The purpose of this study was to determine if the two strength ratios calculated from average strength moments could be different between sedentary subjects and soccer players. The hypothesis was that soccer players would present specific strengths and functional strength ratios. The Hecc/Qcon and Hcon/Qecc ratios are functional ratios and form a means of determining strength in the muscular evaluation of the soccer player. Twenty-one amateur national level soccer players and eleven sedentary subjects were tested for both concentric and eccentric knee extension and flexion strength on the dominant and non-dominant leg with the Kin-Com® isokinetic dynamometer at 3 speeds in concentric contraction (120°·s
$^{-1}$
, 60°·s
$^{-1}$
and 240°·s
$^{-1}$
respectively) and then at 2 speeds eccentrically (120°·s
$^{-1}$
and 60°·s
$^{-1}$
). Soccer players present a concentric extensor and flexor strengths significantly higher than that of the sedentary subjects on both the dominant and non-dominant legs. The functional Hecc/Qcon ratio of the soccer players is significantly lower than that of the sedentary subjects at 60°·s
$^{-1}$
(0.80 vs. 0.93) and at 120°·s
$^{-1}$
(0.88 vs. 1.03) for both legs. In conclusion, the isokinetic evaluation of soccer players and particularly the analysis of the Hecc/Qcon and Hcon/Qecc ratios allow the identification of normative values and can also help to identify potential muscular injuries. Eccentric strengthening exercises can be included in training programs without any risk of altering the specific qualities of the players. The determination of the functional ratios several times during a season could permit the trainer to identify the need for either a collective or individual eccentric strengthening.
