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Low doses of caffeine reduce heart rate during submaximal cycle ergometry.

McClaran SR, Wetter TJ - J Int Soc Sports Nutr (2007)

Bottom Line: After thirty minutes of rest, a warm-up (30 Watts for 2 min) the pedal rate of 60 rpm was maintained at a steady-state output of 60 watts for five minutes; increased to 120 watts for five minutes and to 180 watts for five minutes.Systolic blood pressure (BP) was measured at rest and during each of the three sub-maximal steady state power outputs.BP was significantly higher (p < 0.05) at rest and after the 3 mg/kg caffeine vs placebo (116 +/- 13 vs 123 +/- 10 mm Hg).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Kinesiology& Health, University of Wisconsin Oshkosh, Oshkosh, WI 54901, USA. mcclaran@uwosh.edu.

ABSTRACT

Background: The purpose of this study was to examine the cardiovascular effects of two low-levels of caffeine ingestion in non habitual caffeine users at various submaximal and maximal exercise intensities.

Methods: Nine male subjects (19-25 yr; 83.3 +/- 3.1 kg; 184 +/- 2 cm), underwent three testing sessions administered in a randomized and double-blind fashion. During each session, subjects were provided 4 oz of water and a gelatin capsule containing a placebo, 1.5 mg/kg caffeine, or 3.0 mg/kg caffeine. After thirty minutes of rest, a warm-up (30 Watts for 2 min) the pedal rate of 60 rpm was maintained at a steady-state output of 60 watts for five minutes; increased to 120 watts for five minutes and to 180 watts for five minutes. After a 2 min rest the workload was 180 watts for one minute and increased by 30 watts every minute until exhaustion. Heart rate (HR) was measured during the last 15-seconds of each minute of submaximal exercise. Systolic blood pressure (BP) was measured at rest and during each of the three sub-maximal steady state power outputs. Minute ventilation (VE), Tidal volume (VT), Breathing frequency (Bf), Rating of perceived exertion (RPE), Respiratory exchange ratio (RER), and Oxygen consumption (VO2) were measured at rest and during each minute of exercise.

Results: Caffeine at 1.5 and 3.0 mg/kg body weight significantly lowered (p < 0.05) HR during all three submaximal exercise intensities compared to placebo (range - 4 to 7 bpm lower) but not at rest or maximal exercise. BP was significantly higher (p < 0.05) at rest and after the 3 mg/kg caffeine vs placebo (116 +/- 13 vs 123 +/- 10 mm Hg). Neither dose of caffeine had any effect on BP during submaximal exercise. Caffeine had no effect on VE, VT, VO2, RPE, maximal power output or time to exhaustion.

Conclusion: In non habitual caffeine users it appears that consuming a caffeine pill (1.5 & 3.0 mg/kg) at a dose comparable to 1-3 cups of coffee lowers heart rate during submaximal exercise but not at near maximal and maximal exercise. In addition, this caffeine dose also only appears to affect systolic blood pressure at rest but not during cycling exercise.

No MeSH data available.


Related in: MedlinePlus

Systolic blood pressure at rest and during exercise. Differences in Systolic blood pressure between placebo and caffeine trials. Placebo, 1.5 and 3.0 represent dose of caffeine in mg·kg body weight-1. Values are listed as mean ± SE. * = the mean difference compared to placebo is significant (p < 0.05)
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Figure 2: Systolic blood pressure at rest and during exercise. Differences in Systolic blood pressure between placebo and caffeine trials. Placebo, 1.5 and 3.0 represent dose of caffeine in mg·kg body weight-1. Values are listed as mean ± SE. * = the mean difference compared to placebo is significant (p < 0.05)

Mentions: The mean BP responses for rest and the three submaximal intensities are displayed in Figure 2. Resting systolic BP was significantly higher (p < 0.05) after the CAF3 dose vs placebo trial (116 ± 13 mmHg vs 123 ± 10 mmHg). Neither dose of caffeine had any effect on BP during submaximal exercise.


Low doses of caffeine reduce heart rate during submaximal cycle ergometry.

McClaran SR, Wetter TJ - J Int Soc Sports Nutr (2007)

Systolic blood pressure at rest and during exercise. Differences in Systolic blood pressure between placebo and caffeine trials. Placebo, 1.5 and 3.0 represent dose of caffeine in mg·kg body weight-1. Values are listed as mean ± SE. * = the mean difference compared to placebo is significant (p < 0.05)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2164943&req=5

Figure 2: Systolic blood pressure at rest and during exercise. Differences in Systolic blood pressure between placebo and caffeine trials. Placebo, 1.5 and 3.0 represent dose of caffeine in mg·kg body weight-1. Values are listed as mean ± SE. * = the mean difference compared to placebo is significant (p < 0.05)
Mentions: The mean BP responses for rest and the three submaximal intensities are displayed in Figure 2. Resting systolic BP was significantly higher (p < 0.05) after the CAF3 dose vs placebo trial (116 ± 13 mmHg vs 123 ± 10 mmHg). Neither dose of caffeine had any effect on BP during submaximal exercise.

Bottom Line: After thirty minutes of rest, a warm-up (30 Watts for 2 min) the pedal rate of 60 rpm was maintained at a steady-state output of 60 watts for five minutes; increased to 120 watts for five minutes and to 180 watts for five minutes.Systolic blood pressure (BP) was measured at rest and during each of the three sub-maximal steady state power outputs.BP was significantly higher (p < 0.05) at rest and after the 3 mg/kg caffeine vs placebo (116 +/- 13 vs 123 +/- 10 mm Hg).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Kinesiology& Health, University of Wisconsin Oshkosh, Oshkosh, WI 54901, USA. mcclaran@uwosh.edu.

ABSTRACT

Background: The purpose of this study was to examine the cardiovascular effects of two low-levels of caffeine ingestion in non habitual caffeine users at various submaximal and maximal exercise intensities.

Methods: Nine male subjects (19-25 yr; 83.3 +/- 3.1 kg; 184 +/- 2 cm), underwent three testing sessions administered in a randomized and double-blind fashion. During each session, subjects were provided 4 oz of water and a gelatin capsule containing a placebo, 1.5 mg/kg caffeine, or 3.0 mg/kg caffeine. After thirty minutes of rest, a warm-up (30 Watts for 2 min) the pedal rate of 60 rpm was maintained at a steady-state output of 60 watts for five minutes; increased to 120 watts for five minutes and to 180 watts for five minutes. After a 2 min rest the workload was 180 watts for one minute and increased by 30 watts every minute until exhaustion. Heart rate (HR) was measured during the last 15-seconds of each minute of submaximal exercise. Systolic blood pressure (BP) was measured at rest and during each of the three sub-maximal steady state power outputs. Minute ventilation (VE), Tidal volume (VT), Breathing frequency (Bf), Rating of perceived exertion (RPE), Respiratory exchange ratio (RER), and Oxygen consumption (VO2) were measured at rest and during each minute of exercise.

Results: Caffeine at 1.5 and 3.0 mg/kg body weight significantly lowered (p < 0.05) HR during all three submaximal exercise intensities compared to placebo (range - 4 to 7 bpm lower) but not at rest or maximal exercise. BP was significantly higher (p < 0.05) at rest and after the 3 mg/kg caffeine vs placebo (116 +/- 13 vs 123 +/- 10 mm Hg). Neither dose of caffeine had any effect on BP during submaximal exercise. Caffeine had no effect on VE, VT, VO2, RPE, maximal power output or time to exhaustion.

Conclusion: In non habitual caffeine users it appears that consuming a caffeine pill (1.5 & 3.0 mg/kg) at a dose comparable to 1-3 cups of coffee lowers heart rate during submaximal exercise but not at near maximal and maximal exercise. In addition, this caffeine dose also only appears to affect systolic blood pressure at rest but not during cycling exercise.

No MeSH data available.


Related in: MedlinePlus