Espresso coffee increases parasympathetic activity in young, healthy people.

Caffeine induces modifications of activity of the autonomic nervous system. This study analyzed the effect of a cup of espresso coffee on the heart rate variability (HRV) power spectral analysis, which is a method providing evaluation of the sympathetic and parasympathetic discharge. In young, healthy sedentary subjects (10 male, 10 female; aged 25-30 years), the HRV-power spectrum was evaluated over a period of 150 min after the administration of espresso coffee (caffeine, 75 mg) or decaffeinated coffee (caffeine, < 18 mg) in supine and seated position. Absolute values of the spectrum were summed in low (LF) and high frequencies (HF). The LF and HF spectra were used to estimate the sympathetic and parasympathetic activity, respectively. In the supine position, coffee increases HF, while decaffeinated coffee causes little modifications of HF. In the seated position, HF is not modified by coffee or decaffeinated coffee. Coffee and decaffeinated coffee do not induce any modification of LF in both positions. This experiment indicates that espresso coffee influences parasympathetic activity in the supine position.