Eighteen elite Greek soccer players (age, 27.8 +/- 3.4 years; height, 176.6 +/- 5.2 cm; weight, 75.5 +/- 5.2 kg) were tested on the Cybex(R) II apparatus in order to determine 1) the maximal muscle power for the lower extremity dominant side at angular velocities of 30 degrees /sec, 90 degrees /sec, and 180 degrees /sec; 2) the total muscular output and the relative power at 30 degrees /sec; 3) the relationship between the muscle power of the agonist and antagonist musculature. The absolute maximal muscle power (Nm) at 30 degrees /sec for the different joint movements was as follows: Hip Ext = 269 +/- 39; Hip Flex = 179 +/- 29; Hip Add = 160 +/- 17; Hip Abd = 119 +/- 24; Knee Ext = 247 +/- 29; Knee Flex = 146 +/- 12; PI. Flex = 120 +/- 22; and Do. Flex = 32 +/- 6. The muscle agonist-antagonist percent relationship at 30 degrees /sec was found to be: (hip flex)/(hip ext) = 66%(hip abd)/(hip add) = 74%(knee flex)/(knee ext) = 60%(dor. fle)/(pl. fle) = 28%These findings have significant implications for preseason conditioning programs as well as for minimizing the rate of muscle injuries by restoring the correct relationship between agonist-antagonist musculature.J Orthop Sports Phys Ther 1985;6(5):293-295.