Caffeine has many performance-enhancing effects, according to a January 2019 paper in Sports Medicine. This readily available stimulant increases endurance and strength, but it has no meaningful effect on muscle growth.
Coffee and Muscles
Caffeine and coffee appear to have a similar impact on your workout when the coffee features an equal amount of caffeine as the caffeine supplement, according to the authors of an April 2013 report in PLoS One who tested eight cyclists. Thus, no other ingredient of coffee seems to affect exercise performance.
It's best to drink coffee about an hour before your workout and keep the caffeine dose below 9 milligrams for each kilogram you weigh. Larger doses of caffeine can cause side effects like insomnia. Pregnant women should consult a doctor before drinking coffee as caffeine can have negative effects on an unborn child.
A September 2016 paper in the European Journal of Sport Science documents the performance-enhancing effects of coffee. These researchers tested 54 fit men using a weightlifting and cycling challenge. Ingesting coffee with 300 milligrams of caffeine in it prevented fatigue during repeated cycling sprints.
The authors of a similar study in the July 2018 edition of the International Journal of Sports Physiology and Performance tested 13 runners and showed that ingesting coffee with 3 milligrams per kilogram in it can make you faster. Compared to decaffeinated coffee, drinking coffee caused a 1.3 percent decrease in the time needed for the men to complete a 1.6-kilometer race.
Coffee can also have a positive effect on delayed-onset muscle soreness, in addition to increasing performance. This finding means that coffee has both immediate and delayed effects.
A November 2013 article in the Journal of Strength and Conditioning Research illustrates this dual role. Nine healthy men received either caffeine or a placebo right before completing an intense bout of biceps curls. These researchers used a dose of caffeine equal to about two and a half cups of coffee. This treatment both increased their exercise capacity during the test and decreased their muscle soreness after the test.
Caffeine and Muscle Mass
Some people lift weights to gain muscle mass. According to an August 2015 article from the National Academy of Sports Medicine, the principle of adaption states that repeatedly challenging your body will result in increases in muscle strength and size. Trainers call these increases in muscle size hypertrophy.
The authors of a June 2017 report in Applied Physiology, Nutrition, and Metabolism expressed concern that caffeine might interfere in this process. A November 2016 paper in the African Journal of Traditional, Complementary, and Alternative Medicines describes a test of this hypothesis. These researchers had 24 healthy, younger adults ingest caffeine or placebo during a week-long period of exercise. They then crossed over into the opposite condition during a second week of exercise. The results indicated that caffeine intake caused an increase of interleukin 6. The scientists interpreted this result as showing an anabolic effect of caffeine.
Interestingly, a June 2016 report in Journal of the International Society of Sports Nutrition showed a similar anabolic effect in 21 men given caffeine, apple and peat during 12 weeks of resistance training.
Caffeine and Performance
Yet the anabolic properties of caffeine don't seem very robust. The authors of the June 2017 report in Applied Physiology, Nutrition, and Metabolism couldn't find an anabolic effect of caffeine in laboratory animals. Thus, you should instead take advantage of the indirect effects of caffeine. A March 2019 paper in the British Journal of Sports Medicine showed that these effects include increases in muscle endurance, muscle strength, anaerobic power and aerobic endurance.
You can use those performance-enhancing effects to increase your muscle mass. The authors of a June 2012 article in the International Journal of Sport Nutrition and Exercise Metabolism tested 16 subjects and showed that caffeine motivates people to do more exercise — especially during sleep deprivation. This increase in training volume will likely increase your muscle mass, according to a June 2017 report in the Journal of Sports Sciences. These researchers demonstrated a dose-response relationship between training volume and muscle mass. The more you workout, the more muscle mass you will gain.
Caffeine increases systolic blood pressure, according to the January 2019 paper in Sports Medicine. A February 2017 article in the Journal of Hypertension and Cardiology stated that exercise can have a similar effect. Thus, combining caffeine and exercise might cause heart problems — especially in people with high blood pressure. It's important, therefore, to speak with your doctor before starting an exercise program or ingesting caffeine. That way you can keep a positive relationship between coffee and muscles.
- Brigham Young University: "Effect of Caffeine on Skeletal Muscle Growth"
- Sports Medicine: "Influence of Caffeine Supplementation on Resistance Exercise"
- PLoS One: "Metabolic and Performance Effects of Caffeine Compared to Coffee During Endurance Exercise"
- European Journal of Sport Science: "Effects of Coffee and Caffeine Anhydrous on Strength and Sprint Performance"
- International Journal of Sports Physiology and Performance: "Coffee Ingestion Enhances 1-Mile Running Race Performance"
- Journal of Strength and Conditioning Research: "Effect of Caffeine Ingestion on Delayed Onset Muscle Soreness"
- National Academy of Sports Medicine: "Back to the Basics: Hypertrophy"
- Applied Physiology, Nutrition, and Metabolism: "Effect of Caffeine on Skeletal Muscle Anabolic Signaling and Hypertrophy"
- African Journal of Traditional, Complementary and Alternative Medicines: "Effect of Caffeine Supplementation on Trained Individuals Subjected to Maximal Treadmill Test"
- Journal of the International Society of Sports Nutrition: "Twelve Weeks Supplementation With an Extended-Release Caffeine and ATP-Enhancing Supplement May Improve Body Composition Without Affecting Hematology in Resistance-Trained Men"
- British Journal of Sports Medicine: "Wake Up and Smell the Coffee"
- International Journal of Sport Nutrition and Exercise Metabolism: "Acute Caffeine Ingestion's Increase of Voluntarily Chosen Resistance-Training Load After Limited Sleep"
- Journal of Sports Sciences: "Dose-Response Relationship Between Weekly Resistance Training Volume and Increases in Muscle Mass"
- Journal of Hypertension and Cardiology: "Rate Pressure Product Responses During an Acute Session of Isometric Resistance Training"