SIGNIFICANCE OF ACCELERATION PERIOD IN A DYNAMIC STRENGTH TESTING STUDY

The acceleration period that occurs during isokinetic tests may provide valuable information regarding neuromuscular readiness to produce maximal contraction. The purpose of this study was to collect the normative data of acceleration time during isokinetic knee testing, to calculate the acceleration work (W(acc)), and to determine the errors (ER(exp), ER(work), ER(power)) due to ignoring W(acc) during explosiveness, total work, and average power measurements. Seven male and 13 female subjects attended the test by using the Cybex 325 system and electronic stroboscope machine for 10 testing speeds (30-300-degrees/sec). A three-way ANOVA was used to assess gender, direction, and speed factors on acceleration time, W(acc), and errors. The results indicated that acceleration time was significantly affected by speed and direction; W(acc) and ER(exp) by speed, direction, and gender, and ER(work) and ER(power) by speed and gender. The errors appeared to increase when testing the female subjects, during the knee flexion test, or when speed increased. To increase validity in clinical testing, it is important to consider the acceleration phase effect, especially in higher velocity isokinetic testing or for weaker muscle groups.