Abstract
Caffeine is considered a widely consumed natural and legal psychoactive stimulant with several effects on the body. The present study attempted to investigate the effects of caffeine consumed before and after a physical exercise on cardiovascular and cardiorespiratory functions in healthy adults. 36 healthy adult males were recruited and randomly allocated to one of the three (3) groups: group I (exercise without caffeine consumption), group II (caffeine beverage intake before exercise), and group III (caffeine beverage intake immediately after exercise). The heart rate (HR), QTc interval, blood pressure (BP), respiratory rate (RR), oxygen consumption (VO₂), and carbon dioxide emission (VCO₂) were measured at 0, 5, 10, and 15 min after the exercise. We observed a significant difference in all measured outcomes during the different recovery times in all the groups (p < 0.05). HR, RR, SBP, VO2, and VCO2 gradually decreased with time, DBP contrarily increased with time, and the QTc showed an irregular pattern. We can affirm that ingestion of caffeine before and after moderate aerobic exercise slows down the parasympathetic stimulation, heart rate recovery, and the recovery of HR and QTc with no major effects on BP, RR, VO₂, and VCO₂ in healthy adult men.
Highlights
Caffeine is one of the most consumed psychoactive substances in the world and is closely linked to a human’s life
The systolic blood pressure (SBP), diastolic blood pressure (DBP), and the QTc interval showed significant differences at 0, 5, 10, and 15 minutes in all the three (3) groups (p < 0:05) with SBP gradually decreasing with time but DBP increasing as time passed
Comparison of SBP and DBP values between groups did not show any significant difference at all the measurement times 0, 5, 10, and 15 minutes (p > 0:05) contrary to the QTc interval which showed a significant difference between groups at different measurement times (p < 0:05)
Summary
Caffeine is one of the most consumed psychoactive substances in the world and is closely linked to a human’s life. People usually consume caffeine in various ways in their daily lives, and it is commonly supplied from coffee beans and present in several beverages, such as tea, energy drinks, and soda [1]. According to a study conducted by Kim et al (2020), quantity of coffee consumed by Korean adults was five times higher than milk and more than ten times higher than carbonated drinks. 3~10% of caffeine and metabolites are known to be excreted by urine and to decrease by 50~75% within 3 to 6 hours after caffeine intake. The autonomous system consists of sympathetic and parasympathetic nerves that reach the heart. The initial increase in the heart rate after a physical activity is determined by the increase in sympathetic activity and decrease in parasympathetic activity.
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