Caffeine and Nitrates

Caffeine mechanism: adenosine receptor antagonism

Caffeine blocks adenosine receptors in the brain, reducing perceived effort and improving cognitive function.

Caffeine mechanism: mobilization of intracellular calcium

Caffeine enhances muscle function (contraction) by increasing Ca²⁺ release from sarcoplasmic reticulum.

Caffeine mechanism: catecholamine augmentation and glycogen sparing

Caffeine increases heart rate, blood pressure, and energy availability.

It also increases serum free fatty acids and use of muscle triglycerides by stimulating lipolysis and FFA mobilization, spares glycogen.

Caffeine mechanism: Roel in mTORcI pathway

Caffeine inhibits mTOR activity

What are the psychological effects of caffeine?

Enhance alertness, attention, reaction time, mood, vigilance, and overall cognitive function.

What is an effective dose of caffeine when subjects are mentally fatigued?

200 mg can enhance vigilance during bouts of extended exhausted exercise, as well as periods of sustained sleep deprivation

What are the consequences of large doses (>400 mg) of caffeine?

Increase nervousness and anxiety, impair performance in sports requiring fine motor skills and rapid processing of visual stimuli.

What is the effect of caffeine on ratings of perceived exertion (RPE)?

Caffeine reduced RPE during exercise by 5.6% while improving performance by 11.2%.

Decreased RPE could account for approximately 29% of the improved performance.

What are the effects of caffeine on endurance?

Positive effects on mean power output and endurance time trials.

What are the effects of caffeine on high-intensity anaerobic exercise?

Unclear due to flawed study designs and untrained subjects, but there might be sport-specifc prolonged duration (basketball, soccer, rugby).

Caffeine also has an ergogenic effect on those who don’t consume caffeine.

What are the effects of caffeine on muscular strength?

Positive effects on resistance training.

What does individual variability mean in terms of caffeine?

Some people might have a fast-metabolizing gene for caffeine while some may be more prone to possible adverse effects of carfeine as a potent stimulant because of genetic variations. Different variations of the CYP1A2 gene can mean they are fast metabolizers or slow metabolizers of caffeine.

What is the best practice for caffeine timing?

Consume 60 min prior to event, benefits may be seen within 15 min.

Dosage should be 3-6 mg/kg of body weight

Is caffeine regarded as a safe drug?

Yes, most professional health organizations note it as so!

What is a “moderate caffeine dosage?”

200-300 mg/day

This is about the same as about two 6-8 oz cups of coffee.

What are nitrates?

Supplements or ergogenic aids that increase nitric oxide and have a short half life, meaning that it aids in rapid metabolization.

What are the two major pathways of NO formation?

L-Arginine Pathway

• Conversion of NO → NO₂^- → NO₃^-

• High oxygen level

• Converts amino acid L-argenine using enzymes

Dietary Pathway

• Conversion of NO₃^-→ NO₂^- → NO

• Low oxygen level

• Produces NO from inorganic nitrate from leafy greens

What are the potential benefits of nitrates (aka beet root juice)?

• Improve blood flow (vasodilation)

• Reduces blood pressure

• Healthier skin

• Increase muscle strength and power

• Increase time to exhaustion

What are some sources of nitrates?

• Juice

• Pills

• Vegetables

  • Beets

  • Spinach

  • Broccoli

  • Brussel sprouts

How does nitric oxide decrease blood pressure?

Causes vascular vasodilation → increased blood flow → decreased blood pressure

What does supplementation of nitrate NO₃^- do?

Can produce nitrite NO₂^- and subsequently NO.

What do studies show about supplementing nitrates?

• In a cycle time trial, those consuming beet root juice had a longer time to task failure.

• Beetroot juice was found to lower the oxygen cost of running, by decreasing pulmonary VO₂

What types of athletes benefit the most from nitrate supplementation?

Recreational athletes may benefit more than highly trained athletes, since highly trained athletes already have a high NO baseline in the body.

What are the best practices for supplementing nitrates?

• Acute ingestion, 15 min to 2 hours before performance

• Incorporate nitrates into daily food intake

• Chronic ingestion, consuming 0.5L beet juice x 6 days before competition

What are the side effects of nitrates?

• High blood lactate levels

• Large doses can cause mild gastrointestinal discomfort

• Temporary pink urine/stool

• Potential hypotension in those taking blood pressure medication