Studies related to and

Caffeine Ingestion Reverses The Circadian Rhythm Effects On Neuromuscular Performance In Highly Resistance-trained Men

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 12
Gender Male
Age Range 18-29, 30-44
Body Types Trained
Notes for this study:
Power output in moderately trained men normally decreases in the AM relative to the PM. Caffeine ingestion at 3mg/kg bodyweight was able to reverse the reduction in power in the AM relative to training in the PM, and equalize performance at both times.

Dose Response Effects Of A Caffeine-containing Energy Drink On Muscle Performance: A Repeated Measures Design

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 12
Gender Both Genders
Age Range 18-29, 30-44
Body Types Trained, Average
Notes for this study:
In 12 active and healthy participants (light caffeine consumers at less than 60mg daily), an intake of a caffeinated energy drink (compared to placebo, the same energy drink but not caffeinated) was able to increased blood pressure and heart rate at rest without significantl affecting metabolic rate up to 3mg/kg bodyweight.

Power output, as measured by half-squat and bench, was increased only at 3mg/kg bodyweight with no significant influence at 1mg/kg.

Effect Of Two Doses Of Caffeine On Muscular Function During Isokinetic Exercise

Effect Increase
Trial Design Cohort
Trial Length 24 hours
Number of Subjects 15
Gender Male
Age Range 18-29
Body Types Trained, Overweight, Average
Notes for this study:
Via a single-blind crossover design, caffeine was given to active men at a dose of either 2mg/kg or 5mg/kg bodyweight; maximal torque and power as well as total volume were assessed. Caffeine was able to significantly increase performance by 5-8% in the 5mg/kg group, but no significant change was seen with 2mg/kg.

Effect Of Two Doses Of Caffeine On Muscular Function During Isokinetic Exercise

Effect None
Trial Design Cohort
Trial Length 24 hours
Number of Subjects 15
Gender Male
Age Range 18-29
Body Types Trained, Overweight, Average
Notes for this study:
Via a single-blind crossover design, caffeine was given to active men at a dose of either 2mg/kg or 5mg/kg bodyweight; maximal torque and power as well as total volume were assessed. Caffeine was able to significantly increase performance by 5-8% in the 5mg/kg group, but no significant change was seen with 2mg/kg.

Caffeine And Sprinting Performance: Dose Responses And Efficacy

Effect None
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 17
Gender Male
Age Range 18-29
Body Types Trained, Average
Notes for this study:
Caffiene was dosed at 2,4,6,8 and 10mg/kg bodyweight in a double-blind manner 1 hour before sprinting exercises on an erg bike.

Caffine was unable to increase time to peak power, peak power output, or average power during sprints relative to placebo and noted a reduction in blood lactate levels.

Caffeine Supplementation And Multiple Sprint Running Performance

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 21
Gender Male
Age Range 18-29
Body Types Trained, Average
Notes for this study:
21 trained men were subject to an intermittent sprint protocol of 12 separate 30m sprints separated by 35 seconds, and one group ingested 5mg/kg bodyweight caffeine 1 hour before the test.

Maximum speed increased in the caffeine group, being 1.4% quicker than placebo, and heart rate was elevated on average 3.4BPM greater than placebo subject to the same training.

Effects Of Caffeine On Prolonged Intermittent-sprint Ability In Team-sport Athletes

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 10
Gender Male
Age Range 18-29
Body Types Trained, Average
Notes for this study:
The testing protocol was in trained athletes, with 4 second sprints separated by a 2 minute active recovery at 35% VO2 max. 18 of these sprints were conducted per half, and two halves were done with a break in between.

Caffeine group had greater peak power achieved during the sprints (7% in the first half, 6.6% in the second half) and did a greater total volume of work (8.5% in the first half, 7.6% in the second).

Dose Effect Of Caffeine On Testosterone And Cortisol Responses To Resistance Exercise

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 24
Gender Male
Age Range 18-29, 30-44
Body Types Trained, Overweight
Notes for this study:
At doses of 200,400,600 and 800mg caffeine before resistance training testosterone was increased in all groups yet most significantly (15+/-19%) at the 800mg dose.

Cortisol was increased in all groups with high variability, only the 800mg group had a statistically significant increase in cortisol at 52+/-44%

Power output was also increased, most significantly in the 800mg group.

Acute Caffeine Ingestion Increases Voluntarily Chosen Resistance Training Load Following Limited Sleep

Effect Increase
Trial Design Double blind
Trial Length n/a
Number of Subjects 16
Gender Male
Age Range 18-29, 30-44
Body Types Trained, Overweight, Average
Notes for this study:
Supplementation of 4mg/kg caffeine in elite athletes with minor sleep deprivation was able to significantly increase power output and training volume relative to sleep deprived placebo, and the increase in power output seems to be comparable to that seen in the non-sleep deprived state.

There was an increase in testosterone during exercise that was larger in the sleep normalized caffeine group (12.9%) than the sleep deprived caffeine group (6.4%), and an increase in cortisol reached 21.3% in the group given caffeine and had good sleep.