Effect of caffeine on LT, VT and HRVT

Area of Science:

• Exercise Physiology
• Autonomic Nervous System Function
• Nutritional Supplementation

Background:

• Caffeine is known for its central nervous system stimulant effects.
• Autonomic control influences physiological markers such as ventilatory threshold and heart rate variability.
• The impact of caffeine on these specific thresholds during exercise remains to be fully elucidated.

Purpose of the Study:

• To investigate the influence of caffeine on lactate, ventilatory, and heart rate variability thresholds.
• To assess caffeine's effect on physiological responses during progressive exercise.

Main Methods:

• A randomized, placebo-controlled, double-blind study design was employed.
• Ten healthy adults completed graded maximal cycle ergometry tests.
• Tests were conducted with and without caffeine (5 mg·kg⁻¹), measuring gas exchange, blood lactate, and heart rate variability.

Main Results:

• At rest, caffeine significantly increased blood lactate, oxygen consumption, carbon dioxide production, and minute ventilation.
• Resting heart rate variability showed increased coefficient of variation with caffeine, but other indices had non-significant changes.
• During progressive exercise, only minute ventilation was significantly higher with caffeine; lactate and heart rate variability thresholds were not significantly different.

Conclusions:

• Lactate, ventilatory, and heart rate variability thresholds demonstrate robustness against a physiological dose of caffeine.
• Caffeine's primary effects on these thresholds appear minimal during progressive exercise, despite resting metabolic and autonomic changes.