Caffeine and Nitrates as Ergogenic Aids

Caffeine

• Food ingredient, dietary supplement, or drug.
• Probably the most studied supplement/ergogenic aid.
• Theorized to enhance both health and exercise performance.
• Findings are often contradictory due to variations in:
  • Dose
  • Delivery method
  • Individual variability

Caffeine Content in Selected Products

• 85% of U.S. adults consume caffeine daily.
• A normal therapeutic dose ranges from $100$ to $300$ milligrams.
• Examples of caffeine content in products:
  • Coffee, brewed (8 oz): $80$ to $135$ mg
  • Coffee, instant (8 oz): $65$ to $100$ mg
  • Coffee, decaffeinated (8 oz): $3$ to $4$ mg
  • Coffee, Starbucks (16 oz): $330$ mg
  • Tea, black or green (8 oz): $30$ to $50$ mg
  • Hot cocoa (8 oz): $15$ mg
  • Sodas, cola (12 oz): $35$ to $45$ mg
  • Energy drinks (8 oz): $80$ to $120$ mg
  • Vivarin (1 tablet): $200$ mg

Mechanisms of Action

1. Adenosine Receptor Antagonism
   • Blocks adenosine receptors in the brain.
   • Reduces perceived effort.
   • Improves cognitive function.
2. Mobilization of Intracellular Calcium
   • Enhances muscle function (contraction) by increasing $Ca^{2+}$ release from the sarcoplasmic reticulum.
3. Catecholamine Augmentation and Glycogen Sparing
   • Increases heart rate, blood pressure (BP), and energy availability.
   • Increases serum FFA and use of muscle triglycerides by stimulating lipolysis and FFA mobilization, thus sparing glycogen.
4. Role in mTORc1 pathway
   • Caffeine inhibits mTOR activity.

Free Fatty Acid Utilization

• Caffeine increases free fatty acid (FFA) utilization during exercise.
• Graph shows:
  • Respiratory exchange ratio (R) (VCO₂/VO₂) decreasing with caffeine.
  • Increased FFA and glycerol levels with caffeine.

Effect on Psychomotor Responses and Mental Alertness

• Caffeine may increase or enhance:
  • Alertness
  • Attention
  • Reaction time
  • Mood
  • Vigilance
  • Cognitive function
• Doses of $200$ milligrams have been effective, particularly when subjects are mentally fatigued.
• International Society of Sports Nutrition (ISSN) Position Statement: Caffeine can enhance vigilance during bouts of extended exhaustive exercise, as well as periods of sustained sleep deprivation.
• Large doses (>400 mg) may have adverse effects.
• May increase nervousness and anxiety in some, impairing performance in sports requiring fine motor skills and rapid processing of visual stimuli.

Effect on Ratings of Perceived Exertion (RPE)

• Doherty and Smith:
  • 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.
• RPE Scales:
  • Category Ratio Scale (A):
    • 0: Sitting, relaxing
    • 1: Very, very light
    • 2: Easy
    • 3: Very light
    • 4: Somewhat easy
    • 5: Light
    • 6: Somewhat hard
    • 7: Hard
    • 8: Very hard
    • 9: Extremely hard
    • 10: Maximal effort
  • Borg Scale (B):
    • 6:
    • 7: Extremely easy
    • 8:
    • 9: Very light
    • 10:
    • 11: Light
    • 12:
    • 13: Somewhat hard
    • 14:
    • 15: Hard
    • 16:
    • 17: Very hard
    • 18:
    • 19: Very, very hard
    • 20: Maximal effort

Effects on Performance Tasks

• Endurance
  • Most research available.
  • Positive effects on mean power output and endurance time trial across 44$studies ($3-6mg/kg).
• High-Intensity Anaerobic
  • Unclear due to flawed study designs and untrained subjects.
  • Ergogenic effect among those that do not consume caffeine regularly.
  • ISSN indicates effects on sport-specific prolonged duration activities such as basketball, soccer, rugby, etc.
• Muscular Strength
  • 6$out of$11 studies show significant benefits in resistance training.

Individual Variability

• Genetics play a significant role in how individuals respond to caffeine.
• Responders and non-responders due in great part to genetics.
  • AA = Fast Metabolizers
  • AC = Slow Metabolizers
  • CC = Slow Metabolizers

Best Practice

• Timing
  • Take 60 minutes prior to the event.
  • May see benefits with 15 minutes prior to event usage
• Dosage
  • 3 – 6 mg/kg body weight.
• NCAA urinary concentration < 15 µg/ml.
• WADA removed caffeine from the banned list in 2004.

Summary

• Most professional health organizations regard caffeine as a safe drug.
• A moderate caffeine dosage is equivalent to about 200$to$300 milligrams/day, or the amount in about two 6- to 8-ounce cups of coffee.
• Pregnant women may want to consider abstention, similar to recommendations for alcohol intake during pregnancy.
• Some individuals may be more prone to possible adverse effects of caffeine as a potent stimulant because of genetic variations.

Nitrates

• Goal: Increase nitric oxide (NO) levels.
• Timing is important due to short half-life.
• Sources: Plant foods vs. Processed Meats (hot dogs).

Two Major Pathways of NO Formation in Mammals

1. L-Arginine Pathway (NOS activity)
   • L-Arginine is converted to Nitric Oxide (NO) via nitric oxide synthases (NOS I, II, III).
2. Nitrate/Nitrite Reduction Pathway
   • Dietary Nitrate (NO3$) is reduced to Nitrite ($NO2) by bacterial nitrate reductases.
   • Nitrite (NO_2) is further reduced to Nitric Oxide (NO) by various enzymes (Mo-containing proteins, heme-containing proteins) under low oxygen conditions, with protons, ascorbic acid involved.

Nitrates (AKA Beet Root Juice)

• Potential Benefits:
  • Improve blood flow (vasodilation).
  • Reduces blood pressure.
  • Healthier skin.
  • Increase muscle strength and power.
  • Increase time to exhaustion.

Sources

• Juice
• Pill
• Vegetables:
  • Beets
  • Spinach
  • Broccoli, Brussel Sprouts

Mechanisms

• Nitric oxide (NO) causes vascular vasodilation, increased blood flow, and decreased blood pressure.
• Supplementation with nitrate (NO3^−$) sources can also produce nitrite ($NO2^−) and subsequently NO.

Beetroot Juice and Performance - Does it Work?

• Larson et al. study examining time to task failure during cycling.
  • Compared Placebo (PL) vs. Beetroot Juice (BR) at varying doses (70ml, 140ml, 280ml).
  • Results indicated improved time to task failure with beetroot juice supplementation.

Beetroot Juice and Oxygen Cost of Exercise

• Beetroot Juice Supplementation and the Oxygen Cost of Exercise
• Beetroot juice lowers the oxygen cost of running! (Lansley 2011)

Type of Athletes Who Benefit Most

• Highly trained athletes vs. Recreational athletes.

Supplementation Best Practice

• Acute Ingestion
  • 15$minutes to$2 hours prior to performance.
  • 400 mg nitrate.
  • 5-29 mmol/day show ergogenic effects.
  • DASH diet contains 20 mmol/day.
  • Can get ergogenic effects from daily food intake!
• Chronic Ingestion
  • 0.5$L beet juice x$6$$ days prior to competition.

Side Effects

• High blood lactate levels.
• Large doses may cause mild gastrointestinal discomfort.
• Temporary pink urine/stool.
• Potential hypotension in those taking blood pressure medication.