"Tremax system" consists of a devise and evaluating system to measure statical strength of various muscles. There were some measuring positions for these. In this paper, the positions for leg extention were No.1 to No.4 and for leg curl were No.5 to No.8.
 I measured the strength each of leg extention and leg curl exercise in various knee angles by this system.
 I normalized whole data of the strength, i. e. any value of the strength, which was same man and same exercise, divided by the maximum. This normalized data was %strength, I called.
 All six subjects were members of a Judo club at Keio University.
 Using the numerical data and a least square method, I apporoximate on the relationship between differental knee angle and the %strength during each exercises. Having the variations in prospect with the %strength of the knee angle, the numerically well defined experimental function was liked a parabola.
 y = a + bx - cx², (c>0) 
 From solutioning this function, the equation was as follows ; 
 For leg extention : 
 YE = -492.43 + 9.58 XE -0.039 XE²
 XE = 122.26, yE = 93.12, (point of inflection).
 For leg curl : 
 YC = -126.74 + 2.14 XC - 0.0051 XC² 
 XC = 208.85, yC = 97.22, (point of inflection).
 It was meaned that each value of XE and XC was the best angle for performing a maximam statical strength both of two exercises. Considering these angles, I found the Position that was just a like the knee angle doing the exercise at same. the best measuring position for the leg extention was No.2 and that for the leg curl was No.6.