Nitrate (NOT IN EXAM)

Question 1

What does the ingestion of NO3- lead to?

Answer 1

Enhanced bioavailability of NO - via the NO-nitrite NO pathway, reaction catalysed by bacteria in the mouth and the digestive system

NO plays an important role in the modulation of skeletal muscle function.

Question 2

What foods contain nitrate?

Answer 2

leafy greens and root vegetables

Question 3

What is the average dietary intake of nitrates?

Answer 3

The average dietary intake of adults in western countries is 1-2 mmol/d (~60-120 mg/d) with vegetables providing about 80% of the total

Question 4

What are the effects of increased NO bioavailability?

Answer 4

↑ blood flow to muscle
↑ function of type II fibers
↑ efficiency of mitochondrial respiration
↑ muscle contractile function
immune health

Question 5

What are the 3 main mechanisms of action?

Answer 5

• Skeletal muscle O2 delivery
• O2 cost of mitochondrial ATP resynthesis
• ATP cost of cross-bridge formation

= improved exercise performance

Question 6

What are the effects on exercise economy (O2 cost of exercise)?

Answer 6

• reduced ATP cost of muscle force production
• More efficient mitochondrial oxidative phosphorylation

Question 7

How do you acutely supplement dietary nitrate?

Answer 7

Acute dose (2-3 h pre-exercise)

(5-9 mmol) 310-560 mg nitrate

5x amount you would usually get in a daily diet

Question 8

How do you chronically supplement dietary nitrate?

Answer 8

Chronic supplementation* (3-15 days pre-event)

310-560 mg nitrate per day + 310-560 mg nitrate pre-event

Question 9

When would you consider using nitrate supplementation?

Answer 9

• Prolonged submaximal exercise
  such as endurance events lasting
  4-30 min.
• Training for aerobic fitness.
• High-intensity intermittent events
  with short duration and sprint
  efforts in individual and team
  sports.
• During exposure to hypoxic
  conditions (e.g., altitude training)?

Question 10

Does it always work?

Answer 10

It tends to - but performance benefits are small

Question 11

What in terms of individual variability?

Answer 11

• few studies on females
• Athlete’s training status may also affect the supplement efficacy, with highly-trained endurance athletes (>65 ml/kg/min VO2max) not benefitting
  significantly.
• few studies on age

Question 12

What are potential concerns & safety?

Answer 12

• concentrated beetroot juice can cause mild gut discomfort.
• may cause pink urine and poo
• mistaken use of nitrite or nitrite salt as supplements can be toxic
• chronic use has not been studied

Question 13

What are the effects of nitrates on exercise economy (O2 cost of exercise)?

Answer 13

• Reduced ATP cost of muscle force production
• More efficient mitochondrial oxidative phosphorylation

supplementation of NO3- = lower O2 cost of exercise