Creatine and Beta-alanine Flashcards
Describe creatine:
- Creatine is a natural guanidine compound and is a normal component of the diet, occurring in relatively high amounts (3–7 g kg–1) in skeletal muscle, so that meat and fish are the major dietary sources.
- Some of the body’s creatine content is hydrolysed to creatinine at a fairly constant rate and about 2 g is lost in the urine each day. Either replaced by dietary sources or synthesised from amino acid precursors.
- phosphoryl creatine–creatine system also has an important role in acid–base balance during high-intensity exercise, as absorption of a proton during the creatine kinase reaction promotes activation of key enzymes in glycogenolysis and buffers the H+ produced in glycolysis. This delays intracellular acidosis.
~95% located in skeletal muscle
~1-2% (1-3 g) is degraded to creatinine and excreted(in urine) daily. Also can help cognition and help against brain injury
~50% obtained in diet
Remainder is synthesised from AA: arginine, glycine and methionine
How does creatine work?
Aerobic respiration, not required to maintain ATP availability
- Creatine converted back into PCr through glycolysis
- A classical creatine loading regimen consists of an initial loading phase of 15–20 g per day for 4–7 days followed by a maintenance dose of 2–5 g per day
Describe creatine loading:
Changes in total muscle creatine content
* Relationship between how much creatine you start with and end with
* Starting point is different in different people(natural variation). But finishing level is relatively similar
maintenance dose of 2g/d
- Lead to no change over the 4 week period
- Lower dose loading regime = starting at same level and ending at same level
- 14 days of low dose creatine is equivalent to 7 days of high loading
- Depends on the athlete you are working with to which method is used
What effect does co-ingestion of CHO have on creatine content?
Approx. 1500 kcal per day to exert this effect
- Insulin availability is what is seen to drive creatines effect
- Timing creatine dose around meals allows for same insulin drive of creatine to exert effects
Is there a ceiling effect on creatine supplementation?
is creatine supplementation the same for all athletes?
155 is the maximum ceiling effect through supplementation
- Some athletes may benefit more from creatine supplementation than others
- Also evidence that creatine supplementation can facilitate recovery of muscle volume and functional capacity following muscle atrophy induced by leg immobilization
- creatine supplementation may be a worthwhile option to enhance post-injury rehabilitation and thereby speed return to training and competition.
What are the effects of creatine on glycogen?
- When creatine is fed, it goes into the muscle for storage
- Co-supplementation reaches the same level of creatine supplementation alone within a much shorter time period
- Rapidly loading glycogen into the muscle by supplementing creatine
- Also aids endurance activities as well
- probable gain in body weight due to such a creatine plus carbohydrate loading regimen may be detrimental to performance in many endurance competitions.
Is there a difference in maximal exercise with creatine supplementation?
No significant difference in max workout
- But did complete more work in 1st and 2nd exercise in the same time period
The relationships are very close
- Greater increases in muscle creatine causes greater increases in total work
- Those that have substantial increases can complete more work
- Enhances performance in a 30 second sprint
What is the difference seen from low dose creatine supplementation on performance?
Low dose creatine (~2.3 g·d-1) for 6 weeks enhances resistance to fatigue (five sets of 30 concentric knee extensions at 180o·s-1)
Looks at slower increase in muscle creatine content and concentric knee extensions
- Placebo had no change
Creatine was more resistant to fatigue, performing more closely to their ‘fresh’ performance
Describe β- alanine:
Buffering is related to this reaction
Lots of glycolysis causes a rapid decline of intramuscular pH
- Dynamic buffering moves H+ into blood
How does creatine work with buffering?
- The creatine kinase (CK) reaction results in the breakdown of PCr and the regeneration of ATP
- Also as part of this process H+ is consumed:
H+ + PCr + ADP –(CK) –> Cr + ATP
- So PCr breakdown during high-intensity exercise could contribute to intracellular buffering (Hultman and Sahlin, 1980)
- As such, increasing muscle creatine stores by supplementation might have a small effect on muscle buffering capacity as well as on ATP regeneration
Explain carnosine synthesis:
β-alanine makes carnosine(reponsible for most intramuscular buffering)
- Carnosine’s composition from both β-alanine and histidine causes a buffering action
- β-alanine is a limiting factor of carnosine as there is 25x more of histidine than β-alanine
- If we can increase the amount of β-alanine in the blood then carnosine will be more effective
What are some factors seen in β -alanine supplementation?
Absorption is better from small doses
- Side-effects are tingling of hands and feet(extremities)
- Needed in small doses
- Isn’t easy for an athlete to achieve taking 8 doses a day for 4-8 weeks
Carnosine and β-alanine given in the same amounts causes the same effect.
Shows that β-alanine is a rate limiting factor to carnosine
- Big variability in where people start and finish
- Isn’t a ceiling effect so much for β-alanine
At high exercise intensities are there any differences seen from β-alanine supplementation?
Supramaximal test
- β-alanine group has a linear response
Carnosine has a linear relationship with amount of work done
What type of exercise sees the greatest improvement in performance?
- No significant effect on performance 0.5 mins
- Small, but sig improvement in performance duration 0.5-10 min
- Here is where glycolysis would be used most for performance, so supports the idea
- Tendency for a very small improvement in performance >10 min
