title: Similarity between coffee effects and qi-stimulating events.
abstract: OBJECTIVE
  Previously, we found that qi-stimulating events exerted similar frequency-specific effects on the blood pressure pulse spectrum. Because coffee and qi induce similar stimulatory psychological responses, we aimed to determine whether they would induce similar pulse effects. Such a relationship would suggest a close linkage between the physiologic mechanisms underlying the psychostimulatory responses and vascular effects of coffee and qi. Therefore, the profound investigations into the mechanisms underlying the effects of coffee on the central nervous system and the vascular system may help to elucidate the underlying physiology mechanisms of qi.
  
  
  METHODS
  Each test subject took three rounds of 150 mL coffee (0.1 g/kg, 0.05 g/kg, 0.05 g/kg) in a 30-minute interval. The subject's pulses were recorded at the end of each round. The changes in the test subject's pulse spectrum between before and after coffee consumption were compared with changes induced by a water placebo.
  
  
  RESULTS
  Both coffee and qi caused the intensities of the third, sixth, and ninth harmonics of the pressure pulse spectrum to be relative peaks to their neighboring harmonics.
  
  
  CONCLUSIONS
  Our results suggest that the coffee effect may be considered a qi-stimulating event, and there is a common physiologic factor determining the psychostimulatory responses of qi and coffee as well as their effects on the cardiovascular system, which results in a specific frequency pattern in the blood pulse spectrum. Adenosine, which is the main physiologic compound affected by coffee, might also be the key factor affected by qi.
authors.affiliation: Biophysics Laboratory, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China.
authors.forename: Tse Lin
authors.initials: TL
authors.lastname: Hsu
authors.forename: Jian Guo
authors.initials: JG
authors.lastname: Bau
authors.forename: Wei Kung
authors.initials: WK
authors.lastname: Wang
authors.forename: Sai Ping
authors.initials: SP
authors.lastname: Li
authors.forename: Yuh Ying Lin
authors.initials: YY
authors.lastname: Wang
mesh_terms: D000328:Adult; D002110:Caffeine / Q000008:administration & dosage*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D003069:Coffee; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D008297:Male; D011674:Pulse; D019413:Qi; D012016:Reference Values; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D003069:Coffee; D002110:Caffeine