Isokinetic peak torque and cross-sectional area of the quadriceps

The purposes of this investigation were to examine (a) the relationship between total quadriceps cross-sectional area (CSA) and isokinetic peak torque at contraction velocities of 60 to 300 deg/sec, and (b) the relative contributions of the (SA values of the individual muscles of the quadriceps to the models predicting peak torque at each contraction velocity. Forty-three men (mean age ± SD = 24 ± 5 yr) volunteered as subjects for this investigation. Peak torque values for leg extension (dominant leg) were determined at 60, 120, 180, 240, and 300 deglsec using a (ybex II isokinetic dynamometer (Lumex Inc., Ronkonkoma, NY). The (SA values for the vastus intermedius, vastus lateralis, vastus medialis, and rectus femoris muscles were measured at mid-thigh using magnetic resonance imaging. Full model multiple regression analyses indicated that total quadriceps (SA significantly (p < 0.05) predicted peak torque at all contraction velocities (R = 0.61 to 0.73). Furthermore, the (SA of the vastus medialis was the most potent predictor of peak torque at each contraction velocity. Factors that may have contributed to these findings include fiber type distribution patterns, biomechanical considerations, and/or muscle architecture.