From the Guidelines
Increasing caffeine intake to 700mg daily can significantly increase the risk of muscle twitching, as it exceeds the recommended maximum daily intake of 400mg for healthy adults. This amount can cause various side effects, including muscle fasciculations or twitches, due to caffeine's stimulation of the central nervous system and increased nerve excitability, leading to involuntary muscle contractions 1. At high doses like 700mg, caffeine can also cause other related symptoms such as jitteriness, anxiety, heart palpitations, insomnia, and gastrointestinal distress.
The FDA recommends limiting caffeine intake to 400mg/d, and pregnant women are advised to consume no more than 200mg caffeine/d 1. Additionally, adolescent and child caffeine consumption should not exceed 2.5mg · kg body weight–1 · d–1. The evidence suggests that consumption of ≤400mg caffeine/d in healthy adults is not associated with adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status 1. However, high caffeine intakes, such as 700mg, may increase the risk of anxiety and withdrawal symptoms, particularly in children and adolescents.
Some key points to consider:
- Caffeine stimulates the central nervous system, increasing nerve excitability and leading to involuntary muscle contractions.
- High doses of caffeine, such as 700mg, can cause symptoms like jitteriness, anxiety, heart palpitations, insomnia, and gastrointestinal distress.
- Individual sensitivity to caffeine varies based on factors like body weight, medication use, and genetic differences in caffeine metabolism.
- Reducing caffeine intake gradually rather than stopping suddenly is recommended to avoid withdrawal symptoms.
Overall, it is recommended to limit caffeine intake to 400mg/d or less to minimize the risk of muscle twitching and other adverse effects. If you're experiencing muscle twitches from high caffeine consumption, reducing your intake gradually is advised to avoid withdrawal symptoms 1.
From the Research
Caffeine Intake and Muscle Twitching
- Increasing caffeine intake to 700mg may increase the risk of muscle twitching, as high doses of caffeine can cause caffeine poisoning (caffeinism), which includes symptoms such as anxiety, agitation, insomnia, and gastrointestinal disorders 2.
- However, the relationship between caffeine intake and muscle twitching is not well-established, and more research is needed to fully understand the effects of high doses of caffeine on muscle function.
Caffeine and Muscle Contractility
- Studies have shown that toxic doses of caffeine are required to increase muscle contractility, suggesting that the ergogenic effect of caffeine on neuromuscular function may be limited to high doses 3.
- Caffeine has been shown to increase maximal voluntary activation at a supraspinal level, but it does not alter the force-EMG relationship or motor unit firing rates 4.
- Caffeine may also augment tension production in diaphragmatic muscle by a direct effect on the processes that activate contraction, but it may impair neuromuscular transmission at high stimulus frequencies 5.
Caffeine and Muscle Fatigue
- Caffeine has been shown to affect muscle fatigue in both fast-twitch and slow-twitch muscles, with different effects at different temperatures and twitch rates 6.
- Caffeine may convert activity-induced shortening of half-relaxation times into prolongations, and it may reduce treppe amplitude and duration in fast-twitch muscles while accelerating twitch tension decline in slow-twitch muscles.
- However, the effects of caffeine on muscle fatigue are complex and depend on various factors, including the type of muscle, temperature, and twitch rate.