Acute Effects of Unilateral Self-Administered Static Stretching on Contralateral Limb Performance

**Background:** Prolonged static stretching (SS) has been shown to impair subsequent performance of the stretched muscle. There is some evidence that unilateral SS can have crossover or global effects on range of motion (ROM), but there is scant information regarding whether prolonged SS also impairs contralateral muscle groups. **Purpose:** The objective of this study is to investigate the effects of self-administered unilateral SS with a TheraBand® stretch strap on contralateral hip flexion ROM and knee extension isometric maximum voluntary contraction (MVC) force and muscle activation. **Study Design:** This study used an experimental repeated-measures intervention design. **Methods:** In total, 14 male participants performed self-administered SS of the dominant quadriceps and hamstrings (eight repetitions of 30 s each) with a TheraBand stretch strap. The aim was to observe pre- to post-SS-induced changes in hip flexion (hamstrings) ROM, knee extension (quadriceps) isometric force, and muscle activation (as recorded with electromyography [EMG]) in both dominant (experimental limb) and nondominant lower limbs (control lower limb). **Results:** A significant tested leg x time interaction [F(1,13) = 6.58; P = 0.04; eta2 = 0.210) demonstrated that the ROM increases in both the stretched and contralateral nonstretched legs by 6.7% (d = 0.53) and 4.3% (d = 0.38), respectively. There were no significant interactions for MVC force or muscle activation for either leg. **Conclusion:** The lack of crossover MVC changes suggests that the mechanism for contralateral increases in ROM may be stretch tolerance. **Clinical Relevance:** Individuals who are injured or are undergoing rehabilitation should continue to stretch the noninjured limb to maintain or improve flexibility of the injured limb.