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Performance-enhancing effects of caffeine and L-Theanine among Iranian elite wrestlers: a focus on cognitive and specific physical performance.

  • 2025-09-22
  • Journal of the International Society of Sports Nutrition 22(1)
    • Rouzbeh Razazan
    • Mohammad Hemmatinafar
    • Babak Imanian
    • Nima Jahaniboushehri
    • Rasoul Rezaei
    • Gholamhossein Nazemzadegan

Study Design

Type
Randomized Controlled Trial (RCT)
Population
12 elite male wrestlers (21.8 ± 2.1 years)
Methods
double-blind, placebo-controlled, crossover design, 4 test sessions under randomized conditions: placebo (PLA), caffeine (CAF; 3 mg/kg), L-theanine (THE; 3 mg/kg), and caffeine + L-theanine (CAF+THE; 3 mg/kg each). After 60 minutes, athletes performed the wall-squat test, vertical jump height, medicine ball throw, handgrip strength, and the Specific Wrestling Fitness Test. Cognitive function assessed via Stroop test. Anxiety assessed via STAI.
Blinding
Double-blind

Background

Caffeine is a well-known ergogenic aid that can enhance physical and cognitive performance. However, it often induces side effects, such as anxiety and overstimulation, which can be problematic in high-pressure sports like wrestling. L-theanine, a non-stimulant amino acid found in tea, may help mitigate these effects by promoting a calm yet focused mental state. This study aimed to investigate the acute effects of caffeine, L-theanine, and their combination on physical performance, cognitive function, and anxiety in elite male wrestlers.

Methods

In a double-blind, placebo-controlled, crossover design, 12 elite male wrestlers (21.8 ± 2.1 years) completed four test sessions under randomized conditions: placebo (PLA), caffeine (CAF; 3 mg/kg), L-theanine (THE; 3 mg/kg), and caffeine + L-theanine (CAF+THE; 3 mg/kg each). After 60 minutes, athletes performed the wall-squat test, vertical jump height (VJH), medicine ball throw (MBT), handgrip strength, and the Specific Wrestling Fitness Test (SWFT). Cognitive function was assessed pre- and post-SWFT using a computerized Stroop test. Anxiety was assessed using the State-Trait Anxiety Inventory (STAI), and side effects were recorded.

Results

CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004). SWFT throw count was highest in CAF+THE versus all other conditions (p < 0.001). Post-SWFT Stroop reaction time was faster in CAF+THE than PLA (p = 0.004) and THE (p = 0.036), and accuracy was also higher (p = 0.009 vs PLA). CAF alone increased state anxiety compared to PLA (p = 0.021), while CAF+THE reduced anxiety to below placebo levels (8% incidence vs 33%). Trait anxiety was lower in CAF+THE compared to CAF (p = 0.018). The prevalence of caffeine-induced tachycardia (92%) was notably reduced under CAF+THE (17%).

Conclusion

CAF+THE (3 mg/kg each) enhances elite wrestlers' strength, endurance, cognitive speed, and accuracy while reducing anxiety and physiological side effects commonly associated with caffeine alone. This combination represents a safe, practical supplement strategy for combat sports athletes who must maintain explosive performance and mental control under stress. Coaches are encouraged to trial CAF+THE protocols during training to personalize timing and dosage.

Research Insights

  • L-Theanine→Improved Cognitive Accuracy

    Post-SWFT Stroop reaction time was faster in CAF+THE than PLA (p = 0.004) and THE (p = 0.036), and accuracy was also higher (p = 0.009 vs PLA).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Improved Cognitive Reaction Time

    Post-SWFT Stroop reaction time was faster in CAF+THE than PLA (p = 0.004) and THE (p = 0.036), and accuracy was also higher (p = 0.009 vs PLA).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Improved Grip Strength

    CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Improved Medicine Ball Throw Distance

    CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Improved Vertical Jump Height

    CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Improved Wall-Squat Time

    CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Improved Wrestling Throw Count

    SWFT throw count was highest in CAF+THE versus all other conditions (p < 0.001).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Reduced Anxiety

    CAF+THE reduced anxiety to below placebo levels (8% incidence vs 33%).

    Effect
    Neutral
    Effect size
    Small
    Dose
    3 mg/kg
  • L-Theanine→Reduced Trait Anxiety

    Trait anxiety was lower in CAF+THE compared to CAF (p = 0.018).

    Effect
    Beneficial
    Effect size
    Moderate
    Dose
    3 mg/kg
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