Wk 5 Supplements II Flashcards
Beta alanine =
precursor of the dipeptide carnosine
Beta alanine: sources
muscle foods (meat, fish, poultry) that contain carnosine or similar beta alanine containing di-peptides.
Beta alanine: mechanism
muscular acidosis → reduced force production and increased fatigue → decreased high intensity exercise performance.
Carnosine is responsible for 15% of total buffer capacity.
Beta alanine is synthesized from _ and _ by _ _
from histidine and B-alanine by carnosine synthase
Beta alanine: demographics
Strongly correlates with type II muscle fiber content. Lower in women, declines with age and lower in veg/vegans. Differences between sports eg sprinters vs marathon runners.
Beta alanine: Supplementation
small to moderate performance improvement, 2-3% increases in performance in recreational athletes, 0.5-1% in elite athletes.
Carnosine =
a dipeptide that acts as an intra cellular buffer for H+
Beta alanine: events + examples
30s-1 min
ex: 200m swim, 4k rowing, 3000m steeplechase
Beta alanine: dose
6.4g per day for 4 weeks (split dose), 3.2g/d for remaining 4 weeks.
Beta alanine: side effects
temporary paresthesia
Caffeine: mechanism
crosses the blood brain barrier - directly affects the CNS. adenosine receptor antagonist - binds to adenosine receptors, speeding up neural activity. Also affects other major neurotransmitters like serotonin for example.
remains in system for 5 hours
Caffeine: side effects
positive - improves accuracy, neuromuscular function, cognition, reduces pain perception, short term supramaximal and repeated sprint tasks 3% gains, increases mean and peak power output in anaerobic/1-2 min activities, 1-8% for total work output and repeat sprint performances during intermittent team game activity. Negative - shakiness, anxiety, nausea, poor accuracy, insomnia.
Caffeine: supplementation
1-8% improvement in performance
Caffeine: events + examples
1 min - hours
achery to tour de france
Caffeine: dose
Dose: 3-6mg/kg 45 mins before event, daily limit 400 mgs.
Creatine: where to find it?
Synthesized in the liver and kidney from arginine, glycine and methionine; transported to muscle (2-3g per day).
Creatine: sources
Diet: meat, fish and poultry (1 g/d in typical omnivorous diet). Intake as a supplement (creatine monohydrate or ethyl ester).
Muscle contains _% of body creatine. _ - _% of body pool/d metabolized to creatinine; excreted in urine and resynthesized each day
95%.
1-5% of body pool/d metabolized to creatinine; excreted in urine and resynthesized each day
Creatine production: duration + examples
<10-15 sec, ex track or swim sprints
Creatine: responders vs non responders
responders are likely those with a lower initial level of total muscle creatine content ie vegetarians, or a greater population of type II fibers.
Creatine: supplementation + example events
20-30% increase in skeletal muscle creatine stores. Events: strength power, intermittent high intensity, sprint. Examples: weight lifting, basketball, 400m sprint
Creatine: dose
rapid loading; 5g, 4xdaily for 5 days. Slow loading; 3-5g/d for 28 days. Maintenance; 3-5g/day.
Creatine: side effects
no effects on liver and kidneys, mild GI upset, 1-2kgs incr in weight due to water retention very common.
Sodium bicarbonate: mechanism
Increasing muscle acidity with max exercise results in lacti acid formation, decreasing muscle pH, interfering with muscle contraction. Most important buffers in the blood are hemoglobin, proteins and alkalinizers like sodium bicarbonate (extracellular buffer).
