PURPOSE: To examine the acute effects of static stretching on peak torque (PT) and electromyographic (EMG) amplitude from the vastus lateralis (VL) and rectus femoris (RF) muscles during eccentric muscle actions. METHODS: Thirteen females (mean age ｱ SD = 20.8 ｱ 0.8 yrs) volunteered to perform maximal, eccentric isokinetic muscle actions of the dominant leg extensors at 60 and 180ｰ不-1 on a calibrated Cybex 6000 dynamometer. Bipolar surface EMG electrode arrangements were placed over the longitudinal axes of the VL and RF muscles. The EMG (ｵV) signals were expressed as root mean square (rms) amplitude values, while PT (Nm) was recorded by the dynamometer. Following the pre-stretching PT and EMG assessments, the dominant leg extensors were stretched using one active and three passive stretching exercises (mean time ｱ SD = 21.2 ｱ 2.0 min). After the stretching (4.3 ｱ 1.4 min), PT and EMG measurements were repeated. Prior to the statistical analyses, all PT and EMG amplitude values were normalized to values recorded during a maximal isometric muscle action (% max) performed before the eccentric testing. RESULTS: For PT, there was no two-way interaction (time [pre- vs. post-stretching] by velocity [60 vs. 180ｰ不-1]), no main effect for time, but a significant (p < 0.05) main effect for velocity. For EMG amplitude, there was no three-way interaction (time [pre- vs. post-stretching] by velocity [60 vs. 180ｰ不-1] by muscle [VL vs. RF]), no two-way interactions, no main effect for time, but significant (p < 0.05) main effects for velocity and muscle. Neither PT nor EMG amplitude changed from pre- to post-stretching at 60 or 180ｰ不-1. The marginal means for PT (collapsed across time) and EMG amplitude (collapsed across time and muscle), however, were greater at 60ｰ不-1 than 180ｰ不-1. The marginal means for EMG amplitude (collapsed across time and velocity) were greater for the VL than the RF. CONCLUSIONS: These results indicated that static stretching did not affect PT or EMG amplitude of the leg extensors during maximal, eccentric isokinetic muscle actions. In conjunction with previous concentric muscle action studies, the present findings suggested that the effects of static stretching on PT and EMG amplitude may be mode-specific, affecting concentric, but not eccentric torque production and muscle activation. This information may be useful for researchers, practitioners, and female athletes who perform static stretching prior to performance events involving a heavy eccentric component.Keyword(s): athletics/sports, exercise/fitness, performance