Effect of a Commercially Available Low-Dose Capsaicin Supplement on Knee Extensor Contractile Function

Area of Science:

• Exercise Physiology
• Nutritional Science
• Skeletal Muscle Physiology

Background:

• Capsaicin, the active compound in chili peppers, influences physiological systems, including skeletal muscle.
• Understanding capsaicin's effects on muscle performance is crucial for optimizing exercise and training protocols.

Purpose of the Study:

• To investigate if a 1.2 mg chewable capsaicin supplement enhances isokinetic knee extensor contractile performance.
• To assess the impact of capsaicin on muscle strength, endurance, and fatigue.

Main Methods:

• Randomized, single-blind crossover study with nine recreationally active participants.
• Isokinetic knee extensor assessments conducted 45 minutes after ingesting capsaicin or placebo.
• Comparison of peak torque (strength), summed torque (endurance), and fatigue index.

Main Results:

• Significantly greater knee extensor peak torque observed with capsaicin (126.0 N·m⁻¹) versus placebo (118.8 N·m⁻¹).
• No significant differences in summed torque or fatigue index between capsaicin and placebo trials.
• Effect size (d) indicated a moderate to large effect for peak torque.

Conclusions:

• Pre-exercise capsaicin ingestion may enhance knee extensor muscle strength.
• Capsaicin supplementation did not significantly affect skeletal muscle endurance or fatigue parameters in this study.
• Further research with larger, diverse populations is warranted to confirm these findings.