Caffeine

What does the research say?

Research indicates that caffeine can be an effective aid for building muscle mass. Studies have shown that caffeine intake can improve muscular endurance and strength [1] [8] [9] [17] . This improvement is likely due to a combination of factors, including increased motor unit recruitment, reduced perception of effort, and enhanced calcium release in muscle cells [1] [4] [9] . Meta-analyses have reported small to moderate benefits of caffeine on muscle strength, particularly in the upper body [4] . Some research also suggests a nonlinear relationship between caffeine intake and muscle mass, indicating that moderate caffeine consumption may be optimal for muscle growth [16] . Furthermore, caffeine may enhance adaptations to resistance training, such as gains in strength and power [9] .

Tachycardia

An abnormally rapid heart rate [1] .

Heart Palpitations

Feelings of having a rapid, fluttering, or pounding heart [1] .

Anxiety

Feelings of worry, nervousness, or unease, especially about an imminent event or something with an uncertain outcome [1] .

Headaches

Pain in the head, often described as throbbing or aching [1] [4] .

Insomnia

Difficulty falling asleep or staying asleep [1] [4] .

Tremor

Involuntary quivering movement [4] .

Elevated heart rate

An increase in the number of heartbeats per minute [4] .

Abdominal/gut discomfort

Unpleasant sensations in the stomach or intestines [4] .

Muscle soreness

Aching or pain in the muscles, often after exercise [4] .

Inability to verbally communicate and stay focused

Difficulty speaking clearly or focusing on tasks [4] .

Increased systolic blood pressure

An increase in the pressure of blood against the walls of the arteries when the heart beats [13] .

Trouble sleeping

Difficulty falling asleep or staying asleep [16] .

[1] International society of sports nutrition position stand: caffeine and exercise performance.

This review examines the effects of caffeine on various aspects of exercise performance, including muscular endurance, strength, and cognitive function. It concludes that caffeine can enhance performance in a variety of exercise modalities, particularly aerobic endurance, and highlights its benefits for cognitive performance and alertness.

[2] Caffeine and exercise: metabolism, endurance and performance.

This paper reviews the effects of caffeine on exercise metabolism and performance. It discusses caffeine's potential to enhance endurance and suggests that it may not improve maximal oxygen capacity directly but could allow for training at a greater power output or for longer durations.

[3] Caffeine effects on systemic metabolism, oxidative-inflammatory pathways, and exercise performance.

This review explores the effects of caffeine on systemic metabolism, oxidative and inflammatory pathways, and exercise performance. It highlights caffeine's antioxidant and anti-inflammatory actions and its potential to enhance exercise performance by delaying fatigue and improving alertness.

[4] Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis.

This meta-analysis investigates the effects of caffeine on muscle strength and power. It found that caffeine ingestion improves both muscle strength and power, with significant improvements in upper body strength.

[5] Caffeine and creatine use in sport.

This paper reviews the pharmacology and potential mechanisms of action of caffeine and creatine as ergogenic aids in sport. It discusses their potential benefits and considerations for use in athletic populations.

[6] Effects of coffee and caffeine anhydrous on strength and sprint performance.

This study examined the effects of coffee and caffeine anhydrous on strength and sprint performance. It found that neither form significantly improved strength outcomes more than a placebo, but coffee improved leg press 1RM more than caffeine anhydrous.

[7] The neuroprotective effects of caffeine in neurodegenerative diseases.

This review discusses the neuroprotective effects of caffeine in neurodegenerative diseases such as Alzheimer's and Parkinson's. It highlights caffeine's ability to reduce oxidative stress, inflammation, and apoptosis, and improve cognitive function.

[8] The Influence of Caffeine Supplementation on Resistance Exercise: A Review.

This review evaluates the evidence on caffeine supplementation for resistance exercise. It suggests that caffeine increases maximal strength and muscular endurance and may enhance power. It also discusses the potential effects of caffeine on RPE, pain perception, and hormonal responses.

[9] Effects of Caffeine on Resistance Exercise: A Review of Recent Research.

This review summarizes recent research on the effects of caffeine on resistance exercise. It provides evidence that caffeine ingestion is ergogenic for various aspects of resistance exercise performance, including strength, muscular endurance, velocity, and power. It also discusses factors that may modulate caffeine's effects, such as habitual intake and polymorphisms.

[10] Rapid cooling contracture.

This review discusses the phenomenon of rapid cooling contracture (RCC) in muscle fibers. It describes how caffeine can induce Ca2+ release from the sarcoplasmic reticulum, leading to muscle contraction without membrane potential changes.

[11] Coffee and cardiac arrhythmias: Up-date review of the literature and clinical studies.

This review examines the relationship between coffee consumption, caffeine, and cardiac arrhythmias. It discusses the dose-dependent effects of caffeine on the cardiovascular system and its potential to increase the risk of arrhythmias at high doses.

[12] LTE: Does caffeine truly raise muscle carnitine in humans?

This study investigates the potential effects of caffeine on muscle carnitine levels. It suggests that caffeine may stimulate plasma carnitine clearance, but the evidence for increased muscle carnitine levels is uncertain.

[13] The Effects of Caffeine on Jumping Performance and Maximal Strength in Female Collegiate Athletes.

This study examined the effects of caffeine on jumping performance and maximal strength in female collegiate athletes. It found that caffeine significantly improved jumping performance but did not significantly affect maximal isometric strength.

[14] Reply to LTE: Does caffeine truly raise muscle carnitine in humans?

This study is a response to the LTE paper, further exploring the effects of caffeine on muscle carnitine uptake. It found that caffeine ingestion, combined with L-carnitine infusion, resulted in increased plasma carnitine clearance, suggesting a potential increase in muscle carnitine uptake.

[15] Effect of Caffeine Supplementation on Sports Performance Based on Differences Between Sexes: A Systematic Review.

This systematic review examines the effects of caffeine supplementation on sports performance, considering differences between sexes. It concludes that caffeine improves various aspects of performance, particularly in men, and reduces the perception of fatigue.

[16] Caffeine intake is nonlinearly associated with muscle mass in young and middle-aged US adults.

This study investigated the relationship between caffeine intake and muscle mass in a large sample of US adults. It found a nonlinear association, with a W-shaped trend in males and a U-shaped trend in young females, suggesting optimal caffeine intake levels for muscle mass.

[17] Caffeine, but not paracetamol (acetaminophen), enhances muscular endurance, strength, and power.

This study compared the effects of caffeine and paracetamol on muscular endurance, strength, and power. It found that caffeine significantly improved these performance measures, while paracetamol did not.

[18] Ergogenic Effects of Caffeine on Ballistic (Throwing) Performance: A Meta-Analytical Review.

This meta-analysis examines the effects of caffeine on ballistic (throwing) performance. It concludes that caffeine ingestion enhances throwing performance, particularly in terms of throwing velocity.