Neuromuscular responses to incremental caffeine doses: performance and side effects

Area of Science:

• Exercise Physiology
• Nutritional Science
• Sports Performance

Background:

• Caffeine is a widely used ergogenic aid.
• Its effects on neuromuscular performance are dose-dependent.
• Optimal dosing for different types of resistance exercise remains unclear.

Purpose of the Study:

• To determine the specific oral caffeine dose required to enhance muscle force and power output during single, all-out multijoint movements.
• To investigate the dose-response relationship between caffeine intake and neuromuscular performance.

Main Methods:

• Thirteen resistance-trained men participated in a randomized, double-blind, crossover study.
• Participants ingested placebo or caffeine at 3, 6, or 9 mg/kg body weight.
• Muscle strength and power were assessed during free-weight squats and bench presses at various loads, and via a cycling power test.

Main Results:

• Caffeine significantly increased propulsive velocity at lower loads (25-50% 1RM) across all doses.
• Higher doses (9 mg/kg) were necessary to enhance power output at heavy loads (90% 1RM) and cycling peak power.
• Adverse side effects increased significantly with the 9 mg/kg dose.

Conclusions:

• The ergogenic dose of caffeine for neuromuscular enhancement is load-dependent.
• 3 mg/kg caffeine improves high-velocity actions against low loads.
• 9 mg/kg caffeine is needed for high-load performance but increases adverse effects.