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What is it?

  • The current interest in ß-alanine was initiated by research from Professor Roger Harris (who also lead the original studies into creatine supplementation) and colleagues who found that chronic supplementation with ß-alanine leads to an increase in muscle carnosine content1 and subsequently improves high-intensity cycling capacity.2
  • Carnosine is a L-histidine-containing dipeptide found in several human tissues but displays its highest concentration in skeletal muscle and is formed from the amino acids ß-alanine and L-histidine. Carnosine can be found in red meat, white meat and fish but is rapidly broken down to ß-alanine and L-histidine following ingestion. Thus, carnosine supplementation does not augment muscle carnosine content.
  • Carnosine plays several key physiological roles including:
    1. Proton buffering
    2. Regulating calcium
    3. Preventing antiglycation
    4. Acting as an antioxidant
  • Carnosine is an extremely stable muscle metabolite but it does have a large between individual variability which may be moderated by:
    1. Muscle fibre type composition (carnosine is ~two-fold higher in type II muscle fibres)
    2. Sex (carnosine is lower in women compared to men)
    3. Specific Muscle Group (carnosine concentration varies across different muscles; for example, carnosine is lower in the soleus compared to gastrocnemius)
    4. Age (carnosine increases following puberty in males and tends to increase in females and then gradually decreases with age)
    5. Athlete type (highest in sprint/explosive athletes compared to endurance athletes)
    6. Diet (ß-alanine increases muscle carnosine and one cross-sectional study3 has shown lower levels of carnosine in vegans but a 6-month vegetarian diet in omnivorous women did not decrease muscle carnosine content4)
  • Numerous studies have demonstrated substantial increases in muscle carnosine in responses to a variety of ß-alanine supplementation protocols (~3.2- 6.4g·day−1, for periods ranging from 4 to 24 weeks) and supplementation protocols of this duration appear to be safe.5,6
  • Although L-histidine is an essential amino acid in humans, it is found in sufficient supply in the body, whereas ß-alanine is not. As such, ß-alanine is considered to be the rate limiting amino acid to carnosine synthesis (Harris et al., 2006). It should be noted that although L-histidine is not rate limiting, its availability is not unlimited and may decline upon chronic ß-alanine supplementation.7
  • The increase in muscle carnosine has been shown to improve high-intensity endurance performance in both trained and untrained individuals across a range of exercise capacity tests, fixed duration and intermittent exercise tasks that are typically within a range 30s-10min in duration.8 There are specific examples of when exercise performance may be augmented outside of this duration, whereby more prolonged exercise tasks could be enhanced by an improvement in sprint performance following prolonged exercise.9 Furthermore, one study has also shown that ß-alanine supplementation can increase training intensity during a 5-week mesocycle of sprint-interval training in well-trained cyclists.10
  • Increasing muscle carnosine content with chronic ß-alanine supplementation may offer an alternative to acute sodium bicarbonate loading for high-intensity exercise given that the latter may be associated with gastrointestinal upset in some athletes. Theoretically, ß-alanine loading may also offer an additive effect to bicarbonate supplementation given that muscle carnosine is an intracellular buffer, while bicarbonate facilitates extracellular buffering. The weight of evidence suggests that co-supplementation may result in a small effect size improvement compared to ß-alanine supplementation alone.8
  • Despite ß-alanine being a common ingredient in “pre-exercise” supplement formulas (i.e., acute supplementation) used by athletes there is no evidence that acute supplementation is advantageous to performance.11

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