very explosive manner. Usually, 60-70% of the one repition maximum squat is used. This type of squat is very taxing and should be watched by spotters to help if problems arise during the execution of the exercise. Yessis recommends that no more than 2-3 repetitions per training session are performed and that the athlete goes beyond of what he should be doing if he /she experiences any tremor.
This method develops explosive power out of a static position.
References:
Weineck, J.: Optimales Training. Leistungsphysiologische Trainingslehre unter besonderer Berücksichtigung des Kinder- und Jugendtrainings. 14. Aufl. Spitta Verlag, Balingen 2004.
Yessis, M.: Secrets of Soviet Sports Fitness and Training. Toronto, 1987