Effect of caffeine dose on heart rate variability, rate pressure product and some fatigue indexes after endurance exercise in trained men

Caffeine increases the activity of the sympathetic nervous system in healthy people, changes in the nervous system can be assessed using heart rate variability. The aim of this study was to evaluate the effect of caffeine dose on the recovery of some indicators of the autonomic nervous system after endurance activity.

Subjects were referred to the laboratory in 3 separate sessions with an interval of at least 3 and a maximum of 6 days of wash-out. In the laboratory, after 15 minutes in a sitting position, HR, SBP, DBP, and HRV were measured and after eating the same breakfast containing 540 kcal capsules containing doses of 6 and 9 mg/kg body weight of caffeine or placebo. They received 300 ml of water with the single-blind method.

Exercise Physiology Laboratory, Faculty of Physical Education and Sports Sciences, Guilan University. After supplementation to maximize caffeine concentration in the blood, subjects were seated for 35 minutes. Immediately after that, they started running on a treadmill for 12 minutes, equivalent to 75% of the maximum oxygen consumption. After the activity, there was a 60-minute recovery phase in which HRV levels were recorded at 10-minute intervals.

Men trained with VO2max at least 50 with a history of at least 2 years of regular exercise, with good body composition, no history of acute and chronic diseases, no history of smoking, no cardiovascular problems, no anabolic steroids or central nervous system stimulant And other sports supplements in the last 6 months

Caffeine dose groups of 6 and 9 mg/kg body weight

Parameters related to heart rate variability (RMSSD and LF/HF), systolic and diastolic blood pressure, myocardial oxygen cost, RPP, pain sensation

Use the random selection method by Excel software. In this method, we first enter the names of the subjects in Excel, and then in another part, we specify the position of the desired groups in two separate sections of 6 subjects. Then in these two sections, we will execute the following code so that people are randomly placed in groups of 6 subjects. =INDEX($A$3:$A$12,RANDBETWEEN(1,ROWS($A$3:$A$12)),1)

In this study, subjects were not aware of how caffeine or placebo was distributed. The determined amount of supplement and placebo was weighed for each subject separately and was delivered to the subjects by coding by the laboratory operator on each day of the test.

After analyzing the data, only part of the data related to the main outcome will be shared.

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