Creatine And Nitrates Flashcards
What is creatine? (Endogenously Synthesised from…, where is it stored? diet)
- Endogenously synthesised from AA (arginine, glycine and methionine) in the liver, pancreas and kidneys
- > 95% is stored in the skeletal muscle
- Approx.. 50% obtained from the diet
How is creatine stored? (Ratio of PCr and creatine, total creatine pool, upper limit, vegetarians)
- Two thirds = phosphocreatine (PCr) one third = free creatine
- total creatine pool (PCr + Cr) in the muscle averages about 120 mmol/kg dry muscle mass
- The upper limit of creatine storage is 160 mmol/kg dry muscle mass
- Vegetarians have lower intramuscular creatine stores (90-110mmol/kg dm)
What is creatine turnover? (Synthesis, excretion)
- Synthesis approx 2g/day, 1g endogenous, 1g exogenous (diet)
- Excretion approx 2g/day, creatinine (urine)
How to increase muscle creatine levels?
- 20grams per day for 6 days showed total creatine content increased in all subjects
What are the effects of creatine and muscle hypertrophy?
- Upper body muscle hypertrophy favours the creatine group over the control
- Lower body muscle hypertrophy favours the creatine group over the control
Talk about creatine metabolism during exercise (type II versus type I, maximal exercise, depletion, 80% resynthesised)
- PCr levels higher in type II fibres than type I fibres
- PCr levels decrease during maximal exercise
- PCr can be depleted in approx 10 seconds
- 80% resynthesised in approx 4 minutes
Mechanisms of action? (What are the effects of creatine)
(Cr stores, glycogen, muscle damage)
^ Cr stores 30% = ^ PCr resynthesis
^ Muscle glycogen
Decreased muscle damage
What is creatine monohydrate (CM)?
- White powder, 99% absorbed
- Better uptake mixed with a carbohydrate containing liquid or food
Creatine loading protocols? (High-dose, low-dose, maintenance dose and washout period) ?
Short, high-dose protocol:
- 20g/day for 6 days
- 0.3g/kg BM for 6 days
Long, low dose protocol:
- 3-5g/day for 20-30 days
Maintenance dose:
2-5g/day
Washout period = 4-6 weeks
When to consider creatine use?
- Single (+1-5%) and repeated bouts (+5-15%) of high-intensity exercise
- High-intensity max efforts <150 sec, largest effects on <30 sec tasks
- Power and strength sports, intermittent sports, resistance/interval training
Other creatine uses?
- Endurance exercise- may improve sprint finish
- Concussion
How does individual variability and sport type affect creatine effectiveness?
- Baseline levels of muscle creatine, high muscle creatine levels means they will experience little effects
- Sport type, for example ultra-endurance or exclusively skill-based sports
Concerns of creatine consumption? (Body mass, myths)
- Increase in body mass (1-2kg) as a result of water retention
- Myths, no evidence that it causes kidney damage, muscle cramps, strains
Safety issues of creatine consumption?
- No evidence of adverse effects with long term (4 years) use
- Mild, temporary gut upset can occur but can be attenuated with split dose, and avoidance of high fibre foods with ingestion
- Contamination
What is nitrate? (NO*3, bioavailability, foods, intake)
- Dietary nitrate (NO*3 -)
- The ingestion of Nitrate leads to enhanced nitric oxide (NO) bioavailability
- High nitrate-containing foods include leafy greens and root vegetables
- Average intake is 1-2mmol/d (approx 60-120 mg/d)
What is nitric oxide (NO)?
(Ingestion of dietary NO*3, skeletal muscle function)
- Ingestion of dietary NO*3- -> enhanced nitric oxide bioavailability
- Nitrogen oxide plays an important role in the modulation of skeletal muscle function
What are the effects of Nitric oxide bioavailability? (Blood flow, type II, respiration, contractile function)
^ Blood flow to muscle
^ Function of type II fibers
^ efficiency of mitochondrial respiration
^ Muscle contractile function
What is the effects of nitrates on exercise economy? (ATP cost, phosphorylation)
- Reduced ATP cost of muscle force production
- More efficient mitochondrial oxidative phosphorylation
Supplement regime for nitrates? (Acute dose, chronic supplementation)
- Acute dose (2-3h pre-exercise), (5-9mmol) 310-560 mg nitrate
- Chronic supplementation (3-15 days pre-event), 310-560mg nitrate per day + 310-560mg nitrate pre event
What should you avoid taking with beetroot juice?
Mouthwash or chewing gum as they interfere with its benefit
Different types of food sources approximate to 1 x Beet IT Sports Shot (400 mg nitrate)?
- Beetroot (200g)
- Celery (250g)
When to consider the use of nitrates?
- Endurance events lasting 4-30mins
- Training for aerobic fitness
- High-intensity intermittent events
- Exposure to hypoxic conditions (e.g., altitude training)
Individual variability of nitrates?
- Few studies have investigated the impact on female athletes
- Athlete’s training status may also affect the efficacy. Highly trained endurance athletes (>65ml/kg/min VO2 max) not benefiting significantly
Concerns and safety of nitrate consumption? (Beetroot, pink, nitrite, long-term, contamination)
- Beetroot juice can cause mild gut discomfort
- Temporary pink colour to urine
- Mistaken use of nitrite or nitrite salt as supplements can be toxic
- Long-term effects are unknown
- Contamination
