The effect of medium- and high- dose of caffeine (1,3,7-trimethylxanthine) intake on cardiovascular factors response at baseline and following one-bout aerobic exercise

Caffeine is a naturally occurring substance that is widely consumed in a variety of forms. However, today the results of some scientific data on conflicting effects of caffeine compound on cardiovascular factors have been reported. The purpose of the present study was conducted to identify the effect of different doses caffeine intake on some functional cardiovascular indices response in male volleyball players. Thirty male volleyball players (age 21.47±1.45 years, body fat 10.47±3.11 %, and BMI 23.15±1.26 kg.m2) were allocated equally into three groups (n=10): supplement groups (Caffeine intake: 6 or 9 mg.kg-1) and placebo group (Dextrose intake: 6 mg.kg-1). 45-min after the supplementation, subjects were participated in a one-bout exercise protocol (running on a treadmill for 30 minutes with intensity of 65-75% heart rate reserve). Changes in heart rate and blood pressure (systolic and diastolic pressure) along were determined in three phases (before and 45 min after the supplementation and immediately after the aerobic exercises). The data were analyzed by repeated measure ANOVA, bonferroni and independent T test at α≤0.05. The results showed that the different doses of caffeine ingestion had leading to significant decreased heart rate (P=0.001) and increased the blood pressure indices on the basal (P=0.024). However, heart rate and blood pressure index was significantly increased in all groups after exercise without differences between groups (P≤0.05). Therefore, it can be concluded that medium- and high- dose of caffeine intake has the same effect on variation range of cardiovascular indices after exercise.